JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 1
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 1
The Just-in-Time Production System
HIROYUKI HIRANO
Originally published as Jyasuto in taimu seisan kakumei shido manyuaru copyright © 1989 by JIT Management Laboratory Company, Ltd., Tokyo, Japan.
English translation copyright © 1990, 2009 Productivity Press.
CRC Press
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Contents
Publisher’s Message........................................................................ ix
Foreword to the Original English Edition....................................... xi
Introduction to the Original English Edition................................ xiii
Volume 1
1
Production Management and JIT Production Management....... 1
Approach to Production Management................................................... 3
Overview of the JIT Production System................................................ 7
Introduction of the JIT Production System...........................................12
2
Destroying Factory Myths: A Revolutionary Approach............ 35
Relations among Sales Price, Cost, and Profit......................................35
Ten Arguments against the JIT Production Revolution.........................40
Approach to Production as a Whole....................................................44
Index.............................................................................................. I-1
About the Author.......................................................................... I-31
Volume 2
3
“Wastology”: The Total Elimination of Waste..........................145
Why Does Waste Occur?....................................................................146
Types of Waste.................................................................................. 151
How to Discover Waste..................................................................... 179
How to Remove Waste......................................................................198
Secrets for Not Creating Waste...........................................................226
4
The “5S” Approach..................................................................237
What Are the 5S’s?.............................................................................237
Red Tags and Signboards: Proper Arrangement and
Orderliness Made Visible...................................................................265
v
vi
◾
Contents
The Red Tag Strategy for Visual Control............................................268
The Signboard Strategy: Visual Orderliness.......................................293
Orderliness Applied to Jigs and Tools................................................307
Volume 3
5
Flow Production......................................................................321
Why Inventory Is Bad........................................................................321
What Is Flow Production?..................................................................328
Flow Production within and between Factories.................................332
6
Multi-Process Operations....................................................... 387
Multi-Process Operations: A Wellspring for Humanity on the Job......387
The Difference between Horizontal Multi-Unit Operations and
Vertical Multi-Process Operations......................................................388
Questions and Key Points about Multi-Process Operations................393
Precautions and Procedures for Developing Multi-Process
Operations.........................................................................................404
7
Labor Cost Reduction..............................................................415
What Is Labor Cost Reduction?.......................................................... 415
Labor Cost Reduction Steps............................................................... 419
Points for Achieving Labor Cost Reduction........................................422
Visible Labor Cost Reduction.............................................................432
8
Kanban.................................................................................. 435
Differences between the Kanban System and Conventional Systems....435
Functions and Rules of Kanban........................................................440
How to Determine the Variety and Quantity of Kanban...................442
Administration of Kanban.................................................................447
9
Visual Control......................................................................... 453
What Is Visual Control?......................................................................453
Case Study: Visual Orderliness (Seiton)..............................................459
Standing Signboards..........................................................................462
Andon: Illuminating Problems in the Factory....................................464
Production Management Boards: At-a-Glance Supervision................. 470
Relationship between Visual Control and Kaizen.............................. 471
Contents
◾ vii
Volume 4
10 Leveling...................................................................................475
What Is Level Production?................................................................. 475
Various Ways to Create Production Schedules...................................477
Differences between Shish-Kabob Production and Level Production.....482
Leveling Techniques..........................................................................485
Realizing Production Leveling............................................................492
11 Changeover............................................................................. 497
Why Is Changeover Improvement (Kaizen) Necessary?.....................497
What Is Changeover?.........................................................................498
Procedure for Changeover Improvement...........................................500
Seven Rules for Improving Changeover.............................................532
12 Quality Assurance.................................................................. 541
Quality Assurance: The Starting Point in Building Products..............541
Structures that Help Identify Defects.................................................546
Overall Plan for Achieving Zero Defects............................................561
The Poka-Yoke System.......................................................................566
Poka-Yoke Case Studies for Various Defects.......................................586
How to Use Poka-Yoke and Zero Defects Checklists.......................... 616
Volume 5
13 Standard Operations.............................................................. 623
Overview of Standard Operations.....................................................623
How to Establish Standard Operations..............................................628
How to Make Combination Charts and Standard Operations Charts.....630
Standard Operations and Operation Improvements...........................638
How to Preserve Standard Operations...............................................650
14 Jidoka: Human Automation.................................................... 655
Steps toward Jidoka...........................................................................655
The Difference between Automation and Jidoka...............................657
The Three Functions of Jidoka..........................................................658
Separating Workers: Separating Human Work from Machine Work.....660
Ways to Prevent Defects.................................................................... 672
Extension of Jidoka to the Assembly Line.......................................... 676
viii
◾
Contents
15 Maintenance and Safety......................................................... 683
Existing Maintenance Conditions on the Factory Floor......................683
What Is Maintenance?........................................................................684
CCO: Three Lessons in Maintenance.................................................689
Preventing Breakdowns.....................................................................683
Why Do Injuries Occur?....................................................................685
What Is Safety?.................................................................................. 688
Strategies for Zero Injuries and Zero Accidents..................................689
Volume 6
16 JIT Forms................................................................................711
Overall Management......................................................................... 715
Waste-Related Forms.........................................................................730
5S-Related Forms............................................................................... 747
Engineering-Related Forms................................................................777
JIT Introduction-Related Forms..........................................................834
Publisher’s Message
Hiroyuki Hirano’s JIT Implementation Manual was first published in Japan
in 1989, and Productivity Press published the English translation the following year. In his Foreword to the original English edition, Norman Bodek
refers to the book as a “masterpiece,” and it has certainly stood the test of
time and proven itself during the past twenty years.
This was the first work of its kind to provide, in such great detail, a structured approach to the implementation of what was commonly referred to as
“just-in-time” manufacturing, and to cover so many of the concepts that are
core to what we now call “lean manufacturing”—identification and elimination of waste, visual management, the 5S’s, flow production, kanban, cellular
manufacturing, leveling, quick changeover, poka-yoke, standard work, jidoka,
and so much more.
Mr. Hirano refers to 1989 and 1990 as pivotal years in the transformation of
Japan’s industrial structure, and what better time than the economic transition
we are experiencing in 2009 to re-release this classic work.
The first edition, now out of print, comprised two binders in a slipcase.
In this new edition, prompted by many requests from long-time users of
the original volumes, we provide the same information in a more accessible
­format. These six paperback volumes contain all the original, unedited m
­ aterial
from the original edition, divided into logical sections that follow the steps
Mr. Hirano details for establishing a JIT production system (see Figure 1.6 in
Volume 1, Chapter 1):
Volume 1 Step 1 – Awareness Revolution
Volume 2 Step 2 – The 5S’s for factory improvement
Volume 3 Step 3 – Flow manufacturing
Volume 4 Step 4 - Leveling
Volume 5 Step 5 - Standardized operations
Volume 6 The JIT forms
ix
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◾ Publisher’s Message
In addition, we have included a CD containing PDFs of all the forms in
Volume 6 so readers can easily print the individual forms in multiples, or use
them as models for creating custom forms. Of course, the point of the forms
is to promote engagement of all team members and focus on improvement
activities – not to complete them in isolation and house them in a cabinet
or on a hard drive! We have also added a detailed index for the entire set
of six volumes. For your convenience, the complete index is included in
each volume.
We hope that students, those interested in the roots of lean, and those
many practitioners who have requested that this information be brought
back into print will benefit from this new release.
Maura May
Publisher
Foreword to the Original
English Edition
A year ago Productivity Press published what we considered to be the best
introduction for all employees to Just-In-Time (JIT)—a picture book entitled
JIT Factory Revolution: A Pictorial Guide to Factory Design of the Future by
Hiroyuki Hirano, a top international consultant. I am now proud to offer you
its counterpart—the most comprehensive and detailed manual in the world
today for setting up a complete JIT program. JIT Implementation Manual: The
Complete Guide to Just-In-Time Manufacturing is also written by Mr. Hirano,
who is really making his genius accessible for the first time. At last we have
a place to go to get answers to virtually every JIT problem.
One evening in January 1990, I had dinner with Mr. Hirano and his wife
at a very lovely French restaurant in Tokyo. I told him how pleased I was
with his work and then asked him to explain exactly what he does in his
consulting practice. He started off by showing how he uses one of his forms.
He gathers his client’s conversion team and reviews the homework left from
his last visit. Each member explains the improvements made within the
plant. Afterwards, carrying a pad of these forms, each person follows him
around the plant, where up to 100 problems are identified, indicated by type
(for instance, the 5S’s, one-piece flow, visual management, multi-process
workers, jidoka, leveling, work standardization), and recorded on the forms.
The forms are then posted on bulletin boards and become homework for
his next visit. This is the simple, but very powerful, Hirano method of focusing on improvement activities. And his manual is filled with similar practical
examples from his own highly successful consulting practice.
In an extremely well-written and articulate presentation, this manual provides
a clear structure that enables readers to easily ferret out vital information. The
material is addressed in three sections: JIT concepts, JIT techniques, and actual
tools for putting JIT into practice. Based on his vast experience in factories
xi
xii
◾
Foreword to the Original English Edition
throughout Asia and the West, Mr. Hirano explains in detail over 200 illustrations, charts, checklists, diagrams, and sample JIT management forms that he
uses to implement “JIT Awareness Revolutions” wherever he goes. This m
­ assive
handbook contains answers to virtually every problem a JIT professional will
face, as well as multiple options for every stage of JIT implementation.
If I sound effusive, please understand that I have been searching for such
a resource to offer Productivity Press readers for years. In fact, throughout
the 1980s, Productivity’s industrial study missions to Japan revolved around
my personal quest to find the best source materials for implementing JIT.
And while we have come across numerous consultants and engineers and
translated many superb books and materials, I have waited a long time for a
handbook of the caliber of Hiroyuki Hirano’s JIT Implementation Manual.
This is Productivity Press’s most ambitious publishing project to date.
Known as the “JIT Bible” in Japan, Mr. Hirano’s JIT Implementation Manual
is encyclopedic in scope and provides unparalleled information on every
aspect of JIT, from its philosophical underpinnings to the myriad systems,
techniques, and tools for virtually every factory setting.
To produce this massive project as quickly as possible, many fine people—
both Productivity staff and freelance professionals—were employed. In particular, I wish to acknowledge the efforts of: Bruce Talbot for his splendid
translation and writing; Cheryl Berling Rosen for her editorial and content
supervision; David Lennon and Esme McTighe for their production management; Sally Schwager for her bilingual handling of the numerous queries
between Mr. Hirano and the Productivity staff; Tim Sandler for his copyediting­;
and Micki Amick of Amick Communications for the manual’s design, page
makeup, art production, and project management.
Our mission at Productivity is to publish and distribute the best materials
on productivity, quality improvement, and employee involvement for business and industry, academia, and the general public. Many of our products,
like the Hirano manual, are direct source materials from Japan that we have
translated into English for the first time. It is with great anticipation that
I present this work to our readers. I thank Mr. Hiroyuki Hirano for granting
us the opportunity to produce this masterpiece in English.
Norman Bodek
Publisher
Introduction to the
Original English Edition
In the future, I think we shall look back upon 1989 and 1990 as pivotal years
in the transformation of Japan’s industrial structure.
During these years, abiding yen appreciation and trade friction will continue to devalue the advantages of Japanese domestic production. As a result,
we will see more and more Japanese automakers, electronics firms, and other
manufacturers shifting their production overseas.
Japan’s large “parent” companies are heading overseas in droves, leaving
behind their “child” subcontractors. It would be nice if the parent companies
could take their children with them, but the children generally lack the money,
staff, technology, and marketing power to make the move. So the children are
left behind to fend for themselves. They are entering a bitter battle for survival,
in which many must enter into new industrial fields to pull through.
The high yen and the search for lower costs has also boosted the flow
of Japan’s imports from the Asian NIES (Newly Industrialized Economic
Societies) and the ASEAN countries. These parts and products are generally characterized by large volumes, unhurried schedules for production and
­delivery, and relatively lenient quality standards. By the same token, the goods
that are still produced in Japan tend to have the opposite characteristics—
small volumes, tight production and delivery schedules, top-notch quality,
and marketable prices.
Japan’s ongoing trend toward market diversification has further fueled the
demands for wide-variety, small-lot production with speedy delivery. Let it
be understood at the outset that JIT production is neither one automaker’s
production system nor is it the subcontractor’s curse. Instead, JIT consists of
ideas and techniques for the complete elimination of waste.
xiii
xiv
◾
Introduction to the Original English Edition
In a sense, JIT production is a new field of industrial engineering (IE),
one that thoroughly eliminates the waste that runs rampant in most ­factories
while helping to build products that serve client needs. JIT production is
also the kind of market-oriented or “market-in” production system that is
increasingly needed in today’s fast-changing global marketplace.
This book is a compendium of the experiences and knowledge I have
gained during many years of enthusiastic work in battling waste in factories
and promoting the development of JIT production. As such, this is a manual
for professional consultants. It enables them to tell the plain truth and to
overcome vexing problems.
This book is not for sale to the general public. I would not want it to be
sold that way. It is a book for manufacturing companies that are fighting
desperately for survival and that will go to any length to improve their factories and overcome the obstacles to success. One could even call this book
a “bible” for corporate survival.
Accordingly, this book is intended for only three types of readers: leading
strategists for corporate survival, including top management; in-house JIT
leaders; and professional JIT consultants.
Chapters 1 and 2 describe the JIT production approach and its under­lying
concepts. As you will see, the JIT approach casts off old concepts and introduces a revolutionary way of thinking.
Chapter 3 looks into the nature of waste and tells how we can scientifically identify waste and take comprehensive steps to remove it.
Chapter 4 takes up the 5S’s, which make up the foundation for making
improvements in factories. This chapter will pay special attention to redtagging and kanban techniques as devices for visual control and regulation
of the factory.
Chapters 5 to 15 present explanations, backed by many case studies, of
JIT techniques centered on flow manufacturing.
Finally, Chapter 16 includes a large selection of vouchers, lists, and other
JIT-related forms, many of which can be photocopied and used as is. These
forms can serve as effective tools in paving the way for JIT production.
This manual broadly falls into three parts. The first part presents JIT
­concepts, the middle part JIT techniques, and the last part tools for putting
JIT into practice.
Introduction to the Original English Edition
◾
xv
I will conclude by asking those of you who use this manual to avoid
taking a piecemeal approach, such as adopting only the kanban or andon
systems or aiming at only a limited range of improvements. The overall
flow is the most important aspect of production, and the key ingredient
for c­ reating a good overall flow is comprehensive improvement—in other
words, factory-based innovation. If readers understand this book and find
it useful as a “bible” for building better products, I will gain the satisfaction
of knowing that the five years of effort and expense invested in this project
since its planning stage were not just another form of waste.
Hiroyuki Hirano
February 1989
Chapter 1
Production
Management and
JIT Production
Management
In today’s world, manufacturing industries can no longer afford
to remain complacent in the belief that their chief concern is
to turn out products.
Things were quite different during the early postwar years,
which marked the birth of Japan’s modern industry. Basic
materials—even for such things as shoes and clothing—were
extremely scarce. Anyone who could scrape together enough
materials to make a product could sell it. The successful manufacturers were simply those who had access to materials.
How things have changed. Today, clothing and shoe stores
are everywhere, their shelves jam-packed with merchandise.
Long gone are the days when Japan’s manufacturers could sell
whatever they could make. Now there are literally thousands
of clothing and footwear manufacturers in Japan, and there
must be hundreds of thousands worldwide.
The simple, hard-nosed approach that says, “Manufacturing
is the business of making things,” has grown dangerously out
of date. To become a winner in today’s survival game, manufacturers must make big changes in their way of thinking.
For today, the key to successful factory management is the
realization that manufacturing is a service industry.
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◾ JIT Implementation Manual: Volume 1
Until quite recently, the common orientation among manufacturers was, “Make good products cheaply and quickly.”
This approach became known as the QCD (Quality, Cost,
and Delivery) approach. The QCD approach was a reliable
road to success for many years, but today it takes more than
these three elements to ensure a factory’s survival. Three
additional conditions are now evident:
1. Diversification
The growing diversity of customer needs is accelerating the
trend toward greater varieties of products on the market.
2. Smaller lots
The total market pie is not growing much larger, but
the variety of products are. So, naturally, these products
have to be made in smaller lots.
3. Shorter delivery schedules
As the product diversification trend continues, companies
will go broke if they stick to their old habit of keeping fullline inventories. But what are the alternatives? It is not easy
to predict which product types will sell best and in what
volumes. So companies instead try to replace warehoused
products as soon as they are sold, or they switch over to
special-order production with short delivery schedules.
When taken together, these three conditions call for “widevariety, small-lot production with speedy delivery.”
This means adding new elements to the old tripartite QCD
formula to accommodate product diversification. Today, we
need to add a “P” for product diversification and an “S” for
safety. The result is the PQCDS approach, a service-oriented
approach attuned to current needs (Figure 1.1).
To put it another way, PQCDS is a service that manufacturers
provide by making desired products (P) of high quality (Q) at
low cost (C) with speedy delivery (D) and assured safety (S)
from start to finish.
Production Management and JIT Production Management ◾
P
Q
C
D
S
Safety: Safe factory, safe products
Delivery: Short delivery schedules
Cost: Lower costs
Quality: Higher quality
Products: Product diversification
Figure 1.1
The PQCDS Approach.
Here we have an important transition from being a product
maker to becoming a service provider. Today, manufacturers
must think of themselves as service-industry companies.
Approach to Production Management
Many a factory manager has asked me: “We’re using a computer-based production management system now, but for
some reason we have not been able to reduce our warehouse
inventories or shorter lead-times. What should we do?” (See
Chapter 2 for an additional discussion of the JIT approach to
warehousing and lead-times.)
For some reason, even top managers at factories seem to
think of the computer as some kind of magic wand. They
somehow reckon that once a computer-based system is
installed, the factory will run like a finely crafted timepiece.
I always answer this question the same way: “First you
have to change the president’s mind!” That’s all there is to it.
Let us begin by looking at the issue of lead-time. Generally,
we define a product’s lead-time as the period that begins
when the sales department issues the production plan and
ends when the planned products is shipped.
Figure 1.2 takes a somewhat closer look at the various elements within the lead-time.
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◾ JIT Implementation Manual: Volume 1
PRODUCT LEAD-TIME
Sales
planning
Figure 1.2
Orders Parts
issued delivery
Assembly
lead-time
Processing
lead-time
Procurement
lead-time
Physical Lead-Time
Production/sales
meeting (planning)
Creation of final
production plan
Procurement plan
Paper Lead-Time
Production plan
proposal
4
Product
shipment
Product Lead-Time.
Obviously, a factory cannot go immediately from receiving
a sales plan to building products. The factory managers must
first size up the production capacity situation and then begin
working out a production plan proposal. Next, the production and sales departments need to meet, tailor the proposal
to their specific needs, and jointly approve it.
Once the proposal has been revised and approved, it
needs to be rewritten as the official production schedule,
which includes delivery schedules for the assembly components and other parts and materials required by the schedule.
The official production schedule also includes instructions
for goods procurement and subcontractor orders.
During all of these stages, the clock is ticking but no products
are being manufactured. All that has happened so far is planning, which is to say paper-shuffling and number-crunching.
Still, we are obliged to include these time-consuming planning
processes as part of the overall lead-time. So, before actually
making anything, there is lots of paperwork, which led me to
call this part of the overall lead-time the paper lead-time.
By contrast, three-dimensional materials really start moving
once the production orders are issued and the products are
shipped. First, the procurement people and the subcontractors
get moving when the order book is out. Soon, deliveries of
procured and subcontracted products start arriving. Then the
Production Management and JIT Production Management ◾
factory gets into gear, using equipment such as cutters, presses,
and lathes to process and assemble parts. Once the parts are
finished, they can be assembled into finished products.
Naturally, various kinds of information have been exchanged
throughout these stages, and the flow of production has been
firmly centered on the work in process. The key issues invariably are: how to process the materials, which manual operations to use, and how to move things around. That is why I call
this latter part of the overall lead-time the physical lead-time.
If we introduce computerization to shorten lead-times,
what distinct effects might such a move have on the paper
lead-time and the physical lead-time? Let’s first look at the
possible effects on the paper lead-time.
It is not difficult to imagine the kind of time and energy it
takes when people get together with their calculators to work
out the numbers for an efficient production schedule. To make
the production schedule work efficiently, these planners have
to calculate the correct amounts of various parts and materials,
as well as the proper timing for their delivery.
A computer can be very helpful in facilitating and speeding these paper lead-time tasks. But just how helpful can it
be in shortening the physical lead-time?
For instance, if a factory manager tells a subcontractor,
“We just got a computer to help run our factory,” is the subcontractor supposed to think he needs to start delivering his
products to the factory in half the time? Or is the subcontractor foolish enough to think that installing a computer in his
own factory will enable half-day change-over procedures to
be drastically reduced?
To shorten the physical lead-time portion of the overall leadtime, we need something other than computers. Usually, we
need factory-based improvements. We call the kind of factorybased improvements that result from adopting Just-In-Time
“JIT improvements.”
Thus, the fact is that computers mainly help shorten the
paper lead-time by improving clerical processes. It is only by
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◾ JIT Implementation Manual: Volume 1
DEFINITION OF PRODUCTION MANAGEMENT
Production management means building and
commanding:
a management system (organization framework,
procedures, information, management techniques,
and other information-based organizing factors) and
a physical system (plant equipment, equipment
layout, production methods, conveyance methods,
and other equipment-based organizing factors)
while making effective use of the three M’s (manpower,
materials, and machines) to economically manufacture
products of a certain value and quality, in certain
volume and within a certain period of time.
Figure 1.3
Production Management Defined.
getting involved in making factory-based improvements that
we can effectively shorten the physical lead-time. Our tactics
should differ depending on which kind of lead-time we are
trying to shorten.
In the factory, we are faced with a wide range of problems
and issues. It is the job of production management to sort out
and correct these problems according to market needs.
We should ask ourselves the simple question, “What is
production management?” To answer that question, we need
to return to the basics. Consider the definition of production
management on Figure 1.3.
Factories should be thought of as living entities or organic
systems. Within the factory’s overall system are informationbased factors that are hard to see, and equipment-based ­factors
involving the flow of goods that are easier to see.
We refer to the overall system’s information-based factors as
the management system and its equipment-based factors as the
physical system. The management system includes such things
as the factory’s organization, its hierarchy or organizing framework, its clerical procedures, and other information-related
aspects that readily lend themselves to improvement through
computerization. By contrast, the physical system includes the
plant equipment and its layout within the factory, production
methods, and other equipment-related aspects.
Production Management and JIT Production Management ◾
Today, factories are grappling with a common problem:
how to combine the management system and physical system
so that they function together in a level manner, like the two
axles of an automobile, while serving current needs for wide
product variety, high quality, low costs, and speedy delivery.
It is all well and good to bring computerization into the
information-related aspects, but that will not do much good if
the company’s organization remains in the mass-production
mode of decades past and the manufacturing orientation still
emphasizes large lots. Conversely, companies will find themselves lagging behind the times if they concentrate solely
on factory-floor improvements and ignore the advantages of
computerized information management.
From a comprehensive standpoint, we can make a distinction between “JIT production management” as a program for
developing production management attuned to market needs
and “JIT improvements” as a program for improving efforts
centered on a factory’s physical system.
As the two axles of the “factory automobile,” the management system and the physical system must be kept in pace
with each other, with neither being pushed ahead or held
back relative to the other. Otherwise, the automobile will not
get to its destination of corporate success.
Overview of the JIT Production System
The JIT production system is a market-oriented production system that rests entirely on the foundation of serving
c­ lient needs.
Whenever I have spoken to groups of people about the
JIT production system, someone invariably remarks, “You
mean the Toyota Kanban System, right?” I suppose that is an
indication of how famous the kanban system has become.
The fact is, though, that the kanban system is part—but not
all—of the JIT production system. The kanban system can
7
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◾ JIT Implementation Manual: Volume 1
be thought of as the conveyance system that helps make
the JIT production system work. The JIT production system
first gained public attention in Japan in the aftermath of the
1973 oil crisis, when market demand slacked off. A strong
diversification trend was born, and Japan’s economic growth
slowed to a more modest rate. Amid this environment­
,
the JIT production system gained the media notoriety as a
­recession-resistant production system.
The first aspect of the JIT production system to gain such
attention was the kanban system, in which signs attached to
goods replace vouchers as the medium for giving operating
instructions and production orders.
JIT, or “Just-In-Time,” refers to the timing of production
flow; goods are delivered to the manufacturing lines just in
time to be used, just in the immediately needed quantities,
and just to the production processes that need them. Saying
“in time” is not enough, since parts can arrive at processes a
week or two prior to their use and still be there “in time.”
That is why the most important word in Just-In-Time is the
first word, “just.” Goods need to arrive within minutes, not
days or weeks, of their use on the production line. Only then
can we eliminate waste in such forms as overproduction,
waiting for late deliveries, and excess inventory.
Let’s consider, for instance, a press operation. Imagine a
big pile of cut sheet metal next to the press. All those sheets
are there “in time” to be pressed. The sheet metal could have
been cut yesterday and delivered “in time” to be pressed.
Or it could have been cut and delivered last week or last
month and still be there “in time.” In any case, the sheet
metal is there “in time” but not “just in time.”
When the press operator is ready to press another sheet,
all he needs is one sheet from the previous process. He does
not need 10 or 20 of them. When he finishes pressing that one
sheet, he is ready to get another one from the previous process.
That is the way work-in-process should move, one at a time
from the raw material stage to the finished product stage.
Production Management and JIT Production Management ◾
Just-In-Time
Quality
assurance
Kanban
Visual control
Maintenance
and safety
Leveling
Flow
Manufacturing
Changeover
Jidoka
(human
automation)
Standard
operation
Manpower
reduction
Multi-process
operations
Figure 1.4
Overall Image of the JIT Production System.
It is helpful to picture Just-In-Time production as something like a river, in which separate workpieces float along
in a level manner from station to station as they are sent
downstream. Figure 1.4 presents an overall image of the JIT
production system.
At first glance, the JIT production system seems simple
enough, but when we begin to delve into its inner workings,
we find it to be extremely complicated and full of things that
cannot be well understood until they have been tried out in
the factory. Factory-based improvements are not something
to be talked about, written about, heard, or seen—they are
something to be done. Such improvements are “hands-on” to
their very core.
The following is an introduction to the types of improve­
ments that must be made to bring about Just-In-Time production:
1. Flow manufacturing
Flow manufacturing requires the elimination, whenever
possible, of pile-ups and conveyances to enable workin-process to flow in a level manner through the line.
The goal is to have each workpiece move through the
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chain of processes so it is correctly processed within the
cycle time.
2. Multi-process handling
In the conventional equipment layout scheme, where
­several machines having the same processing function
are grouped together as a shop, one worker might be able
to handle several machines, but handling several processes is out of the question. A different layout scheme,
in which the machines that make up an entire sequence
of processes are grouped together, would enable a single
worker to move with the workpieces from process to
process until the workpiece processing is finished. This
latter arrangement is called multi-process handling.
3. Kanban
The kanban system comprises one of the tools for maintaining Just-In-Time production. Kanban are signs that
contain operation instructions and/or parts delivery information. Kanban are useless in factories that still use the
conventional “shish-kabob” type of production method.
In fact, they tend to increase warehouse inventory levels
in such situations. The factory must first switch over to
flow manufacturing, and must start pulling workpieces
from process to process rather than pushing them.
4. Manpower reduction
Conventionally, production lines have been organized
with a view toward maintaining a steady number of
workers on the line. The JIT production system rejects
this way of thinking and instead organizes production
using the minimum number of workers (personnel costs)
required to meet the demand (fluctuation) of the next
process (the market).
5. Visual control
A key method for making bold improvements is to make
line failures or other factory-floor problems visible and
obvious enough so that anyone can easily spot them.
Various devices can be used to make production line
Production Management and JIT Production Management ◾
problems more visible. Kanban and andon (line-stop
alarm lights) are two such visual control devices.
6. Leveling
A little earlier, I used the term “shish-kabob” in discussing the kind of production scheme that was popular
during the mass-production era. The shish-kabob image
refers to the way that lots were processed in large, separate groups (the larger the better), much like the way
meat and vegetables are set one by one on shish-kabob
skewers. Lots were processed and then warehoused. The
concept of leveling calls for product types and volumes
to be spread out to produce as level a production flow
as possible. Thus, leveling is fundamental to both Just-InTime production and flow manufacturing.
7. Changeover
Here, I am using “changeover” as a broad term that ­covers
not only the replacement of dies and blades, but also
other operations, such as the revision of standards and the
replacement of assembly parts and other materials. The
goal of changeover improvements should be to shorten
the time needed for such operations. They should make
marked reductions in labor-hour requirements in order to
build a strong, flexible manufacturing line that is adaptable to changes.
8. Quality assurance
Quality is not something that just happens when we have
good production equipment. Likewise, having equipment operators work more cautiously does not necessarily reduce the number of defective products. Rather,
quality assurance requires a comprehensive approach
that addresses all production factors, including people,
goods, production equipment, and production methods.
9. Standard operations
Standard operations are essential for maintaining flow
manufacturing once it has been established and for
keeping pace with the production schedule. In short,
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standard operations are the operations that have been
painstakingly developed to achieve and preserve an
effective combination of people, goods, and machines
to produce high quality products economically, quickly,
and safely.
10. Jidoka: Human automation
Jidoka is automation with a human touch, and therefore
differs from automation in the ordinary sense. Jidoka
brings humans into the automation process to ensure
reliability, flexibility, and precision.
11. Maintenance and safety
In the JIT production system, the entire production flow
is stopped whenever even the smallest machine breaks
down. That is why the JIT production system places great
value on maintenance activities that maintain high production capacity. Equal emphasis is placed on safety—
the first and foremost consideration in production—in
order to prevent breakdowns and accidents.
Introduction of the JIT Production System
Introduction Procedure
Adopting the JIT production system entails changing current
production methods into JIT production methods. We generally refer to these kinds of changes as “JIT improvements.”
JIT improvements are quite different from the conventional
industrial engineering (IE) type of factory improvements. The
latter are usually based on analysis of current conditions.
Improvement workers get out stopwatches and other instruments to measure current processes and then analyze them.
Using the analysis results, they try to improve or fix the undesirable conditions.
By contrast, JIT improvements are based on ideals instead
of measurements. Their purpose is to bring the entire factory
Production Management and JIT Production Management ◾
IE Improvement
Analysis of current condition
(induction approach)
JIT Improvement
Ideal system as goal
(deductive approach)
JIT
Current production methods
Figure 1.5
Current production methods
Improvement versus JIT Improvements.
into conformance with the requirements of the JIT production system. While IE improvements use an inductive
approach based on statistical data, JIT improvements address
a single issue—Just-In-Time production—and use a deductive approach to improve the factory (see Figure 1.5).
Rather than taking the slow plodding approach to fixing
apparent problems within the current conditions, the JIT
improvement approach moves by leaps and bounds to bring
the factory as close as possible to the JIT model. As such, JIT
improvement actually goes beyond “improvement” and into
the realm of “innovation.” Perhaps the term “JIT innovation”
is more appropriate than “JIT improvement.”
A factory cannot truly establish the JIT production system
unless it successfully takes on all of the components of the
overall JIT image that were shown in Figure 1.4. Figure 1.6
shows the five major steps in the upward sequence of events
leading to success in establishing the JIT production system.
Step 1. The Awareness Revolution:
Prerequisite for Factory Improvement
All innovation starts in the mind. Once we revolutionize our
awareness of the factory situation, we will naturally want
to improve the factory equipment and its layout and create
­better methods of operation. The JIT improvement concept
does not mean going directly to the factory to make things
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Just-In-Time
Jidoka
(human
automation)
Step 5
Standardized operations
Changeover
Step 4
Leveling
Multi-process
operations
Step 3
Flow manufacturing
Maintenance
and safety
Quality
assurance
Visual control
Manpower reduction
14
Kanban
Step 2
The 5S’s for factory improvement
Step 1
Awareness revoluation: prerequisite for factory improvement
Figure 1.6
Steps in Establishing the JIT Production System.
better. Instead, the most important approach is to begin by
revolutionizing people’s awareness.
Manufacturing companies include all types of job functions, from business management to factory management,
procurement, production, and so on. Production cannot proceed in a level manner unless all of these functions work
well together on a day-to-day basis. And almost all of these
functions are performed by people, not machines.
I am amazed at the kind of question I am asked when
explaining this first step. For example, some people ask,
“Who is supposed to revolutionize our awareness?” Others
complain, “Hey, it’s a production problem, so we’ve got to
change the factory first.”
I have even been told, “Look, the problems start with deliveries, and the buyers and subcontractors need to change first.”
Right.
Obviously, it is important that everyone, including the production workers and the outside vendors, undergo the awareness revolution. But the best place to start is at the top. The
reason for this is that as long as top management harbors
Production Management and JIT Production Management ◾
such thoughts as, “There’s no way to establish JIT with the
way things are at this company,” the necessary changes will
not be made. You can bet on that.
When I hear such doubts coming from top managers,
I always respond, “So, when are you going to get around
to changing the way things are at your company?” Usually,
they realize the futility of their thinking, and admit with a
smile, “I guess we’ll never have JIT unless we do something
about it.”
JIT improvement means more than changing production
methods. Most companies are awash in problems arising from
narrow self-interest or waste. Often, such problems have been
around so long that they are unwittingly considered part of
the “corporate culture.”
The awareness revolution must start at the top of the company. There is no other way. Once top management ­people
become more aware, they gain a heightened sense of what is
wrong with the status quo. This sense of emergency begins
to trickle down to middle management and then to the
­factory workers, until finally the whole company is filled with
an awareness that things must change. It is this awareness
that produces the energy needed to change the status quo.
It creates­a positive, dynamic force for change.
There are various ways to start and encourage this chainreaction, such as holding in-house seminars and starting up
JIT study groups to examine JIT movements and conditions
in other manufacturing companies.
If only one thing sinks into the minds of all the company
employees during these awareness revolution efforts, let it be
that the status quo is not enough to ensure the company’s
survival in the future.
Step 2. The 5S’s for Factory Improvement
Throughout the great effort to render the factory into a close
approximation of the JIT model, we can look to five basic
underlying principles. These principles are summarized
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by five words that, in romanized Japanese, begin with “S,”
and are thus called the 5S’s. The 5S’s are: proper arrangement (seiri), orderliness (seiton), cleanliness (seiso), cleanup
(seiketsu), and discipline (shitsuke).
The most fundamental of these 5S basics are proper
arrangement and orderliness. The success or failure to adhere
to these two basics constitutes a major fork on the road to
JIT success.
You are sure to find plenty of defective products when the
factory is strewn with trash, when its floors and machines are
oily or dusty, or when the production workers do not mind
working in old, soiled uniforms. You will find plenty of late
shipments, too. And low productivity. And low morale.
In any case, such factories are nowhere near being well­organized or well-regulated. Neither are they very neat or clean.
In Japan, about 70 percent of what we generally think
of as factories are not factories. They are warehouses. The
factory­workers build things inside huge warehouses. They
are surrounded by useless things and firmly plant themselves
in front of unnecessary machines. Amid all this clutter, the
workers literally go out of their way to make things. Often,
workers must waste time looking for things that they need,
such as parts, dies, or tools. The workers that have been
there long enough to have figured out where those things are
likely to be are called “veterans.”
Under such conditions, there is really nowhere to begin
making JIT improvements. First, we have to go back to the
most basic of the 5S’s, proper arrangement and orderliness.
To do this, we begin figuring out exactly what and how
much is really needed in the factory.
Putting up a big sign emblazoned with the words “Proper
Arrangement and Orderliness” is obviously not going to do
the trick if the floor is still cluttered with unnecessary parts
and assorted garbage. Improvements do not come from
banners­. Neither do they flow from the mouths of pep-talkers­.
Improvements are things that get done on the spot.
Production Management and JIT Production Management ◾
Two of the biggest obstacles for proper arrangement
and orderliness are poor training and ignorance of proper
methods­
. The most effective way to bring about proper
arrangement and orderliness is to keep things visible. When
trying out a new arrangement plan, a 5-year-old child should
be able to figure out what is necessary and what is not. Once
it is decided where things should go and in what quantities,
any amateur—whether a company president or a visitor—
should be able to easily recognize the rules.
This is what is meant by “visual proper arrangement and
orderliness.” The strategy for bringing about visual proper
arrangement is called “the red tag strategy.” The strategy for
establishing visual orderliness is called “the kanban strategy.”
When carrying out the red tag strategy, the company forms
red tag teams to perform company-wide red tag campaigns
from two to four times over the span of a year. It is vital that
the red tag strategy be maintained for at least a year, or else
the company will likely slip back into its old sloppy habits.
Step 3. Flow Manufacturing
Whenever I am asked what flow manufacturing means, I always
respond, “It means bringing the factory’s underlying waste to
the surface.”
Whether the production method is shish-kabob production
or one-piece flow manufacturing, the product is the same.
One might think that since the end product is the same, it
does not matter which method is used.
However, there is one important difference here. Shishkabob production tends to conceal waste while flow manufacturing tends to reveal it. That is the only significant
difference between the two methods. For beginners looking
to make JIT improvements, it is still much too early to think
about what differences there are between the two methods
when applying them to such matters as greatly improving
productivity and more readily meeting customer needs.
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Shish-kabob production of large lots was fine during the
bygone era of fast-expanding sales. Companies grew larger
without regard to how much “fat” or waste they were accumulating. In the seller’s market of those days, the ­manufacturer’s
waste-related costs could just be added into the product’s
marketable price.
Now it is a buyer’s market. Today’s buyers do not need or
wish to subsidize manufacturers’ waste-related costs. In fact,
nowadays consumers are smart enough to lay the blame for
such waste-related costs directly on the manufacturer.
Unfortunately, waste usually runs deep within any factory.
And deeply embedded waste is not at all easy to discover.
Such waste has, in a sense, spread roots. Like real roots, the
roots of waste sometimes get severed when you try to pull
them out, and you have to go deeper to get the rest of them,
or they will grow back later. Waste has to be eradicated completely. Small-scale improvements will not do the job.
Now let’s get on to how flow manufacturing is employed.
Manufacturing products one at a time allows us to look
right into the depths of how the products are made. All of the
major and minor forms of waste that had been concealed by
the large-lot shish-kabob production method are now visible.
We begin to notice odd things and ask questions like:
◾◾ “Why are we conveying the workpiece from here to
there?”
◾◾ “Why are the parts piling up right here?”
◾◾ “Why does changeover have to take so long?”
Setting up for flow manufacturing is a piece of cake. There
are only seven requirements, as listed in Figure 1.7. If all
seven are met, the factory will have bona fide flow manufacturing. It is as simple as that.
I doubt that the novice at JIT improvement would understand what any of these tersely worded requirements mean.
Below is a more detailed description of each.
Production Management and JIT Production Management ◾
Seven Requirements for Flow Manufacturing
1 Place machine in process sequence
2 Compact specialized and
general-purpose equipment
3 One-piece flow
4 Cycle time
5 Multi-process operation
6 Multi-skilled workers
7 Standing (chair-free) operations
Figure 1.7
Seven Requirements for Flow Manufacturing.
1. Continuous flow production line
This means arranging the production processes (and the
production equipment) into a line or a U-shaped cell.
2. Compact specialized and general-purpose equipment
Costs can be kept down by installing smaller, slower, and
more specialized production equipment. However, some
general-purpose equipment is also needed to facilitate
flexible line reorganization.
3. One-piece flow
This means that each process should handle only one
workpiece unit from the time processing of that workpiece is begun until it is finished.
4. Cycle time
This refers to the need to synchronize processes to keep
pace with client needs and the needs of the next process.
5. Multi-process handling
This is a labor arrangement in which one worker moves
from process to process down the line.
6. Multi-skilled workers
This entails training workers in the skills needed for
multi-process handling.
7. Standing (chair-free) operations
An important improvement in work posture is changing
from sitting to standing, enabling worker mobility.
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Step 4. Leveling
In principle, it is best to start JIT improvements as close as
possible to the client. In the factory, that would mean starting
by reducing finished product warehouse inventories to zero.
If we can tear down the wall of piled-up products that need
to be shipped and sold, we are better able to incorporate
the latest client needs into the factory. Those product “walls”
protect factories from the powerful waves of changing client
needs. They give the factories a false sense of security, especially today when factories need to remain in intimate touch
with market trends.
It is only by tearing down those walls that factories can come
face to face with the needs of today’s market for greater diversification and shorter lead-times. Factories may then promptly
change their production lines to reflect those needs.
Then, as the old QC saying goes, “the next process is your
customer.” After aiming to meet client needs for a certain
product, JIT improvements move on to the product’s sub­
assembly lines, processing lines, materials processing lines,
and outside orders. (See Figure 1.8.) This is called “vertical
development” of JIT improvements. We call it “lateral development” when JIT improvement moves on to other products.
Therefore, as a rule, JIT improvement begins near the
client and moves upstream from the “next process” to the
“prior process.”
To recapitulate, to start off the JIT improvement campaign,
we get rid of the stacks of finished products in the warehouse
and then we change the final assembly processes to suit the
client’s current needs. To do this, we must put an end to the
factory’s shish-kabob style of lot production. The factory is
no longer going to turn out large lots of product A this week
and large lots of product B next week. That is not the way
customers buy things. It is only the way that seems most
­convenient for the factory.
Production Management and JIT Production Management ◾
Customer
NEEDS
Product
inventory
VERTICAL
DEVELOPMENT
Subassembly
line
Outside
vendor
LATERAL
DEVELOPMENT
Assembly
line
Other
models
Processing
line
Materials
processing line
Materials
procurement
Figure 1.8
Sequence for Introducing JIT Improvement.
Although the exact quantities of each product fluctuate
a little, customers invariably buy a wide range of products.
Bringing such diversity into the production system is what
we mean by “production leveling.”
Many people think of production leveling as leveling out
two factors: capacity and load. System engineers who work
with computer-based production control systems are especially quick to make this association. They think in terms of
the various processes’ capacities and the load that production
orders impose on those processes. So when the load piles up
to where it exceeds the capacity, the load “peaks” need to be
leveled out.
But three things are clearly wrong about the load and
capacity approaches to production leveling.
Let us address the first of this approach’s problems by
­asking, “Who determines what a process’s load is anyway?”
The factory does, and usually for reasons of convenience.
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This is the first mistake. The factory people are saying this
is their capacity, regardless of what the client requires. They
need to stand that approach on its head and make the client’s
needs the factor that determines the capacity.
The second mistake is to break up the load of orders from
customers once that load exceeds the predetermined capacity.
Orders from customers should be treated with more respect
than that. Instead of breaking up the load and thereby lengthening lead-time, the factory should pursue other options,
such as temporary overtime work or subcontracting.
The third mistake in this approach is that it relies on people
who sit at their desks with pen, paper, and calculator or computer and plan production schedules, but do not know how
to make the products. It is the old ivory tower syndrome. The
farther production planners are from the production line, the
more impractical their planning becomes. Instead of working
out uselessly detailed production plans, they need to plan
directly for client needs. The simple way is the best way.
For JIT improvement, leveling means thoroughly ­leveling
out product types and volumes in accordance with customer
needs. In other words, we begin by breaking down the
monthly production output into daily units. Then we compare
the daily volume of products with the operating hours and
calculate how many minutes it should take to turn out each
product unit. We call this unit production time “cycle time.”
Then we figure out how many people are needed and what
the c­ apacity is (see Figure 1.9). Naturally, this requires organizing manpower based on the production lines instead of organizing production lines based on a fixed number of workers.
It is all too easy to find factories that calculate such things
as production capacity and production line speed based on
the equipment or the maximum number of worker hours.
That approach is fundamentally wrong. It bears repeating
that it is the customer—not the factory—who should determine how many products are to be made and how quickly.
This fact must never be forgotten.
Production Management and JIT Production Management ◾
Estimate-based
Leveling
Reality-based
Leveling
Constant process capacity
(fixed number of workers)
Orders
Set capacity
Leveling of product
types and volumes
Load accumulates
Result: a level load
Break up excessive loads
Flexible line capacity
(variable number of workers)
Leveling of capacity
and load
Leveling of quality
and volumes
Orders
Figure 1.9
Estimate-Based Leveling and Reality-Based Leveling.
Step 5. Standard Operations
It so happens that many of the important elements we
work with in factories begin with the letter “M”: manpower,
materials, machines, methods (such as work methods), and
money (economics).
Standard operations are those operations which have been
determined as best achieving and preserving an effective
combination of people, goods, and machines in order to produce high-quality products economically, quickly, and safely.
Again, we must deal with a common misconception. Many
people mistakenly think of standard operations as being the
same as standard operating procedures (SOPs). The difference
is that SOPs are only standards for individual operations; they
are merely part of what we mean by standard operations.
Standard operations are standards that string together
a series of operation-specific SOPs in a particular order to
build a certain product. As such, they are more like “standard
­production procedures” than standard operating procedures.
In addition, standardized work procedures serve a dual
purpose. They not only help standardize production, but
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they also help reveal current operating conditions. In view of
this dual purpose, the proper way to establish standardized
work procedures is to follow the steps listed below.
Step 1: Reveal current operating conditions. The first thing
to do is to discover and analyze the actual net time currently required for work operations and the way in which
operations are really being performed.
Step 2: Ferret out the problems. Use the cycle time as a
standard for ferreting out problems regarding the work
balance, ergonomic factors, variation, and so on.
Step 3: Find out the real causes and plan improvement.
Repeatedly ask “Why?” along with other key questions
(the “5 Whys and 1 How”) until you discover the real
cause of the problem, then plan out an improvement to
resolve it.
Step 4: Implement the improvement. Go into the factory
and implement whatever improvements are needed concerning operations, hardware, layout, and the like.
Step 5: Standard operations. Once you have improved
the operations, establish them officially as standardized
work procedures, which will again come under scrutiny
­during the next improvement stage.
From Vertical Development to
Horizontal Development
The first two steps in introducing the JIT production system,
the awareness revolution and the 5S’s, should be developed
throughout the factory and/or company. Obviously, the 5S’s
step will not work unless the awareness revolution step has
been taken. The company is not ready to begin the second
step until the awareness revolution has taken root, at least to
some extent.
Once the awareness revolution and the 5S’s have thoroughly penetrated the factory, JIT improvements can begin.
Production Management and JIT Production Management ◾
These improvements begin with what is most obvious and
expand from single improvement points to “lines,” and
finally to “planes” and “cubes.” Below are descriptions of
each expansion phase.
Point Improvements
Even Just-In-Time improvements cannot begin with flow
manufacturing. Instead, they must begin with a rooting out
of the basic causes of workpiece pile-ups at certain processes
and a change in production methods to eliminate the need
for product warehouses. We must ask the basic question
“Why?” at each point where workpieces are being conveyed
between processes, to find out whether such conveyance
can be eliminated. We must observe each worker’s movements and see if they can be made simpler, more efficient,
and less wasteful.
These are all “point” improvements. Like seeds planted in
furrows, these small point improvements must be carried out
as a foundation to support larger improvements later on. (See
Figure 1.10.)
Point Improvements
Point
Point
Point
Figure 1.10
Point Improvements.
Line Improvements
After accumulating a certain amount of point improvements
aimed at workpiece pile-ups, wasteful conveyance, and the
like, we reach a breakthrough point where suddenly things
begin to flow. Such a phenomenon indicates that enough point
improvements have been made in the factory to pave the way
for some line improvements. From a technical ­viewpoint, this
is where flow manufacturing begins.
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Line Improvements
Line
Line
Figure 1.11
Vertical
development
Line Improvements.
Once we start making line improvements in the factory, it is
time to change the production method from “push” production
to “pull” production, plan for production leveling, and develop
standard operations. It is also important that we move promptly
to make improvements whenever problems occur in the flow
of work-in-process and that we practice “visual control.” These
are the kinds of activities I call “line improvements.”
Line improvements always occur as the result of an accumulation of point improvements. There is no sense in trying­
to force a quantum jump to line improvements without any
foundation. Neither is it wise to try to use rigid rules for
drawing a straight line from one desired improvement to the
next. But we need at least to understand the line’s starting
and ending points in order to know what kind of line we
are drawing. This kind of drawing between points is called
“vertical development.” (See Figure 1.11.)
We generally use this kind of vertical development to
build model lines. Model lines can be selected for a p
­ articular
type of production line segment or for a particular type of
­product. In either case, the person in charge of the model
line must be someone who is really enthusiastic and eager to
do a good job.
Plane Improvements
Once we have vertically developed improvements on our
model line at the selected production line segment, we are
ready to display the model line to people at other processes
to use as a reference for carrying out their own point and
line improvements. This way, a single line improvement at
Production Management and JIT Production Management ◾
Plane Improvements
Plane
Figure 1.12
Plane Improvements.
one part of the factory floor becomes two and then three
lines at various other parts until, finally, the whole factory
floor has been improved. This is “plane improvement.” We
also call this type of follow-the-model improvement “lateral
devel­opment,” as illustrated in Figure 1.12.
Cube Improvements
Product manufacturing cannot be done well by a factory alone.
The factory needs market information from the company’s
sales arm and component deliveries from buyers and outside
vendors. It also needs a distribution organization to deliver the
finished products to market.
Once the circle of JIT improvement has expanded to where
it encloses the entire factory, it can be gradually raised to other
“planes” outside of the factory. In this way, plane improvements become “cube improvements.” (See Figure 1.13.)
Cube Improvements
Height
(3rd dimension)
Figure 1.13
Cube Improvements.
Organizing for JIT Introduction
JIT production is an “industrial revolution” that aids corporate survival and helps revolutionize employee awareness.
This means that JIT production is a form of innovation, and
innovation requires casting away fixed ideas and old habits.
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As such, JIT introduction is not something we can do in our
spare time. It is a major undertaking, and to get substantial
results it desperately needs the support of top managers
cheering, “Let’s get to it!” and factory floor leaders urging,
“Let’s move this thing forward!”
The entire company has to get behind JIT introduction as a
sort of company-wide “JIT Improvement Project.” Figure 1.14
illustrates the method for promoting company-wide involvement in JIT introduction.
JIT improvements are neither academic accomplishments
nor problem-hunting tours of the factory by the technical staff.
As shown in Figure 1.14, they are nuts-and-bolts changes that
work their way through the entire production organization to
improve the factory.
Such improvement organizations for JIT production cannot
succeed unless everyone carries out his or her duties seriously
and enthusiastically.
◾◾ The president’s duties: Company-wide reinforcement of
JIT production.
Just-In-Time includes more than production. JIT must
also be extended to all other arms of the company, such
as sales, procurement, subcontractors, distributors, and
so on.
◾◾ Duties of the factory superintendents, division chiefs, and
department chiefs: Establishment and company-wide
achievement of goals for JIT production.
Most factories run on an internal organization that has
evolved and developed over many years. That is why
two factories that belong to the same company may
be quite different from one another. Faced with such
long-cultivated traditions, JIT improvements cannot succeed unless the factory management—including the
supervisor, division chiefs, and department chiefs—all get
involved. It is especially important that they get involved
Production Management and JIT Production Management ◾
The Goal: Achieving and Maintaining JIT Production
Implementation Measures and Improvements
Quality assurance
Maintenance
and safety
Visual control
Implementation Measures
Kanban
Multi-process
operations
Leveling
Standardized
operations
JIT production
teams,
motivation
of team
members
Establish
and achieve
companywide goals
for JIT
production
Plan for JIT
production
goal completion timetables
and goal
management
The 5S’s
Proper arrangement (seiri), Orderliness (seiton),
Cleanliness (seiso), Cleanup (seiketsu), and
Discipline (shitsuke)
Jidoka
(human automation)
Manpower
reduction
Changeover
Flow
manufacturing
Awareness revolution
Duties within the Staff Hierarchy
Ferret out
and study
problems
Organize
and run JIT
production
improvement
teams
Establish
and develop
JIT
production
organization
Companywide
reinforcement
of JIT
production
Establishment JIT production JIT production
and company- guidance and brainstorming
wide achieveeducation/
sessions and
ment of goals
training
campaigns
for JIT
production
Company president
JIT production project
Superintendent
and/or division chief
Department chiefs
Section chiefs
Section chiefs
Foremen
Foremen
Foremen
Foremen
Equipment Equipment Equipment Equipment Equipment Equipment Equipment Equipment
operators operators operators operators operators operators operators operators
JIT’s Ten Commandments
1. Throw out old, tired production method
5. Correct mistakes immediately.
concepts.
6. Improvements should not be costly.
2. Don’t think of reasons why it won’t work,
7. Wisdom arises from difficulties.
think of ways to make it work.
8. Ask “why” at least five times until you
3. Don’t make excuses, just deal with
find the real cause.
current conditions.
9. Better the “wisdom” of ten people than
the “knowledge” of one.
4. Don’t wait for perfection; 50 percent
10. Improvements are unlimited.
is fine for starters.
Figure 1.14
Promotion of Company-wide JIT Production.
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30 ◾ JIT Implementation Manual: Volume 1
in such things as improvement follow-ups and ensuring
the thorough implementation of JIT production.
◾◾ Duties of department chiefs and section chiefs: Giving
guidance, education and training in JIT production, and
creation and management of JIT improvement teams.
Even within the same factory, we often find that JIT
improvements reach different degrees of advancement in
different departments. When advancement is poor, much
of the blame can be placed at the feet of the department
chief and the section chiefs. An unenthusiastic department chief alone is often enough to slow progress. Or
perhaps the section chiefs are just following orders and
have no real interest in what they are doing. Successful
JIT promotion groups include department and section
chiefs whose enthusiasm attracts the interested participation of the foremen and equipment operators.
◾◾ Duties of section chiefs, foremen, and equipment operators: Gaining hands-on experience in JIT production and
ferreting out and studying problems.
The foremen and equipment operators are the ones who
best understand how the factory works. By the same
token, they are the ones who tend to be most reluctant
to discard the traditional way of doing things. Therefore,
they need to gain a great deal of courage and fervor to
overcome such reluctance. They need to be convinced
that there is no use complaining about the changes. There
is, on the other hand, every reason to push forward to
make the improvements.
Figure 1.15 shows an example of how one company set-up
its promotional organization.
How to Promote and Carry Out JIT Improvements
Once we have set-up an organization for introducing JIT
production, we are ready to begin improvement activities.
Production Management and JIT Production Management ◾
(4) JIT consultants
JIT promotion director:
Company president
JIT promotion
assistant director:
Company managing director
Promotion
committee
(3) Factory
superintendents
JIT promotion headquarters
Leader: Head of production
engineering
Assistant leader: Assistant
head of production
engineering
(3) General managers
(3) Factory managers
Factory A’s group
Factory B’s group
Factory C’s group
(1) Leader
(12) Improvement
team members,
including 3 department heads and 6
section heads
(1) Leader
(11) Improvement
team members,
including 3 department heads and 6
section heads
(1) Leader
(6) Improvement
team members,
including 2 department heads and 3
section heads
Figure 1.15 Example of Promotional Organization for JIT Production.
However, these are not improvements in the ordinary sense
of the word. Instead, the factory is looked at as a dynamic
system, and improvements made as if to a living entity.
Conventionally, small improvements in the factory occur
every day and have an accumulative effect. In factories
where improvement activities are assigned only to a certain
group (or even just one person), improvements can still be
­accumulated, but it is a very difficult task. That is why the
factory needs a company-wide promotional organization.
In addition, there are five key points to observe in introducing JIT improvement activities.
Point 1. Set-Up an Improvement Promotion Office
Set aside an empty room in the factory. The room should
be large enough for about ten people, or however many are
on the improvement project team. This is the room where
improvement teams can come to work out an agenda of
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problems and brainstorm corrective measures. The room
should never be used as a recreation room.
The improvement teams should meet here one day a week
to study improvement issues. The other days they should be
busy carrying out improvements.
Point 2. Have at Least One “Improvement Day” a Week
For all improvement project members, the cycle of improvement meetings and activities should be at least weekly. Do
not let people get the idea that they should only be making
improvements on the day meetings are held. On nonmeetings
days, people in every part of the factory should be busy ­carrying
out improvement measures.
“Improvement Day” activities should also include progress
reports on current improvement campaigns, brainstorming
for new improvement points, and assignment of improvement
activity duties.
Point 3. Improvement Meetings:
One Hour Is Better Than Two Hours
Improvement meetings are not the goal of JIT improvements.
The first and foremost goal is to make the necessary changes
to create a factory that effectively responds to market needs.
Just sitting at a desk and talking about improvements is not
going to change anything.
Therefore, the meetings should be short and to the point. We
simply figure out the key agenda items, brainstorm improvement ideas, assign improvement jobs, set a delivery deadline,
then get back to the factory to start making the improvements. We should try to finish the meeting within an hour,
or within two hours at the most.
When scheduling the meetings, be sure to avoid meal times
when people need to eat. Eating is important to labor productivity. The best time for improvement meetings (Figure 1.16)
is usually in the evening, right after work.
Production Management and JIT Production Management ◾
Figure 1.16
An Improvement Meeting.
Point 4. Create an Improvement List
During a one-hour walk through the factory, any sharp-eyed
observer can usually spot ten to 15 items in need of improvement. All items should be entered on an improvement list to
be used for proposing improvement ideas at weekly improvement meetings.
The items do not have to be typed. The list can be on a
blackboard or poster on the wall of the improvement promotion office, where people can casually jot down things they
have noticed. However, the list should contain columns with
the following headings to enhance clarity:
1. Improvement number
2. Improvement item name
3. Description of improvement
4. Related section/department
5. Improvement leader
6. Delivery deadline
7. Result
Because this list will be used for making improvements, it is
important that every column be filled in to keep the status and
progress of improvements as clearly visible as possible. It is the
responsibility of the improvement project leaders to check the
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“Result” column at each meeting to gauge the overall­progress
of improvement activities.
Point 5. Improvements Happen in the Factory!
Improvement meetings are basically for confirming the previous week’s improvement campaigns and assigning duties for
the next week’s campaign. After that, it is time to get back to
the factory where improvements actually happen.
Once the meeting is over, the various improvement teams—
such as the equipment layout team, jig redesign team, and
5S’s enforcement team—should go directly to the places in
the factory where the improvements are to be made. The
improvement teams may be there until late in the evening,
but when they finish, they will get a sense of real achievement. Making improvements cannot be done halfheartedly
or left half done. A “hang in there” attitude must be maintained until the end.
Chapter 2
Destroying
Factory Myths
A Revolutionary Approach
Relations among Sales Price, Cost,
and Profit
1. Costs + profits = sales price
2. Sales price − profits = costs
What do you notice when you look at these two equations?
If you get the impression that they say the same thing, you
have a knack for math. Mathematically, there is no difference between the two equations. However, if you are a business manager or someone fluent in finance concepts, you
would recognize the equation’s algebraic similarity, but you
would also insist that they are two completely different ways
of thinking.
How can we explain this?
In the first equation—costs + profits = sales price—the
method for determining the sales price is to add a profit
­margin onto costs. Specifically, we first identify and add up
all the costs involved in manufacturing a planned commercial ­product. Then we tack on a profit margin to reach a sales
price. We can call this the “cost up” method.
The second equation—sales price − profits = costs—sets
the sales price according to the market price.
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To do this, we first find out how much the planned product will likely fetch on the market and take that value as the
sales price. Then we need to decide how big a profit margin
is required. The total costs are what is left over when we
subtract the profit from the sales (market) price.
After that, we can go on to ask questions like, “What kind
of materials can we use and still keep the costs within the
equation’s total cost figure?” We can also work out our choices
of production methods and labor resources in this way.
The costs + profit = sales price approach is based on predetermined costs, and is therefore a production-oriented
approach. In Japan, the latest jargon describes this as the
“product-out” approach.
On the other hand, the sales price − profit = costs approach
takes the opposite direction by starting with the market as a base.
It is therefore a market-oriented (or “market-in”) approach.
Which approach do you think is better suited to today’s
highly competitive markets? In a mature market, the productoriented approach will only work for an extraordinarily popular and distinctive product. Otherwise, the product would be
outsold by similar products whose prices follow downward
moving market trends. In addition, we should not regard
profit as a side product. Instead of being pleasantly surprised
by the appearance of a profit, we should take more positive
steps to ensure one.
The sales price is almost always being pushed downward
by market needs. That leaves only one viable method for
squeezing a profit out of the equation: lowering costs.
In recent years, the companies that have been the biggest
profit-earners are the ones that have been best able to keep
costs down. The losers have been those that have not been
able to cut costs. You cannot blame many of the losers for
not trying. Many have tried Total Quality Control (TQC), cost
reduction projects, suggestion systems, small group activities, and various types of employee committees, but none of
these have been thorough enough to bring real success.
Destroying Factory Myths
Many of the losers in today’s tough markets have been
companies that sincerely pulled together in pursuit of certain
goals. The problem for them has been the same old story:
the attitudes of employees, many of whom lack the confidence or courage to reach the goals. Employees who think
of what they cannot do instead of simply planning the next
step ahead are the root of these failures. The key word here is
“innovation.” Companies that forget that word are just biding
their time until bankruptcy.
Another key concept is that profit is not something that “pops
out” of the manufacturing and marketing processes and lands
in the laps of the company employees. Rather, it is something
the company has to create and earn through hard work.
Companies have to take a more positive attitude toward
profit-earning. They have to be creative and come up with
devices and schemes that will help create profit. The way to
start is to throw out every single conventional idea. The ­factory’s
local mythology—the proud tales of how many years the
­factory has been turning out good old Product X—has to be
discarded and replaced by a cold, hard look at market needs.
Some companies have been able to do this, and some have
not. Some just do not have the inner strength for it. Let us
briefly examine what the anatomy of an unprofitable factory­
might look like, as illustrated in Figure 2.1.
In this example, the company figures its sales price using
the production-oriented method, and then launches its sales
activities. However, the actual costs turn out to be much more
than the original estimate. This shrinks the profit to a m
­ odest
or very small amount. Unless the factory can recover its profitability, morale will start to sink.
Some belt-tightening is needed, and such things as R&D and
improvement campaigns are the first to go. Soon the ­factory
falls into the bad habit of slashing precisely the programs that
might alleviate the problem. Such short-sightedness ends up
creating a genuinely unprofitable factory.
Now let us compare this money-losing factory to the one
whose anatomy is shown in Figure 2.2.
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38 ◾ JIT Implementation Manual: Volume 1
Modest or very small
PRODUCTION
SALES
+
COSTS
PROFIT
= SALES PRICE
Maximum
Minimum
Not what customers want
Not very high quality
Not economical
Not fast
Not what customers want
Not using recent technology
Not a good corporate image
Week product development
Not in pace with diversification
trends
Desire for improvement
Low-cost improvement
Factory has no new technologies of which to be proud
No improvement in work
conditions and productivity
Factory uses same old
distribution channels
Shortages keep causing
shipping delays
No clear product development ideas or plans
Emphasis on large-lot
production
No surveys to identify market
needs
Defective goods accepted as
inevitable
No commitment to R&D
Waste creating more waste
Satisfied with traditional
business ties
Erroneous belief that today’s
Late shipments accepted as
products will sell well tomorrow
commonplace
Belief that the current production
method is the best possible
Not interested in emphasizing quality
Lots of waste
Apologetic but unrepentant
of late shipments
Belief that the current products
are the best possible
Not interested in new technologies
Deteriorating image
Products are not very popular
ANATOMY OF AN
UNPROFITABLE FACTORY
Figure 2.1
Anatomy of an Unprofitable Factory.
Weak R&D program, no image-boosters,
no funding for surveys
Plagued by human errors and
defective goods
Not keeping pace with
changing needs
Destroying Factory Myths
◾
Maximum
SALES
PRODUCTION
SALES PRICE –
PROFIT
=
COSTS
Minimum
Maximum
What customers want
Use recent technology
A good corporate image
Strong product development
Multi-model mixed production
Work to eliminate human
errors and defective goods
R&D of homegrown
technologies
Major improvements in
distribution channels
Ongoing improvement in work
conditions and productivity
Long-term product development program
Adoption of JIT production
Periodic surveys of
market needs
Small-lot, one-piece flow
manufacturing
Basic R&D
Quality built in at each process
Image-boosting sales
promotion
Product development bases
on market surveys
Current products can be greatly
improved
Development/adoption of
new technologies
Image-boosting campaigns
Emphasis on products that
sell
All employees involved in
eradicating waste
Identification and removal of
causes for late shipments
Current products can
be greatly improved
Efforts to improve quality
Waste eradication efforts
Efforts to prevent late shipments
ANATOMY OF A
PROFITABLE FACTORY
Figure 2.2 Anatomy of a Profitable Factory.
All employees involved in
improvement activities
Basic R&D image-boosting campaigns
and market surveys.
Responsive to diversifying
needs
What customers want
High quality
Economical
Prompt
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As can be seen, anatomically speaking, these two factories
are almost complete opposites. In the latter case, the sales
price is set according to the “going price” on the market.
The company’s sales division is busy carrying out energetic
marketing activities in sales promotion, distribution channels,
and other areas. Meanwhile, all of the employees in the production division are equally busy with broad-reaching efforts
to completely eliminate human errors, product defects, and
waste. As a result, the company is able to maintain sales, suppress costs, and turn a good profit.
When profits rise, so does employee morale. In addition, management is more willing to underwrite such initiatives as R&D,
sales promotions, plant investment, and improvement activities.
Here we have an example of a profitable factory, fueled by
innovation. And remember, innovation is the key to success.
Ten Arguments against the JIT
Production Revolution
People naturally tend to harbor a mild affinity toward one
another. Co-workers tend to harbor a very strong affinity with
their system of “the way things are done,” which they have
built together over the years. As far as they are concerned,
no system could be better for them. They have no desire to
change it. After all, their routine is leveled and is very easy to
live with. Even in the finest-looking factories, life goes on in
the traditional, albeit obsolete, manner.
Improvement starts at the factory:
“Hey Joey, could you roll that set of machines over here?
I want to link them up with this process.”
“Hey, no way. Why all the hassle?”
“Haven’t you heard? We’re dropping this lot production stuff
and gearing up for one-piece flow.”
Destroying Factory Myths
Ten Arguments Against JIT Improvement
1. JIT improvements won’t do any good!
2. It sounds like a good thing, but we still don’t
want to do it!
3. Looks good on paper, but . . .
4. Costs are already as low as that can possibly get!
5. But we’ve already been doing things that way!
6. We don’t want people looking over our
shoulders and telling us what to do!
7. We can’t lower costs any more without
lowering quality!
8. Everything is going just fine now. Why change it!
9. That’s a lousy idea! We already tried that
20 years ago!
10. Look, we understand this stuff better than
anybody (so don’t tell us what to do).
Figure 2.3
Ten Arguments against JIT Improvement.
“Do you have any idea what kind of quality problems these
changes are going to create?”
“Come on, move it. I want you to have this set-up for onepiece production before I come by again.”
“If you say so, but it won’t work.”
The three common excuses encountered at this point boil
down to: “I don’t want to change things,” “It’s too much t­ rouble,”
and, “I’m afraid I’ll get laid off.”
Aside from these common excuses, I have been able to identify ten arguments against JIT that are often encountered on
the path of JIT improvement. Figure 2.3 lists these arguments.
These are just some of the wide variety of anti-JIT arguments
one runs into when trying to promote JIT improvements.
To elaborate a bit:
1. “JIT improvements won’t do any good!”
Here we have a sweeping condemnation of the whole JIT
improvement program.
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2. “It sounds like a good thing, but we still don’t want to
do it!” and
3. “Looks good on paper, but...”
Here we have agreement in general and disagreement on
all particulars.
4. “Costs are already as low as they can possibly get!” and
5. “We can’t lower costs any more without lowering quality!”
Here the obstacle is the fixed idea that costs are already at
their minimum.
6. “But we’ve already been doing things that way!”
7. “We don’t want people looking over our shoulders and
telling us what to do!” and
8. “Everything is going just fine now. Why change it?”
Here we have a general reluctance to change the status quo.
This is very common among workers in factories that are still
managing to turn some kind of profit.
9. “That’s a lousy ideal! We already tried that 20 years
ago!” and
10. “Look, we understand this stuff better than anybody (so
don’t tell us what to do).”
Finally, here we have the kind of resistance that is born out
of cockiness and defensiveness.
Alas, JIT means having to deal with all kinds of people
and their reluctance to change. JIT improvement has tended
to stir up the same old resistance that has arisen many times
in the past. Many years ago, General Electric ran into the
same kind of resistance when it was making big changes
with VA/VE programs.
Destroying Factory Myths
Innovations come in waves. Each time a new wave of innovation comes roaring in, the environment must be flexible
enough to adapt to it. People are innately tough customers­
when it comes to buying ideas that threaten the status quo.
And in factories, the word “change” is virtually taboo.
Nevertheless, JIT improvement requires that all fixed ideas
be cast aside so a new consciousness suitable for the new
environment may be cultivated. Achieving this task takes much
longer than merely improving operations or equipment. It
demands that the very same things be done again and again.
From the company president down to the factory workers­,
the subject of improvement has to be openly discussed.
During such discussions, we are bound to run into negative
comments, such as, “There’s no way that JIT stuff is going to
work in our factory.”
There is also the idea that the people responsible for JIT
improvement are not qualified for the job. In such cases,
they can prove their point by asking the disgruntled factory
people a few pointed questions, such as:
“Look at your factory. Defects are out of control, shipments
are always late, and warehouse inventory seems to have no
limit. What are you going to do about it? What specific plans
do you have to solve these problems?”
The response to that is usually dead silence. Sometimes,
you have to challenge fixed ideas directly.
People are not going to unleash themselves from their
gut feelings of resistance and their fixed ideas unless they
are instilled with the basic spirit of improvement. Figure 2.4
shows a policy statement illustrating this basic spirit at a
kitchenware company. Figure 2.5 shows a manifestation of
this spirit at a fishing equipment manufacturer.
These signboards usually measure about one square meter
and are made of vellum. They can be either hung from ceilings or posted on walls. It is a good idea to display these
signboards not only in management meeting rooms, but also
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Statement of Basic Spirit
1 Let’s throw out the “how-to” habits (the factory’s myths)!
2 Don’t try to explain why it won’t work, think of a way to
make it work!
3 Instead of making excuses, make the current situation
different!
4 Immediately start doing what is right and stop doing
what is wrong!
5 Don’t wait for the perfect plan; 60 percent is better than
nothing!
6 Fix mistakes right then and there!
7 Wisdom grows out of difficulties!
8 Ask “Why?” at least five times to find the true cause!
Then find out “How” to make the improvement!
Remember the five W’s and one H!
9 Ten wise men are better than one whiz kid.
10 Improvements are unlimited!
Figure 2.4 Basic Spirit of Improvement at a Kitchenware Company.
in factory meeting rooms and at various processes along the
production lines.
This way, whenever someone starts griping, “We can’t do
that,” we can save our breath and just point at the sign.
These signboard statements of the “basic spirit” for
improvement can serve as bold reminders for workers who
have forgotten what the basic spirit is all about.
If not out of sight, the “basic spirit” is less likely to be kept
out of mind.
Approach to Production as a Whole
Fixed Ideas and the JIT Production Approach
In most factories, fixed ideas about how things should be
manufactured are unwittingly created over the years. The fact
that they get created is bad enough. Worse still is the fact that
they are quickly adopted as the gospel truth.
In other words, such fixed ideas are developed into a local
“mythology” at each factory, and the factory’s inhabitants are
Destroying Factory Myths
O-N-P Basic Spirit
1 Do it now!
2 No excuses!
3 Make the forms we need!
4 Bring the top managers into the factory to check
out the problems!
5 Destroy the myths!
6 Improvements are unlimited!
7 Things can only get better than they are now!
8 Don’t wait for the perfect plan. Getting at least
halfway there is better than not trying.
9 Ask “Why?” at least five times to find the true cause!
10 Fix mistakes right then and there!
11 Don’t waste time thinking about it—do it!
12 Finish what you start!
13 Don’t let worries slow you down!
14 Don’t waste energy thinking of reasons why it won’t
work. Think instead of ways to make it work.
15 Wisdom arises from difficulties!
16 Don’t throw money at problems, use your brains! And if
your brains aren’t enough, use your sweat!
17 You won’t have the ability to do it until you have the
mind to do it!
18 Constant “fine-tuning” of equipment is not a
good thing—it means operators are covering up
for faulty engineering.
19 Constant money will not produce more money!
20 Those who do not want to do the job are not fit for the job!
21 Lot sizes show how strong the company is!
22 Ignore any orders without a deadline!
Figure 2.5 Policy Statement at a Fishing Equipment Company.
naturally suspicious of anything that threatens to desecrate
such sacred lore as the following.
“Economy means economy of scale: Lot sizes must be at
least 1,000 units.”
“Fine-tuning the dies is how a die press operator shows his
skill.”
“Sampling inspection is the most intelligent way to find
defects.”
“Stand to work? You must be kidding! This work takes precision handwork, and you’ve got to sit down to do that.”
“I’ve been working here for 20 years and I’ve already
­figured out the best way to do this job.”
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I could go on for pages and pages with more of these
“myths.” There seems to be an inexhaustible supply of “why
it’s got to be done this way” myths at every factory.
The people who still subscribe to these myths have little
idea how outdated they became when the “whatever you
make will sell” era came to a close. They may hear consumers
complain, but they don’t really listen to the complaints and
think about them.
It is amazing how many factories are still like that.
When visiting such factories to discuss the JIT production system, I have sometimes gotten the impression that
introducing JIT improvement programs at factories so firmly
rooted in shish-kabob production is like praying to a horse
or giving a penny to a cat.
As I said earlier, we have to begin with the awareness
revolution. It is a good idea to somehow make the need for a
change in consciousness a topic on everyone’s mind at both
the start and end of the workday routine. It is also a good
idea to make the adoption of the JIT production ­system
a theme for QC circles and other small group ­
activities.
Another effective device is to invite outside experts to give
employee seminars.
If the 5S’s are the foundation for improving the factory, then
we could say that the awareness revolution is the premise­
for JIT production. If we can change people’s minds, we can
do anything.
JIT production system concepts should be used to overhaul conventional thinking and cannot simply be used to
supplement the old philosophy. Hard as this is, JIT awareness revolution means discarding work methods that are the
result of years of study and experience, and long-accumulated
know-how. It even goes beyond that and requires everyone
to consider the present way of doing things as the worst
possible way.
The kind of “improvements” called for by the JIT production system are not the easy kind of minor improvements that
Destroying Factory Myths
make current conditions a little bit better. JIT improvements
begin in the mind, expand to every corner of the factory, and
take root to radically change the factory. They do not simply
make the current situation a little better. Each JIT improvement is an innovation, a revolutionary advancement that introduces a whole new concept and m
­ ethodology. It is probably
more correct to describe the activity of JIT improvements as
“­revolutionizing the factory” rather than merely improving it.
Likewise, a JIT awareness revolution does not just improve
our ideas about manufacturing systems—it introduces revolutionary, boldly innovative ideas.
Lesson 1. JIT Means Innovation
“Just-In-Time”
To put it briefly, Just-In-Time means manufacturing and procuring “just what is needed, just when it is needed, and just in the
amount needed.” The Just-In-Time concept must be applied
not only to manufacturing, but to all other aspects of the business, including subcontracting, procurement, and distribution.
As mentioned earlier, Just-In-Time tends to be interpreted
as meaning “in time,” which is quite wrong.
The “In Time” concept is already fairly well observed in
factories everywhere. After all, a factory cannot function
­
unless its buyers and subcontractors deliver their goods in
time for them to be used in the factory. Similarly, a downstream process cannot operate on workpieces until the workpieces have been finished at the previous upstream process.
Outside vendors and subcontractors all have deadlines
for the products they deliver to specific processes in the
client factory. These deadlines are extended down the line
as a delivery deadline for product shipment to sales firms,
and then as the sales firms’ delivery deadline for shipment
to customers.
If we think of Just-In-Time as simply beating the delivery
deadline, we understand very little of what JIT is all about.
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Beating the delivery deadline is what “in time” means. Just-InTime means something quite different.
Let us suppose next Friday is our delivery deadline date.
The In Time concept interprets this as meaning we need to
deliver our products by next Friday. We could deliver them
next Thursday if we wish. We could even deliver them on
Monday. Or, if they are ready now, we could send them over
immediately and not even wait for next week.
The same principle can be seen at work within factories.
For instance, next to the press machine there might be a
large pile of workpieces that has been sent down from the
previous process. The In Time concept says that is OK. In
fact, though, the workpieces are a little too much in time.
Compare that with an example in which the press operator calls out “Ready!” and immediately receives a single workpiece from the previous process. He presses it, then calls
out “Ready!” again and receives another workpiece. Here we
have a manifestation of the Just-In-Time concept.
But even when we add the term “just” to “in time,” we still
are not saying half of what Just-In-Time really means.
This is because the JIT production system is more than
just a new production method and production system for
maintaining delivery deadlines, building things in small production runs, and so on. It is also a technique for thoroughly
eradicating waste by rooting out deep-seated waste wherever
it exists in the company—in both factories and offices—and
using JIT improvements to eliminate the waste.
Let us consider for a moment just how thorough this eradication of waste under the “Just” concept really is.
For example, if we interpret the “just” in Just-In-Time as
meaning “about one month,” that means the factory is allowed
to operate with one month of inventory-related waste.
If we take the “just” to mean “about one day,” then we will
have a day’s waste. We can go on to even smaller time increments, such as an hour, minute, or second, and in all of these
cases we are managing the factory based on a waste measure.
Destroying Factory Myths
The JIT production system uses the “just” in Just-In-Time
as a waste gauge. In this sense, this Just concept lies at the
very heart of the JIT production system, and this system will
not work at factories that have forgotten to eradicate waste as
­thoroughly as possible. Likewise, a person who doubts the
need to thoroughly eliminate waste will not be able to capably­
carry out JIT improvements.
If the reader is such a person, I suggest he or she put
down this manual, and just get back to work.
Lesson 2. Take “Just” to the Max!
Production Is Music: Help Your Factory
Play a Masterpiece
I’m not really talking about inviting an orchestra into the f­ actory
to perform. But music does serve as an apt metaphor for the
sweet harmony of a level-running factory. Production is a lot
like music. Waste-free production is like a stirring composition, a masterpiece if you will. Music includes three essential
ingredients: melody, rhythm, and harmony. In masterpieces,
all three of these elements are masterfully composed and
performed. Conversely, no matter how original and ­alluring
the harmony is, if the melody is awkward or the rhythm
inconsistent, the result will be less than a masterpiece.
The exact same thing goes for the hum of product-building
in factories. What does the factory offer as the closest ­analogy
for melody? On a sheet of music, the melody is usually a
string of notes placed according to tone on the five-line t­ reble
clef form. I suppose the factory analogy for the melody would
be the flow of workpieces from one process to the next.
Sometimes this flow continues in straight lines, and at other
times it makes U-turns. Sometimes the workpieces move along
one at a time, and at other times they flow together in lots.
The most melodic of factory melodies is the “flow manufacturing” system.
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What would serve as an analogy for rhythm? There are so
many types of rhythm, from the graceful waltz to the snappy
tango and the fast-paced rock ‘n’ roll beat. In the factory, the
rhythm is the pitch of production, the rate at which work-inprocess moves through the flow of production. We also call
this the cycle time. Some products can bebop through the line
with a very rapid rhythm while others need to waltz along.
The rhythm of the factory must be “leveled” to keep in
pace with the cycle time.
Finally, what can we call the harmony of the factory?
Harmony means a concordant combination of tones, a blend
that is pleasing to the ear. The factory makes harmony when its
people, materials, and machines come together in a waste-free
combination that unites all three in harmonic activity.
“Standard operations” are what we use to build such an
efficient and harmonious combination of people, materials,
and machines.
Thus, production—like music—has three essential ingredients. Flow manufacturing, leveling, and standardized o
­ perations
are to production what melody, rhythm, and harmony are to
music. (See Figure 2.6.)
These three elements make up the lion’s share of what is
needed to establish JIT production and are the mainstay for
introducing the JIT production system. Please remember this
as part of the procedure for introducing JIT production. And
please remember that it takes much time and effort to create
a factory that can delight us with masterpiece production.
Figure 2.6
Music
=
Production
Melody
=
Flow production (one-piece flow)
Rhythm
=
Leveling (cycle time)
Harmony
=
Standard operations (combination
charts and operations charts)
The Three Essential Elements of Music and Production.
Destroying Factory Myths
Lesson 3. Production Is Music
The Next Process Is Your Customer
In Japan, it is not hard to find factories that have “The Next
Process Is Your Customer” signs posted here and there.
Usually, this saying is understood as referring to the need to
provide good quality and to prevent defects. In other words,
since the next process is your customer, be sure to deliver
only the best products.
However, if you have a close look at these factories, you
will find that many of them operate completely under a “push”
method of production. This robs some of the true meaning
from “The Next Process Is Your Customer” slogan.
When looked at in terms of how goods are moved through
the line, there are only two types of production methods.
(See Figure 2.7.)
The first is the method in which workpieces that have been
finished at one process are immediately sent on to the next
process. This is what we call “push” production. Sometimes
this method calls for transfer tags to be attached to each
workpiece, and the tag is marked each time the workpiece
is transferred downstream. In this method, the movement
Push Production
Next process
Previous process
Transfer tag
Forced
sale
Merchandise
Merchandise
Work-inprocess
pile
Pull Production
Money
(kanban)
Store
Customer
Merchandise
Figure 2.7
Push Production and Pull Production.
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of goods is not sensitive to the readiness of the receiving
­process. At each process, workers simply follow the production schedule in deciding what to do next. Once that is done,
they send the finished workpiece along to the next process.
We could say that the previous process is “forcing” the sale
of its product to the customer at the next process. If the next
process does not happen to be ready for the workpiece, the
worker there has to say something like, “Oh, you’ve finished
another one already. Well, just set it down over there.” Soon
there is a work-in-process pile.
In stark contrast to this is the “pull” production method, in
which the “customer” at the downstream process goes to the
previous process to get “just what is needed, just when it is
needed, and in just the amount needed,” which he pays for
with a currency called kanban.
This makes the previous process a sort of “store” that the customer (next process) visits. Of course, the store is responsible
for selling only high-quality merchandise to its customers.
The key difference between these two production methods
is their respective proximity to the production method called
for by the production schedule. In other words, it is the way
they relate to the flow between information and materials.
This flow between information and materials is illustrated
in Figure 2.8. In the “push” production example, the final
assembly schedule (i.e., production schedule) is used as the
basis for creating delivery schedules for all of the subassembly­,
processing, and materials processing stations. All of these
stations are part of the in-house production system.
The same delivery schedule also includes delivery deadlines for parts procured from outside vendors and subcontractors. There are various names for this kind of production
planning, such as “required volume planning,” “parts development,” or Material Requirements Planning (MRP). Note that
MRP is usually a computer-based system for schedule parts
and materials deliveries based on the production schedule.
Destroying Factory Myths
Push Production
Required volume
planning
Production
planning
Procurement
(outside vendor
schedule)
Materials
processing
schedule
Processing
schedule
Subassembly
schedule
Buyer
(of outside
vendors’
products)
Materials
processing
stations
Processing
stations
Subassembly
stations
Main
assembly
stations
Pull Production
Production
Schedule
Buyer
(of outside
vendors’
products)
Materials
processing
stations
Processing
stations
Flow of information
Figure 2.8
Subassembly
stations
Main
assembly
stations
Flow of materials
Flow of Information and Materials in Push and Pull
Production Systems.
Usually, the production schedule must deal with a complex
array of components numbering in the hundreds, thousands,
or even tens of thousands, and often a computer is brought
in to assist in the scheduling tasks.
The major drawback is that the information and materials
are not matched. The information is out anywhere between
three days and a week before the goods. In other words, the
required volume planning is completed several days before
the planned products are manufactured at the factory. It is
during these several days that the required goods are delivered to the factory and operator instructions are issued.
Another problem is that each process operates according to its own instructions, completely independent of other
processes. We call this type of production “independent
process production.”
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Independent process production suffers from inflexibility in the face of scheduling changes. For various reasons,
the production schedule might undergo one revision after
another, but these changes cannot be easily carried over
to the individual production processes. As a result, the first
“official” delivery deadlines in the original production schedule become firmly established as each independent process’s
delivery deadline and are thereafter very difficult to change.
The process station’s workers tend to regard such last-minute
changes as an intrusion and a hassle. This does not bode
well for these Japanese factories in today’s era of a high yen,
ongoing trade friction, and diversifying customer needs.
By contrast, the “pull” production method has, in principle, no delivery schedule save for the final assembly ­schedule
(production schedule). The main assembly processes “pull”
just what they need from the subassembly processes. Since the
subassembly processes use processed parts, they in turn pull
just what they need from the processing line. In other words,
nothing happens upstream until something has happened
downstream. Since production at the previous (upstream)
processes depends on production at the next (downstream)
processes, we call this production method “previous processdependent production.” This type of production emphasizes
the true importance of the next process as the customer.
In light of these two very different types of production,
we could argue that at most of the factories that display “The
Next Process Is Your Customer” signs, the real meaning of
the signs is “We pretend to use kanban.” Unless the factory is
actually using pull production instead of push production, its
kanban do not amount to anything more than a “­theoretical”
or “decorative” improvement. Unless the factory realizes the
importance of matching information with the materials and
aggressively revamps its whole production system with a
“proactive improvement” attitude, the waste inherent in the
push production system will not be removable.
Destroying Factory Myths
Lesson 4. The Ocean Pulls the Flowing River
“Stop and Go” Production and
“Process and Go” Production
A factory where the company president is cautiously watching over the machines and equipment is a tragedy. The main
character in this tragedy is not the president, but rather the
equipment operators who live under the president’s gaze.
Imagine a factory where the company president has just
had the latest, most sophisticated equipment brought in, and
now stands there telling the operators, “It’s your job to o
­ perate
these things. Get to it!”
Imagine, in this age of diverse models and small lots, a
company president having installed all sorts of machines
designed for mass production and then commanding the
workers, “Set the machines up for the whole range of
­product models and start turning out products!” Imagine the
kind of agony those workers are going through in trying to
use machines that are fundamentally incompatible with the
f­ actory’s needs.
No doubt the company president had thought that the latest­
machines and equipment would readily solve his f­actory’s
various problems.
He may be proud to inform us, “This is great! This new
equipment will double our production capacity!” or, “This
brand new equipment will take care of our quality problems.
He might even go so far as to claim, “This new equipment
will enable us to meet our client’s delivery deadlines.”
Let us suppose that the factory has usually been incapable
of meeting its client’s short delivery deadlines, and that is one
big reason why the president bought the latest equipment,
which is supposed to cut processing time in half. The goal
here is to shorten the manufacturing lead-time.
Shortening lead-time by reducing processing time is a
mighty bold and eccentric way of doing things. We can spend
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a fortune on faster processing machines and still not shorten
the lead-time one bit. We might succeed, however, in shortening the life of the company.
When we look at production as a flow of materials, we
can recognize four main categories of components in this
flow: retention, transfer, processing, and inspection. The first
thing this teaches us is that making things requires much
more than just processing.
As we go through the manufacturing process, imagine
that you are one of the parts that has been delivered to the
factory and is about to undergo the entire lead-time of the
manufacturing process. To start with, you are warehoused
along with the other purchased parts and materials. This falls
under the “retention” category. Now, it would be nice if the
processing machines could walk over to the parts warehouse,
pick out the things they need, and process them, but we have
not reached that day yet. So the factory needs to move you
and all the other goods from the warehouse to the processing machines, a task that falls under the “transfer” category.
Next, you and the other materials that have just been
delivered to the processing machines sit in a pile until the
machines finish processing the previous lot of materials. This
sometimes takes a long time. At last, the machines start in
on the first of your lot of materials. You are the last in that
lot and are still waiting. All of this waiting is part of the
“­retention” category.
Finally, you—the last of the lot—are picked up and, in a
few brief seconds, get processed. Those fleeting seconds are
in the “processing” category.
After being processed, you are plopped onto a pile of processed units. Then you go through another round of retention,
transfer to the next group of process machines, more retention,
and processing.
To return to our music analogy, we can say that the four
parts of this manufacturing process—retention, processing,
Destroying Factory Myths
Stop-and-Go Production
Parts
warehouse
Machine 1
Retention
point
Machine 2
Retention
point
Inspection
Retention
point
Retention points: 8 (6 in factory)
Transfers: 4
Product
warehouse
Retention
point
Processing points: 2
Inspections: 1
Process-and-Go Production
Parts
warehouse
Product
warehouse
Machine 1 Machine 2 Inspection
Retention
point
Retention
point
Processing Processing
Retention points: 4 (2 in factory)
Transfers: 2 long, 2 short
Processing points: 2
Inspections: 1
Figure 2.9 “Stop-and-Go Production” and “Process-and-Go Production.”
retention, and transfer—comprise the four-beat bar of music
that most factories use to add value to materials.
Just as only one four-beat bar can hardly be called music,
we need to repeat the bar a number of times to create the
“music of production.” In view of retention’s large role in
this type of production, we shall call this type “stop-and-go
production.” (See Figure 2.9).
Within the four-beat, stop-and-go pattern of this type of
production, the beats that take up the lion’s share of the
manufacturing lead-time are the two “retention” beats. In the
example shown in Figure 2.9, there are eight retention stages
from the parts warehouse to the products warehouse. Six
of these retention stages are within the factory, where they
directly relate to the manufacturing lead-time.
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There are lots of retention points, and together they eat up
a lot of time. Once a pile of workpieces is set down somewhere, it tends to stay there for half an hour, an hour, or more.
Sometimes part of the pile gets left there overnight to make
operations or changeover more convenient. Meanwhile, parts
that have been delivered to the parts warehouse can easily
wait there for a month or more. Whether the total retention
time adds up to hours, days, or weeks, it still eats up a tremendous amount of lead-time. Retention is clearly the worst
culprit when it comes to lead-time consumption.
Materials do not do anything but wait at retention points.
Having several retention points means we must have some
means of moving materials from one retention point to the
next. That is where the “transfer” category comes in.
The nice thing about this category is that it never comes
close to eating up as much lead-time as the “retention” category
can. In most factories, each transfer takes one or two minutes.
Still, outside vendors can take several hours to transfer parts
and materials to the factory. In any case, out of retention,
transfer, and processing, transfer is the second worst culprit.
Inspection is a separate culprit altogether and should be considered apart from the categories that make up the four-beat
pattern of production.
Finally, we have the “processing” category, which eats up
the least lead-time. A single workpiece’s total processing time
in the factory commonly adds up to a minute or two. Most
individual processes take less than a minute. Some take only
several seconds. Press processes usually range between one
and two seconds, while drilling machines average about two
or three seconds.
It should be obvious by now that bringing in the latest
production equipment to shave a few seconds off of the
total processing time is not going to help much in reducing
the overall lead-time to enable earlier product shipments to
­customers. A pressing need to meet the client’s short delivery
Destroying Factory Myths
deadlines is therefore not much of a reason for any company
president to invest in the latest production equipment.
Obviously, the best way to shorten the manufacturing leadtime is to get rid of the worst culprit: retention. Once we
do that, our stop-and-go production system can be turned
into a “process-and-go” production system in which the fourbeat pattern of retention, process, retention, and transfer are
replaced by the four-beat pattern of process, transfer, process,
and transfer.
Today, shorter lead-times are in big demand by consumers
and are also a major factor enabling the expansion of client
orders. Old and worn as the expression is, it still rings quite
true in the world of manufacturing: “Time Is Money.”
Lesson 5. When the Flow of Goods Stops,
the “Lead-Time” Clock Keeps Ticking
Approach to Efficiency: Estimated Efficiency
and True Efficiency
Factories are full of talk about efficiency. Factory people are
always trying to improve the equipment operators’ efficiency,
the equipment’s own efficiency, the efficiency of the operations, and various other types of efficiency. The prevalent
attitude is, “Let’s try to turn out products even just a little bit
better than we do now.”
Different people, however, have very different understandings of this “efficiency” concept. Most people view such things
as efficiency and productivity as a ratio of “output”-to-“input.”
In other words, people think of productivity as the value of
production output divided by the cost of production input.
This definition is expressed as an equation below.
PRODUCTIVITY =
PRODUCTION OUTPUT
PRODUCTION INPUT
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Assuming that this equation is correct, one could propose
three measures for boosting productivity
Measure 1: Increase the production output.
PRODUCTIVITY ↑ =
PRODUCTION OUTPUT ↑
PRODUCTION INPUT →
In this equation, I have used arrows to indicate constant
levels (→), increases (↑) and decreases (↓).
Measure 2: Decrease production input.
PRODUCTIVITY ↑ =
PRODUCTION OUTPUT →
PRODUCTION INPUT ↓
Here, we have kept the production output constant (→)
but have lowered (↓) the production input, which raises
(↑) productivity.
Measure 3: Increase production output and decrease production input.
PRODUCTIVITY ↑ =
PRODUCTION OUTPUT ↑
PRODUCTION INPUT ↓
This is a combination of Measures 1 and 2, in which we
raise (↑) productivity by lowering (↓) production input and
raising (↑) production output. Obviously, there are also other
ways to boost productivity, and there are various ways of
applying the three measures just described.
When we think of “raising” productivity or efficiency, the
notion of “raising” tends to lead us first to Measure 1, in which
we aim simply to raise production output.
For instance, let us consider the example shown in
Figure 2.10. Here, we have a factory that is trying to boost
productivity by increasing the number of product units manufactured daily by ten people from 200 units to 250 units.
According to the productivity equations illustrated, the
“­estimated efficiency” plan in Figure 2.10 should have worked
Destroying Factory Myths
ESTIMATED EFFICIENCY
Our
production
order is for
200 units.
Figure 2.10
We can do better
than that. We’ll
make 250 units!
TRUE EFFICIENCY
Ten people making 250 units
means 50 units of waste. On the
other hand, eight people making
200 units means improvement.
Estimated Efficiency and True Efficiency.
to boost productivity. However, the important thing to note here
is that no matter how much we boost the production o
­ utput,
there is no real gain unless the client’s production orders keep
pace with the increase. Making products that are not on order
with a client is simply creating waste—over­production waste
and warehouse waste.
The most important equation to remember is:
Volume of orders = Production output
If the current volume of orders and the current production
output are both 200 units, there is only one measure to use
to boost productivity: Measure 2 (decrease production input).
Cutting the required production staff from 10 persons to
8 persons­would be a true improvement in efficiency. I would
like to stress that the manpower reduction approach is an
indispensable means of improving efficiency.
Therefore, the JIT production system would have us change
the productivity equation to read as follows.
VOLUME OF ORDER = PRODUCTION OUTPUT
PRODUCTION OUTPUT
PRODUCTIVITY =
PRODUCTION INPUT
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Lesson 6. The Customer Decides
How to Improve Efficiency
Manpower Reduction
As in the case of “human automation” (jidoka) rather than “automation,” manpower reduction also has a special meaning within
the JIT production system. In Japan, this particular meaning of
manpower reduction was born in the 1970s, when oil crises
ushered in a “stable growth” era. From about 1955 until the
early 1970s, Japan enjoyed a period of rapid economic growth
with fast-expanding markets which encouraged manufacturers to restrict the variety of products and maximize the output
volumes. Today’s commonly known concepts of “­automation,”
“labor reduction,” and “manpower reduction” have been inherited from the rapid-growth, small-variety, large-lot era.
The validity of these concepts and their methodologies has
steadily diminished in recent years. Market expansion is no
longer a given, and consumer needs are clearly becoming more
diverse and individualized. In order to continue to provide
products attuned to market trends, manufacturers are being
forced to switch over to wide-variety, small-lot production.
While expanding product variety and shrinking modelspecific volumes, manufacturers must also keep their prices
down to succeed in today’s highly competitive markets. This
difficult business environment encouraged the development
of the “worker hour minimization” concept behind JIT’s manpower reduction. Basically, this concept says that production should have an output matching market needs, using
the minimum number of workers (minimum labor cost) to
produce that output in a timely manner. (See Figure 2.11.)
We are all familiar with the popular “labor reduction”
and “employee reduction” concepts. Both of these concepts
remain within the framework of rigid staff assignment systems. Generally, each equipment operator is responsible for
handling only certain different types of equipment. As a
Destroying Factory Myths
Labor
Reduction
Staff
Reduction
Manpower
Reduction
Market changes
Market changes
Market changes
....
Figure 2.11
(Rigid staff
assignments)
(Rigid staff
assignments)
(Flexible staff
assignments)
Less labor by
existing staff
Reducing staff
regardless of
market changes
Maintaining
minimum staff
needed to meet
market changes
Labor Reduction, Staff Reduction, and Manpower
Reduction.
result, the staff assignment system is not flexible enough to
accommodate suddenly lower market demand for some of
the company’s products.
Strictly speaking, labor reduction means that even when
the market demand drops or automation advances, the company does not decrease the number of its workers. Instead,
the company only reduces the amount of labor the workers
perform. Personnel costs remain the same.
Staff reduction means reducing the number of staff when
demand goes down or when automation makes workers
redundant. The redundant workers are still kept within the
same rigid staff assignment system. This has nothing to do
with market fluctuations, but is done simply to reduce staff
at certain jobs.
By contrast, manpower reduction means promptly changing staff assignments at each process in the factory to reflect
the latest market changes. Once it is known what the current
client orders are, the factory produces exactly that volume of
products while using only the smallest required number of
staff. Obviously, this system requires a flexible staff assignment system instead of a rigid system.
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Thus, the basic principle of JIT manpower reduction is
prompt and flexible adaptation of factory operations and staff
assignments to incorporate current market trends. As such,
JIT manpower reduction goes hand-in-hand with a flexible
production system and contingency management.
The following essential items enable such manpower
reduction and market adaptability.
Flow manufacturing—One-piece flow manufacturing in
pace with market demands is essential for JIT manpower re­
duction. Instead of allowing materials and products to pile up,
one-piece flow manufacturing turns out just what is needed,
just when it is needed, and in just the required amount.
Multi-process handling—This means linking production
equipment in lines that suit the flow of products, and having
each operator handle several processes within the flow manufacturing system. This requires that operators stand (and
walk) while they work, and that they be trained in various
equipment-operating skills.
Separating human work and machine work—This
process begins by grouping all the little “islands” of operators
and their equipment into a flow-oriented line (or manufacturing cell), thus placing together both people and machines.
Next, the operators get trained in multi-process handling and
are taught how to separate their work from the machine’s
work. Finally, they work out ways to reduce human work
(such as in setting up and removing workpieces) by changing
conveyor configurations or other means.
Movable machines—No matter how brilliant an improvement plan is, it may end up in the trash can if machines are
unable to be moved to positions specified by the plan. Needless to say, such obstacles can put a damper on enthusiasm for
improvement. The worst offenders are the machines that have
been bolted to the floor, seemingly stuck there for eternity.
Since the market is always changing and improvements make
progress from day to day, it only makes sense that equipment
Destroying Factory Myths
Figure 2.12
Attaching Casters to Make Equipment Movable.
should be movable enough to enable equipment­layout
changes when switching production over to different product
models. Figure 2.12 shows an example of how immovable
equipment can be made movable.
Standard operations—Operations that vary from person
to person create big problems. Instead, we need to standardize operations and develop jidoka to make the operations
standard and simple enough for anyone to learn easily. We
begin by standardizing current operations and then proceed
to make improvements.
Flexible staff assignment system—Instead of the traditional fixed staff assignment system, we should be using a
system that is flexible enough to accommodate staff assignment changes in accordance with labor requirements set by
market demand.
Mutual aid system—Even the best-laid plans for balanced workloads can run into trouble when the production
pitch gets too high or when some other problem causes
an imbalance in workloads. To prepare for such eventualities, workers­should be able to temporarily lend a hand
to adjacent upstream or downstream workers. Such “mutual
aid systems” are especially helpful during that tricky phase
when process improvements are being worked out. As such,
the mutual aid system should be considered a prerequisite
for improvement programs.
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Lesson 7. Move from Labor Reduction to
Worker Hour Minimization
Individual Efficiency and Overall Efficiency
Imagine a home electronics manufacturing plant, in which
20 or 30 female assembly workers are standing along an
assembly line conveyor, busily building TVs or VCRs. Those
not familiar with this kind of work find such an arrangement quite amazing. They also wonder exactly what all those
assembly workers are doing.
Almost all of the workers on such assembly lines perform
work that includes five or six simple screw turns or wire
bonds, and they perform this task over and over all day long.
(See Figure 2.13.)
In such cases as this, we set a pitch time of 30 or 40 seconds,
then the workers work together trying to keep up the pace.
To the ordinary observer, it appears that all of the workers
are doing just this. However, someone trained in JIT who has
a sharp eye for identifying waste would cite this as a prime
example of “idle time waste.”
The fact is, if you have 30 people working on a line, their
actual production pitch will vary significantly from person to
Component Efficiency
Pitch: 10 seconds
m!
o
Zo
Overall Efficiency
Pitch: 30 seconds
Pitch: 30 seconds
Sweatband
One person works frantically
(and without a conveyor) to assemble
one unit every 10 seconds.
Figure 2.13
Component Efficiency and Overall Efficiency.
Destroying Factory Myths
person. Some people may always finish in 10 seconds while
others struggle and sometimes take longer. Once a worker
has finished assembling a unit in 10 seconds, she should
have nothing to do but start in on the next unit. This is
where conveyors come in handy. They keep the flow moving
at one unit per pitch increment. But when a worker finishes
early, she must wait out the remainder of that pitch increment
until the conveyor brings the next unit. There is nothing she
can do for her neighboring workers during this time.
Although everyone claims to be working precisely at the
pitch time, faster workers have their work slowed down by
slower workers. This kind of “coordinated work” is actually
quite susceptible to “idle time waste.”
The conveyor’s disadvantage is that it tends to hide idle
time waste and its advantage is that it keeps things moving at
the pitch time. This means that no matter how much improved
an individual’s efficiency becomes, that improvement can still
do nothing to raise the line’s overall efficiency. Obviously, it
would be quite valuable to have individual efficiency improvements reflected in the line’s overall efficiency. But we can see
that there is a clear difference between individual efficiency
and overall efficiency.
If we take the same assembly line, remove the electric
conveyor, and instead have the assembly workers lined up
beside one long workbench, the units will gradually begin to
pile up next to certain workers due to individual differences
in pitch. The piles of work-in-process reveal all those hidden
individual differences in pitch.
If we break up the long workbench into individual workbenches for each worker, then the piles of work-in-process
become even more obvious.
If we separate the individual workbenches by some distance, it would leave room for work-in-process to pile up
indefinitely. The line would soon lose all signs of having a
production flow. So you can see why JIT professionals have
so little interest in the “coordinated work” arrangement.
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This example also underscores the fact that efficiency
improvement has nothing to do with upstream or downstream processes and has everything to do with raising
efficiency at individual processes. To do this, sometimes
factories “­automate” a task that is being performed either
manually or by a simple machine by installing a high-speed
machine, computer-controlled machine, or other absurdly
expensive machine.
I sympathize with such factories, and there are a lot of
them. In fact, I would say that the vast majority of the world’s
factories are guilty of these kinds of mistakes.
I am not denying that individual improvements in efficiency can add up to an overall improvement throughout the
company. But the improvements have to start with individual
people, machines, and processes, and only then should they be
developed into improvements in line efficiency, factory-wide
efficiency, and company-wide efficiency, including the sales
and distribution arms. It is very important to maintain this
kind of comprehensive view of efficiency improvement.
Once management installs and activates highly sophisticated and ultra-expensive machinery on the production line
to improve efficiency at certain processes, it is naturally concerned about getting its money’s worth. This leads it to press
for higher and higher capacity utilization rates. In the meantime, the idea of letting client orders determine production
output gets put on the back burner.
In this day and age, the comfortable notion that if a p
­ roduct
is made, it will sell one way or another, no longer holds true.
The smart idea for today is, “Let’s make only what will sell, but
make it more efficiently.” Once we take this perspective, pushing up capacity utilization for its own sake is clearly a mistake.
Pressing and forging processes are prime targets for managers who limit their view to process-specific efficiency improvements. Both of these processes require die changeover, which
tends to take a long time. The managers try to minimize this
time consumption by minimizing the number of necessary
Destroying Factory Myths
die changes. The way to do that is by making fewer models­
in larger lots. Soon the factory is back to the old large-lot
­orientation. The problem is the managers’ belief that the fewer
the die changes, the higher the efficiency.
These managers have forgotten that production includes
more than pressing and forging processes. Unless production
is made level throughout all processes, the overall result may
well be a loss in efficiency.
The JIT production system not only includes techniques
for thoroughly eliminating waste, it also includes techniques
for creating and maintaining a level production flow. We need
to stand firmly behind both of these principles.
Lesson 8. Where Muddy Streams Appear,
Floods May Follow
Approach to Waste: Just-In-Time and Cost Reduction
“We’ve found it! Now let’s get rid of it!” Words such as these
are often used by improvement teams that finally pinpoint
a true cause of waste, inconsistency, or irrationality and set
about making the improvement to eliminate it.
The Just-In-Time concept is a very effective tool for eliminating these three evils. It is especially useful for eradicating waste
in such common manifestations as “overproduction waste,”
“idle time waste,” “conveyance waste,” and “warehouse waste.”
Figure 2.14 illustrates some of the essential ingredients in
any well-organized effort to eliminate waste and cut costs.
Kanban and Cycle time
conveyors determined
by required
Just
volume
-inTime
Production
Flow
“pulled” by
manufacturing
downstream
processes
Cost reduction
Level production
Figure 2.14
Just-In-Time and Cost Reduction.
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These ingredients are described below.
1. Cycle time is determined by the required amount
Usually, factory managers use equipment capacity and/or
manpower resources as a basis for determining the cycle
time or pitch. That is a big mistake. If, for instance, we
know that our equipment can handle a 20-second pitch,
but our client orders are not enough to cover the resulting amount of production volume, we are going to have
a product glut. Conversely, if we select a pitch that is
too slow to keep up with client orders, we will have a
product shortage.
Obviously, the right thing to do is make client orders the
basis for setting the cycle time or pitch.
2. Production is “pulled” by downstream processes
Unlike the flow of rivers, the impetus for the production flow should not be upstream processes “pushing”
the work-in-process to downstream processes, but rather
downstream processes “pulling” the work-in-process from
upstream processes. In other words, the worker at the next
process is truly the customer in that he or she goes to the
“store” (the previous process) and “buys” what is needed.
This effectively prevents unneeded work-in-process from
being passed downstream.
3. Implement flow manufacturing
Just-In-Time production is impossible as long as work-inprocess is grouped into lots, which we call “shish-kabob”
production. Instead, work-in-process must move in single
units all along the “flow manufacturing” line.
4. Use kanban and conveyors between appropriate processes
Flow manufacturing stands at the very core of Just-InTime production and is therefore essential to the JIT production system. However, the current level of technology
for certain processes that involve heat treatment or gilding still require the lot production method (or subcon-
Destroying Factory Myths
tracting). It is therefore appropriate to use kanban and
conveyors between these processes.
5. Level production is a prerequisite
In order to make all of the factory’s processes flow as
level as possible, we need to have a thoroughly even distribution of product models and volumes. Once we have
leveled the assembly lines, we can synchronize them
and level them with the subassembly lines, and finally
the parts processing lines.
Lesson 9. The Amount of Cost Reduction Achieved
Is Proportionate to the Amount of Effort Invested
When Economical Lot Sizes Are Not Economical
As mentioned earlier, pressing and forging processes require
metal dies. Drilling processes need bits, and cutting processes need blades. As for the assembly processes, they
need to deal with multiple components. None of these facts
pose any problems as long as the factory produces only one
product model. But single-product factories are an endangered species.
In today’s manufacturing world, factories must always be
switching their production from one product model to the
next. Naturally, this means that metal dies must be changed
at pressing and forging processes. Drill bits and blades need
to be changed at drilling and cutting processes. And component sets need to be changed at assembly processes. We use
the term “changeover” in reference to all of these types of
equipment set-up work.
Not surprisingly, workers tend to dislike changeover and
would much prefer to avoid product model changes by sticking with single-model large-lot production. Large lots are
naturally more popular at factories than small ones. But
­
­anyone responsible for managing the company’s operating
capital will be quick to point out that there must be limits to
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l
ota
st t
o
c
us
l
vio
ota
e
r
P
st t
o
c
w
se
Ne
ou s
reh cost
a
W ce
an
en
t
in
a
m
Costs
Cost
reduction
Previous changeover costs
New changeover costs
Smaller
lots
Figure 2.15
Volume
Changeover Improvement for Smaller Lots and Lower
Costs.
lot sizes. The need to balance these opposite interests gave
rise to the “economical lot sizes” concept.
As shown in Figure 2.15, the economical lot size is the lot
size that achieves the best balance between (that is, the lowest
total for) inventory maintenance costs and changeover costs.
It is not too difficult to understand how economical lot
sizes can be determined based on process-specific cost measures. However, this method of determination may not work
so easily on a larger scale, such as an entire production line
or an entire factory.
On such larger scales, it becomes apparent that making lot
sizes even just a little smaller will benefit such economical
considerations as lower warehouse investment costs, turnover
of operating assets, profit ratio, and cash flow.
We also need to remember that production lead-time is not
simply the sum of process-specific operation times. Lead-time
is actually proportionate to production lot size, which is to say
the amount of work-in-process. Therefore, a long lead-time
means that a great deal of work-in-process must still be
manufactured before the product can be shipped. If production schedule changes are made after a production run has
already begun, the flow of materials and information in the
Destroying Factory Myths
factory—and the flow of management processes—will all fall
into disorder. Production cannot be made that flexible.
In JIT, we use “factory graveyards” as a nickname for the
kind of warehouse inventories factories accumulate when they
stick to large-lot production. Such factories may seem impressive in the huge array of materials they contain, but their true
“insides”—full of concealed waste and other problems—are
in pretty bad shape.
Today, factories should not resemble those large, awesome,
but hopelessly outdated beasts known as dinosaurs. Rather,
they should be more like small, agile, and alert mice.
Once we have managed to shorten the manufacturing
lead-time, we can responsibly shorten the main schedules,
such as for sales and production, and can be more flexible
toward schedule changes. As a result, we can help minimize
“lost opportunities” in marketing.
In dealing with today’s fast-paced technological advances,
we can also help minimize the impact of all-too-frequent
design changes. In other words, having a shorter lead-time is
a key factor enabling adaptability to changing sales figures.
It also saves time. And since time is money, it saves money.
Thus, smaller lots do not necessarily mean higher costs.
When we look at the various components of warehouse
maintenance costs, we find: interest, insurance, taxes, storage costs, and obsolescence costs.
How do these costs compare with higher changeover costs
incurred by small-lot production? Such costs include: manufacturing-related clerical costs, mechanical changeover costs,
loss of materials, and set-up and removal (labor) costs.
Let us take a close look at these two sets of component
costs. It should be easy enough to spot which set is most
conducive to improvements.
In the first set of component costs, almost all of them resist
improvement, no matter how hard the company employees
might try to attack them. For instance, the only way to reduce
warehouse maintenance costs is by decreasing lot sizes.
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By contrast, the component costs for changeover—such
as the manufacturing-related clerical costs, mechanical
changeover costs, and loss of materials—are all amenable
to improvement if people get together and brainstorm some
improvement ideas. In short, these costs are prime targets for
JIT improvement activities.
In fact, JIT shows us how we can even get rid of our fixed
idea of “lots” by changing factories into a level system where
products are built in short production runs without disturbing the overall flow of the factory.
Lesson 10. Do Not Neglect the Economic Forest by
Focusing on Economic Trees
Motion and Work
One of the things factory workers tend to mumble on their
way out the gate at the end of the day is something along the
lines of, “Man, I worked my tail off today.”
Ordinarily, we take such expressions at face value. But
if we look beneath the surface, we will find that different
people have widely different understandings of the meaning
of “work.” Some people feel that simply being at the company for eight hours is work. These people make time their
measure of work, in that every minute or even every second
they spend at the company is regarded as work. They watch
the clock and keep careful track of their overtime as defined
in the employee’s manual.
Other people evaluate work in terms of “sweat.” There
is a long tradition in Japan and in the West of regarding a
person’s perspiration as irrefutable evidence that he or she
is hard at work. People are suspicious of work that does not
cause the worker to sweat. In fact, given a choice between
two equally productive work methods—one that produces
sweat and one that does not—they will usually pick the
sweat-producing method.
Destroying Factory Myths
Then there are people who derive their sense of work
satisfaction from the “added value” their work produces.
­
These are just a few of the different ways people understand
the meaning of work.
I would suggest that the people I first described—the “time”
workers—are actually more “not working” than working. The
“sweat work” people perform more motion than work. It is
the “added value” people that come closest of the three to
actually working. For simplicity’s sake, we will include the
“not working” people in with the “moving” people.
As I mentioned earlier, people have different perceptions
of work. Even within a single day’s work time, we can recognize such differences between the “moving” people and the
“working” people.
Equipment operators ordinarily work an eight-hour day.
Obviously, not all of that eight-hour time is spent working. In
fact, the great majority of that time is spent “moving” rather
than “working.” (See Figure 2.16.)
As noted in Figure 2.16, “work” is only the part of the
operations that actually adds value. Every other part of the
OPERATIONS
Figure 2.16
MOTION
WORK
WASTE
ADDED VALUE
Everything within these
operations that does
not add value is regarded
as motion, which can
also be called waste.
Only that which adds
value is called work.
Motion and Work.
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operations is called “motion” rather than “work.” In everyday
work operations, there is rarely a clear distinction between
actions that actually are “working” and those that merely are
“moving.” The two just mix together in our overall actions.
What seems to be “working” at one instant may turn into
“moving” at another, and vice versa.
It is not easy for an untrained eye to distinguish between
the two. Many factories make the careless mistake of starting
out their improvement campaigns with the general notion
that whatever moves is work and what does not is waste.
Obviously, their improvement campaigns are not going to
be very successful until they learn to make the distinction
between “work” and “motion.”
Waste that is not recognizable as such is the most insidious
kind of waste. If we can learn to recognize this kind of waste,
we are well on our way to success in eradicating waste.
The following is a list of some of the things we might
encounter as we stroll through a typical factory. Odds are
that we would not be able to recognize these motions as
10 examples of waste.
1. Workers grunting and groaning as they carry a heavy load.
2. Workers counting parts once the operation is done.
3. Workers moving stacks of parts from the floor to a cart.
4. Workers inserting parts into plastic bags before sending
them downstream.
5. Workers removing the plastic bags from parts received.
6. Workers who have finished today’s work and are proudly
starting in early on tomorrow’s.
7. Workers securing parts to be processed.
8. Workers repeating the cycle of picking up parts, processing them, and setting them down elsewhere.
9. Workers watching out for defects while their machines
are operating.
10. Workers searching for parts, tools, or jigs.
Destroying Factory Myths
The above are 10 typical examples of waste in factories. I
could list more. In fact, I could fill this entire book with typical
examples of waste. That is how much waste exists in factories.
Imagine standing with the president of the company that
owns the factory and watching such a waste-filled factory in
operation. What do you suppose the president might say if
you remarked, “Boy, your workers are really moving around
a lot, aren’t they?”
Unfortunately, a large number of company presidents
would respond with something like, “Yeah, our factory people really work hard for us.”
Personally, I would not blame you if you responded to
that by making a sour bulldog face and stomping out of the
­factory. When people fail to recognize the difference between
“motion” and “work,” you can be sure their eyes are blind
to waste. Let us see just how different “motion” and “work”
really are.
The only result of motion is higher costs. Well, actually,
it has one other result: eating up profits. Now you see why
we call “motion” waste. In sharp contrast to this, the result
of “work” is to fulfill a function. This function is generally a
value-adding function.
Motion and work are mixed together within the typical
equipment operator’s activities. But motion (waste) is clearly
the main ingredient. As a result, the equipment operator’s
activities actually add very little value.
Consider the example of a press operator illustrated in
Figure 2.17.
1. The first step in the press operator’s activity: picking up
and moving an unprocessed workpiece.
This movement adds absolutely no value to the workpiece. Therefore, it is an example of waste. The waste
can be reduced by shortening the distance of this movement. Of course, the best thing would be to eliminate
the movement (and the waste) altogether.
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PRESS
1
2
6
4
5
3
UNPROCESSED
WORKPIECE
Figure 2.17
PROCESSED
WORKPIECE
Activity of a Press Operator.
2. The second step: moving a hand to push a button.
A complete waste. The worker’s hand is not holding anything and is moving through empty air.
3. The third step: pushing the button.
During the instant it takes to push the button, the worker
is adding value to the workpiece. To be precise, this
button-pushing operation takes about one second,
­
assuming the press is a relatively small one weighing
about 100 tons. And while we are being precise, we
should note that even that one-second button-pushing
operation includes some waste. The time it takes the
upper die to reach the workpiece—the time the upper
die spends pressing nothing but air—is waste. And that
accounts for almost all of the time it takes to press the
workpiece. And we should also note that in this process,
it is the machine—not the worker—that adds the value.
4. The fourth step: moving a hand to remove the workpiece.
Again, the worker moves his hand through empty air.
All waste.
5. The fifth step: removing the processed workpiece, moving it,
and setting it down nearby.
Moving the workpiece is just handling time. All waste.
6. The sixth step: moving to pickup the next unprocessed
workpiece.
All motion, no work. All waste.
Destroying Factory Myths
In this example, the easiest way to reduce waste is to
reduce the distance the worker must move in order to pickup
unprocessed workpieces and set down processed ones.
As just described, almost everything that happened in this
example was a form of waste. We should remember that anytime “working” means taking workpieces down from shelves,
setting them down, or carrying them somewhere, it is not
actually “work,” but “motion.” And motion means waste.
Recently, companies have started to rationalize their conveyance and improve their material handling procedures,
in many cases by introducing Automated Guided Vehicles
(AGVs) or other automatic material handling vehicles. These
devices are generally very well received in factories, since they
spare workers the chore of having to lug materials around.
But they should not be viewed so optimistically.
Generally, these automatic transport systems do little or
nothing to speed up material handling or shorten the distance involved therein. The best approach is to think, “Let’s
cut off transport-related waste at the root.”
I call this kind of automation “skin-deep automation” or
“make-believe automation,” since in the final analysis it just creates conveyance-related, equipment-related, and energy-related
waste. The genuine solution is to begin by organizing and
regulating the factory to improve the equipment layout to the
point where they no longer need conveyors of any kind. The
idea is to proceed with caution before adopting any simple
“automation” plan.
Lesson 11. Operations Should Flow
Like a Clear Stream
Inherited Waste and Inherent Waste
No matter how good a factory is at manufacturing products,
you can bet that it stands knee-deep in waste. Starting with
the most obvious, we could cite a typical factory for having
too wide a “green belt” around it, having too large a building,
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having management functions that no one seems to understand, and so on.
Waste can be found hiding in even the most magnificent
factories. And in factories at the other end of the quality
spectrum, just about everything we see is waste.
I remember when, during one factory inspection tour, the
company president first led me into what appeared to be a
warehouse. Everywhere I looked I saw parts, products, and
boxes stacked almost to the ceiling. I advised that we look at
the factory and then come back to the warehouse. Then the
company president’s smile dropped into a frown as he said,
“This is the factory.”
In an attempt to lessen his embarrassment, I offered,
“Oh, I thought it was a warehouse since there aren’t any
workers here.”
But my host’s face only turned a brighter shade of red.
“No, they’re over there, behind those boxes,” he said.
He was right. There they were, hidden from view by stacks
of boxes, as if playing hide-and-seek.
The situation was so bad in that factory that I saw a
worker stretching to place more parts boxes on top of a stack
that was already too high. Like a stack of pennies, the stack
reached the point of instability and I began to wonder if it
would fall.
Just as I saw the stack swaying dangerously to one side,
another worker appeared out of nowhere just in time to help
set the stack even. The company president and I applauded
their fast-thinking teamwork.
Then I thought to myself, “It’s amazing that such a spirit of
cooperation survives in a place like this!”
This whole affair makes for a humorous anecdote, but
there is nothing funny about it as far as the company’s future
is concerned. In fact, there are a great number of factories
that are just as comical and just as pitiful. It is no exaggeration to say that, in most cases, it is not a matter of finding
waste in the factory, but of finding the factory in the waste.
Destroying Factory Myths
These days, I often hear of factories that, barely turning a
profit, suddenly decide to “rationalize” and “modernize” by
installing computer-based management and robot systems.
Meanwhile, waste lives on as a nonendangered species. The
waste lives on in new forms as the factory is reorganized,
computerized, and automated. JIT improvement experts call
this “systematic waste-making” and regard it with unmitigated disgust.
Let us take an example of “waste-making computerization.”
Once a factory introduces a new production system, the
managers need to make up a new bill of materials. Such bills
of materials are used to indicate which parts are needed to
build which products. (See Figure 2.18.)
The various steps (or “layers”) in the production system
from the materials stage to the final product stage is called
the “depth” of the bill of materials. Generally, more complex
products have deeper bills of materials.
Consequently, some manufacturers are proud of having
very deep bills of materials, since this is seen as evidence of
how complex and sophisticated their products are. In most
cases, though, the depth of a bill of materials is much more
a function of how complicated the production system is than
a function of product complexity.
The reason why a part or assembly part gets established as
an item in the bill of materials is that the part requires some kind
of “management.” Generally, these kinds of items include:
◾◾ Materials: ordering and delivery management (order
management).
◾◾ Parts (group 1): work instructions (operation management).
◾◾ Parts (group 2): work-in-process planning (work-in-process
management).
◾◾ Parts (group 3): supplies for outside vendors (supplies
management).
◾◾ Assembly parts: feed assembly parts to assembly lines
(assembly feed management).
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Parts list before improvement
Parts list after improvement
Products
Products
Parts (group 3)
(caulking)
Depth of parts list (1 layer)
Assembly parts
Depth of parts list (5 layers)
82
JIT
improvement
Parts (group 2
(drilling)
Parts (group 1)
(pressing)
Materials
Materials
Production method
before improvement
Materials
Pressing
Parts
(Group 1)
Parts
(Group 2)
Caulking
Production method
after improvement
Parts
(Group 3)
Drilling
Pressing
Parts
(Group 1)
Drilling
Parts
(Group 2)
Parts
(Group 3)
Outside
vendor’s
subassembled
goods
Assembly
parts
Caulking
Materials
Subassembled
goods
Assembly
parts
Products
Figure 2.18
Assembly line
Products
Depth of Parts List and the Factory’s Production Method.
Assembly line
Destroying Factory Myths
In the factory, where work-in-process stocks tend to pile up,
work-in-process management, as well as operation management aimed at preventing defects and improving efficiency,
are important enough to warrant inclusion as items in the bill
of materials.
However, we should also regard including these items in
the bill of materials as evidence that work-in-process tends
to pile up and that the flow of goods does not always flow
in a level manner. Perhaps the work-in-process piles up precisely because the flow of goods is not level. The piling
up of work-in-process creates the need for management.
The managers then want to have a computer to help them
­manage the flow of goods.
Once they bring a computer in, a waste-filled flow of goods
gets augmented by a waste-filled flow of information. The
end result is a waste-filled production management system.
Naturally, any system that creates so much waste is bound
to have a deep bill of materials. And as the bill of materials
gets deeper, more and more things get included as items to
be handled at the factory. The vast numbers of items to be
handled and accounted for create a need for an expensive,
sophisticated computer system.
The factory now includes a whole new task: entering the
long (and still growing) list of bill of materials items into the
computer system. And then there is the additional big task of
revising the computerized bill of materials whenever the bill
is changed, due to things like the installation of new equipment. A third computer-related task is the lengthy processing
required to calculate the required material orders for such a
deep bill of materials. All those computer-related tasks create
the need for a staff of trained computer programmers and
operators. As you can see, waste creates more waste.
The same kind of self-perpetuating growth of waste can
occur when factories hastily introduce industrial robots or
other automated equipment. A waste-filled factory becomes
an automated waste-filled factory. The waste gets processed
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automatically by systems such as AGVs, automated warehouses,
and other automatic material handling lines.
The worst part of this phenomenon is that waste that would
have been relatively easy to identify and remove becomes
much more firmly embedded and hidden in the manufacturing system after it is carried over into sophisticated systems
such as automated production lines. Waste gets harder and
harder to remove. Eventually, it gets to the point where the
entire factory, or even the entire company, must be torn apart
to be improved.
Lesson 12. Remove Waste Before It Sinks Deeper
Improving the Intensity and Density of Labor
Generally, we tend to think of improvements, rationalization,
and removing waste as means of intensifying labor. In factories where workers have strong unions, there has sometimes
been a great deal of resistance to such changes. Naturally,
the changes have to be worked out in negotiations with the
union leadership.
Union leaders have sometimes expressed opinions such
as: “We’re already working as hard as we can! There’s just no
room for improvement.”
Not surprisingly, such narrow-minded thinking usually
comes from companies that are operating in the red. Such
thinking also shows just how little the employees understand
about the waste hidden in work operations.
As explained earlier, each work operation consists of two
parts: “motion,” which is action that does not directly add
value to the workpiece and is therefore waste, and “work”
which does add value. Motion—the wasteful part—is usually
by far the larger of the two parts.
JIT improvement is a program for thoroughly removing
the enormous amount of waste hidden in work operations.
Figure 2.19 illustrates the waste elimination technique that
forms the basis of JIT improvement.
Destroying Factory Myths
LABOR INTENSIFICATION
Work
Operations
Work
Waste
Work
Work Waste
“working” “moving”
Waste
Waste
Waste
Work
Work
Waste
Removing waste
Work
HIGHER LABOR DENSITY (improved efficiency)
Figure 2.19
Improvement of Labor Intensity and Labor Density.
If we were to simply increase the amount of work without
removing waste, the workers would have a very good reason
to complain. Such a change would be nothing more than
intensifying their labor.
We need to make a large and important distinction between
the intensity and the density of labor. Intensifying labor without removing waste aims solely to increase production output.
For instance, we can require the workers to work faster, which
would raise the production output. This is what intensified
labor alone means.
This is not the right way to go about improving things.
We need to take a very different approach—improving labor
density. We start by finding and removing waste from within
work processes. More specifically, this waste elimination
stage includes:
◾◾ Understanding the entire work process.
◾◾ Quickly recognizing the actual value-adding function of
the process.
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◾◾ Applying the concepts of “motion” and “work” to study
the work process.
◾◾ Distinguishing clearly between wasteful “motion” and
value-adding “work.”
◾◾ Immediately doing whatever is possible to remove wasteful “motion” from the work process.
Let us consider an example. A certain press worker’s work
process starts with fetching a workpiece from a site about
eight feet away and pressing it. The first improvement is to
have the workpieces set close enough so that the worker
does not need to take any steps to reach them. That one
improvement removes 16 feet (round trip) of “walking waste”
or about six seconds of “time waste.”
Now, what shall the worker do with these six seconds of
freed-up time? Ideally, they should be used for value-adding
actions. If this can be done, we can “naturally” (that is, without strain) translate that much more labor time into higher
production output. In other words, we can increase the production output without intensifying labor. The worker will
work at the same speed as before, but will “naturally” have
greater output.
The more we can increase the ratio of “work” to “motion”
within a work process, the greater the density of labor
becomes. By definition, higher labor density means more
value is added to the product per unit of labor cost.
Now you can see why we call removing waste the very
basis of JIT improvement. The thing that JIT improvement
team members need to be most careful in checking is whether
or not their improvements actually remove waste.
In view of the above, it is fair to say that JIT improvement
does not in any way require intensification of labor.
Any worker in any factory should be able to confirm this
for him or herself. If the worker feels that an improvement
has sped up the work or has made it more difficult, it can
only be a sign of errors in the improvement.
Destroying Factory Myths
Lesson 13. Removing Waste Means Turning
Wasteful Motions into Productive Work
Approach to Inventory and Lead-Time:
Inventory and Lead-Time
Everyone—the manufacturers and their clients—face a highly
competitive business environment. In the economic jungle—
as in the real jungle—you either eat or are eaten. This harsh
business environment has led to rising client demands for
lower costs and shorter delivery deadlines. For their part,
factories seek “compressed delivery deadlines.”
Imagine some company managers who, faced with tough
market competition, come to you for advice on how to shorten
delivery deadline periods by as much as 50 percent. Let us
also assume that the factory managers have already tried
installing new equipment and implementing a TQC program,
but without the expected results. They are getting desperate
for answers.
Now imagine how surprised they would be if you were to
simply suggest, “That’s easy enough, just reduce your c­ urrent
inventory 50 percent.” No doubt, they would probably appear
mystified and wonder how the subject of conversation got
switched from delivery deadlines to inventory. Again, you
need only explain, “What’s the mystery? It’s really very ­simple.
Just cut the current production lot sizes in half.”
Now watch what happens. Their minds, already bewildered
by your connection of delivery deadlines and less inventory,
collapse into total confusion as they consider yet a third
apparently unrelated factor: lot size.
Maybe someone will seek to clarify things by asking, “Let
me get this straight. We cut delivery deadlines in half by cutting inventory in half, which means cutting lot sizes in half.
But doesn’t that mean we’ll also be cutting our production
output in half?”
Now they are getting somewhere. You can continue by
adding, “Cut output in half? Yes, I suppose it does. But you
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can fix that by doubling the number of production runs.”
Again, mass confusion. “Wait a minute. We cut inventory and
lots in half and then we double the production run?”
By now, their brains’ logic circuits have probably shorted
out and their ears are about ready to start spurting fireworks.
That might be a good point to end the consulting session,
and just leave them to think about it.
It is truly amazing how many top managers at manufacturing companies are ignorant of basic production principles.
They should at least be able to immediately recognize the
relationship between lead-time and inventory.
Let us look at the line chart shown in Figure 2.20 below.
Quantity
300
d
ive
ce
e
r
t
un
o
Am
t
sen
nt
u
o
Am
200
Manufacturing
lead-time
Amount of in-process
inventory
100
80
60
40
20
0
7/1
2
3
4
6
7
8
9
10
11
13
14
15 Time
7/1
2
3
4
6
7
8
9
10
11
13
14
15 Total
25
37
0
0
24
61
24
24
24
85
21
45
23 24 21 20 24 24 26 22 23 21
313
108 132 153 173 197 221 227 269 292 313
23 23 21 24 23 22 26 24 25 20
276
68 91 112 136 159 181 207 231 256 276
Remainder
37
12
37
40
40
Time
received/
sent
Received
Sent
41
41
37
38
40
40
40
36
Actual number
Total
Figure 2.20
Line Chart.
37
Destroying Factory Myths
The vertical axis in this chart represents “quantity” while
the horizontal axis stands for “time.” The broken line shows
the “amount received” and the solid line the “amount sent.”
Manufacturing lead-time is what fills any gap between the
amount received and the amount sent. Wider gaps mean
longer lead-times. Moreover, longer lead-times mean larger
amounts of in-process inventory.
In other words, the relationship between manufacturing
lead-time and in-process inventory can be described using
the following two equations.
Manufacturing lead-time =
in-process inventory expressed in day units
Amount of in-process inventory =
manufacturing lead-time × daily production output
Although our example refers to in-process inventory, it can
be applied similarly to inventories of products or m
­ aterials.
If we cut our product inventory in half, we need to cut
our lead-time in half, too. The same goes for our material
inventory. If we cut that in half, we need to cut the delivered
lots in half and double the number of deliveries.
In the factory, problems crop up in all kind of areas,
including delivery deadlines, quality, and inventories. None
of these problems exist independently of the others. They
are all interrelated, and we must learn how they connect.
Factories having trouble meeting delivery deadlines are
probably also suffering from excess inventory, difficulty in
switching to wide-variety and small lots, and ongoing missing parts and other defects. All of this relates to what we call
“the character of the factory.” The most visible aspect of this
“character” is inventory. The inventory situation is so visible
that a JIT consultant can generally appraise it immediately
upon entering the factory.
Inventory is the JIT consultant’s best teacher.
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Lesson 14. Inventory Tells the Whole Story
Why Is Inventory Bad?
Many of us think of inventory as a “necessary evil.”
During times of booming markets and brisk sales, we
appreciate the necessity of inventory as the “ammunition” for
doing business. But when the market boom fizzles out and
sales slump, we suddenly feel the “evil” of inventory, too.
Inventory is thus a two-faced entity, sometimes an angel and
sometimes a devil. In JIT production, inventory always has
only one face: the Devil’s.
If you were to ask me why inventory is a bad thing, I could
give you the following general reasons.
1. Inventory adds weight to the interest payment burden
Anytime we need to procure capital, we must pay the
cost of such capital. The general term for this cost is
“interest.” For whatever amount of time the materials
purchased with such capital sit “idle” as inventory, the
invested capital does nothing except incur interest debt
and is therefore a pure and simple addition to the company’s interest payment burden.
2. Inventory takes up space
Obviously, inventory has some bulk and therefore needs
space. If we allow inventory to accumulate, we soon must
either put up with cramped factory floors or must invest
further capital in new shelves or new warehouse facilities.
3. Inventory creates the need to convey and handle waste
Stopping something to keep it in one place implies
movement before and after the stopping. Moving things
to intermediate locations from where they will need to
be moved again, and loading and unloading these things
from the conveyors are all forms of waste.
4. Inventory invites defects
If left idle long enough, “nonperishable” items will begin
to rust or otherwise suffer time-related deterioration.
Destroying Factory Myths
Simple logic also dictates that the more times a thing
is handled, the greater its chance of receiving dents or
other damage-related defects through mishandling.
5. Inventory creates unnecessary management costs
We incur storage costs whenever we stop the flow of
goods and we incur transportation management costs
whenever we move those goods. The more defects we
have, the more we must put out for QC. A poorly-run
factory eventually finds itself up to its ears in management costs.
6. Inventory eats up valuable stocks of materials and parts
We cannot make products out of thin air. We must have
the materials and parts to make them. If we use our current inventory of materials and parts to make products
that cannot be sold immediately, and therefore sit idly as
product warehouse inventory, we have eaten up stock
of materials and parts—the value of which will become
painfully clear if a big order comes in for a different
­product that we now lack the components to make.
7. Inventory gobbles up costly energy
Unnecessary inventory means unnecessary consumption of energy. Whether that be electricity, pneumatic or
hydraulic power, or whatever, the company has to pay
for it.
These are just some of the “evils” of inventory. And I have
not even mentioned the real reason why inventory is bad.
When you get right down to it, inventory is bad because it
conceals the factory’s problems.
All factories have problems. Problems pile up in even the
very best factories. Inventory casts a sort of camouflaging
shroud over these problems, and this makes the problems
that much harder to analyze and solve.
For instance, workers at a process that turns out defective
products by the dozens may choose to pile up a “buffer” stock
of products for inspection. The inspectors can identify and
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Inventory
(used to avoid superficial problems)
Increased retooling
Occurrence of defects
Equipment
breakdowns
Unbalanced processes
Missing items
Schedule revisions
Large
equipment
Factory
(Problems pile up in every factory.)
Figure 2.21
How Inventory Conceals Problems in the Factory.
pull out the defective products and thereby prevent “passing along trouble” to the next process. But this solution only
covers up the real problem, which is the process’s tendency
to turn out defective goods. The inspection stock (inventory)
solves the superficial problem of “passing along trouble” but
does nothing to address the real problem. (See Figure 2.21.)
The more a factory uses inventory to escape its peripheral problems and avoid dealing with its real problems, the
more the real problems will grow, sending roots deeper and
deeper into the manufacturing system. Eventually, they begin
to weaken the very “character” of the factory. In this way, it
is fair to call inventory “the opium of the factory.” Like an
opium habit, the inventory habit is best never started.
Lesson 15. Inventory Is the Opium of the Factory
Inventory and Finance
Just about everything under the sun has some sort of function. One gizmo’s function is to take in coins and dole out
refreshments, while another’s is to conduct electricity and
Destroying Factory Myths
convert it into light. Everything that has a function requires
some kind of input and produces some kind of output. In
many cases, that output becomes some other thing’s input.
The same principle can be seen at work in companies. In
the case of manufacturing companies, they acquire capital,
lay in stocks of materials, turn these materials into products,
and then sell the products to acquire, among other things,
recyclable capital.
We find a similar situation when we switch from managing materials to managing money—which many regard as the
pivotal aspect of company management. Put very briefly, the
function of finance management is to procure and operate
capital. Capital procurement is the input and capital operation is the output.
Now we are ready to ask, “What is inventory’s role
within the context of this money-recycling activity we call
finance management?”
Please look at the balance sheet shown in Figure 2.22. The
right side of the balance sheet is the credit side, which lists
liabilities and shareholders’ equity. The left side is the assets
side. Usually, the capital procurement figures are listed in the
liabilities section while the operating figures are listed in the
assets section.
In the balance sheet shown in the figure, the assets and
liabilities are listed in ascending order of “fluidity.” To make
this fluidity a little easier to grasp, we added a downward
arrow and the term “cash-convertible” next to the credit side.
This cash-convertible arrow indicates that the lower an item is
positioned on the assets list, the easier that item is to c­ onvert
into cash.
As we can see in the balance sheet, inventory items such
as finished goods, work-in-process, and materials are positioned within the more cash-convertible category of “current
assets.” However, they are not as cash-convertible as other
items in that category, such as cash, notes receivable, and
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Assets
Liabilities
Total Assets
Figure 2.22
xxx
Total Liabilities and
Shareholders’ Equity
Reimbursable
I. Current Assets
I. Current Liabilities
xx
xx
Notes payable
Cash
xx
Accounts payable—trade x x
Notes receivable
xx
Short-term loans payable
Accounts receivable—trade x x
xx
xx
Accrued amount payable
Finished goods
xx
and accrued expense
Work-in-process
xx
xx
Allowance for taxes
Materials
II. Fixed Liabilities
II. Fixed Assets
xx
Property, plant, equipment
Bonds payable
xx
xx
Buildings
Long-term loans payable
xx
Machinery and equipment x x
Allowance for employee
xx
Land
retirement benefits
xxx
Intangible fixed assets
Total Liabilities
Good will
xx
Shareholders’ Equity
xx
Patent rights
I.
Capital
stock
xx
Investment and other assets
xx
x x II. Legal Reserve of
Investments in securities
xx
Investments
Retained Earnings
x x III. Surplus
III. Deferred Charges
xx
Voluntary reserves
xx
Unappropriated retained
earnings at end of term
(Earnings at end of term) x(x x)
Total shareholder’s equity) x x x
Procurement
Balance Sheet Summary
(As of [date])
Operation
◾
Cash-convertible
94
xxx
Position of Inventory in a Corporate Balance Sheet.
trade-related accounts receivable. In fact, they are the least
cash-convertible of all of the current assets.
The task of managing a company’s activities begins with
procuring capital. If this procured capital can be recycled
within a year, it is considered a “current liability.” If recycling
takes a year or more, it becomes a “fixed liability.” In either
case, having use of the capital incurs a capital cost known
as interest.
As mentioned earlier, the company uses this interestbearing capital to lay in stocks of parts and other materials,
add value to the materials through manufacturing, then sell
the finished goods for a profit, part of which can be recycled
into further capital.
The gist of the problem is that people in these companies
work so hard to earn the profit used to recycle ­capital, only
to waste that capital by “putting it to sleep” in raw material­s,
Destroying Factory Myths
work-in-process (in which some value has already been
added), and products that do not “move” but just sit there
as inventory.
Capital costs “move” with the clock and thus never sleep.
The company must keep paying these costs while its inventory snores away.
It should be apparent by now just how much inventory
betrays the whole principle of finance, which is to “procure
and operate capital.” Although businesspeople make use of
the term “inventory investment,” the truth is that inventory
alone offers no return on investment and therefore should
not be considered an investment at all. How helpful it would
be if everyone kept this simple fact in mind.
Lesson 16. Inventory Is Not an Investment
When “Appropriate” Inventory Is Not Appropriate
People in training for the job of inventory management often
run into texts with titles along the lines of, “Inventory: Not
Too Much and Not Too Little Keeps Production Running
Smoothly.” “Not Too Much” foreshadows the text’s admonitions to drastically reduce inventory.
But what does “Not Too Little” refer to? It refers to a common piece of advice: Make sure you have at least some excess
inventory. It does not mean “minimize” inventory. It says that
we are supposed to maintain a little “fat” in the inventory, but
not too much.
The philosophy behind this “keep a little fat” approach to
inventory is that having a little extra inventory on hand as
a sort of “buffer” will enable the factory to respond quickly
to surprise sell-outs or shortages of materials and products.
However, in view of the wide range of products demanded
of factories by today’s diversifying market needs, how little
can “a little fat” really be and still serve as a buffer? We have
to face the fact that, in today’s marketplace, surprise sell-outs
and parts shortages are still bound to happen when we
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maintain a slightly (or even seriously) overweight inventory­.
Planning a little fat into our inventory in preparation for or
in response to product sell-outs is a sure-fire way to end up
with lots of excess inventory.
Inventory managers find themselves between a rock and a
hard place: Too little inventory results in parts shortages and
too much puts a heavy load on business management. This
uncomfortable situation has helped give rise to a wonderful
concept: “appropriate inventory.”
Appropriate inventory means enough inventory to avoid
a strain on capital while also avoiding loss of sales due to
shortages. It sounds great in theory, but how can appropriate
inventory be realized?
There are even some formulas we can use to determine
appropriate inventory levels. In one formula, the calculation
is based on the sales target. The other is based on cash flow.
There are many different formulas expressing different inventory management perspectives.
For example, the following formula is common for sales
target-based calculations.
APPROPRIATE = ANNUAL SALES TARGET (VALUE)
INVENTORY
MERCHANDISE TURNOVER
Let’s insert some actual figures into this formula by saying
that annual sales target (value) equals $32 million and merchandise turnover is 16 times per year.
$32 Million
APPROPRIATE =
= $2 Million
INVENTORY
16 times (per year)
We can also use these figures to calculate the inventory
per merchandise turnover time as follows:
365 days / 16 times = 22.8125 days
This means a turnover cycle of about 23 days. But is this
theory going to work in practice?
Destroying Factory Myths
In today’s wildly erratic markets, how likely is it that any
manufacturing company’s $32 million sales target will really
be that accurate? And how many manufacturers can afford to
ignore the considerable impact seasons and climactic changes
have on sales? Sales levels are easily influenced by the strategic
actions of competitors. And then there is the unpredictability
of raw material prices, currency exchange rates, and so on.
Understandably once a company’s sales division sets its
annual sales target, the sales managers must come up with
all sorts of ad hoc strategies to actually reach the target. We
also need to ask exactly how managers determine the merchandise turnover rate that serves as the denominator in the
above formula.
Ordinarily, they use past merchandise turnover rates as
their basis for calculation. They then apply various business
performance indices as well as the company’s current goals in
determining the current year’s merchandise turnover. These
factors change according to the production lead-time and the
yield, but they do not change as easily as the sales levels.
So, we can already see that the appropriate inventory is
determined using a formula in which both the denominator
and the numerator are prone to instability.
Using a formula that divides one unstable factor by another
unstable factor to obtain what is treated as a stable value is
like trying to divide one negative number by another negative
number to obtain a positive number. To put it another way,
the appropriate inventory value obtained using the above
formula is only as reliable as the unreliable figures used in
the formula. (See Figure 2.23.)
Better that we should face the facts: Even if we take the
unreliable figures for annual sales and product turnover
and temper them with adjustments for estimated seasonal
changes, lead-time, and profit ratios, we can still end up with
an inventory level that is way off from what turns out to be
actually needed.
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Our company maintains
an appropriate inventory
of 1.5 months’ worth.
How can they say that
is ‘appropriate’? l thought
the appropriate inventory
was zero!
Changeable
data
Figure 2.23 Estimated Appropriateness and Real Appropriateness.
Certainly, it is very important that companies set targets
for sales totals, inventory turnover, and other important business performance measures. However, when companies start
entrusting these figures to provide them with a prescription
for appropriate inventory, it is very easy for them to adopt an
attitude of trying to uphold the validity of the figures for the
sake of “stability” and at the expense of actual conditions.
Rather than hoping to banish the term “appropriate inventory,” I would only hope everyone remembers that the only
really appropriate inventory is zero inventory.
Lesson 17. The Appropriate Inventory is Zero Inventory
Estimated Lead-Time and Real Lead-Time
Customers are very picky people. They tend to suddenly want
products that they never even bothered to look at before.
And when they want them, they want them now.
Fashion wear is a prime example of this. Fashion boutiques
regularly report cases where some outfit that has stood virtually unnoticed in the window for weeks suddenly starts
catching shoppers’ interest. Even in the world of food, there
is the old saying, “The food that tastes best is whatever you
want to eat at the time.”
Destroying Factory Myths
These days, customers are like people who suddenly fall
ill in the middle of the night. They may not have seen a
­doctor in years, but now they need one. Right now, in the
middle of the night. There is no time to wait.
A factory’s customers rush to order suddenly vital products
and want them shipped ASAP. If the factory doesn’t fill their
needs, they will probably try a different factory next time.
Today, very few factory managers can still afford to tell
such customers, “Look, these are all the models we make,”
or “We’ll need at least three months before we can ship it.” In
a sense, customers have already embraced the Just-In-Time
concept: “What I want, when I want it, and in just the amount
I want.”
Customers end up asking for products to be manufactured
and shipped immediately, and factories can only reply, “Sorry,
but it takes time to make those things.” This creates a gap
between customers and manufacturers. Manufacturers have
come to regard inventory as something that fills this gap.
We call the period between the customer’s placement of an
order and the customer’s receipt of the product the “­customer
lead-time.” Even if we assume that the factory can begin
manufacturing the ordered item right away, this customer
lead-time must still include the time needed to make the
order. This period is called the manufacturing lead-time. The
customer lead-time also includes the time needed to deliver
the product, which is called the “transportation lead-time.”
Let’s stop there, omitting any consideration of time needed
for clerical work in processing the order, and construct the
simple formula:
Customer lead-time = manufacturing lead-time
+ transportation lead-time
Figure 2.24 shows two illustrations based on this formula.
However, this lead-time is not short enough to meet the
customer’s delivery deadline. So let us suppose that the
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REAL LEAD-TIME
Customer lead-time
Manufacturing lead-time
Transportation
lead-time
Use
(customer)
Make
(factory)
ESTIMATED LEAD-TIME
Customer lead-time
Manufacturing lead-time
Retention
Make
(factory)
Keep
(warehouse)
Figure 2.24
Transportation
lead-time
Use
(customer)
Estimated Lead-Time and Real Lead-Time.
company decides to put up a warehouse between its factory
and its customers in order to do away with the manufacturing lead-time and enable a shorter “estimated lead-time,”
whose formula would simply be:
Customer lead-time = transportation lead-time
Here, the warehouse is supposed to make up for the disadvantage of having a manufacturing lead-time. It also means
the factory managers can more comfortably plan their production schedules, since they only need to stock that thick
wall (the warehouse) between itself and its customers. There
is a downside to this scheme, though. The thicker the warehouse wall becomes, the less able the factory is to respond
Destroying Factory Myths
quickly to market changes. That slow response becomes a
serious flaw in the factory’s character. Production gets stuck
in a slow, predictable rut.
It reminds me of the difference we can see between
animals who are raised in a zoo and those who never left
the wilderness.
Once a factory pursues the inventory option, they do not
stop with product inventories. Inventories start piling up
between processes or in the assembly line, and then there
are the inventories of materials and subcontracted parts.
At each of these inventory sites, a power struggle takes
place between the “users” and “providers” of the stocked
items. This power struggle is described in the first table.
User
Provider
Product inventory
Market needs
>
Factory’s
responsiveness
In-process inventory
Capacity of
downstream process
<
Capacity of
upstream
Materials inventory
Negotiating power and
leadership of buyers
and outside vendors
<
Resilience of
manufacturers
How can we get rid of these inventories? The second table
lists different methods to use for different types of inventories.
If manufacturers hope to survive in today’s harshly competitive markets, they must learn how to rid themselves of
these inventory “buffers” and become more responsive to
meeting their customers’ short-term demand for everchanging
products. Companies make a very big mistake when they
depend on something like the above estimated lead-time
to meet their customers’ needs. A strong, healthy factory
is one that can meet needs for prompt delivery based on a
real lead-time.
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Product inventories
Since market needs cannot be weakened,
we have to strengthen the factory’s
responsiveness to those needs.
In-process inventories
Raise the capacity and flexibility of
downstream processes. Do this by thoroughly
implementing the “next customer is the
customer” concept.
Materials inventories
Strengthen the negotiating power and
leadership of buyers and contractors
coordinators.
Lesson 18. The Slow-but-Safe Approach
Robs Factories of Their Brilliance
Approach to Equipment: Automation and
Human Automation (Jidoka)
The world is full of automatic machines. As their name implies,
almost all of these automatic machines are “self-moving.” We
just flip the ON switch, and leave the rest up to the machine.
Today, there are even automatic machines busy making other
automatic machines.
Still, not everything is perfect in robotland. For instance,
very few automatic machines have the ability to stop upon
detecting defects caused by worn or missing components.
Automatic machines that seem to be the ultimate in convenience at one moment can suddenly become mass producers
of junk at the next moment.
Obviously, this will not do. The natural response is to put
a human inspector on the job to watch out for such sudden
quality changes. But the need for a human dilutes the meaning
of automatic machines as labor-saving devices, even though
this is what has to be done to maintain product quality.
This paradoxical situation gave rise to the idea of jidoka, or
human automation. Jidoka is what enables the machine to be
stopped the moment a defect occurs, a machine component
breaks, the production flow backs up, or a mistake-proofing
alarm goes off. People apply their own human wisdom and
Destroying Factory Myths
Automation
“Defects? What defects?”
Figure 2.25
Jidoka
“Stop!
We’ve got a defect coming!”
Automation and Human Automation (Jidoka).
experience-based “know-how” to equip the machine with
devices that are able to detect any of the above conditions
and bring it to an immediate stop.
In JIT production, we use the term “automated ­machine” to
refer to machines that, once activated, will run on their own
regardless of defects. We use “human automated machine”
or “ jidoka machine” to refer to machines that include
“wisdom-based” defect detection improvements, such as
those just described. We must always make a clear distinction between these two types of machines. It may be helpful
to remember that jidoka machines include more value-adding
“work” in their operations than do automated machines. (See
Figure 2.25.)
Lesson 19. Let’s Make Jidoka Machines
That Do All the Human Work
Improve Work Operations before Improving Equipment
There are basically three types of improvement methods
used in JIT improvements. The first is the awareness revolution, the second is improving operations, and the third is
improving equipment.
Many people get confused over which method to start with.
Some companies are too anxious to exhibit the success of
improvement activities and hastily pursue the improvements
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JIT improvements
Figure 2.26
Step 1: Awareness revolution
People
Step 2: Improving operations
Methods
Step 3: Improving equipment
Tools
Sequences for Carrying Out JIT Production.
that promise the most obvious results. Other companies,
under pressure from parent companies to lower costs, go after
improvements aimed at drastically lowering prices within a
very short time frame, such as two or three months.
There are many ways to approach making improvements,
but there is a recommended sequence for carrying out
improvements, as shown in Figure 2.26.
The first step is the awareness revolution. The reasons for
this can be summed up in two words: people and money.
Production is rooted in people. People build in the defects.
People go over the delivery deadline. People push up costs.
The starting point for manufacturing is always people.
Therefore, we begin by revolutionizing people’s awareness.
Building from the ground up, we begin with improving
what is most basic—people’s perceptions and attitudes—
before going on to improve operations and equipment. If
we can change people’s awareness, we can change their
operation habits centered on shish-kabob lot production and
can avoid having to waste money on high-priced advanced
equipment. But none of these things will change unless we
lay the groundwork through the awareness revolution.
Of these three types of improvements—awareness revolution, operations improvements, and equipment improvements—which tends to cost the most money? The answer is
obvious: equipment improvements. After that comes operations improvement, and then the awareness revolution, which
doesn’t need to cost anything at all.
Destroying Factory Myths
The awareness revolution means helping others realize
that conventional lot production no longer makes sense and
helping them reach the heartfelt resolution that it is high time
to switch to one-piece flow manufacturing. Resolution and
determination are free.
Thus, there are two very good reasons for starting with
the awareness revolution: people and money.
The term “awareness revolution” is not at all an exaggeration.
What we are really talking about here is revolutionizing our
perceptions and attitudes about manufacturing. JIT improvement is not about finding and correcting errors and misperceptions in our current way of thinking. JIT improvement is
plainly radical and revolutionary; it demands that we wholeheartedly discard the conventional wisdom that we have
gradually developed over the past two or three decades.
Some people may object, “It’ll take too long to revolutionize everyone’s awareness.” That is a valid objection. It could
easily take years to “brainwash” everyone into supporting
JIT production.
That is why we begin at the top of the company. If we can
get the managers, including the improvement team leaders,
to start saying, “Right! Let’s get to it!” that will do for starters.
Go on to improving operations, and while that is happening,
the hands-on experience of making actual improvements
will ignite the spark of JIT revolutionary thinking in the participating factory workers.
The second step, as mentioned above, is improving
work procedures.
Why put improving work procedures ahead of improving
equipment? Again, there are two reasons: money and what
we might call “industrial fundamentalism.”
By making it perfectly clear where each thing is to be
placed during the flow of production, by having clearly
defined work methods and advancement methods, and by
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thoroughly eliminating waste, we can make improvements
that will ably serve as the basis for standardized operations.
By contrast, improving equipment consists mainly of
introducing new machines and redesigning production lines
toward the goal of “workerless automation.”
Back to the first reason: money. Which kind of improvement costs more, operations or equipment? Again, the answer
is obvious: Improving equipment costs more.
One trap companies barely in the black tend to fall into
is jumping into equipment improvements before getting very
far with operations improvements. Enthusiastic suggestions
such as, “Hey, we really need an NC drilling machine!” or
“Let’s get a computer to help us automate this line!” are often
acted upon prematurely.
I have seen many cases where an improvement team
was such only in name. What it really had become was a
bunch of equipment procurement consultants! I must admit,
it is fun to buy things. Especially if the things you buy are
interesting­. Everyone naturally gets excited at the chance to
follow their interests and buy or build the kind of “toy” they
always wanted. It is also a great way to avoid having to “hang
in there,” putting all your experience and know-how to work
in brainstorming improvements.
I have often been asked, “What makes JIT improvements
succeed?” There is only one answer: “Going into the red.”
What I mean by this is that the best approach to making
improvements is the poor man’s approach—do not spend
any money. Once everyone realizes that there is no money
to throw at problems, they will start getting serious about
using their smarts to improve operations. Money is best kept
a forbidden option when improving work procedures.
As mentioned above, the other reason for putting work
procedure improvements ahead of equipment improvements
is “industrial fundamentalism.”
The process of production is a flow that begins with gathering materials and ends with shipping finished products.
Destroying Factory Myths
The ways in which things are built and advanced along this
flow determines the flow itself. These various means within
the production flow are called “devices.” Improving operations means improving these “flow devices” within the production system.
People are production’s main asset and flow devices make
up its foundation. Machines and other equipment are just
one of the elements that make up the flow devices. They are
simply tools that facilitate production.
When we look at production in this manner, how can we
possibly justify ignoring the flow devices—the very founda­
tion of production—and instead focus on improving the production tools known as the equipment? But people often
make the big mistake of failing to take this “fundamentalist”
perspective. Instead, they consider improving the equipment
the basic point and then try to adjust the flow devices to suit
the improved equipment.
I call this erroneous reasoning the “company cop-out.”
People realize that to change production’s flow devices, they
first must change people’s attitudes. But changing people’s attitudes is much easier said than done. After all, those attitudes
are deeply intertwined in the complex web of interdependency
that forms part of the company’s “character” or “culture.”
How much easier it seems to avoid all that awareness
revolution hassle and solve the problem with money. This
“quick fix” temptation is a major stumbling block, leading
to the endless pit known as “plant investment.” Quite a few
U.S. and European companies have stumbled into that pit.
The world’s largest automaker and Europe’s oldest automaker
are among the stumblers.
JIT improvement faces a more hostile environment in Europe
and America, where the workers are less motivated and the labor
unions more powerful than they are in Japan, which means
that Western managers find it harder to influence the corporate
character or culture. Pressured by an emphasis on short-term
evaluations of their company’s business performance, Western
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managers are even more sorely tempted to use the “company
cop-out” and prematurely invest in new equipment.
Japan is more fortunate in that Japanese companies regard
their employees as their basic asset. And that is the way it
should be: Go straight to employees to improve flow devices.
We need to understand that equipment improvements are
appropriate only as a secondary development built upon a
solid foundation of improved flow devices.
Lesson 20. Don’t Jump to the Equipment Conclusion!
Five Problems Typically Encountered When
Improving Equipment
To sum things up from the previous section, production is
rooted in people. We start by focusing on people and on
their work as it relates to flow devices for production.
In doing their work related to production flow devices,
people invent and introduce tools to facilitate production.
Production equipment is among these tools. Remember: First
comes the flow devices and next comes the tools. No one
would even dream of chartering an airplane for a trip across
the street to the neighborhood market. A pair of shoes on
your feet will do just fine for that.
The tools change only after the work-related flow devices
change. If we have a shish-kabob, large-lot production system­,
we will want to have equipment suitable for that kind of
system­. The product’s parts may be tiny, but when you put
them together into lots of 10, 100, or even 1,000 they can get
rather bulky. Such huge production lots require big equipment
in order to reach a similarly large scale. Soon we start putting a
greater emphasis on how big and fast a machine is rather than
on how well it performs its function. Likewise, we start concentrating on the speed of specific processes and lose sight of
the overall production flow. Before we know it, we are investing absurd amounts of money in big, advanced equipment.
Destroying Factory Myths
The basic concept for production flow devices is that we
build using only what we need for one-piece flow manufacturing. This is the idea that we must keep in mind when
deciding what equipment to use.
Admittedly, this idea is not much fun compared to the
thought of customizing the production equipment to suit your
own fancy and buying new equipment that comes equipped
with interesting technologies. I suppose we never really lose
that childhood desire to playfully take toys apart or to show
off new toys to our friends.
Production engineers and equipment technicians often
get together to ask equipment-loving managers for new toys.
Managers should be forewarned never to buy equipment just
because some people think it would be nifty. It would even
be a mistake for managers to pay for the equipment out of
their own pockets.
There is something that poses even greater ­
production
problems than money: what to do about the production
flow once one or more new pieces of equipment have
been brought in. And if the new equipment really messes
up the ­production flow, who is going to take responsibility
for c­ orrecting the situation? Often, the whole factory has to
be redesigned in order to find a production flow that can
include the new equipment.
Figure 2.27 illustrates five types of problems one can run
into when making equipment improvements.
Problem 1: Equipment improvements cost money—
A woodworking plant was having trouble with a production
bottleneck in its plywood fabrication process. Specifically,
pressing the boards was taking too long and the company
management decided to scrape the money together to buy a
high-frequency press to speed up the pressing time. However,
it was only after the press was delivered that they discovered
that the previous process (frame-making), which used metal
tacks to hold the frames together, was not compatible with the
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Equipment improvements
cost money.
M
BLE
PRO
$
Unless work procedure
M improvements have
E
L
B
been made, equipment
PRO
improvements will only
reinforce waste.
Large,
expensive equipment
FAILURE
M
The equipment improvement cannot be started
over again.
M
Production is becoming more equipment-oriented
than people-oriented.
M
Factories lose all concern for the client’s needs.
BLE
PRO
BLE
PRO
BLE
PRO
Figure 2.27 Five Types of Equipment Improvement Problems.
high frequency press. As a result, the company was unable to
use its expensive new toy.
It is amazing how common these kinds of mistakes are.
People tend to think only of specific processes (workers
think only of their own) and they do not give much thought
to what effects a new piece of equipment’s characteristics
or design might have on other processes. They also tend to
bring new equipment into the production line without first
considering what it will mean for the overall line. The result
is that expensive equipment gets abandoned because it is
difficult, and sometimes impossible, to make it work as part
of the production line.
Destroying Factory Myths
Need we be reminded that the point of improvements is
to remove waste, not add to it?
Problem 2: Unless operation improvements have
been made, equipment improvements will only reinforce waste—This tale comes from a factory that builds
control components. Management had decided to shoot for
the goal of a completely automated, “workerless” factory,
and had instructed equipment engineers and technicians to
analyze the current situation. The plan was to automate the
entire ­factory—from receiving materials to shipping ­finished
products. The company came up with the mega-money
­
needed for this ambitious project, and within six months the
equipment was installed and running. The automated equipment churned out products similar in quality to what they
had had before. The factory was able to cut its workforce
drastically and both the company president and factor superintendent were pleased as punch.
But they overlooked a few things. In order to include five
value-adding processes, they needed to lengthen the production line several hundred meters. Most of the new line
was occupied by industrial robots that pickup, set down,
and otherwise arrange parts. Although it would have been
quite possible to have parts soldered in a one-piece flow, the
robot system required that parts be arranged into batches of
about 20, which the robots dip into a soldering vat. Since the
­soldering is done in batches, it is hard to achieve consistency.
Therefore, management brought in a computer-controlled
robot to inspect the soldering.
As you can see, the company neglected removing waste
from their old operations, and therefore simply incorporated
that invisible waste into the automated system. When waste
is due to human operations, it can almost always be removed
by improvements in operations. But once the waste is embedded in a complicated set of equipment, it may well be stuck
there forever.
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This automated production line is accompanied by several
hundred meters of in-process inventory The company has
also tied up its money in an unmanned material handling
system that has absolutely nothing to do with adding value
to its products. Suddenly control parts have become a very
expensive product to make!
Problem 3: The equipment improvement cannot be
started over again—At a diecasting plant, an increase in
production volume resulted in a bottleneck at the shotblasting process. The company’s solution was to buy a much
larger shotblasting machine that could handle several times
the ­current production volume. It was so big and bulky, however, that it had to be placed in another room for use whenever a bottleneck occurred.
Sure, the new shotblasting machine could handle several
times the processing load, but to do so required shotblasting diecastings in batches. The diecastings banged into each
other while being deburred by the shotblasts, resulting in a
great number of damaged, defective diecastings. The ­factory
managers then decided to station two people as quality
inspectors responsible for sorting the defective diecastings
from the nondefective ones. The amount of stock-on-hand
doubled and the big machine’s placement in another room
required a forklift for conveyance.
Without bothering to first improve the operations, this
factory saw its problem simply in terms of insufficient
­
capacity and jumped to the conclusion of installing a larger
machine. Waste created more waste because, after installing
the large machine, the shotblasting process included more
waste (in inspection, conveyance, etc.) than before.
In such cases as this, even when the people concerned
realize their mistake and start gnashing their teeth in regret, it
is too late: The equipment has been bought and the improvement cannot be started over again.
Problem 4: Production is becoming more equipmentoriented than people-oriented—Even in smaller factories,
Destroying Factory Myths
it is not hard to find such things as large, expensive production machinery and equipment, and multimillion-dollar
automated production lines. There are numerically controlled
(NC) machines for functions ranging from coating to drying,
rinsing, shotblasting, vat soldering, lathing and drilling, and
some factories line these advanced machines up in fully automated machining lines or assembly lines. Some companies
invest a mint in automated conveyance systems and sophisticated automated warehouses until their factories begin to
appear more like conveyance and warehousing centers than
manufacturing centers.
These types of equipment improvements cost lots of money,
only further embed waste into the production system, and in
many cases cannot be rejected as a bad idea once they are
installed. Soon, the worst possible thing happens: The factory
employees take the attitude, “Well, we bought all this expensive stuff, now we’d better get maximum use out of it.” This is
an attitude that changes the orientation of factory work away
from the workers and places it on the equipment.
Let us imagine, for instance, a factory where the workers
have dug a large pit to accommodate a big new machine.
Once the machine is installed, there it sits, stuck in one place,
as if to proclaim, “No matter what kind of product we switch
to, I have to do my work right here.”
I am amazed at how inflexible some “flexible automated
production lines” actually are. They generally cannot handle
a wide range of product models. Consequently, the lots on
these lines gradually grow larger and larger.
Problem 5: Factories lose all concern for customer
needs—When factory managers grow attached to fixed
ideas, such as: “That machine has to stay where it’s bolted,”
“Frequent changeovers reduce efficiency,” and, “We’ve got to
increase capacity utilization,” the factory’s “character” seems
to lose all concern for customer needs.
The high cost and irreversibility of equipment improvements
are serious problems indeed, yet they are nothing compared
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to the problem of a company that has become more concerned with its equipment than with its customers’ needs.
Lesson 21. Use the Manufacturing Flow to
Design the Equipment
Twelve Conditions for Introducing New Equipment
As mentioned earlier, some factories have rushed into buying
and installing new equipment in the name of “improvement”
or “rationalization” before thinking of how their current
operations and methods might first be improved. The managers at these factories bring in new equipment as something
separate from the factory’s work operations and then, when
things do not work out as well as planned, they believe the
factory workers are at fault.
This tendency is especially prevalent among the equipment engineering staff at corporate head offices. Knowing
precious little about how things are actually made at the
­factory, these engineers instead study up on the “elegant” functions and advanced technological features of state-of-the-art
equipment, and are lured by their interest into encouraging
the purchase of large, expensive new machines. Later, when
product model changes, quality problems, operational snags,
and other problems start cropping up, these engineers typically write a report to their superiors with the verdict that
“the factory workers have not yet learned to use the equipment correctly.” Guilt invariably lies on the factory floor, not
in the engineering department.
Meanwhile, at the factory, the foremen and workers have
had no choice but to try their hardest to “get the hang” of
using equipment that is in many ways ill-suited for their
­manufacturing needs. And still it is the factory people, not the
engineers, who come under fire from top management. This
shows how little the top managers understand the situation.
To help enlighten everyone in this regard, I have put
together the following list of 12 guidelines for introducing
Destroying Factory Myths
new equipment. I hope that all equipment engineers at corporate headquarters will read this list, and especially hope
that top managers take these guidelines to heart.
Guideline 1: Use today’s sale’s figures, not next year’s
forecast figures—Many companies opt to buy new equipment based on one- or two-year projections of how much
they can expect to reap in sales revenues. In other words,
these companies are counting their chickens before they are
hatched. Once they have installed and start using the new
equipment, the companies find they have much more production capacity than they need, and have bought into an
“overkill” solution for their previous capacity shortages. Yet
despite their new capacity for much larger production volume, the volume stays about the same.
In recent years, it has become more difficult for manufacturing companies to forecast sales figures. We are no longer in
an era where steady, rapid growth can be taken for granted.
That is why it is imperative that companies be more conservative by introducing only the equipment they need to support
profitability based on today’s figures. If the volume of orders
starts expanding, the company can respond prudently by gradually adding to its small manufacturing cells. Market needs can
vary widely, so it is best to introduce equipment conservatively,
and only when warranted by current market needs.
Guideline 2: Remain fully committed to one-piece
flow manufacturing—Some processes, such as pressing,
cleaning, and soldering, naturally lend themselves to processing workpieces in batches. The tendency is to design such
processing equipment to handle increasingly larger lots. But
this is a mistake.
It seems more rational and easier to opt for batch processing whenever possible, and it seems a sure-fire productivity
booster. But we need to remember that presses, rinsers, and
such do not manufacture products on their own. Certainly,
we can raise the capacity of each of these processes by using
them for batch processing, but the result will be an uneven
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flow and a net lowering of production capacity for the overall
manufacturing system. Once we begin devoting some equipment to batch processing, we also will find ourselves soon
moving toward bigger and bigger machines with ever larger
and larger capacities.
No matter how much a particular process can handle and
how quickly it can handle it, it will not add to overall profitability if it exceeds the pitch specified by the order shipment
schedule. It is far better to have equipment that will reliably
turn out quality products one piece at a time in pace with
the shipment pitch than to have even the most impressive
batch-processing equipment. (One-piece production flow is
described further in Chapter 5.)
Guideline 3: Emphasize cycle time over speed—The
speed at which the line moves should be directly tied to the
specified production volume for that day. Obviously faster
production speeds mean higher daily output levels. That fact
alone leads many engineers toward faster machines. There
are even engineers who virtually equate increased speed
with more advance technology.
The amounts specified in customer orders should determine how many minutes or seconds it should take to process parts or quasi products. We call this amount of time the
“cycle time” or “pitch” of production, and we should gear
our equipment to keep pace with that pitch. (Cycle time is
described further in Chapter 10.)
Guideline 4: Make the equipment both versatile and
specialized—How many managers have shouted the battle
cry “From now on, we’re going to have wide variety production!” while rushing out to spend a fortune on expensive
general purpose machines? Once the factory actually starts
using one of these do-it-all machines, it finds that changeovers do not go very smoothly and that the machine has
various other restrictions, so that the productivity gain is not
what everyone had expected. Often, these general purpose
Destroying Factory Myths
20 workers/line
A
A
10 workers/line
5 workers/line
B
B
A
C
A
C
A
B
C
D
D
A
B
C
D
C
B
C
B
D
D
D
Two product
models per line
(Specialized lines)
One product model per line
Four product
models per line
Figure 2.28 Specialized Lines to Meet Wide Variety Production Needs.
machines, which are supposed to do everything, do not do
anything particularly well.
But suppose, for instance, that we have a manufacturing
line staffed by 20 workers. If we are running four product
types through this line, we can split the line in half, with
each half operated by 10 workers and specializing in two of
the four product models. Alternatively, we could even split the
original line into four lines with five workers apiece, and each
line could specialize in just one product model. This is a much
better way to meet the need for wide variety production­. (See
Figure 2.28.)
This principle works the same way for individual machines.
Get rid of the general purpose machines with their waste­ridden hodgepodge of functions. Instead, stick to inexpensive
machines that can be used as specialized machines but can also
be made versatile enough to handle product model changes.
Guideline 5: Keep equipment compact and readily
movable—With any hope, the days are numbered for huge
machines that get plopped down for eternity in one place
as if to say, “This is where I stay no matter what product we
switch to!” New products are being developed all the time, and
the product diversification trend is still gaining ­momentum.
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Factories are learning that the most efficient equipment layout
is the one that suits the current product models. The grouping
of equipment into in-line patterns requires equipment that is
both compact and furnished with casters or other devices for
easy movability.
Guideline 6: Make equipment easy to operate and
keep machine work and human work separate—We can
never get far in training workers in the various skills needed
to handle several machines if the machines are so “user hostile” that it takes a “an old hand” to handle them ­correctly.
Likewise, machines that require constant nursing and supervision are hardly conducive to production efficiency.
Instead, the machines should be easily operable by any
worker and the workers should be able to physically separate themselves from the machines while the machines are
running. Only then are the machines appropriate for multiprocess handling. The basic rule for workers being trained
in multi-process handling is that this work is chair-free. They
must stand (or walk) while working.
Guideline 7: Workpieces should enter and exit each
machine at the same spot—Often, machines—especially
woodworking machines—take unprocessed workpieces in
one side of the machine, process them, and expel them on
the other side. Such an arrangement stands in the way of
both single-worker handling and multi-process handling by
usually requiring a worker on one side to feed workpieces
into the machine, and a second worker on the other side to
take out the processed workpieces.
To avoid this situation, the workpiece must either be processed in a fixed position or must be automatically returned to
the entry point after processing. The best-designed machines
are those that support “set-up, set-up work” or “remove,
remove work” (in which the worker either sets up or removes
a series of workpieces at a series of machines) by expelling
each processed workpiece or leaving it where it is, if it is
­easily extractable.
Destroying Factory Myths
Guideline 8: Build in inspection functions—Automated machines that are simply automated—meaning they
just move by themselves—will keep on moving even after
they begin turning out defective products. Before long, there
is a large pile of defective junk in front of the machine. To
avoid this, we need to turn machines that simply “move” on
their own into machines that really “work” on their own.
We can do this by installing poka-yoke (mistake-proofing)
devices that can “inspect” (detect) when the first defective
product has been made or can sometimes even detect when
the first one is about to be made. Once these devices detect
a defect, they shut off the machine. (Poka-yoke is described
further in Chapter 12.)
Guideline 9: Keep defective and nondefective products easily countable—In the case of inspection devices
for semiconductors and other high-precision products, it is
especially helpful to keep defective and nondefective units
clearly separated and countable at a glance.
Guideline 10: Make equipment easy to maintain—
Regrettably, there are many engineers who seem to only
care about how well machines build or process products.
Obviously, that is a good thing to care about, but if the
machine is going to be a reliable workhorse over time, it
needs to be user friendly for maintenance workers. The idea
is to give full consideration to both the machine’s work functions and its maintainability.
Guideline 11: Keep a clean machine—One does not
need to visit too many factories to find machines that are
oozing oil or that are surrounded by scattered processing
debris. Aside from frequent sweeping and cleaning in line
with the “5S” doctrine, shop floor workers need to pinpoint
what things are causing the mess and improve them. After
all, the 5S’s are much easier to maintain if the equipment
barely makes a mess to begin with!
Guideline 12: Make sure the equipment keeps you
informed—Poka-yoke devices are not enough: After detecting
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a defect and shutting down, each machine should also be able
to light an andon (alarm lamp) and/or sound a buzzer to let the
operators know something has happened. Together, poka-yoke
and andon enable both visual and auditory control.
Lesson 22. Think of Machines as Living Things
Approach to Inspection and Management:
Sampling Inspection and Full Lot Inspection
The following describes something that happened at a QC
meeting held in a certain factory.
The company was having no luck reducing the steady
stream of defect claims and other complaints from its customers. It had tried hanging big banners with QC slogans
such as “Quality First” and “This Month Is Quality Assurance
Month,” but to no avail. Its whole QC effort was just one big
defeat. The customer complaints had even increased since
beginning its QC campaigns.
The factory superintendent spoke out loudly. “We must
double our inspection staff and approach this thing more
rationally!” he said.
Perhaps the superintendent had grown cynical about the
whole affair. But his suggestion was serious, although fundamentally flawed.
Already, we can identify two misunderstandings held by
the group. The first is the notion that inspection somehow
eliminates defects. No matter how many quality inspectors
you put in the factory, the defects are already built into the
products long before the inspectors spot them. Defects are
results. Clamping down on these “defect” results will not
reduce them. At best, such a move will succeed only in screening out the major defects and marginally reducing ­customer
complaints. The point they missed is that defects must not be
built into the products in the first place.
Their second misunderstanding concerns the real meaning
of “rational.” Each product passes through the care of many
Destroying Factory Myths
people on its journey from factory to market and finally to
the customer. Each of these people may have a different idea
of what is rational.
Some may reason that full lot inspection just takes too
much time and statistical studies have shown that sampling
inspections do the job well enough. This belief about inspections is especially popular in factories. Many factory workers
will vehemently assert that sampling inspection is by far the
most rational way to inspect products.
The truth is that they do not know the truth.
The truth is that “rational” is a very treacherous term. It
means “compatible with reason.” But, as alluded to above,
perceptions of reason differ from person to person. In fact, it
is nearly impossible to find a common perception of ­reason
shared by everyone. So the problem is that one person’s
­reason might be another person’s folly. There is no way to
satisfy both of them.
What kinds of people are likely to find sampling inspection a reasonable idea? For starters, the people in the factory
are bound to find it reasonable. After all, who in a factory
likes the job of rooting out defective products? They would
much rather have to apologize now and then for shipped
defects than to take all the time and trouble to perform full
lot inspections.
Figure 2.29 illustrates a common situation: a factory that
has decided it could live with an Acceptable Quality Level
(AQL) of 0.1 percent, which means an average of one defective product per 1,000 products.
Production people are proud to report an AQL of “only”
0.1 percent. But from the customer’s perspective, that means
that the company is happy to sell a lemon to one unlucky
customer per thousand! The unlucky customers will not start
smiling again when they consider the company’s 99.9 percent
nondefective rate. He or she is too busy regretting the purchase of a 100 percent defective product.
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We’re maintaining
an AQL of 0.1 percent!
You have one
defective product
in every thousand?
Yeah, I guess
you’re right.
Figure 2.29
But you know,
the customers who
get defective products
are not going to think of
it as 0.1 percent defective.
To them, those products
are 100 percent defective!
Estimated Quality.
Remember this: One little “oops” by the maker brings one
big “ouch” to the buyer. Sampling inspections go with the
odds. The odds are good, but not nearly good enough to
avoid having losers. Factories that are market-oriented never
stray from taking the customers’ perspective in their approach
to manufacturing their products.
The so-called rational approach works great in general.
But we need to consider how rational our approach seems to
the individual customer.
Naturally, countless factory managers counter the above
with, “Yeah, but do you know what switching to full-lot
inspection would do to our costs?” Yes, I know. But then again,
100 percent quality—more than anything else—separates the
manufacturing amateurs from the true professionals. After
all, what are all those “expert” production engineers for?
What is the whole field of industrial engineering for if not
100 percent quality?
Destroying Factory Myths
Lesson 23. Quality is Built into
Products at Each Process
Monitoring and Managing
I cannot recall how many times I have had discussions such as
the following with top managers at manufacturing companies.
“We don’t know what to do. We can’t seem to increase our
control level at all. We can’t even get a handle on all the
in-process inventory between the process stations.”
“Hmmm. Tell me more.”
“It’s just that we want to gain a better understanding of
what is going on and somehow manage to control it in a
more timely way. But how can we start doing that?”
“Well, sounds like I’d better teach you the best way to do
that.” (This last remark always ignites an eager sparkle
in their eyes.) “Let’s totally eliminate inventory between
processes. Down to zero.”
The managers invariably greet that last remark by dropping their jaw and staring in wide-eyed amazement. It is
not what they expect to hear—not even close, in fact. They
expect me to say things like, “Let’s make better use of computers. We’ll install network monitors all over the factory so
we can immediately enter data to keep track of how operations are going and where the inventory is moving.”
But the real solution is simply not that complicated.
When managers express the desire to “have better control,”
they are admitting a failure to understand how factory operations proceed and why they slow down at times. They are
also admitting that they have not clearly identified the causes
of various shop floor problems, such as product defects and
excess between-process inventory. To solve these problems,
they imagine it necessary to build a new, more sophisticated factory management and control system, even though
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building and maintaining such a system will cost a fortune
and take untold months or years of effort. Ironically, the end
result will be a production system that has become even
more complicated and thus more difficult to understand.
Take a look around any large factory and see how many
signs include the word “control” or “management.” Such signs
are everywhere. There is “production management” to manage
the entire production system, “financial management” to manage the money, “personnel management” for the ­employees,
“sales management” to keep an eye on the market, and various other self-explanatory types of management or control,
such as “client order management,” “process control,” “delivery
management,” “quality control,” “subcontract management,”
“cost management,” “inventory control,” “in-process inventory
control,” “shipment management,” and so on.
One could easily gain the impression that people in manufacturing are embracing the concepts of “control” and “management” like some kind of security blanket.
Some deliveries have been late. What does the company
do? It creates a “delivery management” system, replete with a
“deadline monitoring system” to monitor whether or not current delivery deadlines are kept.
Some defects occur. Quality is the lifeblood of the company, so the managers make a big fuss about developing a
“QC organization,” again replete with a “quality monitoring
system” to continually keep track of defect occurrences.
What? Too much inventory? Time to set-up an inventory
control organization, replete with...
And so it goes. Figure 2.30 provides an amusing illustration
of how “monitoring” gets mixed up with “managing” (especially in Japanese, where both words are pronounced kanri).
In other words, when factory managers (monitors?) find a
problem, they tend to respond by adding the word “management” or “control” to the name of the problem. They put off for
later the idea of looking into what actually caused the problem to occur and what can be done to correct­the situation.
Destroying Factory Myths
There’s too much
stuff on the floor.
We’ve got to do a
better job in our
in-process inventory
control!
The warehouse
There’ve
is overflowing.
been a lot of late
Time to get
deliveries. We’ve got
serious about
to get tough with our
warehouse
delivery management
inventory
system!
control!
Quality’s getting worse.
We’ve got to beef
up the quality
control system!
Capacity utilization
is down, so we’ve
got to organize some
capacity utilization
management!
Figure 2.30
Hey, he’s not
managing. He’s
monitoring!
Monitoring (kanri) and Management (kanri).
Still, almost all managers have this proclivity toward attaching the security-blanket words “management” and “control.”
The more “management” and “control” systems they create
in response to problems, the higher costs rise. I suppose we
could call such costs “security-blanket costs.”
If these managers would instead channel that same energy
toward repeatedly asking, “Why did that problem occur?”
until they reach the real root of the problem, they would
already be halfway toward implementing improvements to
correct the situation.
In most factories, inventory (warehouse inventory, in-process
inventory, and between-process inventory) is like a huge, thick
blanket that covers up a panorama of causes for p
­ roblems.
If they could only pull that blanket away, all sorts of causes
would suddenly become visible. Yank away the cover of
in-process and between-process inventory, and suddenly it is
obvious how poorly organized the production system is and
what can be done to start preventing defects.
Therefore, the first thing to do is reduce inventory to zero.
Next, make improvements to solve the most serious problems
that suddenly appear. Then redesign the entire ­production
system so that materials fed into the system can be sent
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through it smoothly—without any retention—to become
fi
­ nished products.
Some people who still have not completely caught on to
this idea might still be wondering, “Once we’ve gotten all that
inventory out of there, don’t we need to set-up a manage­
ment system to control the timely flow of inventory?”
To those people, I simply say, “If you have inventory, you
need inventory control. If you don’t have inventory, you don’t
need inventory control.”
Another way to put this is: The best type of management
removes the need for management. We might observe just as
accurately that management systems and organizations, once
established, have a life of their own.
I could cite case after case in which companies whose scope
and volume of business were steadily shrinking still kept their
management divisions as big as ever. Management organizations know how to grow, but do not know how to shrink.
Parkinson’s Law is alive and well.
Lesson 24. Keep Monitoring Out of Managing
Approach to Promoting Improvements: Pseudo
Improvement and Real Improvement
Here is an exchange I once had with a factory employee
while starting to implement JIT improvements:
“Hey, what’s all this?” I asked, pointing to a pile of cardboard.
“Oh, that’s the cardboard we use to box up Product A.”
I knew right away what kind of beginner’s mind-set I was
dealing with. Did this person really think I didn’t know what
cardboard was? Did he think that I was touring the factory
to learn about the products they were making? A JIT-minded
person would recognize immediately that I was really asking,
“Why is this pile of inventory here?” I turned and left that
workshop. The people there did not have the slightest idea
what JIT improvements meant. It was a waste of time at that
Destroying Factory Myths
point. This person was a rank beginner, a “white belt” in the
martial art of JIT improvement.
At other workshops, people had a somewhat better understanding of JIT. When I asked the same question to one
worker, he said, “We don’t have anywhere to put that stuff
right now, so we’re keeping it there just for now.”
He was beginning to get the idea. But he should have realized I was not interested in hearing excuses. I wanted to know
what they were going to do to remove the pile of inventory.
A somewhat more advanced beginning JIT student would
say something like, “Right. We’ll get right to it,” and then
make a note of it. The attitude is correct: Acknowledge the
problem, then write a memo. Now we are getting somewhere.
I would give that person a beginner’s black belt.
A still more advanced JIT beginner would get out the
memo pad and make a note of it while acknowledging the
problem with a simple “Right” or “Got it.” Then he would
issue an improvement instruction and have the improvement
made as soon as possible. Then he would check up on the
improvement and make any overlooked items the next items
for improvement. Acknowledge, act, and follow up. That puts
this person in the second rank of black belts.
Unlike the JIT white belts, the JIT black belts knew how to
go about making improvements as soon as the inventory pile
was pointed out to them. This makes the difference between
“pseudo improvement” and “real improvement.” Let us take
another look at this important distinction.
Improvement item pointed out—“What’s with this pile of stuff
here?” (points toward in-process inventory).
Pseudo improvement
The worker seems confused at first when the problem is pointed
out. He would not be so confused if he knew what he was
doing. But since he does not understand what JIT improvements really are, he feels a vague sense of guilt as if he were
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lazy or not doing things right. Still ignorant of how to make real
JIT improvements, he starts making pseudo improvements.
He scans the walls for a large enough space, where he
puts together some shelves. He then moves the pile of stuff
from the floor to the shelves. A look of pride appears on his
face as he claps the dust off his hands. This man is clearly
a “white belt.” If possible, he should be downgraded to an
even lower rank should he have the inclination to tell a JIT
inspector, “I made an improvement.”
Real improvement
As soon as the problem is pointed out, the factory employee
gets right on it. During the next two or three minutes, he asks
a series of “Why?” questions to get to the root cause of the
problem. This questioning process is a must for making real
improvements. We call the process the 5W1H method, in which
we need to ask “Why?” at least five times to get to the real cause,
then we ask “How?” in order to make the improvement.
The pseudo improvement, in which my question, “What’s
with this pile of stuff here?” prompted the worker to build
shelves and move the stuff to the shelves, the worker’s
“improvement” made the workshop appear neater but it also
grants approval to the pile of inventory by “enshrining” it on
specially-built shelves. Instead of removing inventory-related
waste, this approach only adds permanence to it.
The 5W1H method is a radically different approach that
brings real improvements. We begin this approach by s­ imply
asking “Why?” as in, “Why did that pile of inventory accumulate there?” This brings a response, such as, “The people at the
previous process have been putting their deliveries there.”
At this point, some people might rush into a pseudo
improvement, saying,” Well, let’s build some shelves and
get that stuff off the floor!” as a simple (actually, simplistic)
solution to the problem.
But that is not the right approach. Instead, we need to
ask “Why?” again, as in, “Why do the people at the previous
Destroying Factory Myths
process put their deliveries there?” Let us suppose the response
this time is, “Because they’re done with it.” Now one important
fact has surfaced: The factory is using the “push” production
method. We have found the basis for an improvement plan:
The factory needs to switch from “push” to “pull” production.
But we are still not done asking “Why?” at least five times.
The third “Why?” might be, “Why is the previous process
producing so much stuff?” The response to that could be,
“They can’t send the workpieces downstream one at a time,”
or “They have to process batches for economy’s sake.”
Each of these responses should be addressed by a fourth
“Why”? To the first response, we can ask, “Why can’t they send
them one at a time?” and, to the second response, “Why is
it uneconomical to get rid of batch processing?” Let us suppose the response to both of these questions is, “Because the
changeovers take so much time.” This brings another problem
to the surface: the need to improve changeovers at the previous
process. (See Figure 2.31.)
While this and the “shelving solution” are both improvements, one is just a pseudo improvement and the other is
real improvement. No matter how much thought, action,
time, and expense go into a pseudo improvement, it will not
improve the workplace a bit. Only by getting to the bottom
Pseudo
Improvement item
Build new shelves
Figure 2.31
IMPROVEMENT
Real
Improvement item
Switch to “pull” production
Arrange in-line processes
One-piece flow
Changeovers
Pseudo Improvement and Real Improvement.
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of the problem through the 5W1H method can we make sure
our improvements are real ones.
The “white belt” workers who do not know how to make
real improvements need to be handed a 5W1H sheet and told
what to do with it. (See Figure 2.32.)
Lesson 25. 5W1H
“Mental” Improvements and “Physical” Improvements
This JIT manual includes explanations of the things most
essential to JIT improvements in factories:
◾◾ JIT’s basic concepts
◾◾ Improvement techniques and their functions
◾◾ Improvement “know-how” and case studies
JIT improvement consultants make use of know-how that
they have accumulated over many years.
Some aspiring students of JIT may imagine that if they read
this manual cover-to-cover without overlooking a single­word
or phrase, they can expect to be full-fledged JIT improvement
consultants when they close the back cover. The same thing
may happen in companies with industrial engineers. They
may read this manual and then fancy themselves veteran
JIT/IE professionals. As soon as these people put this book
down, they will be off preaching the JIT gospel to others.
Let us nip this potential disaster in the bud right now. JIT
improvement is not a theory or technique. JIT improvement
is a discipline, one might even say an art, that is based at
first on faith and then, gradually, on accumulated experience, wisdom, and intuitive “gut feelings.” JIT improvement
is a process, a path leading toward revolutionary progress
in manufacturing, and this manual is nothing more than an
entry and basic guide to that path.
Destroying Factory Myths
◾
5W1H SHEET
Improvement item notification:
What’s with that pile of stuff here?
Why No. 1: (Interpretation of
improvement item notification)
Why is there a pile of in-process
inventory here?
Current status:
Current status:
They were delivered here by the
people at the previous process.
Current status:
Why No. 2: or improvement
proposal (HOW):
Why No. 2:
Why does the previous process
deliver this stuff here?
Why No. 2: or improvement
proposal (HOW):
Current status:
Current status:
They already have made a
lot of these goods.
Current status:
Why No. 3:
Why do they send it downstream?
Why No. 3:
Why did they make
so many of them?
Why No. 3:
Current status:
The whole factory uses the “push”
production method.
Current status:
They can’t do one-piece flow
manufacturing.
Current status:
Processing large batches
is the only economical way.
Improvement proposal:
Switch to “pull” production.
Why No. 4:
Why can’t they do one-piece flow
manufacturing?
Why No. 4:
Why isn’t one-piece
flow economical?
Current status:
The two processes are separate
from each other.
Current status:
They’ve never tried doing
one-piece flow manufacturing.
Current status:
The changeovers take too long.
Improvement proposal:
Bring the two processes in line.
Improvement proposal:
Improvement proposal:
Learn to do changeover
within cycles.
They send it to us after they are
done with it.
Figure 2.32
Learn to do one-piece flow
manufacturing.
Example of How to Use the 5W1H Sheet.
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JIT improvement expertise cannot be garnered from books.
Neither can it be learned by talking about it or by listening
to others talk about it.
Several years ago, TQC was all the rage in Japanese manufacturing circles. In fact, the TQC movement spread from
factories to hospitals and even government offices.
Its application scope seemed boundless.
TQC had a lot going for it. After all, there is nothing at all
wrong with asking everyone in the company to brainstorm
solutions to problems and make improvements. However, the
result was often long on form and short on substance. It
became obvious that people were aiming their improvement
efforts toward a impressive announcement meeting rather
than toward substantial changes in the workplace.
JIT improvement eliminates all emphasis on formalities
and announcement meetings.
Factories that have embraced TQC often become wall-towall displays of advocatory posters, signboards, and banners
emblazoned with such popular TQC slogans as “Orderliness
and Cleanliness,” “Let’s Raise Productivity,” “Let’s Reduce
Inventory,” and “The Next Process Is Your Customer.”
Nothing gets improved in factories full of TQC posters.
Or perhaps I should say that factories get filled up with TQC
posters because nothing gets improved.
I remember seeing a factory floor where a “Let’s Reduce
Inventory” banner that hung from the ceiling was partially
hidden by a huge heap of inventory. That is what happens
when form becomes more important than substance.
JIT improvements are not a set of slogans to be written
here and there.
TQC makes use of the “Seven QC Tools.” One of these tools
is the Pareto chart, which is often used to analyze defects.
These charts quite legibly indicate the type and number of
defects and are drawn very neatly Then they are posted
in the factory so everyone can read them. This is all fine
and good, but it is unfortunate indeed what often happens
Destroying Factory Myths
afterward. People start reading the charts as if they were
lottery results or TV game-show competitions, saying, “Hey,
look who scored number one in defects this week!” After a
while, it gets hard to tell the best from the worst.
People also tend to get distracted from the real point of the
charts by their natural tendency to admire the craftsmanship
of its carefully drawn illustrations. This unfortunate tendency
to channel the seven QC tools toward making impressive
statistical displays for people to admire instead of making
full-fledged improvement efforts has prompted the invention
of a nickname for QC’s seven tools: QC fireworks.
JIT improvement gets rid of the flash and bang of TQC and
keeps things pure and simple. JIT improvement is not about
seeing, reading, talking, listening, mathematizing, announcing,
or writing. It is about improving.
So how can we properly define JIT improvement? My suggestion is that JIT improvement is factory-based improvement
toward the realization of JIT production. These factory-based
improvements are not primarily based on reading, writing, or
even seeing. As their name implies, they are about improving factories.
JIT improvement emphasizes only one verb: doing. (See
Figure 2.33.)
“Mental” Improvements
Reading
Listening
Watching
JIT Improvements
Heart
Hands
Talking
Announcing
Writing
Body
Factory
Figure 2.33
“Mental” Improvement and “Factory” Improvement.
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In JIT improvements, we just show up at the factory and
get cracking. Everyone immediately starts using their wits
and their bodies to make improvements.
Everything involved in making the improvement happens
right there at the factory. Each person is on his or her feet
and stays standing for hours, if necessary. If we stay on our
feet and remain focused on the factory itself, the factory will
be the teacher, providing the ideas and clues needed to start
making improvements.
The factory itself will softly whisper into our ears such
invaluable teachings as the movement of the machines, the
flow of goods, the items in need of improvement. To be able
to hear these barely audible whispers, we need to stand very
calmly and explore the factory with deep interest. As we do
this, we gradually and naturally acquire skill in identifying
such things. We need to do what we can to foster this skill.
Nothing could be more foolish than launching improvement
campaigns from desks and blackboards. In study rooms, we
have to rely on our mental pictures of the factory. That leaves
too much of a gap between what we remember and what
conditions actually exist in the factory. When ­improvements
are based on such mental images instead of the factory itself,
the result can only be disappointment and despair.
People who have had more than the average number of
years in academia tend to fall into the bad habit of making
such “mental” improvements. In seeking to make improvements, we must use the body—not the mind—as the main
perceptive instrument. We need to feel as if we had cut off
our own heads and sent them home for a while.
Lesson 26. The Factory Is the
Best Teacher of Improvements
Bottom-up Improvements and Top-down Improvements
Generally, there are two ways to make things better.
Destroying Factory Myths
One way is to meticulously research current conditions
and methods, analyze the research results, then improve the
problem points. This is the inductive method. The other way
is to state the ideal conditions and methods, and gradually
improve current conditions until they approximate the ideal.
This is the deductive method. Whenever people speak of
“improvement,” they are speaking of at least one of these two
methods. The inductive method is the conventional industrial
engineering (IE) method. The deductive method is the JIT
improvement method.
The conventional IE method is an attempt to raise the level
of quality based on a thorough analysis of current conditions.
It is thus a “bottom-up improvement” method.
By contrast, the JIT improvement method takes the ideal of
“JIT production” as the basis or final cause for making improvements. It is thus a “top-down improvement” method. Actually,
the ideal at the top does not go down in any way but is used to
pull conditions upward, and so it would be more precise to call
JIT a “top-up improvement” method. For simplicity’s sake, it is
better to keep a sharp contrast with IE’s bottom-up approach
by calling the JIT approach “top-down improvement.”
The same contrast in methods can be seen in other
fields, too. For instance, in budgetary accounting there is the
“build-up method” and the “zero-base method.” In price
setting­, there is the “cost-based method” and the “market value
method.” In systems design, there is the “analytical ­system
design” method and the “work design” method.
Perhaps the closest analogy to factory improvement is
child rearing. Here, the two methods are the “faultfinding”
method, in which the child is scolded for everything he or she
does wrong, and the “dream-instilling” method, in which the
vision of achieving a future goal or hope is deeply instilled
in the child.
It is not always easy to say which factory improvement
method is better—the IE method or the JIT method. It depends
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very much on the company. However, we must not lose sight
of the critical need for companies to root out bad habits and
make fundamental changes to survive in today’s world of trade
friction, fluctuating exchange rates, and severe competition.
Such radical change does not come from “improvements”
in the ordinary sense of the word, that is, in small, incremental improvements. Instead, such companies require innovation and revolutionary changes. And for making those kinds
of changes, the conventional IE method is difficult indeed.
What makes the IE method so difficult is that, as a method
based on analysis of current conditions, it must begin with
“recognizing” and therefore to some degree “accepting” current conditions. We study the status quo in order to make it a
little bit better, but we never ask the radical question, “Why are
things the way they are?”
For example, consider a factory that has a conveyance system. To make just one improvement in this system, we must
take totally different approaches depending upon whether
we use the IE method or the JIT method.
If we use the conventional IE method, we begin by carefully analyzing the conveyors and the way things are distributed by them. We can then note that the conveyors place
some items in sites from where they can easily be removed
and other items in less accessible sites. We can graphically
analyze this phenomenon in a “conveyor use index” chart.
The chart plots items that are left piled on the floor as the
lowest value in optimum conveyor use and items that are still
being moved on the conveyor as the highest value in optimum conveyor use. As shown in the graph in Figure 2.34,
there are five levels of conveyor use including the lowest and
highest just described.
Using the IE method, we identify the low points on the
analyzed use index and seek to improve them to have higher
use levels (therefore easier to convey), so that the overall
average use index becomes higher.
Le
f
Use Index
tp
Lo iled
ad o
e n
M d o floo
ov n
ac r
e
ar
Un d
t
lo
ad
Lo ed
ad
on
e
M d o to fl
ov nt
oo
o
e
pa r
Le d
ft
lle
o
t
M np
ov al
ed let
Lo
ad
e
M do
ov nt
ed o
ac
ar
t
Destroying Factory Myths
Still being moved
Loaded on cart
Loaded in box set
on blocks
Average use index = Total use indicators
Number of levels
Loaded in box
set on floor
=
(0+3+4+0+2+4+2+4+3+4)
10
= 2.6
Piled directly
on floor
Need to study how steps 1
and 2 can be used here.
1
Figure 2.34
2
3
4
5
6
7
8
9
10
Conveyor Use Index (IE Method).
To be sure, this sort of improvement should help goods flow
more smoothly, and if they actually do flow more smoothly,
that itself can be expected to have positive effects.
However, this improvement method falls short of asking
the radical “Why?” question: Why does this conveyor system
have to exist? Therefore, it is not a revolutionary method.
Instead, it accepts the conveyance system as a fait accompli
and goes directly to attempting improvements in it.
I know of many factories that have thoroughly implemented this conventional IE approach. In every one of these
factories, roller conveyors have been installed between every
process. Conveyors cover these factories like so many cold,
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black ­carpets. In-process inventory is set upon these narrow
conveyors. The utmost goal of the IE method for improving­
these conveyors is to raise their average use index to the
highest­use level. Beyond that, the IE method envisions
nothing­in the way of further improvements.
Now let us examine how we might apply the JIT method
in one of these factories. We would begin by getting rid
of all of the roller conveyors. Why? Because, as mentioned
earlier, the JIT method regards improvements to an existing
conveyor system as “pseudo improvements,” which JIT professionals avoid like the plague.
After getting rid of the roller conveyors, the JIT method
calls for the creation of a new factory layout and new work
methods that allow production to proceed without any conveyance system at all. If such improvements are made, the
factory will be rendered free of any need for conveyance and
its attendant problems.
As you can see, both of these methods (IE and JIT) are
called “improvement methods,” but that is about all they have
in common.
JIT is so revolutionary that some people have half-seriously suggested it is a religion. Perhaps it is. Like most religions, JIT offers an ideal state of being (for factories, at least)
and challenges the factories to try to attain that state. But
there is nothing evangelical about JIT. If anything, JIT is an
inner-directed, contemplative “religion” that asks its followers to focus on their own companies, factories, workplaces,
and selves. JIT begins with a quiet introspection into all of
these things. If it has any close cousin in the field of religion,
it would probably be the Japanese Zen sect that sprang from
contemplative Buddhist sects in India and China.
JIT has no set organizational structure or “how to” manual.
No doubt this makes the goal of approximating JIT production all the more difficult. When people hear this, they often
ask, “So what is the best way to carry out JIT improvements?”
Destroying Factory Myths
To this frequent question, I have two answers up my
sleeve. One is, “Go into the red.” In other words, take the
poor man’s approach to making improvements and spend as
little money as possible.
The other answer is, “Believe in JIT.” This answer goes
especially to top managers, for it is they who must first
believe in JIT in order to get middle managers and their subordinates to believe. Although belief in JIT must start with
top managers­, its most essential believers are the ­factory
employees­. If they truly believe in JIT, they will make big
improvements in their factories.
I should also add that the goal of JIT production should
never be far from the hearts and minds of everyone. Getting
there requires faith.
Lesson 27. Keep JIT in Mind and
Apply Improvements to Yourself
“Yes” and “Yes, I’ll Do It Right Away”
Day-to-day life is awash in information, provided via such
media as newspapers, books, radio, television, and so on. As
a result, we all have second-hand knowledge about a wide
variety of subjects.
For example, you or I may not be athletic in the least,
but if we watch sports programs on television, we come to
understand a lot about certain sports without having to actually go out and run, jump, or sweat. Likewise, some people
develop a strong sense of affinity and familiarity with foreign
lands and peoples based solely on what they have read in
travel literature or have seen on TV.
We can find the same kind of people in the field of JIT
improvements. People who have never even set foot in a
factory will confidently explain such things as flow production to their friends. Such people have achieved some skill
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at “mental improvements,” but have no experience at all in
“physical improvements.”
I do not know how many times I have heard discussions
and debates on JIT improvement that include nothing but
“mental improvements.” Mental improvements, no matter
how skillful and eloquent they may be, are of no help at all
in the real world of physical improvements. Mental improvements are devoid of value unless they are followed up by a
trip to the factory, long and diligent efforts, and results that
are seen and felt physically.
Second-hand knowledge is useless for JIT improvements.
JIT improvements need hands-on learning.
Let us take an imaginary trip through a factory that is currently undergoing some improvements. Right now we are
standing in front of a manufacturing cell where an important improvement—switching to flow production—has just
been made.
“You have a U-shaped cell now, so you’ve got to stop
working with lots.”
Even a simple instruction such as this one spurs different
reactions at different workplaces. The reaction is a good indication of how fully the JIT improvement method has been
accepted and incorporated. I have been able to delineate
seven stages of JIT acceptance, as illustrated in Figure 2.35.
WHY?
YES, I’LL DO IT SOON.
STAGE “Yes, I’ll do it right away.”
STAGE “Yes, I’ll do it.”
INSTRUCTION:
“You’ve got
to do this.”
STAGE
STAGE
STAGE
STAGE
STAGE
Figure 2.35
Method.
“Yes, I understand.”
“OK.”
“Yes, I’ll look into it.”
[silence]
“But, blah, blah, blah, . . .”
(Very bad)
(Worse)
(Absolute worst)
Seven Stages in the Acceptance of the JIT Improvement
Destroying Factory Myths
Stage 1: “But, blah, blah, blah...”
Excuse-making is the worst possible response. It would be
better not to say anything than to try to make excuses. During
a factory visit, I can tolerate about three excuse-makers if
I am in an exceptionally good mood, but if my mood is not
so expansive, even one excuse-maker is enough to convince
me that the factory is not worth any more of my time. I’m not
at all interested in visiting factories where the people are only
pretending to be carrying out JIT improvements.
Stage 2: [silence]
There are actually two types of silent responses. One is when
the person is too wrapped up in trying to figure out how
to make the improvement to say anything, and the other is
when the person is just plain put off by the instruction.
The first kind of silence is OK, though not exactly polite,
but the second kind is very bad indeed. The person who
responds this way usually lacks perseverance and patience,
resists change, and harbors resentment against those who
propose changes. JIT leaders are always being “stabbed in
the back” by this type of person. Rather than feel the chill
wind blowing through the knife holes in his or her back, it is
better that the JIT leader just find the nearest exit.
Stage 3: “Yes, I’ll look into it.”
This can be seen as the total opposite to the silent response
at the second stage. The respondent sounds upbeat and
attentive. But the chances are that he or she is making an
empty p
­ romise. I have learned that you can trust a ­factory
worker who says, “I’ll look into it,” about as much as you can
trust a typical politician who says, “I’ll be sure to address
that p
­ roblem.” They might as well be saying, “OK, I won’t
do a thing.”
On my next visit, I usually voice a short, sarcastic remark
such as, “My, you folks are really doing a lengthy study of
this problem,” before moving directly to the next workshop.
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To sum things up so far, the three bad responses are:
“But blah, blah, blah,” “[silence],” and “Yes, I’ll look into it.”
Factories where such responses are common are on the fast
track to Nowhere as far as JIT improvement is concerned. To
get back on the right track and survive as a business, they
need to launch a company-wide campaign to abolish such
counterproductive attitudes to make room for JIT improvement to firmly take root.
Stage 4: “OK.”
Like a silent response, a simple “OK” can have more than one
meaning. It may seem like a simple and total acceptance of the
instruction, but it is not very good communication. One c­ annot
tell, for instance, whether the meaning is, “Yes, the current way
is wrong,” or “Yes, you’re right.” A more precise answer that
reflects the respondent’s meaning would be better.
Stage 5: “Yes, I understand.”
While not as bad as a too simple and too vague “OK,” this
response still suffers from vagueness.
Improvements are not primarily something to be “understood” intellectually. They are things to be done in the factory. Understanding them without doing them means nothing.
In fact, it is only by doing them that we can really understand them. So, I usually meet this response with something
like, “After you’ve made the improvement, I’ll be able to see
whether you understood it or not.”
Stage 6: “Yes, I’ll do it.”
When the person immediately gives this response, you know
he or she has cleared a big hurdle. It is very big step indeed
to get from a simple “Yes” to an energetic, “Yes, I’ll do it.”
There is only one hurdle left: the question of when it will
get done. Obviously, if the respondent’s intention is to get it
done about six months from now, he or she has not really
made it to Stage 6 after all.
Destroying Factory Myths
Stage 7: “Yes, I’ll do it right away.”
During a factory visit, when I give even the mildest kind of
instruction and hear this sincere response, I know I am dealing with a JIT champion who has taken the JIT improvement
method to heart.
When the typical type of response in a factory improves
from “Yes,” to, “Yes, I’ll do it,” and finally, “Yes, I’ll do it right
away,” I can tell just how far the people have come in understanding JIT. After all, JIT is almost synonymous with “doing
it right away.”
Lesson 28. Attitude Adjustment:
From “Yes” to “Yes, I’ll Do It Right Away”
A Passion for Improvement
JIT improvement includes more than building a few custommade jigs and removing waste from operations. Obviously,
these small improvements can add up to something big
and are a key part of JIT improvement. But the real gist of
JIT improvement is the discarding of old ideas and habits,
changing over to flow production, and otherwise ­overhauling
the entire factory until it becomes a factory that efficiently
serves the current needs of the marketplace. This amounts to
­nothing short of a factory revolution and a major innovation
in the way to conduct business.
JIT improvement rightfully stands among the ranks of
other movements that have resulted in major business innovations. JIT turns factory improvements into innovations. The
most important prerequisite for innovation is enthusiasm.
The ability to remain constantly enthusiastic—something we
admire in young people—is a vital part of the JIT improvement approach.
But what about the over-30 set? How are they supposed to
keep up their enthusiasm?
One good way is to put some psychological distance
between ourselves and our workplace. When a series of
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Improvement
“can do” energy
Doubt (”Why?”)
Child’s eyes
Enthusiasm
Conflict
Youth
Figure 2.36
JIT Improvement (Innovation) Cycle.
problems occurs in the workplace and cause disorder, we
need to be detached and objective enough to look at the situation with a child’s eyes and ask the typical child’s ­question:
“Why?” The more we lose this ability to wonder and ask
“Why?” the harder it becomes to revolutionize the factory and
its long-established traditions.
After we learn to keep wondering and asking “Why?” we
come to the next hurdle: dealing with difficult problems. This
is the time for brainstorming. It is also the time when conflicts begin.
If we rub two objects together, we get friction. Likewise,
friction also may occur in the human mind when improvement
ideas rub up against current habits. It gets people’s ­dander up,
but by the same token, it can also get their enthusiasm up.
If we can keep fanning the flames of this enthusiasm, all we
need after that is the determination and strength to revolutionize the factory. Then we just do it.
This entire process moves in cycles: First we go to the
workplace, then we look around with a child’s eyes and ask,
“Why?” Next, we confront conflict and fire up our hearts with
youthful enthusiasm, then we pour our energy into making
the improvements. This cycle is called “the JIT Improvement
(Innovation) Cycle.” (See Figure 2.36.)
Lesson 29. Improvement Is Enthusiasm
About the Author
Hiroyuki Hirano believes Just-In-Time (JIT) is a theory and technique to
thoroughly eliminate waste. He also calls the manufacturing process the
equivalent of making music. In Japan, South Korea, and Europe, Mr. Hirano
has led the on-site rationalization improvement movement using JIT production methods. The companies Mr. Hirano has worked with include:
Polar Synthetic Chemical Kogyo Corporation
Matsushita Denko Corporation
Sunwave Kogyo Corporation
Olympic Corporation
Ube Kyosan Corporation
Fujitsu Corporation
Yasuda Kogyo Corporation
Sharp Corporation and associated industries
Nihon Denki Corporation and associated industries
Kimura Denki Manufacturing Corporation and associated industries
Fukuda ME Kogyo Corporation
Akazashina Manufacturing Corporation
Runeau Public Corporation (France)
Kumho (South Korea)
Samsung Electronics (South Korea)
Samsung Watch (South Korea)
Sani Electric (South Korea)
Mr. Hirano was born in Tokyo, Japan, in 1946. After graduating from
Senshu University’s School of Economics, Mr. Hirano worked with Japan’s
largest computer manufacturer in laying the conceptual groundwork for the
country’s first full-fledged production management system. Using his own
I-145
I-146
◾
About the Author
interpretation of the JIT philosophy, which emphasizes “ideas and techniques for the complete elimination of waste,” Mr. Hirano went on to help
bring the JIT Production Revolution to dozens of companies, including­
Japanese companies as well as major firms abroad, such as a French
automobile manufacturer and a Korean consumer electronics company.
The author’s many publications in Japanese include: Seeing Is Understanding: Just-In-Time Production (Me de mite wakaru jasuto in taimu
seisanh hoshiki), Encyclopedia of Factory Rationalization (Kojo o gorika
suru jiten), 5S Comics (Manga 5S), Graffiti Guide to the JIT Factory Revolution (Gurafiti JIT kojo kakumei), and a six-part video tape series entitled
JIT Production Revolution, Stages I and II. All of these titles are available
in Japanese from the publisher, Nikkan Kogyo Shimbun, Ltd. (Tokyo).
In 1989, Productivity Press made Mr. Hirano’s JIT Factory Revolution:
A Pictorial Guide to Factory Design of the Future available in English.
Business Improvement
JIT Implementation Manual
The Complete Guide to Just-in-Time Manufacturing • Second Edition
Volume 1
The Just-in-Time Production System
HIROYUKI HIRANO
“It is a book for manufacturing companies that are fighting desperately for survival and that will go
to any length to improve their factories and overcome the obstacles to success. One could even call
this book a ‘bible’ for corporate survival.”
—Hiroyuki Hirano
Known as the JIT bible in Japan, JIT Implementation Manual — The Complete Guide to Just-inTime Manufacturing presents the genius of Hiroyuki Hirano, a top international consultant with vast
experience throughout Asia and the West. Encyclopedic in scope, this six-volume practical reference
provides unparalleled information on every aspect of JIT— the waste-eliminating, market-oriented
production system. This historic, yet timeless classic is just as crucial in today’s fast-changing global
marketplace as when it was first published in Japan 20 years ago.
Providing a comprehensive introduction to the just-in-time production system, Volume 1: The
Just-in-Time Production System dispels outdated myths and ideas about manufacturing that are
still prevalent. Supplying essential background information on the JIT approach to production
management, this user-friendly resource builds a strong foundation for implementation.
PP9016
ISBN: 978-1-4200-9016-1
90000
www.taylorandfrancisgroup.com
9 781420 090161
w w w. p r o d u c t i v i t y p r e s s . c o m
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 2
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 2
Waste and the 5S’s
HIROYUKI HIRANO
Originally published as Jyasuto in taimu seisan kakumei shido manyuaru copyright © 1989 by JIT Management Laboratory Company, Ltd., Tokyo, Japan.
English translation copyright © 1990, 2009 Productivity Press.
CRC Press
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Contents
Volume 1
1
Production Management and JIT Production Management....... 1
Approach to Production Management................................................... 3
Overview of the JIT Production System................................................ 7
Introduction of the JIT Production System...........................................12
2
Destroying Factory Myths: A Revolutionary Approach............ 35
Relations among Sales Price, Cost, and Profit......................................35
Ten Arguments against the JIT Production Revolution.........................40
Approach to Production as a Whole....................................................44
Volume 2
3
“Wastology”: The Total Elimination of Waste..........................145
Why Does Waste Occur?....................................................................146
Types of Waste.................................................................................. 151
How to Discover Waste..................................................................... 179
How to Remove Waste......................................................................198
Secrets for Not Creating Waste...........................................................226
4
The “5S” Approach..................................................................237
What Are the 5S’s?.............................................................................237
Red Tags and Signboards: Proper Arrangement and
Orderliness Made Visible...................................................................265
The Red Tag Strategy for Visual Control............................................268
The Signboard Strategy: Visual Orderliness.......................................293
Orderliness Applied to Jigs and Tools................................................307
Index.............................................................................................. I-1
About the Author.......................................................................... I-31
v
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◾
Contents
Volume 3
5
Flow Production......................................................................321
Why Inventory Is Bad........................................................................321
What Is Flow Production?..................................................................328
Flow Production within and between Factories.................................332
6
Multi-Process Operations....................................................... 387
Multi-Process Operations: A Wellspring for Humanity on the Job......387
The Difference between Horizontal Multi-Unit Operations and
Vertical Multi-Process Operations......................................................388
Questions and Key Points about Multi-Process Operations................393
Precautions and Procedures for Developing Multi-Process
Operations.........................................................................................404
7
Labor Cost Reduction..............................................................415
What Is Labor Cost Reduction?.......................................................... 415
Labor Cost Reduction Steps............................................................... 419
Points for Achieving Labor Cost Reduction........................................422
Visible Labor Cost Reduction.............................................................432
8
Kanban.................................................................................. 435
Differences between the Kanban System and Conventional Systems....435
Functions and Rules of Kanban........................................................440
How to Determine the Variety and Quantity of Kanban...................442
Administration of Kanban.................................................................447
9
Visual Control......................................................................... 453
What Is Visual Control?......................................................................453
Case Study: Visual Orderliness (Seiton)..............................................459
Standing Signboards..........................................................................462
Andon: Illuminating Problems in the Factory....................................464
Production Management Boards: At-a-Glance Supervision................. 470
Relationship between Visual Control and Kaizen.............................. 471
Volume 4
10 Leveling...................................................................................475
What Is Level Production?................................................................. 475
Various Ways to Create Production Schedules...................................477
Contents
◾ vii
Differences between Shish-Kabob Production and Level Production.....482
Leveling Techniques..........................................................................485
Realizing Production Leveling............................................................492
11 Changeover............................................................................. 497
Why Is Changeover Improvement (Kaizen) Necessary?.....................497
What Is Changeover?.........................................................................498
Procedure for Changeover Improvement...........................................500
Seven Rules for Improving Changeover.............................................532
12 Quality Assurance.................................................................. 541
Quality Assurance: The Starting Point in Building Products..............541
Structures that Help Identify Defects.................................................546
Overall Plan for Achieving Zero Defects............................................561
The Poka-Yoke System.......................................................................566
Poka-Yoke Case Studies for Various Defects.......................................586
How to Use Poka-Yoke and Zero Defects Checklists.......................... 616
Volume 5
13 Standard Operations.............................................................. 623
Overview of Standard Operations.....................................................623
How to Establish Standard Operations..............................................628
How to Make Combination Charts and Standard Operations Charts.....630
Standard Operations and Operation Improvements...........................638
How to Preserve Standard Operations...............................................650
14 Jidoka: Human Automation.................................................... 655
Steps toward Jidoka...........................................................................655
The Difference between Automation and Jidoka...............................657
The Three Functions of Jidoka..........................................................658
Separating Workers: Separating Human Work from Machine Work.....660
Ways to Prevent Defects.................................................................... 672
Extension of Jidoka to the Assembly Line.......................................... 676
15 Maintenance and Safety......................................................... 683
Existing Maintenance Conditions on the Factory Floor......................683
What Is Maintenance?........................................................................684
CCO: Three Lessons in Maintenance.................................................689
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Contents
Preventing Breakdowns.....................................................................683
Why Do Injuries Occur?....................................................................685
What Is Safety?.................................................................................. 688
Strategies for Zero Injuries and Zero Accidents..................................689
Volume 6
16 JIT Forms................................................................................711
Overall Management......................................................................... 715
Waste-Related Forms.........................................................................730
5S-Related Forms............................................................................... 747
Engineering-Related Forms................................................................777
JIT Introduction-Related Forms..........................................................834
Chapter 3
“Wastology”
The Total Elimination of Waste
If you were to ask someone, “What does the JIT Production
System mean?” and that someone were to reply, “It means
making just what is needed, just when it is needed, and in
just the amount needed,” that would indicate he or she has at
least an intellectual grasp of the JIT Production System.
On the other hand, if the person’s response was something
like, “It means the total elimination of waste,” that would
suggest that perhaps this person has learned JIT physically
as well as intellectually. I might add that the JIT Production
System is a philosophy that seeks that point of truth where
improvement activities and manufacturing activities become
completely intertwined. But it is an empirical, hands-on
­philosophy that devalues any ideas that are not grounded in
the factory.
Only people who have physically learned the JIT Production
System can truthfully answer the question, “Why should we
make just what is needed, just when it is needed, and in just
the amount needed?”
Many people would answer this question with, “to better
respond to customer needs” or “to reduce inventory.” However,
making just what is needed, just when it is needed, and in
just the amount needed first requires a flow in the factory.
The factory’s flow is what brings all of the waste to the
surface, where we can apply JIT techniques to totally eliminate the waste. JIT means ideas and techniques for the total
elimination of waste.
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Why Does Waste Occur?
There are all kinds of waste in the world. People waste time,
space, buildings, products, and so on. Even the way we dress
can be seen as wasteful. After all, what useful function does
a necktie serve? Or a collar? Or a crease?
Naturally, we can expect factory waste to exist in many
forms. When waste becomes bad enough, the waste is no
longer in the factory—the factory is in the waste. Finally, the
waste may get so dense it strangles the factory.
Just how does waste occur in the first place?
First, we must reach a universal understanding of what
waste is. Different people have different ideas about what
does and does not constitute waste. Common definitions
of waste include, “Whatever is not useful is wasteful,” or
“Whatever does not contribute to profitability is waste.” These
two definitions alone exhibit a significant difference in how
waste is understood.
For example, let us suppose I consider neckties a form
of waste. I argue that neckties serve no useful purpose
whatsoever. But someone who uses his necktie to clean his
eyeglasses might disagree with me. For him, neckties are
­
quite useful indeed. Some people might even find their neckties useful after they have washed their hands and can find
nothing else to dry them.
Definitions of waste are just as diverse in the factory. Let
us take inventory as an example. When product sales are
on the rise, inventory becomes a wonderful thing. There is
nothing the sales department hates more than production
shortages of hot-selling items. Consequently, it views inventory
as “necessary.”
Once sales slow down, however, inventory changes from
angel to devil. At such times, inventory appears especially diabolical to the managers who suddenly face cash flow problems.
These managers might go as far as to say that inventory is
“unnecessary” without really knowing what they are saying.
“Wastology”
JIT production means removing waste. But when different
people have different ideas of what waste is, their enthusiasm for joining together in improvement activities is bound
to wane. For that reason, if for no other, we should all have
the same idea of what waste really is.
So, let us think for a moment: What constitutes waste in
the factory?
We can start counting specific types of factory-related waste,
such as the wasteful use of telephones, vouchers, meetings,
control work, conveyance, and the like, and we would probably never finish counting. Taking telephone-related waste
as an example, we cannot say that all use of telephones is
wasteful. Sometimes it is worthwhile.
It is not easy to find the essential meaning of waste, therefore, when waste appears in such variety and is often mixed
with nonwaste. Indeed, how can we all agree on a common
definition of waste when we cannot even clearly identify it?
Perhaps we should approach this problem from the opposite
angle by seeking to define what is useful, and then regarding
everything that does not fit that definition as waste.
In a factory, “useful” is the same thing as “value-adding.”
Machining and other types of processing done in the factory
is what adds the most value to the products. So we can say
then that everything that does not add value is a form of
waste. Clearly, we can see the equivalence between adding
“no value” (that is, valuelessness or worthlessness) and waste.
We could further emphasize the wastefulness of everything
in the factory that does not add value by noting that waste
does not process anything, nor does it add any value.
Once everyone agrees upon this back-door definition of
waste as “everything that does not add value” suddenly and
mysteriously all kinds of waste becomes visible.
Where before we saw no waste, we begin to see waste in
the way things are counted, waste in the way the workpieces
are set on the operator’s table, in the way the operator picks
up screws and a screwdriver, in the way he screws in the
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FUNCTION:
Fastening two workpieces so that
they will not become separated
Waste in
turning screw
Adds no value
Figure 3.1
Only the last turn of
the screw serves the
fastening function.
ve
esi
Value is added
in this one
moment.
h
Ad
Applying adhesive
serves the same
function and adds
the same amount
of value at lower cost.
Waste in Screw-Fastening Operation.
screws, and in the way he puts back the screwdriver and
passes on the assembled workpiece.
Thus, the simple task of fastening screws into workpieces
suddenly becomes full of waste. The only value-adding part
of this whole operation is the function of fastening two workpieces so that they will not become separated. Everything that
does not directly serve this function is waste. (See Figure 3.1.)
In some cases, the entire screw-fastening operation itself
is pure waste because there may be a cheaper way to fulfill
the same function. Using a chemical adhesive instead of a
screw may, for instance, serve the function of fastening two
things together.
In any case, this one simple example of a screw-fastening
operation should be enough to demonstrate just how full of
waste factories are. It is an exaggeration to say that everything that goes on in the factory is wasteful. We should ask
ourselves how waste could have been so successful in taking
root in today’s factories.
All kinds of problems, large and small, crop up in factories
on a daily—or even hourly—basis. We can safely say that no
factory is without problems and that every factory finds itself
“Wastology”
buried in piles of problems. How much waste a factory contains,
however, depends on how well it responds to its problems.
These “factory problems” are the seeds of waste, and ineffective responses to these problems allow the seeds to germinate
and grow. The following is my list of “waste-creating” moments
that commonly occur in various factory departments.
1. Manufacturing
a. This other guy is not busy right now, so I’ll use him
on my line for the time being.
b. There’s no place to put those things, so let’s put them
down there for the time being.
c. This process has been turning out some defectives, so
let’s increase output for the time being to make sure
we produce enough good ones.
2. Conveyance
a. This stuff is heavy, so let’s borrow a forklift for the
time being.
b. For the time being, we’d better count them to make
sure we have the right amount.
3. Inspection
a. We are receiving too many quality complaints, so let’s
add more inspectors for the time being.
b. We need to reduce the number of defectives, so let’s
draw up some Pareto charts for the time being.
4. Equipment
a. We need to increase our output, so let’s bring in
another machine for the time being.
b. There’s been a machine breakdown in production,
so let’s call in some maintenance people for the time
being to do some emergency repairs.
5. Control/management
a. Next month’s production schedule has not been
decided yet, so for the time being let’s just do this
month’s over again.
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b. We’ve been having an awful lot of late deliveries.
We’d better make a list to keep track of them for the
time being.
The fact of the matter is that the waste that fills up and
destroys so many factories starts with such simple incorrect
responses to problems.
Notice that I have been careful to include the words “for the
time being” in all of the above instances. We tend to do things
“for the time being” when we want to do something right away
and do not want to take time to find a more permanent solution. In other words, we are temporarily avoiding the problem
rather than solving it. Such stopgap responses imply that we
do not understand what is really causing the problem.
Virtually all the waste that exists in factories originates in
such “evasive” responses. This is particularly true of waste in
inventory and conveyance.
Problems occur all the time in factories. People are kept
busy finding “evasive” responses to these problems as they
occur. The only way to solve the problems is to look directly
at them to find the real root cause and then remove that
cause. The important thing is to switch from makeshift problem-dodging to real problem-solving.
As shown in Figure 3.2, once a stopgap measure has been
employed to “avoid” the problem, people start institutionalizing the stopgap measure by assuming it is the correct measure to take. Then they start making it a habit. Finally, after a
few years, no one even questions the ways things are done,
since they seem to be the “natural” way of doing things in
the factory.
Once such erroneous responses become substantiated as
the natural way of doing things, even people who intellectually
recognize the inherent wastefulness will be hard put to make
any improvements that actually root out the ­problem’s true
cause. The only solution for getting rid of such deeply embedded waste is a truly radical one: the JIT factory revolution.
“Wastology”
Real
improvement
Stopgap
improvement
Problem solved
“For the time being, let’s...”
Evading the problem
(Creating waste)
“We’ve got to...”
Institutionalization
(Acknowledging waste)
“We’ve been doing it
like this...”
Habituation
(Getting used to waste)
“No one has any objection
to the way we do this now...”
Substantiation
(Unrecognized waste)
Figure 3.2
How Waste Takes Root and Gets “Substantiated.”
Types of Waste
In Japanese factories, one often hears of the need to “tighten
the cost belt” or “Eliminate the 3 Mu’s.” The 3 Mu’s are the
three main types of waste that improvement groups target
in their improvement activities. Each of these types has a
Japanese name that begins with the syllable mu. They are
defined as follows:
◾◾ Waste (muda) = Capacity exceeds the load.
This is a waste of capacity.
◾◾ Inconsistency (mura) = Capacity sometimes exceeds the
load and the load sometimes exceeds the capacity.
Here, the problem is one of variation.
◾◾ Irrationality (muri) = Load exceeds capacity.
Capacity is overtaxed by an unreasonable load.
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WASTE (narrow sense)
Capacity > Load
WASTE
(broad sense)
INCONSISTENCY
Capacity > or < Load
IRRATIONALITY
Capacity < Load
Figure 3.3
Waste as Seen within the JIT Production System.
The goal is to arrive at a “rational” balance where capacity
and load are about equal.
Upon hearing this, some JIT novices might nervously conclude that they not only have to look for plain old waste
(muda) but must also make separate improvement efforts
to deal with inconsistency (mura) and irrationality (muri).
Fortunately, this is not so. These are just theoretical distinctions. In practice, irrationality shows up as inconsistency,
which is always tied in with waste. In the practical-minded
JIT production system, people involved in factory-based
improvement activities are not asked to make distinctions
among the 3 Mu’s but instead concentrate their efforts on
eliminating waste in the broad sense, which includes inconsistency and irrationality. (See Figure 3.3.)
In other words, JIT’s “total elimination of waste” is intended
to cover all of the strictly defined types of waste. In addition
to the 3 Mu classification, there are many ways to organize
waste into categories. Below are descriptions of three such
classification schemes: 5MQS waste, production factor waste,
and JIT 7 waste.
5MQS Waste
The 5MQS scheme identifies seven types of waste, five of
which begin with the letter “M”: Man, Material, Machine,
Method, and Management. The “Q” in the 5MQS formula
stands for Quality and the “S” for Safety.
“Wastology”
Man (People-related waste)
Material
Walking waste
Watching waste
Searching waste
Operating waste
Invisible waste
Waste of parts
Waste of bolts
Waste of welds
Waste of functions
Retention waste
Method
Shish-kabob production
waste
Inventory waste
Conveyance waste
Waste in picking up and
setting down workpieces
Figure 3.4
Management
Waste of materials
Waste in meetings
Waste in management/
control
Waste in communications
Waste in vouchers
Safety
Waste of disaster
prevention methods
Waste in fixing defects
“Safety first” really requires
removing all waste that
can lead to accidents
and/or injuries.
Machine
Waste of large machines
Waste of general purpose
machines
Waste of conveyors
Waste in machines that
“process air”
Waste created by breakdowns
Waste in machine handling
Quality
Waste in making defective
goods
Waste in fixing defects
Waste in making mistakes
Waste in inspection
Waste in quality control
5MQS Classification of Waste.
Figure 3.4 lists the specific forms of waste that are grouped
under the 5MQS categories.
The following describes some of the main forms of waste
illustrated in Figure 3.4.
Walking Waste
In JIT production, the basic policy is that everyone stands (or
walks) while working, especially since most workers are handling several processes at once. But such multi-process handling
requires that the workers “walk” at least a few steps as a kind
of secondary operation to their main processing operations.
Walking and working are not the same thing. In factory
workshops, walking usually takes about one second per step.
These steps add up fast, resulting in considerable “walking
waste.” The proper response to this situation is to ask, “Why
does this worker have to take X number of steps?” and then
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see if an improvement can be made to reduce the required
number of steps.
Watching Waste
This kind of waste is most abundant in factories that have
brought in automated equipment, NC machines, and the
like. At such machines, the operator sets up the workpiece,
pushes a switch, and then watches the machine do its work.
Whenever I’ve asked one of these operators why they are
standing there watching the automatic machine work, he or
she always has an answer ready, such as, “I’m watching out
for flying fragments” or, “I’m making sure the shavings don’t
cause problems.” Still, the fact is that these operators are
“whiling­” more than “watching.” They have some free time
while the machine is working, so they “while” it away by being
a spectator to the machine’s work. To avoid just this kind of
waste, JIT’s “human automation” (jidoka) makes a point of
clearly separating machine work from human work.
Searching Waste
In changeover procedures that require about 30 minutes, it is
not easy to tell when five of those minutes are spent searching for jigs and tools. However, when the same five minutes
of searching time goes into a 10-minute changeover, the
“searching waste” is quite obvious.
Searching waste is especially common in subcontractor factories. The answer to this problem is the most basic of the “5S”
basics: proper arrangement (seiri) and orderliness (seiton).
Waste of Large Machines
It often happens that people at processes where workpieces
are being processed one at a time without any problems
suddenly decide it is better to “maximize output” by gathering workpieces into lots of dozens or even hundreds before
“Wastology”
1
2
3
Inventory waste
Conveyance waste
Insert
Large Cleaning
Chamber
Extract
Inventory waste
Loading waste
Fixed-idea waste
Plant investment waste
Chain conveyor waste
Non-flexible production waste
Unloading waste
Distribution waste
Inventory waste
Conveyance waste
Inventory waste
Figure 3.5
Waste Related to One Large Cleaning Chamber.
processing them. This rapid boost in output also means a
rapid increase in waste.
Large machines that are built for such large-lot processing
are themselves manifestations of this kind of waste. I have
seen many large presses, cleaning chambers, furnaces, and
shotblasters that fit this description.
Figure 3.5 illustrates all the forms of waste that can be
created by just one large cleaning unit. There are also some
related forms of waste having to do with overall production
that are not even listed, such as waste in overall lead-time
and quality-related waste.
Conveyor Waste
In factories that produce home electrical and electronic goods,
almost every assembly line operation uses conveyors. I have
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been quite surprised at the extent to which these factories
have seen fit to use conveyors. When I ask why, I am usually
told that the conveyors help maintain a steady pitch.
I cannot argue with the benefit of a steady pitch, but we
need to look at the price paid for that benefit in terms of waste,
specifically waste related to moving things to and from the
conveyor and “idle time waste” resulting from an imbalance
among operations. When viewed from this perspective, conveyors are not so much a tool for maintaining a steady pitch
as they are a materials-handling tool that links operators.
Factories such as these become dependent on their conveyors
and fail to see all the waste the conveyors conceal. For them, the
first step in JIT improvement is to go “cold turkey” by getting
rid of the conveyors and their fixed ideas related to them.
Waste in Machines That “Process Air”
Often, after the operator presses the “start” button, the machine
does nothing but “process the air” for a few seconds before actually machining or otherwise processing the workpiece. Cutter
blades spin without cutting anything but air and presses move
without pressing anything but air. (See Figure 3.6.)
To remedy this problem, we need to find out what the
minimum required amount of space is between the blade,
Any time spent pressing only air is waste.
Figure 3.6
Waste in Machine (Press) That Processes Air.
“Wastology”
die, or other tool and the workpiece, and then modify the
machine to get as close as possible to that minimum space.
Waste of Parts
Here, we need to look at the basic functions of the parts
and materials used in the product and then repeatedly ask
“Why?” while applying value analysis (VA) and value engineering (VE) techniques to eliminate waste.
We can begin the questioning by asking: “Why is this part
necessary?” or “What is this part’s basic function?” Once we
have asked this of all the product’s parts, we can grasp what
their basic functions are. We are then ready to ask questions
such as: “Could these parts be replaced by this part?” or?
“Is there some way we can reduce the amount of materials
or number of parts?” or, “Could this function be combined
with some other basic function in the same part?” This line of
questioning will help us reveal and eliminate waste.
Waste of Materials
The need for proper arrangement (seiri) and orderliness
(seiton) is just as great in management departments as it is in
manufacturing.
First, we figure out which materials are really necessary
and which are not, then we immediately toss out all the
unnecessary things. Hanging on to nonessential materials
fills up lockers and otherwise takes up space. It also contributes to time wasted in searching for necessary things amid
piles of unnecessary things.
To do this, we need to find out where the management
materials come from. For example, at least half of the material
generated by computers is expendable. To find out which
half, we can experiment by no longer outputting and distributing the materials. The departments that need certain
materials will demand them. Judge all materials that are not
in demand as superfluous.
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Waste in Meetings
I can tell how efficiently and seriously a factory’s employees
pursue their work by looking at two things: the cleanliness of
their bathrooms and the efficiency of their meetings.
Meetings happen for all kinds of reasons; there are productivity meetings, advancement meetings, and quality meetings. At many of these meetings, the participants either meet
without really discussing anything or discuss something without really making any decisions. In both cases, the meetings
generate nothing but waste.
Shish-Kabob Production Waste
The more trouble it is to switch to new products and carry
out the required changeover, the more people tend to opt
for “shish-kabob” (lot) production. Shish-kabob production
is a tempting option when one-piece flow becomes difficult.
However, we should be mindful of its many disadvantages,
which include the following:
◾◾ Diminishes production opportunities
◾◾ Lengthens lead-time
◾◾ Increases inventory
◾◾ Increases defectives
◾◾ Eats up space
◾◾ Consumes more parts and energy resources
◾◾ Slows capital turnaround
◾◾ Conceals waste and other problems
The list could go on and on, but I will stop with these eight
drawbacks of shish-kabob production to avoid wasting space.
Waste in Picking Up and Setting Down Workpieces
This kind of waste is particularly prominent at factories that
are not well organized for manufacturing. Often, workpieces
“Wastology”
must be picked up, set down, and counted at each process
in the line.
The people at such factories seem unaware of the fact
that processing and assembling workpieces is a constant
battle against material handling costs. The same value can
be added to products even without all the “picking up and
setting down.” All it takes to reach that point is human wits
and energy.
Waste in Making Defective Goods
It is not difficult to surmise that quality consciousness is
generally abysmal when defective products are taken apart
so that their parts can be recycled to build other products.
I have seen this happen, especially with molded plastic parts
and aluminum diecasts.
And it is not hard to find workers at such factories who
shrug their shoulders at defective products and say, “No big
loss. We can recycle the parts.”
Addressing defective products is too little too late. We need
to find ways to prevent people and machines from ­making
defect-causing mistakes in the first place. JIT’s essential techniques for doing this are human automation, poka-yoke
(­mistake-proofing), and company-wide awareness revolution.
Waste in Disaster Prevention Measures
Accidents and injuries are a clear sign of truly excessive waste
in the factory, and are the kind of “social waste” that people
should regard as Public Enemy No. 1. Safety guidance and
assurance must be a key underlying factor in any campaign
to rid factories of waste.
Production Factor Waste
This approach to waste takes the “flow of goods” in production as the basis for finding and eliminating waste. The flow
of goods at a typical factory is characterized by:
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1. Procurement staff ordering and accumulating materials,
which they send to the materials warehouse as “retained”
goods.
2. At the processing stage, a conveyor system carries the
materials to the processes on the production line.
3. The conveyed materials to be processed are “retained”
next to the processing equipment.
4. The materials next to the processing equipment are
picked up and “processed.”
5. After being processed, the goods are set down and
“retained” on the other side of the same machine.
6. The conveyor carries these goods to the inspection process.
7. The goods are retained at the inspection process, awaiting inspection.
8. The goods are inspected.
9. The inspected goods are set down again and retained on
the other side of the inspection process.
10. The conveyor carries the inspected goods to the warehouse, where they are retained prior to shipment.
If we take just the four key flow factors (retention, conveyance, processing, and inspection) from these ten steps in the
flow of goods, we get a pattern of:
1. retention →
2. conveyance →
4. processing → 5. retention →
7. retention →
8. inspection →
10. conveyance and retention.
3. retention →
6. conveyance →
9. retention →
Let us examine the function performed by each of these
four main flow factors.
1. Retention
We can define retention as stopping the flow of goods without adding any value to them. Other words used for this are
“stockpiling,” “warehousing,” and “temporary storage.”
“Wastology”
Warehouse inventory
INVENTORY
Goods are retained in a
warehouse that is set apart
from the production flow.
Standby-for-processing
inventory
In-process inventory
Retention of entire lots
Standby-for-lot
inventory
Goods are retained while
the rest of the lot is being
processed.
Figure 3.7
Breaking Down Overall Inventory into Different Types of
Inventory.
Upstream
process
Inventory
Downstream
process
Figure 3.8
Unbalanced Inventory.
Every time we have retention, we have some kind of inventory. Figure 3.7 shows how overall inventory can be broken
down into different types of inventory.
In this case, retention occurs for several reasons, including:
Capacity imbalances—Figure 3.8 shows a container of
waste overflowing as an analogy of what happens to in-process
inventory when there is capacity imbalance between upstream
and downstream processes.
In terms of capacity balance/imbalance, the relationship
between upstream and downstream processes can always be
expressed as one of the following three formulas:
Upstream process = downstream process (Synchronized)
Upstream process > downstream process (Inventory)
Upstream process < downstream process (Shortage)
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Assembly
station
Processing
station
Processing
station
Processing
station
Figure 3.9
Centralized
processing
Retention of goods
Assembly
station
Assembly
station
Accumulation of Inventory in the Flow of Goods.
Goods flowing from several lines to one process (flow of
goods). When goods flow from several processes in other
lines to just one process, they tend to pile up at the point of
convergence. Conversely, goods pile up when they are sent
from one process to several others. (See Figure 3.9.)
Avoiding changeover and/or product model changes
(anticipatory manufacturing)—Since the processing department hates having to replace dies, blades, and the like, it tends
to minimize changeover in assembly, which causes retained
goods to pile up.
End-of-the-month rush (anticipatory manufactur­
ing)—When the factory people are told to follow a monthly
pro­duction schedule, they tend to take it easy during the first
half of the month and then “step on the gas” during the latter
half, especially the last week.
Consequently, assembly parts tend to pile up during the
middle and end of the month and product inventories pile up
at the start of the month.
Opportunistic buying, policy-based buying (anticipatory buying)—This happens most often with raw materials.
Manufacturers that buy materials whose prices fluctuate
widely or that have long lead-times try to buy these materials
a little more cheaply by entering annual procurement contracts or using other anticipatory buying tactics.
After-sales service part requests (anticipatory manu­
facturing)—This refers to the manufacturing of “­
service
parts” or “spare parts” to be used in repairing the delivered
“Wastology”
products. The manufacturer keeps an inventory of such parts
to be able to respond quickly to service part requests.
After looking at the functions served by these different
types of inventory, we can see that the two main causes for
inventory retention are anticipatory manufacturing and anticipatory buying.
Inventory begins piling up when the upstream processes
begin turning out more than the downstream processes can
accommodate. This also happens when work-in-process gets
bundled into lots to avoid changeover. Finally, it happens
when required goods are produced before they are required.
All of this adds up to increased inventory.
Retention adds to costs without adding anything to value. It is
useful only as a “cushion” against problems such as shortages.
Now we have reached the crux of the problem. Because
inventory acts as a cushion, people tend to think of it as
a solution to production flow problems. The truth, though,
is that inventory merely evades problems and does not solve
them. No matter how much inventory we accumulate, the
real causes for problems will not go away.
2. Conveyance
Conveyance can be defined as an occurrence whenever
goods are being moved without having any value added. We
also call such activity “transport” or “transferring.”
Figure 3.10 illustrates the functions of conveyance within
the production flow.
“Conveyance” between two retention points is sometimes
done by hand, but when there is enough volume to warrant
it, we usually employ a conveyance machine such as a conveyor, cart, or forklift to do the work.
“Material handling” between a retention point and a processing point is only rarely used for processing of lots and
is generally used for one-piece processing. In this latter
case, the moving of materials is almost always done manually. When I analyzed the flow of production at a certain
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Retention
MOVEMENT
(transferring)
Retention
This movement between retention
points is often called “conveyance.”
Retention
Process
This movement between retention
point and a process is often called
“material handling.”
ce”
ce”
n
n
an
an
on
o
o
y
y
i
i
i
s
e
e
t
t
t
s
nv
nv
ten
ten roce eten
Re
“Co
P
“Co
R
Re
“Material handling”
Figure 3.10
The Difference between Conveyance and Material
Handling.
electronic equipment assembly plant, I obtained the following breakdown of the four main flow factors.
◾◾ Processing points: 6
◾◾ Retention points: 24
◾◾ Conveyance times: 16
◾◾ Inspection points: 3
It is amazing how many retention points and conveyance
times occur. These two factors, in fact, make up over 80 percent of the total. While it is true that retention does not itself
require any labor, conveyance often requires a lot of worker
hours. In fact, conveyance accounts for about 80 percent of
the worker hours involved in the 16 times things are moved
in this factory.
This curious fact deserves a little more thought. We have
already defined conveyance as moving things in a way that
raises costs without adding value. In view of the entirely negative effect of conveyance, we should not be content with just
shortening conveyance distances and times. We need to make
a radical improvement by getting rid of conveyance entirely.
To do this, we must abolish the specter of retention.
Conveyance tends to happen wherever retention points occur.
“Wastology”
ion
nto
e
t
Re
ss
ce
Pro
ss
ce
Pro
ss
ce
Pro
n
tio
ten
Re
“Material handling”
Figure 3.11
Material Handling in One-Piece Flow Production.
If we can get rid of retention completely by linking processes
together, conveyance will die a natural death. Doing this will
entail the following:
1. Begin by having one person process workpieces one
piece at a time. This will teach people how poorly the
equipment is laid out.
2. Change the equipment layout to accommodate “one-piece
flow.” People will find out how mobile the equipment
really is.
3. Add casters to make hard-to-move equipment more
mobile. People will begin to understand what real improve­
ments are.
As shown in Figure 3.11, once we get the processes linked
together, one-piece flow becomes possible for the first time.
Now, if we can only get rid of the retention points, we can
stop using conveyors. All that will remain is short transfers of
workpieces between processes.
Note that we have not eliminated all transferring of workpieces between processes, but have only shortened their
distances (and times). Why? Because in this case, completely eliminating all movement of workpieces—including
­material-handling movement—would turn all of the process
stations into one all-inclusive process station. That might
sound good in t­heory, but in practice it requires heavy
equipment investment, much longer processing times, and
lower output. To avoid all that, we opt for a three-station
arrangement. This still means that a capacity gap is likely to
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appear between one process station and the next. So, for the
time being, this JIT-oriented production layout gives rise to
shish-kabob production.
3. Processing
In the present context, processing means adding value to a
workpiece as it proceeds through the production line. It is
the work that goes into the workpiece.
Basically, two types of value-adding take place in production lines. One type is processing in the narrow sense, which
means altering the shape or chemical makeup of the raw materials or parts that comprise the workpiece. The other type of
value-adding is assembly, which simply means putting together
materials and/or parts to add value. (See Figure 3.12.)
In improving processes, there are two main methodological models to choose between: the “ideal model” and the
“analytical model.” If we choose the ideal model, we need
to find out what the essential functions of the process are,
then ask ourselves, “How can this process best fulfill those
functions?” This “ideal model” calls for a deductive approach,
an approach that lends itself to two kinds of improvements:
VA/VE improvements and technology-specific improvements.
If we adopt the analytical model, we need to study the
various processing operations and ask ourselves, “How can
these operations be made more efficient?” Thus, the analytical
mode requires an inductive approach. This approach lends
itself to technology-specific improvements and to breaking
up and combining processing operations.
Assembly
PROCESSING
Higher added value via joining or
attaching parts and/or materials
Processing (narrow sense)
Higher added value via altering shape
or chemistry of parts and/or materials
Figure 3.12
Two Types of Production Value-Adding.
“Wastology”
VA/VE improvements
Ideal Model
PROCESSING
“What are the essential
functions?”
Deductive approach
Top-down type
Revolutionary improvements
Example: Applying a chemical
adhesive instead of fastening
screws
Technology-specific
improvement
Example: Vacuum forming of
CVCC engines
Technology-specific
improvement
Analytical Model
“What are the operational
methods?”
Inductive approach
Bottom-up type
Incremental improvements
Figure 3.13
Examples: Catalytic engine,
deburring machine
Break up and combine
operations
Example: Production line
reconfiguration
Improvement Approaches for Processing.
Figure 3.13 illustrates these models and approaches.
By definition, processing means adding value. In view
of this, most production engineers think of processing as
established and somehow beyond improvement. They aim
their improvement efforts elsewhere and do not stop to think
about improved processing. I call such production engineers
“lateral improvement makers.”
By contrast, some production engineers take a more critical look at things. For example, they might ask, “Why are
we drilling holes at this process?” when inspecting a drilling
process or “Why are we putting in screws?” when viewing a
machine screw-fastening process.
The more critical the engineer is, the more he or she is able to
make improvements that reach into product functions or even
into product design. These are “vertical improvement makers.”
Vertical improvements require the kind of inquisitiveness
and wisdom seldom seen in the analytical (IE) approach,
which accepts the current processing arrangement and then
tries to make it work a little more efficiently.
4. Inspection
This last but not least of the four major factors in production flow can be defined as the identification and elimination
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of defectives from the production flow. As such, inspection
does not add any value.
Some people might take exception with the above definition of inspection and instead argue that inspection is
“defect-finding behavior.” But this latter definition is far from
accurate. “Defect-finding” sounds too much like “improving”
or “problem-solving.” While it is true that finding defects is
an effective way to reduce defect complaints from customers­,
it does nothing to reduce the number of defective goods
being produced on the line.
Keeping a large inspection staff to minimize customer complaints gives the manufacturer a false sense of security while
defective goods continue to be produced and inspection costs
continue to climb.
We have to change the concept of inspection from “finding
defects” to “reducing defects.” In JIT, reducing defects goes
beyond recognizing them and doing something to make them
a little less frequent. JIT declares all-out war on defects and calls
on us to find ways of preventing their recurrence altogether.
Thus, JIT requires a three-step progression from “finding
defects” to “reducing defects” and finally “preventing defects.”
Naturally, this means inspectors must change their whole
attitude toward their work. Figure 3.14 shows how JIT views
inspection work.
INSPECTION
Sorting inspection
Quality control
methods
Defect-finding inspection
Using SQC methods to
reduce defects
Information inspection
Downstream process
control methods
Defect-reducing inspection
Defect-reducing inspection
at downstream processes
Back-to-the source
inspection
Independent quality
control by
process operators
Defect-preventing
inspection
Figure 3.14
Defect-reducing methods
by operators at their own
processes
How JIT Views Inspection Work.
“Wastology”
Sorting inspection—In sorting inspection, defect-finding­
inspectors sort nondefective processed workpieces from defective ones and throw out the latter.
This type of inspection may reduce complaints from
customers, but it will not do anything to reduce the number
of defects.
Information inspection—This type of inspection reduces defects. When a defect occurs, the related data are
used to find the process where it occurred and to correct the
defect-causing problem.
Three ways to perform information inspections are:
◾◾ Quality control method
This is also known by the acronym SQC (Statistical
Quality Control). After taking detailed statistical data of
the conditions at each process, any defect can be traced
back to the process where it occurred and then can be
corrected. (See Figure 3.15.)
◾◾ Downstream process control method
To make inspections as objective as possible, the inspectors inspect every workpiece and use statistical data for
feedback at each downstream process to check up on
the previous process. (See Figure 3.16.)
◾◾ Independent quality control method
Also known as “independent inspection,” this method
requires process equipment operators to conduct their
own quality inspections of goods processed at their own
stations to provide faster information feedback for the
downstream process control method. (See Figure 3.17.)
Information feedback
Process
Process
Process
Process
Inspection
Flow of
goods
Figure 3.15 Information Inspection Using the Quality Control Method.
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Information feedback
Process
Figure 3.16
Inspection
Inspection
Inspection
Process
Process
Process
Flow of
goods
Information Inspection Using the Downstream Process
Control Method.
Information feedback
Figure 3.17
Inspection
Inspection
Inspection
Inspection
Process
Process
Process
Process
Flow of
goods
Information Inspection Using the Independent Quality
Control Method.
Back-to-the-source inspection—This is a defect-preventing
approach in which we find the error leading to defects, distinguish among the resulting defects, and then make improvements that prevent defects from occurring even if the same
error occurs again.
The two main methods used in this type of inspection are
poka-yoke and human automation. (Poka-yoke is described
further in Chapter 12.)
As you can see, “inspection” comes in all types, each based
on a different approach to defects. Just the same, we must
always remember that the basic act of inspection contributes
nothing to higher added value. That is why we should be
concerned to prevent defects in the first place, so as not to
waste untold labor expenses on inspections.
In this brief discussion of the four major production flow
factors—retention, conveyance, processing, and inspection—
“Wastology”
we have seen why each factor occurs, what the functions of
each are, and which methods can be used to manage them.
The important point of reference in thinking about these
four main factors is their relationship to the adding of value
to products. Remember—anything that does not somehow
add value to the product is only waste.
More than anything else, the severity of our vigilance
against waste determines whether our improvements will be
revolutionary, incremental, or just empty gestures.
◾◾ Highest severity
This means we look at all four factors—retention, conveyance, processing, and inspection—with a keen eye
for identifying and eliminating waste. This is especially
true of retention, conveyance, and inspection, which are
nothing but waste, and is also true of processing. To
bring critical inspection right to the heart of the process,
we need to ask, “Why is this processing necessary?”
◾◾ Second-highest severity
Here, we regard only processing as a value-adding f­actor
and look toward retention, conveyance, and inspection as
targets for waste-eradication efforts. This level of severity
does not make for “vertical improvements” that overlap
waste removal across factors, that eliminate waste from
processing, or that carry waste-removing improvements
all the way upstream to the design stage.
◾◾ Second-lowest severity
At this level, processing is obviously above suspicion as
a source of waste and inspection is indispensable for
removing defective goods. Consequently, we aim our
waste-removing efforts entirely toward retention and
conveyance.
When severity is at this level, our improvement efforts
will probably not go beyond material handling.
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◾◾ Lower severity
If we adopt this level, we see not only processing and
inspection, but also retention and conveyance as necessary to production. We would never go as far as to
get rid of retention and conveyance. Instead, we “solve”
retention problems by establishing new places to pile
things or by building new shelves. Likewise, we “solve”
conveyance problems by bringing in more carts or introducing an automated transfer system. All such improvements are actually nothing but empty gestures.
JIT’s Seven Types of Waste
In JIT, we classify waste into seven types. Each of these types
has been identified by the highly critical waste-removing eyes
of veteran JIT improvement staff.
Carrying out factory-based improvements on these seven
types of waste can prevent waste from becoming institutionalized in the factory. The “production factory waste” described
in the previous section is included in JIT’s seven types of
waste. However, the JIT approach requires strongly motivated
people who have developed an “instinct” for removing waste
using IE methods. (See Figure 3.18.)
JIT’s seven types of waste are:
1. Overproduction waste
2. Inventory waste
3. Conveyance waste
4. Defect-production waste
5. Processing-related waste
6. Operation-related waste
7. Idle time waste
While these types of waste are found most commonly
in the factory, JIT has seven additional types of waste that
“Wastology”
R
n
tio
n
ete
ce
n
an
tio
vey
n
ten
Re
Co
Conveyance
waste
ng
ssi
ce
Pro
Ins
pe
cti
on
Production
factors
Processing-related
waste
Inventory
waste
Defect-production
waste
Overproduction waste (operation methods)
Operation-related waste (operation contents)
Idle time waste (operation balance)
JIT’s Seven Types of Waste
Figure 3.18
JIT Waste and Production Factor Waste.
can be effectively applied to management divisions. These
management-related waste are:
1. Overkill waste
2. Work/material accumulation waste
3. Conveyance/walking waste
4. Human error waste
5. Waste inherent in management and clerical processes
6. Operation-related waste
7. Idle time waste
As you can see, the two sets of waste have many similarities, such that factory-based waste eradication efforts can
almost be applied as they are to management divisions. This
is because:
1. A keen eye for waste remains keen no matter where it
looks.
2. JIT’s seven types of waste are impartial.
3. Removing JIT’s seven types of waste from the factory
easily develops into removing all types of waste from all
types of places.
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The types of waste are actually almost limitless. There is
waste in memos, in communication, in details...in everything.
Once we’ve created some time for waste-eradication efforts,
the thing to do is to go to the factory and start with JIT’s
seven types of waste. At first, we should expect to find these
seven types (and variations on these types) to be lurking in
every square inch of the factory.
Just remember: No factory is without waste. If we can enter
the factory with that thought on our minds, we are starting
out just fine. Next, we need to get to the heart of waste by
asking “Why?” at least five times. This should naturally lead
us to the deepest roots of waste, after which we need only
put our ingenuity to work in coming up with improvements
to eradicate the waste.
The three essentials for starting out are: train the eyes to
spot waste, remember that no factory is without waste, and
start right in the factory.
Let us look at JIT’s seven types of factory-based waste in
more detail.
1. Overproduction Waste
Overproduction waste can be defined as “producing what is
unnecessary, when it is unnecessary, and in an unnecessary
amount.” Does this sound familiar? It is a mirror image of the
Just-In-Time definition.
Overproduction waste is the worst of all forms of waste.
It contributes to retention and inventory waste. More inventory naturally leads to more conveyance. Overproduction
waste is like a wedge that opens the door for various other
kinds of waste.
So, we start asking “Why?” Why does overproduction
occur? Simple: Workers and machines have excess capacity.
They put this excess capacity to work in turning out excess
products. Once we have reached the root cause of over­
production, we can immediately start making improvements.
To begin with, we can use devices such as kanban and the
“Wastology”
“full work system” to tie production processes together in a
flow, after which we can synchronize the worker and machine
cycle times with product cycle times. This may require some
­leveling, worker hour reductions, or equipment downsizing.
2. Inventory Waste
Originally, inventory strictly meant stock in warehouses. But
in its broader definition, inventory means whatever is being
retained at retention points inside or outside the factory.
Some of these retained items are warehouse inventory and
some are in-process inventory (see Figure 3.19). Generally,
we refer to in-process inventory as one type of broadly
defined inventory.
Therefore, “inventory waste” should be understood to generally include not only waste in the warehouse, but also waste
related to all stock-in-hand, such as in-process inventory. This
means materials, parts, assembly parts, and whatever else piles
up at retention points located at or between process stations.
In JIT improvement, we regard this inventory in all its
variety as “symptoms” of a “sick” factory. In other words, just
as doctors look for such typical flu symptoms as fever, weariness, and dizziness, JIT “doctors” need to look at inventory
as symptoms of ill health in factory operations. Inventory
sometimes piles up as finished product inventory and other
Retained goods
In-process inventory
(at and between processes)
GOODS
Goods in transit
Figure 3.19
Warehouse inventory
(short-term, long-term, or “dead”
warehouse inventory)
Conveyance
(by hand, forklift, cart,
or conveyor)
Material handling
(picking up and setting
down items)
Warehouse Inventory and In-Process Inventory.
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times as in-process inventory. And defectives can lead to very
big piles of inventory.
Behind the symptoms of inventory stacks we can find the
causes of the illness. Once we have identified these causes,
we are ready to begin therapeutic or surgical treatment. The
treatment, of course, is JIT improvement, aimed at revolutionizing the factory.
The most important prerequisite for uprooting and sweeping
away inventory waste is the awareness revolution. Inventory
waste will stay put unless people firmly believe in No Inventory.
People naturally tend to take the easy way out. Keeping inventory piles here and there is an easy way to avoid all sorts of
problems. But we need to realize through and through that
inventory avoids but never solves problems.
3. Conveyance Waste
Conveyance waste is another broad term covering everything
from conveyance made necessary by poor layout, material
handling (such as picking things up, setting them down, and
stacking them up), and just moving things around. Sometimes
the wastefulness of the existing conveyance system is due in
large part to complexity involving excessive conveyance distances and heights, or underutilization of conveyor systems.
Conveyors and material handling systems not only take a
heavy toll on productivity, but also eat up valuable space in
the factory. Moreover, the more times an item is moved or
handled, the greater the chance of its being dented or otherwise damaged.
The basic approach to correcting this situation is to first
redesign the equipment layout, then take away the conveyors
and minimize the amount of material handling.
4. Defect Production Waste
Human errors invite defects and defects are the watershed
for a long cascade of events. Customer complaints increase.
“Wastology”
Rising customer complaints lead to beefed up inspection
staff. This usually results in fewer complaints.
However, the reduction in complaints does not in any
way mean a reduction in defective goods (except shipped
defectives). To reduce the occurrence of defects in the first
place, we need to go all the way back to their original
causes. Defects produce waste in and of themselves and
give rise to the waste produced thereafter until someone
finally gets around to correcting the defect. In addition, they
disrupt the normal flow of goods and have a big impact
on productivity. That alone is good reason for switching
from sorting inspection that just separates the defectives
from the non­defectives to back-to-the-source inspection that
builds ­quality in at each process. It is also a good reason for
adopting defect-prevention methods, such as poka-yoke and
human automation, to prevent equipment malfunctions, as
well as better training and more standardized work methods
to help minimize human errors.
5. Process-Related Waste
Once people get the hang of performing a particular job, they
lose sight of the job’s function and simply “do the job.” For
example, I have seen cases where a factory worker, whose
job includes drilling machine screw holes, continues to drill
the holes even after design changes call for welding to be
used as the fastening method instead of machine screws.
I have also seen workers aggressively drive numerous
screws into exterior casing as if they were trying to win a
boxing match with the casing. They were certainly putting in
far more screws than required to serve the casing’s function.
They were putting screws in where none had been needed
in earlier models. I’ve even seen this sort of thing happen
in cases where an adhesive or welding process had already
fastened the casing firmly enough.
Obviously, we need to ask, “What is the basic function of
this work procedure?” and “What is the basic function of this
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part?” The conservation-minded approach is taken not only
by JIT experts, but also by experts in industrial engineering
(IE) and value engineering (VE).
6. Operation-Related Waste
Not everything that happens in a day’s work adds value.
In fact, the vast majority of the typical worker’s labor is
“­movement” and very little indeed is actually “work.”
Movement is waste. More precisely, movement that does
not directly add value is nothing but waste. Work operations
are the movements workers make while they are working.
Operation-related waste can be created by poor equipment layout or by poorly placed parts, jigs, and tools. To
improve such situations, we begin by asking, “Why is this
operation necessary?” to see if the operation might not be
eliminated altogether. If it turns out that the operation does
serve a legitimate function, we then get to work in reducing the amount of movement required by the worker to do
the operation. In order, we start with feet movement, then
­proceed to hips, shoulders, arms, hands, and fingers.
7. Idle Time Waste
“Idle time waste” is a broad term that includes both human
idle time and machine idle time and covers a wide variety
of cases. Idle time is generally time spent waiting for something. However, the causes for such waiting can be broken
down into causes originating from the “waiting side” and
those originating from the side that makes the waiting side
wait. In many cases, the causes come from both sides.
The main causes on the side that makes the idle time
occur include people, machines, workpieces, and conveyances devices. An even wider variety of main causes exists on
the waiting side, but the biggest factors there are human- and
machine-related factors. For example, if the workpiece is causing the idle time to occur, the causes and required improvements might be similar to those shown in Figure 3.20.
“Wastology”
Delaying Side
Waiting Side
Workpiece(s)
Late
Missing
Operator
Working
too fast
Machine(s)
Figure 3.20
Causes at the Waiting Side and the Delaying Side.
Figure 3.21, found on page 182, provides a table listing
JIT’s seven types of waste under the categories of description, contents, causes, and responses.
How to Discover Waste
I have heard many complaints arising from cases where people have set out to remove waste from their factory only to
be disappointed at the results. They say they have genuinely
worked hard to make improvements, but their efforts do not
seem to be leading anywhere. Naturally, they want to know
why. Generally, the reasons for such slow progress are not
so much the expected reasons—such as faulty improvement
plans or difficulty in implementing the improvement—as
they are factors such as:
1. Being unable to recognize waste as it occurs in the factory.
2. Waste remains hidden within abnormal conditions or
problems in the factory and is thus not readily apparent.
3. Even when waste becomes evident in connection with
abnormal conditions or problems in the factory, people
do not know enough to recognize the waste.
If an inability to see the waste as it occurs is the reason, the
previous section of this chapter should help them get at least
a theoretical understanding of the types of waste. Once they
have gained such an understanding, the people concerned
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TYPE
DESCRIPTION
Overproduction “Making what is unnecessary,
when it is unnecessary, and
Waste
in an unnecessary amount.”
Inventory
Waste
Inventory waste is when
anything—materials, parts,
assembly parts—is retained
for any length of time. This
includes not only warehouse
stock, but also items in the
factory that are retained at
or between processes.
Conveyance
Waste
Created by conveying, transferring, picking up/setting
down, piling up, and otherwise
moving unnecessary items.
Also created by problems concerning conveyance distances,
conveyance flow, and
conveyance utilization rate.
CONTENTS
POSSIBLE CAUSES
RESPONSES
Obstacle to flow goods
Increase in inventory (broad
sense) Occurrence of defects
Lowering of capital turnover
rate Anticipatory buying of
parts and materials Obstacle
of flexibility in planning
Overstaffed and/or overequipped Large lot (shishkabob) production
Machines are too big and
too fast Machines have
devices that turn out
products to quickly
“Full work” system Onepiece flow Thorough
implementation of kanban
Single changeover operation
Worker hour reduction
Production leveling
Long-term delivery deadlines
Picking out the roots of improvement Waste of space
Creation of need for conveyance and inspection Increase
in conveyance costs Acceptance of inventory as normal
or as a “necessary evil”
Acceptance of inventory as
normal or as a “necessary evil”
Poor equipment layout
Shish-kabob production
Obstruction of flow
Anticipatory production
Idea-based production
Revolution awareness
regarding inventory U-shaped
manufacturing cell layout
of equipment Production
leveling Regulate the flow
of production Thorough
implementation of kanban
Single changeover operation
Poor layout Shish-kabob
production Single-skilled
workers Workers sit while
working Conveyance system
has low utilization rate
U-shaped manufacturing cell
layout of equipment Flow
production Train multi-skilled
workers Stand while working
“Water beetles” Raise
utilization rate
Uses up space Increase
conveyance-related worker
hours Requires more conveyance equipment Leads to
dented and damaged products
DefectProduction
Waste
Waste related to costs for
inspection of defects in
materials and processes,
customer complaints, and
repairs.
Higher materials expenses
Lower productivity Improvement of jigs using human
automation Thorough implementation of standardization
Promotion of VA/VE
techniques
Inspection places emphasis
on downstream responses No
set methodology or standards
for inspection work Omission
of standard operations
Human automation and
standard operations
Poka-yoke (mistakeproofing) Full-lot inspection
Building quality in at each
process Flow production that
eliminates picking up and
setting down workpieces
Processingrelated
Waste
Unnecessary processes and
operations traditionally
accepted as “necessary.”
Unnecessary processes and
operations Increase in staff
and worker hours Reduction
in operation ease Increase
in defects
Inadequate study of process
procedures Inadequate study
of operations Ill-suited jigs
Standardization was not
thorough enough Materials
not yet studied
More appropriate process
design Review of operations
Improvement of jigs using
human automation Thorough
implementation of standardization Promotion of VA/VE
techniques
Operationrelated
Waste
Unnecessary movement,
movement that does not
add value, movement that
is to slow or too fast.
Increase in staff and worker
hours Skills remain latent
Instability in operations
Unneeded movement
Isolated “island-like”
operations Lower morale
among employees Poor
layout No education or
training
Gradual switch to flow
production U-shaped
manufacturing cell layout
of equipment Distinction
between “superficial standardization” and real standardization Following through
on the basic principles of
improving operations
Idle Time
Waste
Waste of which the causes
originate in waiting from
materials, operations,
conveyance, inspection, as
well as idle time attendant to
monitoring and operation
procedures.
Waste in labor, operations,
time, and machinery Increase
in in-process inventory
Obstruction of flow Poor
equipment layout Trouble
at upstream processes
Capacity imbalances
Large-lot production
Production leveling
Product-specific layout
(U-shaped manufacturing
cell layout) Pola-yoke
(mistake-proofing) Human
automation Changeover
within cycle time
Figure 3.21
JIT’s Seven Types of Waste and Corresponding Responses.
must head straight into the factory and gain a practical grasp
of waste by actually identifying it and dealing with it.
This section explains how to develop a “sixth sense” for discovering waste in the workplace. This explanation has three
parts, which are listed below in order of their appearance.
“Wastology”
◾◾ Finding waste according to its “back-door definition.”
◾◾ Bringing latent waste to the surface with one-piece flow
under current conditions.
◾◾ Analyzing current conditions to discover waste.
Finding Waste according to Its
Back-Door Definition
No matter how many books we read or how many video
programs we watch to build up our knowledge of what constitutes waste, when we go to the workplace prepared to start
eliminating waste, we find it hard just to find the waste in the
first place. In such cases, we tend to think, “I must have misunderstood the book” and we go back to the office to study.
But then the next time we give it a try in the workplace, we
run into the same failure and frustration.
People who have little or no experience in making improvements have a particularly hard time identifying waste in the
factory. When faced with the complex nuts-and-bolts operation of a factory, an understanding of waste based on a few
hours of book-reading is hardly enough to inspire confidence
toward making changes.
But that is just the way it goes at first. We have to take a
cold, hard look at the current situation in the factory. It may
take hours of standing and observing before we begin to get
a “sense” of the waste that lurks in the operations performed
by the factory’s workers and machines. Discovering waste is
a hands-on activity, and to develop our skill in that activity
we need experience in the real things: the factory, the facts,
and the work-in-process.
Every operation that occurs in the factory is chock-full of
waste. Waste is so common that its own ubiquity makes it
hard to see. We sense that we are losing our ability to distinguish what is wasteful from what is not. When this happens,
we desperately rely on our instincts and start blindly looking
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for waste. This makes waste even harder to find. This is a
dilemma that many JIT novices fall into.
At times like this, the thing to do is take a deep breath and
start thinking differently. In fact, we need to take an opposite, “back-door” approach to finding waste by ceasing to look
for waste. That’s right: If waste is too hard to distinguish, then
just stop looking for it.
Instead, go around to the “back-door” and look for waste’s
opposite: work. (Remember, work is defined as whatever adds
value to the work-in-process.) In most cases, whatever operation we study will be full of waste in all its confusing variety.
It may, however, also include one or two small value-adding
functions that we may rightfully identify as “work”—“work”
that is much easier to identify than waste.
To do this, we need to continually ask ourselves, “What
is this operation doing?” We need to closely inspect the
entire process.
For instance, if the process is an assembly process, we even
need to look at how the machine screws are fastened. Once
we have realized, “Oh, this is a screw-fastening process,” we
are ready to repeatedly ask ourselves “Why” questions, such
as, “Why do they need a screw-fastening process here?”
This line of questioning brings us to the realization that the
function of the process is to fasten two parts together, and
the fastening agents in this case are the machine screws.
We are now ready to get to the bottom of the function we
have just identified by looking at the “work” (value-adding)
involved. In this case, the “work” is the second or two during
which the final turn of the machine screw is made to a­ ctually
fasten the two parts together. Now that we have identified the
“work,” we automatically know what the “waste” is: ­everything
else—picking up the screw and screwdriver, inserting the
screw, and so on.
Believe it or not, if we have come this far, we are already
halfway there in making an improvement. To make further
progress, we need to continue asking “Why?” For example,
“Wastology”
why must the operator take a step each time he picks up a
screw? Let us suppose the answer to that question is that the
box of screws is kept three feet from the operator’s work position. Now we ask “Why?” again: “Why is the box of screws
kept three feet away from the operator?”
This series of “Why” questions should continue for at least
five questions. This is the “5W” portion of the 5W1H procedure that is further discussed at the end of this chapter.
Asking “Why?” at least five times will take us from the surface
phenomenon of the problem through successively deeper
levels of causal factors until we reach the real cause or causes
that form the crux of the problem.
If we start making improvement plans (in other words,
if we jump to the “How to make an improvement” question) after asking “Why?” only once or twice, our improvement plan will be as superficial as our inquisition. I call such
improvements “empty gestures” or “surface improvements.”
This book will emphasize the 5W1H (five “Whys” and one
“How”) method again and again because it is an extremely
important tool for digging beneath “surface waste” to discover the “true, deep-down waste.”
Figure 3.22 summarizes the five main points concern­ing
the most effective way to discover waste.
Bringing Latent Waste to the Surface with
One-Piece Flow under Current Conditions
Factories come in all kinds. At some factories, people have
learned to make deep-reaching improvements while other
factories are still making surface improvements or do not
wish to make any improvements at all. Some factory workers
are making rapid progress in carrying out improvements and
others are moving at a yawn-inducing pace.
Fortunately, I know just the thing to wake up drowsy
workers at factories whose improvement campaigns are either
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Five Key Points for Discovering Waste
via the Back Door
POINT
Look at the three real things
Factory
Facts
Work-in-process
POINT
Ask “What?”
Ask WHAT the operation is about.
POINT
Ask “Why?”
Ask WHY the operation is necessary.
POINT
POINT
Everything that is not work is waste
(waste’s back-door definition)
Once you have found out what the operation’s
essential function is, you can properly identify as
waste everything in the operation that does not
directly execute that function.
Ask “Why?” at least 5 times
Ask WHY at least 5 times concerning each wasteful
part of the operation. This will lead you to the real
waste.
Draft an improvement plan
Ask “How?”
Figure 3.22 Five Key Points for Discovering Waste via the Back-Door.
sluggish or nonexistent: one-piece flow. (Chapter 5 describes
one-piece flow production in more detail.)
Most people get a highly inaccurate first impression of what
one-piece flow is all about. They imagine one-piece flow production as something that first requires a new equipment layout
to follow the process sequence, a worker trained in multiprocess handling skills, and various other time-consuming
preparations. When such people hear me suggest switching to
one-piece flow, they tend to say something along the line of,
“Sounds good, but the present layout is all wrong.” As usual,
the person is theorizing instead of being practical.
JIT means the total elimination of waste. But we cannot
eliminate waste unless we first identify it. One-piece flow
offers an effective technique for manifesting the waste that is
latent within current conditions.
Instead of thinking up reasons for not giving this technique
a try, we should simply switch to one-piece flow using the
­current conditions. Suddenly, we notice some amazing things:
“Wastology”
The conveyor movement that used to bring 100-unit lots of
workpieces to the process now must make 100 movements
to bring 100 single workpieces. This hundred-fold increase
in conveyor use makes conveyor waste noticeable, to say the
least. It also helps us realize what kind of waste results when
machines are placed farther apart than they need to be. Or,
if carts were used to move the 100-unit lots a few feet to the
next process, one-piece flow shows us that the workpieces
can also be moved one at a time by hand. The vast cleaning
chamber that cleans the 100-unit lots seems like massive overkill when the workpieces come through for cleaning one at a
time. One-piece flow also shows us how unnecessary the inprocess stock shelves and carts are and how poorly balanced
the processes are in terms of their relative capacities.
One-piece flow also brings up some big problems, such as
how to efficiently transfer workpieces one at a time. Applying
our “shop smarts” to these problems is how we can go
about solving them. Remember, one of the ten “Basic Spirit”
­principles for improvement is: “Problems give you a chance
to use your brain.”
Even people who have an impossible time trying to understand waste intellectually will gain sudden enlightenment once
they have tried out one-piece flow in their own workshop.
Analyzing Current Conditions to Discover Waste
JIT does not follow the traditional IE approach to improvement, which emphasizes analysis of current conditions. This is
because JIT improvement is a deductive approach wherein we
begin with recognizing the “ideal” of JIT production and the
gap between current conditions and that ideal, then we get to
work to bring conditions as close as possible to the ideal.
By contrast, with IE improvement, we begin by analyzing
current conditions and then see what we can do to improve
their efficiency. As such, IE improvement takes an inductive
approach. The advantage of this approach is that it reliably
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leads to higher efficiency. IE improvement of the conveyance
system will likely result in a more efficient conveyance system­.
However, the conveyance system will always be there since
IE does not question the existence of current systems, but just
tries to make them run better. In addition, analyzing current
conditions takes time, and this creates the disadvantage of a
long lead-time for improvements. Meanwhile, the production
diversification trend continues to accelerate, the size of individual orders continues to shrink, and the marketable life of
new products is getting shorter and shorter. The way things
are going, there may soon be many cases where IE improvement teams complete their analysis of current conditions and
are finally ready to make the improvement, only to find that
the product has been discontinued or the staff changed.
In response to these trends, we need a type of IE that dispenses with the emphasis on time-consuming analyses without losing effectiveness. The following describes a method for
analyzing current conditions that does not take a long time,
but produces good results.
1. Arrow Diagrams: Finding Waste in the Flow of Goods
When we look at production processes from the perspective
of the flow of goods, we can broadly divide these processes
into the four major flow factors of retention, conveyance, processing, and inspection. Obviously, various kinds of waste
can be found within processing alone, but the places within
the flow of goods where waste is found in greatest ­abundance
are at the retention and conveyance points.
Arrow diagrams do not take a lot of time or labor to create­,
but they are very good for flushing out the major types of
waste in production. As such, arrow diagrams can be applied
against the factory’s equipment layout diagram by marking
the major problem points in product flow in the diagram
based on the arrow diagram’s analysis of the four major flow
factors. Once the big problem points have been identified
and illustrated this way, it is easier to make improvements.
“Wastology”
Description
Amount
of waste
When the work-in-process flow is stopped
(not for processing, conveyance, or
inspection)
Large
Conveyance
When the position of work-in-process is
changed
Large
Processing
When the work-in-process is changed
physically or chemically for added value
Medium
Inspection
When foods are inspected for
conformance to quality and dimensional
standards
Large
Analysis factors
Retention
Figure 3.23
Symbols
Process Analysis Symbols.
Process Analysis Factors and Corresponding Symbols
1. Retention: Retention is when work-in-process of any kind
is held or stored somewhere without being immediately
involved in processing, conveyance, or inspection.
2. Conveyance: Conveyance is when the position of workin-process is changed. Conveyance occurs most often
between retention points.
3. Processing: Processing means altering the shape of chemical makeup of the work-in-process in a way that adds
value to it.
4. Inspection: Inspection means checking the amount, size,
shape, and quality of products to see if the product f­ ulfills
its functions and meets the relevant standards.
Figure 3.23 shows the graphic symbols that correspond to
these four factors.
How to Create Arrow Diagrams
1. Recognize the analytical purpose: The purpose is not to
create an arrow diagram. The purpose of the analysis is
to discover major forms of waste. To actually remove the
waste, the equipment layout will have to be changed,
superfluous operations eliminated, and other improvements made. Arrow diagrams facilitate such improvements
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Figure 3.24
Purpose:
Cost reduction
Maintain quality while removing major
forms of waste
Measure the results
Improvement:
Carried out
immediately
at the workplace
Change the layout and flow pattern of goods
Get rid of superfluous operations
Create a summary chart of flow analysis
(after improvements)
Analysis:
Create an
arrow diagram
Reveal current conditions
Make waste recognizable (and actually
recognized) by everyone
Create a summary chart of flow analysis
(before improvements)
Acknowledging the Purpose of Arrow Diagrams.
by making the current flow of goods more obvious and
comprehensible in graphic representation. Everyone in
the improvement team needs to recognize these points.
(See Figure 3.24.)
2. Select the product to be analyzed: P-Q analysis (described
in detail in Chapter 5) is an analytical method that compares products (P) and quantity (Q). It is very useful when
applied to products for which a large output is needed. It
also is useful with products that tend to encounter a lot
of problems along the production flow.
3. Prepare a factory layout diagram: This diagram should
contain the entire factory’s layout, and should indicate
the positions of all machines, work tables, and other
equipment. Since these diagrams are referred to again
and again for each product, the original should be kept
in a safe place and photocopies should be made for writing in remarks based on specific analyses.
4. Do a flow analysis: Flow analysis is not something to
be done at some desk using a mental picture of the factory The ways things are done at the factory are beyond
what anyone can mentally picture or remember. Instead,
we must go to the factory and make the flow analysis
while watching what actually goes on there. Use the four
flow factor’s symbols (triangle for retention, small circle
“Wastology”
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189
ARROW DIAGRAM
SHOP NAME:
PCB Assembly
PRODUCT
NO:
DIAGRAM
CREATED BY:
CREATION DATE:
A3-11-2010
1/31/89
PROCESS SYMBOLS
RETENTION CONVEYANCE PROCESSING INSPECTION
Nishizawa
(C) = Carts
(M) = Manual operation
Conveyance distance:
150 meters
Staff: 49
Shelving Shelving Shelving
First dip
2
Second dip
Circular con1
veyor (insert)
Parts bins Parts bins Parts bins Parts bins
Shelving Shelving
Shelving Shelving
Shelving
Shelving
Repairs
6
Tester
Shelving Shelving
Shelving Shelving
5
3
Inspection
Shelving
Shelving
Inspection
Insertion
machine
Apply
Apply
backing backing
Inspection Inspection
Inspection
Shelving
Shelving
Inspection
Shelving Shelving
Shelving Shelving
Work table Work table
Inspection
Shelving
Elevator
Shelving Shelving
Figure 3.25
Arrow Diagrams of Printed Circuit Board Assembly Shop.
for conveyance, large circle for processing, and diamond
for inspection) when drawing the arrow diagram for
flow analysis. Connect these factor symbols with lines
containing arrows that indicate flow direction. Feel free
to use other numbers and symbols, such as those that
appear in the example shown in Figure 3.25, to describe
the contents of the various processes.
5. Write up a summary chart of flow analysis: After completing the arrow diagram, we should draw up a summary
chart of the flow analysis and enter the relevant volume
and distance information under the “before improvement” columns. (See Figure 3.26.)
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Summary Chart of Flow Analysis
Data:
Figure 3.26
Inspection
Lots
No. of times
Processing
Lots
No. of times
No. of times Conveyance
Distance
Time
No. of units Retention
No. of times
Lots
Inspection
After improvement
No. of times
Lots
No. of times Processing
No. of times Conveyance
Distance
No. Part name/No.:
Time
Before improvement
Product name/No.:
No. of units Retention
◾
No. of times
190
Summary Chart of Flow Analysis.
Arrow diagrams such as the one in Figure 3.25 are one of
the simple analytical tools developed by conventional IE that
can provide very useful results. However, most of IE’s other
statistical tools take a lot of time and labor to achieve similarly effective results, and much of this work is usually done
at a desk and away from the factory.
JIT improvement’s emphasis of eliminating waste leaves
no room for playing around at some desk with analytical
symbols and numbers. The whole point of JIT i­ mprovement
is to make every judgment in the factory, in our actual
work environment.
2. Operations Analysis Table:
Finding Waste in People’s Actions
Not everything workers do adds value to the workpiece.
On the contrary, almost everything the typical worker does
is mere “movement” that adds no value at all. Operations
“Wastology”
a­ nalysis tables are analytical tools that help us bring the waste
inherent in worker operations to the surface.
To fill in an operations analysis table, write down the
operator’s actions in the order they are performed. This will
help later in finding the major manifestations of waste within
these worker operations.
There are five key points to remember when using operations analysis tables.
◾◾ Point 1: Fill it out at the factory. Do not use, “I know
that job like the back of my hand,” as an excuse for ­filling
out the table anywhere but in the factory. Look at the
real situation in the factory as you fill out the table.
◾◾ Point 2: Everything that is not work (value-adding)
must be counted as waste. Always look as critically
as you can to distinguish work from movement as you
observe the worker’s actions. Start by trying to identify
the value-adding aspects of the operations.
◾◾ Point 3: Look for the nitty-gritty details. Look for as
much detail as you can spot, then write all those details
on the table. Detailed understanding requires detailed
observation.
◾◾ Point 4: Once you finish filling out the table, set
an improvement goal. Go over all of the observationbased data you have written in, including “work” actions
and “movement” actions, movement of goods and the
time required for that, idle time, and inspections. Then
set an improvement goal.
◾◾ Point 5: Thoroughly eliminate waste from everything except “work” operations. After making an analysis to distinguish “movement” operations from “work”
operations, carry out improvements to eliminate as much
of the “waste” as possible. Write down the improvement
results on the operations analysis table and then ­confirm
them. Figure 3.27, on the next page, shows how the operations analysis table might appear at this point.
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Operations
Analysis Table
Section
Operation
Aluminum casting
Deburring
Processes
Part No.
Author:
Press/drill
A11-21-301
(name)
1
Load castings onto cart
2
Transfer to press
3
Unload with workpieces
to be pressed
4
Transfer to drill press
6
7
Unload with workpieces to
be drilled
Drill workplaces
(lot size: 100 units)
Load drilled workpieces onto
cart
8
Transfer to shotblaster
9
Wait until shotblaster is empty
10
12
Suspend workpieces in shotblaster using crane
Shotblast workpieces
(lot size: 100 units)
Load shotblasted workpieces
onto cart
13
Transfer to inspection station
14
Inspection
(lot size: 100 units)
6
11
15
After Improvement (date: 12/07/88)
Distance
Work
Description of
operation
Time
Movement
Transfer
Idle
Inspect
No.
Work
Before Improvement (date: 10/28/88)
10'
300
10'
Description of
operation
Develop small shotblaster
and install in U-shaped cell
Transfer to press
(via cart)
Press
Drill
10'
Shotblast
200
Inspect
10'
10'
200
3'
5'
10'
500
16
Figure 3.27
Operations Analysis Table: Aluminum Casting Deburring Operation.
Time
Distance
◾
Movement
Transfer
Idle
Inspect
192
“Wastology”
◾
193
Standard Operations Combination Chart
No. required: 303 (600)
Process No.: 391-3637
Time
1
Pull out workpiece
3
2
Process S101 gain (small)
at circular saw bench
Process S102 gain (large)
at circular saw bench
Finish B101 hinge fastening
at multi-spindle drilling
Insert edge (using cutter)
at work table
Cut edge (using cutter) at
work table
15 10
Set up new workpiece
2
3
4
5
6
7
Figure 3.28
23 18
12
13
7
7
Analysis No.: 1of 1
Walking
Description
Manual
Auto feed
Sequence
Item name: Door jamb (lintel) Cycle time: 89" (54" needed)
Manual operations Entered by: Kawano
Auto feed
Walking Date: 1/31/89
Operation times (in seconds)
5 10 15 20 25 30 35 40 45 50 55 65 70 75 80 85 90
2
2
2
2
2
2
2
Combination Chart for Standard Operations.
3. Standard Operations: Finding Waste by
Combining People, Goods, and Machines
Standard operations serve a very important function in the
realization of JIT production in that they provide a method for
finding the most efficient operational combination of people,
goods, and machines to safely produce high-quality products
at low cost.
To establish this type of standard operations, we must
first analyze the current operations to flush out their inherent
waste and impracticalities. Things cannot be standardized
unless they are first identified.
Figure 3.28 shows how a combination chart for standard
operations might look prior to making an improvement.
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Looking at the chart shown in Figure 3.28, we can see that
the basic problem is the need to produce 600 door jambs
per day when one day of operation time equals 450 minutes
(7.5 hours). To do this, we need a cycle time of 54 seconds,
whereas the current cycle time is 89 seconds. Obviously, a production shortage is inevitable unless we bring in extra equipment or resort to overtime work to make up the difference.
However, there is another option: We can use this combination chart to discover waste in the current combination of people, goods, and machines, and then we can
make improvements to realize a more efficient (cycle timereducing) combination.
4. Waste-Finding Checklists
Waste-finding checklists are a good tool to have when inspecting workshops for waste. We can record the types and magnitudes of waste that we find at each process to make such
waste readily apparent. There are two kinds of waste-finding
checklists: workshop-specific ones and process-specific ones.
We should use a workshop-specific waste-finding checklist when looking for types and magnitudes of waste within
a certain workshop’s processes. This type of checklist works
best for finding major forms of waste. Next, we should use
a process-specific checklist when probing deeper into the
major forms of waste that have already been identified at
certain processes in order to discover smaller, more subtle
forms of waste. (See Figure 3.29.)
A more casual name for this checklist would be “the
major waste checklist.” Figure 3.31 shows an example of
this checklist form, which, as mentioned, we carry with us
while inspecting the types and magnitudes of major waste in
a particular workshop.
When filling out this checklist form, first enter the number
and name of the process concerned, then rank the magnitude
of the seven types of waste (each type has its own column in
the form) according to Figure 3.30’s five levels of magnitude.
“Wastology”
Workshop inspection
Find major forms of waste at each
process
Note the types and magnitude of
such waste
Waste-finding checklist
(workshop-specific)
Determine ranking of improvements.
Observe the first process to be improved.
Find small (subtle) forms of waste within
the process
Observe the types of and magnitude of
such waste
Waste-finding checklist
(process-specific)
Brainstorm improvement ideas and
carry them out.
Figure 3.29
How to Use Waste-Finding Checklists.
0
1
2
3
4
Magnitude
of
waste
Figure 3.30
No waste found
Very little waste
A little waste
Considerable waste
A lot of waste
Five Levels of Magnitude.
Workshop name:
Waste-finding Checklist
(workshop-specific)
Figure 3.31
5
6
7
Defect-production waste
Processing-related waste
Operation-related waste
Idle time waste
Improvement ranking
4
Waste magnitude total
3
Conveyance waste
Process name
2
Inventory waste
No.
1
Overproduction waste
data:
Improvement ideas
and comments
Waste-Finding Checklist (Workshop Specific).
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After that, it is very simple: We just add up all these level
numbers and enter the sum in the “Waste Magnitude Total”
column. After we have done this for each process, we will be
ready to rank the processes according to their waste magnitude totals and thereby obtain a priority-based sequence for
improvement. Finally, we need to brainstorm some improvement ideas, which we should enter in the “Improvements
Ideas and Comments” column on the right side of the form.
Waste-finding checklist (process-specific). We can also
call this the “Minor Waste Checklist.” Here, we are looking for
detailed, subtle forms of waste that lurk within each process.
Figure 3.32 shows how the form for this checklist appears.
When filling out this form, fill in every minor manifestation of waste you can find and enter it under the most
appropriate of the seven types. Next, check up on your waste
observations by having another look. If you see the waste
again, check the YES column to confirm it. If not, check the
NO column. Both of these columns appear in the form under
the “Confirmation” heading.
For example, let us suppose we have discovered that there
are no production schedules or control signs posted at the
process. If a second look confirms this, we check the YES
column. If we find the allegedly missing items are present
after all, we can check the NO column.
Any items that receive a check in the YES column need to
be rated for magnitude (under the “Magnitude” column). Here,
we have only three magnitude levels. (See Figure 3.33.) This
second form includes both negative and positive waste-related
statements. Naturally, the magnitude rating is different, depending upon the type of statement (See Figure 3.34).
Example 1:
No production plan or control board
Few control boards
Almost no control boards
No control boards at all
“Wastology”
Major
waste
Workshop
name
Waste-finding Checklist (process-specific) 1
Date:
Confirmation MagCauses and
YES NO nitude improvement plans
Description of waste
1. No production schedule or control boards
2. No leveling of production schedule
4. Items missing
5. Defective goods produc
Waste-finding Checklist (process-specific) 2
8. Too much capacity
Description of waste
9. Lots grouped into batch
4. Pile-up during conveyance
5. Change of conveyance devices in mid-transfer
11.
6. Previous and/ or next process is an another floor
12. Not balanced with nex
7. Conveyance requires manual assistance
1. Omission in process
8. Conveyance distance too long
6.
7.
8.
9.
10.
11.
Process
Name
1. Complaints from nex
2. Defect within process
3. Human errors
5. Defective due to wro
6. Omission in process
7. Defect in processing
8. No human automoti
9. No poka-yoke
10. No inspection with
11.
12.
Type 5. Processingrelated waste
Description of waste
Confirmation
YES
1.
7. Left or right hand is idle
8. Idle time used for observation
9. Workpiece setup/removal
10. No standardized repetition of operations
11. Worker operates using different motions
each time
12. Operations divided up into little segments
13.
14.
15.
1. Idle time due to workpiece delay from
previous piece
2.
3.
4.
5.
1. Walking
2. Turning around
3. Leaning sideways
2. Idle time due to machine busy status
3. Idle time due to missing item(s)
4. Idle time due to lack of balance with
previous process
5. Idle time due to lack of planning
6. Idle time due to lack of standard operations
7. Idle time due to worker absence
8. Idle time due to too many workers
(more than two)
9.
10.
Total
Overall improvement points:
Figure 3.32
Waste-Finding Checklist (Process-Specific).
Level number
Meaning
Figure 3.33
2
3
Considerable
A little waste
waste
A lot of
waste
Three Magnitude Levels.
Numbers
Negative
statements
Affirmative
statements
Figure 3.34
1
1
2
3
Not much
Hardly any
None
Just a little
Some
A lot
Negative/Positive Statements.
Date:
Causes and
MagNO nitude improvement plans
6. Wrist movements
4. Defective due to mis
4. Leaning over
Waste-finding Checklist (process-specific) 3
Major
waste
10.
Type 6. Operation-related waste
5. No inspection within
9.
Type 7. Idle time waste
3. No human automa
4. No poka-yoke
Date:
Confirmation MagCauses and
YES NO nitude improvement plans
10. Using push production
2. Defect in processing
Type 2. Inventory waste
Major
Type 3. Conveyance waste waste
6. Equipment breakdownsProcess
Name
7. Too much manual assist
Type 4. Defect-production waste
Type 1. Overproduction
3. Production not in sync with production schedule
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Example 2: Missing item(s)
Only one or two missing items
A few missing items
Many missing items
Once we have used these forms to elucidate the types and
magnitude of waste, we need to go back to the processes
concerned with the people who work there and start looking
for the causes of all this waste. Only then are we ready to
start brainstorming for improvement ideas.
How to Remove Waste
We have seen how forcibly switching over to one-piece flow
under current conditions can bring underlying waste to the
surface and how analyzing current conditions using wastefinding checklists can help clarify problem points.
Now we must recognize the important fact that identifying and elucidating waste does nothing to eliminate it. So far,
we have only identified the targets, and we still do not know
what kind of improvement measures to aim at them.
Our next step is to develop an “intuition” for waste and
the “courage” to call it what it is. This step is necessary if we
are to develop the “strength” we need to enter the workshop
and start cutting waste out by the roots.
Things that have always seemed just fine suddenly become
discernible as waste when the competition in market prices or
deliveries gets fierce. A switch to a new product or a modified
design tends to create lots of new waste. Latent waste also
suddenly becomes apparent when certain methodological or
staff-related changes happen. Waste undergoes transformation
with astounding ease and multiplies with alarming speed.
If factories are to maintain minimal waste under such circumstances, waste elimination must somehow keep pace
“Wastology”
with waste proliferation. To do that, we need to have just the
type of intuition, courage, and strength described above.
In this section, we will discuss the work of removing
waste in five main parts, which are listed below in order of
their discussion.
◾◾ Basic attitude for removing waste
◾◾ Removing waste from the movement of goods
◾◾ Removing waste from the actions of people
◾◾ Removing waste from the movement of machines
◾◾ Removing waste from the combination of people, goods,
and machines
The Basic Attitude Needed to Eliminate Waste
JIT improvement has many enemies. When we find waste
and attempt to eliminate it, we usually run into all kinds
of enemies.
We run into the enemy called “Resistance.” This enemy
grumbles such things as, “If we do it your way, we’ll never
be able to produce enough!” Then there is the enemy called
“Intimidation,” who warns, “OK, but you’re to blame if there
are any defectives!” Finally, there is “All’s Well,” who pleads,
“Can’t we just leave well enough alone?”
No matter how many outside seminars on JIT production
a company’s managers attend, no matter how many in-house
guest seminars and training courses they hold under the banner of the Awareness Revolution, the enemies are still there,
lying in wait. People do not really take waste elimination
personally until it zeros in on their own workplace.
During the waste-finding stages, people who were filled
with enthusiasm at awareness revolution seminars suddenly
start donning the armor of, “I can’t do that!” or the helmet of,
“That’s just impossible!” whenever the waste to be removed
has some personal connection. It is amazing how fast people
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Ten Arguments Against JIT Improvement
1. JIT improvements won’t do any good!
2. It sounds like a good thing, but we still don’t
want to do it!
3. Looks good on paper, but . . .
4. Costs are already as low as they can possibly get!
5. But we’ve already been doing things that way!
6. We don’t want people looking over our
shoulders and telling us what to do!
7. We can’t lower costs any more without
lowering quality!
8. Everything is going just fine now. Why Change it?
9. That’s a lousy idea! We already tried that
20 years ago!
10. Look, we understand this stuff better than
anybody (so don’t tell us what to do).
Figure 3.35
Ten Arguments against JIT Improvement.
can change from progressive to reactionary when they are
asked to change their work habits.
In the final analysis, many people are willing to embrace
the awareness revolution and analyze current conditions to
discover waste because these things will not put any real
heat on them or prescribe any painful medicine. But when
the time arrives for removing the waste, suddenly they feel as
if they had been doused with gasoline and set afire or forced
to drink poison. It is the same old story: People tend to agree
on generalities and disagree on particulars. Resistance and
defensiveness can generally be counted on to raise their ugly
heads at every workshop the waste removers visit. Figure 3.35
lists what I have found to be the ten main arguments against
JIT improvement.
If I had to choose the three worst arguments, I would select
the following.
Third worst: “Costs are already as low as they can possibly get!”
People who have labored long and hard just to get costs down
to their current levels tend to regard JIT’s demands for further
cost-cutting as unreasonable, if not downright impossible. Not
“Wastology”
only is this attitude presumptuous, but it is also clear evidence
of basic ignorance about waste. At the average factory, every
activity that actually adds value to the product is accompanied by several thousand (even tens of ­thousands) of wasteful
activities that enhance nothing but costs. But people still tend
to judge by their sweat, and think that their cost-cutting efforts
have done everything possible. There seems to be some idea
that when the going gets hard, the job is finished.
Factories will not improve unless the factory people keep
two things in mind: Improvements are limitless, and there is
no end to cost-cutting.
Second worst: “Everything is going just fine now. Why
change it?”
This is the argument I hear first at factories that are currently making some kind of profit. As long as the profit/loss
balance is in the black, people do not concern themselves
with such issues as fast-changing markets and growing customer complaints. People get complacent thinking, “Why
should I work any harder when we’re doing fine as it is?” But
do such people really think the business world will always
be kind enough to let them “coast” and still make money?
How soon people forget that what goes up must come down.
To keep things up takes effort, and the amount of effective
effort continually committed to keeping profitability up is
directly proportional to how long it will indeed stay up.
The complacent question, “Why change?” can remain a
common refrain for years, until people start noticing how
tough things are getting and...ooops, they have slipped into
the red! Then, suddenly, they start asking a new question:
“How can we change?”
Worst of the worst: “It sounds like a good thing, but we
still don’t want to do it!”
The reason why this is the absolute worst argument is very
simple: It is the one I hear most often, and at all kinds of
factories. Here are just a few examples:
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◾◾ At a home electronics manufacturing company: “Yeah,
well I’m not surprised JIT worked at Toyota. But I’m afraid
this company is just not in the same league as Toyota.”
◾◾ At a kitchenware manufacturing company: “JIT is suited
for automakers and others that do a lot of machine processing. It wouldn’t work at a factory like ours that works
mainly with natural wood materials.”
◾◾ At a farm equipment manufacturing company: “We’re different than other manufacturers. During the busy ­season,
our sales jump four or five times higher than during the
slow season.”
◾◾ At a typical manufacturing subsidiary: “JIT might work
at our parent company, but there’s no way it would work
here. Maybe if our parent company got into it first, we
could follow suit.”
◾◾ At a long-established European automobile manufacturing
company: “Are you kidding? JIT is based on a Japanese way
of thinking. We think differently in this country.”
Unfortunately, these kinds of remarks are to be expected.
I doubt there has ever been a factory where none of the
above arguments have been launched against the specter of
radical improvement. Everybody thinks they are somehow
a “special case,” an exception to the rule. This idea alone is
taken as a good enough excuse for evading all the difficult
aspects of improvement.
In recognition of the seriousness of this problem, a Japanese
watch manufacturer posted a list of “taboo phrases” on signs
and posted the signs at various conspicuous places. (See
Figure 3.36.)
Thus, there is no end to the variety of arguments one runs
into when attempting to carry out improvements at factory
workshops. I suppose factory workshop people are conservative by nature. If the current way of making things seems to
be paying off, they are just not interested in making any big
“Wastology”
Taboo Phrases
Let’s all banish these words from our lips as we
discuss making improvements in our work!
1. Never say, “Do it yourself!”
2. Never say, “We can’t get costs any lower.”
3. Never say, “This is good enough.”
4. Never say, “I’m too busy to do it.”
5. Never say, “That’s not part of my job.”
6. Never say, “I can’t do it” of “It won’t work.”
7. Never say, “It’s your responsibility not mine.”
8. Never say, “We ‘re already doing fine.
We don’t need to change.”
Figure 3.36
Taboo Phrases at a Japanese Watch Manufacturer.
changes. This is especially true of those in charge, who tend
to be especially stubborn about maintaining the status quo.
Shop veterans who have been on the job for 10 or 20 years
are alarmed by the prospect that all their years of accumulated production know-how will be reduced to nothing by
the JIT revolution. They are afraid, and they worry whether
they would even be able to become the type of worker that
JIT demands. Resistance is therefore a natural instinct for
such people.
However, JIT leaders have neither the time nor the energy
to deal with each individual’s resistance. The only alternative
is for the workers themselves to become aware of the reasons
for their resistance and to overcome that resistance. It is not
enough to accept the JIT awareness revolution intellectually,
for then we get the type of “agreement in general, disagreement on particulars” problems described above. Our revolutionized awareness must also be a physical and emotional
commitment to change.
Figure 3.37 above illustrates the Ten “Basic Spirit” Principles for Improvement. These statements are explained further below.
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Ten “Basic Spirit” Principles for Improvement
1. Throw out all of your fixed ideas about how to do things.
2. Think of how the new method will work—not how it won’t.
3. Don’t accept excuses. Totally deny the status quo.
4. Don’t seek perfection. A 50-percent implementation rate
is fine as long as it’s done on the spot.
5. Correct mistakes the moment they’re found.
6. Don’t spend money on improvements.
7. Problems give you a change to use your brain.
8. Ask “Why?” at least five times until you find the ultimate cause.
9. Ten people’s ideas are better than one person’s.
10. Improvement knows no limits.
Figure 3.37
Ten “Basic Spirit” Principles for Improvement.
1. Throw Out All of Your Fixed Ideas
about How to Do Things
As soon as we scratch the surface of workshop resistance
to change, we discover all kinds of fixed ideas about “the
way things are done.” It is fair to say that the majority of the
waste in the workshop is originated in these fixed ideas; fixed
ideas about equipment layout, about manufacturing methods,
about machine selection and operation, about manual work
operations—the list is endless. One gets the impression that
the workshop’s present condition is just one big, solid heap
of fixed ideas and preconceived notions.
As long as that big heap of fixed ideas is there, there is
no room for improvement to gain even a foothold. So we
have to start by throwing out the entire heap. To do this, we
must drop our die-hard “professional expertise” and return
to a beginner’s mind, the novice who carefully and conscientiously works to make products one at a time. This is a basic
principle of manufacturing.
2. Think of How the New Method
Will Work—Not How It Won’t
I have many times pointed out a needed improvement only
to hear comments that invariably include words such as “but”
“Wastology”
or “so it won’t work.” These should be among the “taboo
phrases” in improvement activities. When we can hear p
­ eople
singing the “But...so it won’t work” song all over the factory, it
is a sure sign that the factory’s days are numbered.
3. Don’t Accept Excuses—Totally Deny the Status Quo
When workers start coming up with “reasons” why something
will not work, all the JIT leader hears is excuses. Unwelcome
excuses, at that. I have been to workshops where the resident
“expert” has gone on and on for 20 or 30 minutes—some
have babbled on for hours—to inform me of the myriad different “reasons” why the status quo must be preserved. After
a while, people stop listening. Once a bored co-worker even
pulled out a pillow and took a nap!
Rather than embarking on the long and winding road of
excuse-making, we need to start fresh by totally abandoning
our attachment to the status quo and turn wholeheartedly
toward contemplating positive action.
4. Don’t Seek Perfection—A 50-Percent
Implementation Rate Is Fine as Long as
It’s Done on the Spot
The intellectual types that run some factories are generally
characterized by their perfectionism. When it comes to ­making
improvements, their inclination is to gather some paper and
head for their desks, where they immediately start ­drawing
layout schematics and calculating economic lot sizes. As soon
as we try to discuss some specific improvement plans with
such people, they launch into long-winded discussions of
the ramifications, and so forth. Meanwhile, factory-based
improvement activities get put off for later.
For example, when I once suggested that a certain workshop should switch from sitting while working to standing
while working, the person in charge decided that an analytical
study must first be done to determine the ergonomic impact
of such a change. He also wanted to seek the opinions of
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every worker concerned before designing a new, higher work
table at which to stand.
But it did not stop there. Since the workers were of various
heights, he thought it necessary to include a height-adjustment
function in the new work table. But the difference in height
was so great that he thought it would also be prudent to
install a pedestal for the shortest worker. Then he figured
that the cement floor needed to be covered with wood to
reduce fatigue caused by standing on hard surfaces. After
that, he figured he should eliminate the labor and hassle of
adjusting the table’s height manually by installing an electronic control device. The end result was a plan that entailed
spending gobs of money and extending the improvement
implementation period for years.
A key thing about improvements is that they must be done
right away. An improvement does not need to be completely
planned out in advance, just do 30 or 40 percent of it, then
take a look at it and figure what needs to be done next to
complete it. Improvements dreamed up on a piece of paper
in an office rarely work as planned in the factory. Unless
an improvement’s implementation is be­gun right away, we
will find ourselves spending all kinds of money to get it the
way we theoretically want it. But the fact is that most of the
improvements that cost a lot of money are failures.
There have been many, many sad and ironic cases in
which factory managers decided to bring in new and expensive equipment to improve production for a certain product,
only to find that the product’s market life ended before the
equipment was even up and running.
Factories should be regarded as living entities sadly lacking in first-aid care. We need to practice “JIT improvement”
by making just the improvements needed, just as soon as
they are needed, and in just the amount needed.
“Wastology”
5. Correct Mistakes the Moment They Are Found
Whenever we sense anything wrong at the factory, that is the
time to do something about it. Once we make an improvement to correct the mistake, we may well find another problem has surfaced. Again, we get right to it, solving problem
after problem just as soon as they are noticed.
Improvements do not always happen smoothly. Sometimes
people who are full of enthusiasm for making JIT improvement lose heart as soon as problems appear with the change,
and instead of trying to solve the problems, they go back to
square one.
For example, suppose we are switching a workshop over
from shish-kabob production to one-piece flow production. We suddenly decide it was all a big mistake and, without even trying to solve the problems, we go back to the
old shish-kabob routine. That kind of attitude will get us
nowhere. We need to be persistent, even stubborn, in maintaining the momentum of improvement without giving up
and backtracking.
6. Don’t Spend Money on Improvements
I will be the first to admit that improvements made at great
expense are much easier than those that do not cost much. We
have more freedom to do things when we feel free to spend
$10,000 here and $20,000 there. Making improvements without spending much money is, by contrast, a tough challenge.
“Don’t spend money on improvements” is saying that
taking­the easy and expensive way out does not encourage
us to use our wits. These days, a lot of companies are opting
for the apparent expediency of throwing money at problems.
But where is the resourcefulness in that? The success of an
improvement depends not on how much money we put into
it, but how much wisdom and ingenuity we invest.
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Improvements that arise from brainstorming and that do
not cost much money can be implemented right away. To
put it another way, there is no time for spending money. We
have to make the improvement as soon as possible, before
the office-bound people get hold of the problem and start
writing up big improvement plans that will end up costing
a small fortune. Harsh as it sounds, our attitude should be:
“Don’t spend money on improvements. Use your wits. If you
haven’t got any wits, then use your sweat. If you haven’t got
either, then just be quiet and go away.”
7. Problems Give You a Chance to Use Your Brain
Ingenuity and “know-how” do not kick in when all is well
and good. Only when we are suffering under the burden
of difficult, confusing problems are we required to become
resourceful and use our brain.
The same goes for JIT improvement. Improvement ideas
are not going to sprout and grow in a workshop environment
of satisfied, unquestioning workers. What the JIT leader has to
do is stir up some trouble. By this, I mean such things as trying out one-piece manufacturing flow under the current conditions and stopping the line whenever a problem occurs.
If we avoid rocking the boat and simply throw money
at problems, we will never find out just how ingenious the
­factory staff can be. That would be a true disgrace. We need
to encounter difficulties and put our minds to work in solving them, not our money.
As the old saying goes, “A tree that grows money will never
be wise, and a tree that cultivates wisdom will never need to
grow money.” Which tree is better at facing adversity?
8. Ask “Why?” at Least Five Times until
You Find the Ultimate Cause
Improvement begins with the simple question “Why?” We
need to look at the factory with the unclouded and curious
eyes of children and, like children, we need to ask “Why?”
“Wastology”
about everything we see. “Why?” is the fuel that pushes
improvements off the launch pad.
◾◾ “Why are we using conveyors here?”
◾◾ “Why are the equipment operators sitting?”
◾◾ “Why are they driving screws into that workpiece?”
◾◾ “Why are they carrying those things around?”
◾◾ “Why..?” “Why..?” “Why..?”
Just like a child, when we get an answer for our first “Why?,”
we ask “Why?” about the answer. But sooner or later, the person
the child is asking runs out of answers. That dead-end point is
where the “wall of fixed ideas” lies. Consider an example.
“Why?” #1: “Why do you carry these workpieces over there
when you’re done with them?”
Response: “Huh? Oh, because I’m taking them to the next
process.”
Note: The worker is surprised at such a simple question, for
which he feels the answer is obvious.
“Why?” #2: “But why are you carrying them to the next process?”
Response: “I said why. Because they need to get processed
there.”
Question: “I know that. But why must you carry them?”
Response: “Well. I guess it’s because this process is over here
and the next process is way over there. Does that
answer your question?”
Note: Notice that the worker is getting a little unsure of what
to say.
“Why?” #3: “Why are the two processes so far apart?”
Response: “Hmmm... I guess it’s because that process is in
another department.”
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Note: Now the worker is starting to get curious, too.
“Why?” #4: “Why does the factory keep processes belonging
to different departments so far apart?”
Response: “I wonder why, too. It’s been this way since
I started working here, and I’ve never thought about
it until now.”
Note: The questioning has reached its mark—the “wall of
fixed ideas.”
When we reach that “wall of fixed ideas” (whether it
takes four “Whys,” five “Whys,” or more) it is time to start
brainstorming improvement ideas. For example, we could
link the two processes together or even change the whole
factory organization.
We have just seen an example of how the five “Whys”
(5W’s) lead up to the question of how (1H) to make an
improvement. This fact-finding method is known as the
“5W1H” approach.
Have you ever asked anyone “Why?” until you find their
“wall of fixed ideas”?
9. Ten People’s Ideas Are Better Than One Person’s
Expertise in JIT improvement is not what we cultivate just by
reading books, attending lectures, and pondering solutions.
Such expertise is earned by hands-on work in the factories,
looking at problems point-blank. It is a knowledge we gain
with our whole being, mental and physical. If we attempt to
carry out improvements based on book knowledge alone,
we are doomed to failure. If we get our knowledge the
hands-on way in the factory, we are destined to succeed.
Experiential wisdom makes all the difference. When searching for an answer to a physical problem, what possible value
could one man’s book knowledge have in comparison to the
“Wastology”
experience-based wisdom of the people who have poured
their wits, toil, and sweat into the matter?
10. Improvement Knows No Limits
Improvement is boundless. This means two things, essentially. It means that our fast-changing world will always
demand ongoing improvement. That is the horizontal meaning. Vertically, it means that improvements can always be
taken to a deeper level. Improvements point the way toward
further improvements.
If the thread of ten people’s experiential wisdom can be
woven along these horizontal and vertical axes, it will create
a tough fabric of improvement that is always tailored to meet
the world’s everchanging needs.
Removing Wasteful Movement of Things
Arrow diagrams are good tools for finding major forms of
waste within the movement of things. They are easy to create­
and bring major waste to the surface so that anyone can
­recognize it.
The sequence of major waste related to the movement of
things goes from retention (Step 1) to conveyance (Step 2),
nothing at processing and inspection (Steps 3 and 4), then
material handling (Step 5).
Making arrow diagrams is a good way to bring the retention and conveyance steps into focus. But the question is how
to remove this waste once we have it in focus. Fortunately,
there is a way that does not require any specialized training.
In fact, it is quite simple.
We just try to remove all of those retention and conveyance points. There is no magic involved in eliminating waste.
The only way to effectively remove this kind of waste is to
eliminate the retention and conveyance itself.
Figure 3.38 shows a flow diagram of the same printed circuit board factory we had discussed earlier (see Figure 3.25).
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Before Improvements
ARROW DIAGRAM
SHOP NAME:
PCB Assembly
PRODUCT
NO:
DIAGRAM
CREATED BY:
CREATION DATE:
A3-11-2010
1/31/89
PROCESS SYMBOLS
RETENTION CONVEYANCE PROCESSING INSPECTION
Nishizawa
(C) = Carts
(M) = Manual operation
Conveyance distance:
150 meters
Staff: 49
Shelving Shelving Shelving
2
First dip
Second dip
Circular con1
veyor (insert)
Shelving Shelving
Work table Work table
Inspection
6
5
Cleaning
3
Inspection
Inspection
Shelving
Shelving
Tester
4
Shelving Shelving
Shelving Shelving
Repairs
Apply
Apply
backing backing
Inspection
Shelving Shelving
Shelving Shelving
Shelving Shelving
Shelving
Shelving
Insertion
machine
Inspection Inspection
Parts bins Parts bins Parts bins Parts bins
Shelving
Shelving
Inspection
Shelving
Elevator
Shelving Shelving
After Primary Improvements
ARROW DIAGRAM
SHOP NAME:
PCB Assembly
PRODUCT
NO:
DIAGRAM
CREATED BY:
CREATION DATE:
A3-11-2010
2/6/89
Shelving
Circular conveyor (insert)
PROCESS SYMBOLS
RETENTION CONVEYANCE PROCESSING INSPECTION
Nishizawa
Shelving Shelving
2
First dip
(C) = Carts
(M) = Manual operation
Conveyance distance:
150 meters
Staff: 49
Second dip
1
Shelving
Work table Work table
Shelving Shelving
3
Insertion
machine
Shelving
Work table Work table
Shelving
4
Cleaning
Repairs
Shelving
Cleaning
Shelving
Work table Work table
Shelving
Shelving
212
Shelving
Shelving
5
Tester
Shelving
6
Inspection
Inspection Inspection Inspection
Apply
Apply
backing backing
Apply
Apply
backing backing
Elevator
Shelving Shelving
Figure 3.38
Shelving
Arrow Diagrams of Printed Circuit Board Factory
Before and after Primary Improvements.
“Wastology”
This is how the factory looked prior to improvement. This
factory takes up two floors and includes six major processing
lines, among which are 24 retention points and 16 conveyance points.
As the first improvement, we got rid of several retention
and conveyance points and brought all of the inspection processes together at one station. These two actions made the
overall flow of goods a little more streamlined.
As a whole, the post-improvement layout had a smoother
flow of goods than the pre-improvement one. After this first
improvement, there were still 14 retention points, eight conveyance points, and one inspection point. This meant a reduction of 10 retention points, eight conveyance points, and two
inspection points. It also enabled the factory to reduce its
workforce by seven persons, from 49 workers to 42 workers.
This first set of improvements turned what was a very
wasteful factory layout into a typically wasteful one, such
that if we go there and look at things, we can get a grasp of
how the goods are flowing. Now it is time to get into some
full-fledged improvements by abolishing lots and switching
to one-piece flow, and then to multi-process handling. To do
this, we must do something about the larger pieces of equipment that are taking up too much space, and we need to
further reduce the labor force by about 50 percent.
To recapitulate, we began our improvements by removing the obvious major forms of waste from the retention
and conveyance processes. Interestingly enough, in most
cases conveyance waste occurs because of goods being
retained. Therefore, we can say that retention is the mother
of conveyance.
Our next improvement step was to eliminate the retention
of goods that so often gives rise to conveyance waste.
1. Eliminating Retention Waste
Retention is when a workpiece remains in one place for any
length of time, waiting for the next production step to occur.
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Lot waiting
Lot 3
Lot 2
Lot 2
Lot 1
Processing
Process waiting
Machine/people (capacity) waiting
Materials waiting
Operation method waiting
Figure 3.39
Process Waiting and Lot Waiting.
“Waiting” is the key word here, since it is a visible phenomenon that always goes hand in hand with retention.
We should look for two kinds of waiting: “process waiting,”
which means the workpiece is at a process waiting its turn to
be processed; and “lot waiting,” which means the workpiece
is waiting to join the rest of the lot.
Removing “process waiting” waste. Process waiting
can happen in three different ways. In all cases, the entire lot
is being kept waiting due to some problem that has caused
a pause in processing. The three kinds of process waiting are
called “machine/people (capacity) waiting,” “materials waiting”
and “operation method waiting.” (See Figure 3.39.)
Machine/people (capacity) waiting refers to situations in
which the workpieces are ready for processing, but they
must wait because the machine and/or its operator are busy.
The causes and waste removal methods for this type of waiting are:
1. Capacity imbalance between processes.
When there is a gap between the previous and next
process, we can identify this as a capacity imbalance.
To solve this, we need to match the previous process’s
capacity to the next process’s capacity so that they are
synchronized. This usually calls for some kind of system
“Wastology”
or device (such as the full work system) that will keep
the capacity of upstream processes from exceeding that
of downstream processes. The result is “pull” (rather than
“push”) production.
2. Accumulation/dispersion of processes.
Imbalances can occur when workpieces are accumu­lated
at one process and then are dispersed among several others. This usually calls for a study of the process se­quence
and balance, but usually the best response turns out to
be bringing all processing together into one line. To do
this, we must use only small, in-line equipment.
Materials waiting occurs when we have everything we
need to start processing—except for one essential part that
for some reason or other is not on hand. In other words,
the cause is a “missing part.” If the part is being supplied
by an outside vendor, then the solution must be something
along the lines of JIT’s “vendor guidance,” “delivery method
re-evaluation,” or a “restructuring” based on an evaluation
of vendor performance. If the missing part is manufactured
in-house, we need to investigate and correct the cause directly.
Likely causes include process imbalance, defects, or machine
breakdowns. In any case, we must first make improvements
to correct the cause.
Operation method waiting tends to happen when the factory is understaffed and workers are processing lots at more
than one process station. We call these kinds of work operations “caravan operations.” The first thing to do in this case
is to bring all the processes into one line, then implement
multi-process handling, and finally switch to one-piece flow.
Removing “lot waiting” waste. Lot waiting means that
the workpiece’s lot is being processed and that one part of
the lot has been processed and waits on the downstream
side of the process machine while the other part waits on
the upstream side. Lot waiting happens for only one reason:
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lot processing. When we ask “Why?” again—“Why are they
doing lot processing?”—we may discover one of the following reasons:
1. The processes are separated.
The previous and next processes are separated in such a
way that precludes one-by-one conveyance, and so the
workpieces are processed in lots. To remove this form
of waste, we must redesign the equipment layout into an
in-line formation, get rid of conveyance altogether, and
establish one-piece flow.
2. Mass production equipment.
If the machines and other equipment in the factory are
mainly designed for high output, they tend to be used for
lot production. This is especially common where lots are
subdivided into batches for batch processing, such as for
cleaning, polishing, pressing, or inspecting. The appropriate improvement is to carry out one-piece flow using
compact machines that can be kept in pace with the cycle
time. The key point in manufacturing such machines is
that they should emphasize the essential processing or
assembly function and do away with nonessential functions. This makes them much less expensive to build.
3. Product changeover takes too much time.
Switching products takes a long time, so the factory uses
large lots to minimize the number of changeovers. At
assembly stations, changeovers in part sets and operation
methods tend to cause bottlenecks, so they try to do all
their jig and die changeovers at the processing stations­.
To solve such problems, we can try “changeover within
cycle time” at all assembly stations, go all the way to
“zero changeover,” or aim for “totally mixed production.”
These improvements are designed to reduce the multiple
changeovers at processing stations to single changeovers
or even zero changeovers.
“Wastology”
4. Operations are hard to balance.
This type of thing happens all the time at labor-intensive
assembly processes. Obvious differences in operator
skill level and operations that are inherently difficult to
balance lead such assembly lines toward lot processing in which each worker works at a separate little
island. Improvement tactics for this problem include the
“SOS system” for immediate line balancing, the “baton
touch zone” method, or training workers in multiple
skills to enable multi-process handling.
Figures 3.40A and 3.40B list the causes and improvement
suggestions for removing retention waste in the form of
“process­waiting” waste and “lot waiting” waste, and notes
the kinds of resistance we can expect to encounter when
trying­to actually remove the waste.
Removing Wasteful Movement by People
Generally, we can use the term “operations improvement”
to refer to the activity of removing the wasteful motions that
workers make. This includes torso motions, foot motions,
hand motions, and every other motion that workers make, all
of which contain waste.
Naturally, each motion is actually a combination of various
motions, and we need to see what goes into these combinations before we begin removing wasteful ones. To do this,
the most important question is “Why?” Why does waste occur
in such-and-such movement? We need to keep asking “Why?”
until we are able to know what the essential motions are for
building the product.
For example, let us just consider manual conveyance
(­carrying and cart-handling) operations. Here, we need to
look for ways to keep the hips from turning, better ways
to use the carts, and so on. Again, to do this, we need to
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Cause
Improvement (Waste
Elimination) Point
Expected Resistance
Waiting for machines
and/or people
1. Unbalanced processes
Unbalanced due to gap
between previous and next
process.
Synchronization
Upstream process needs to be
synchronized with downstream process.
Pull Production
Need a device or system (such
as full work system) to keep
the previous process from
producing in excess of the
next process’s capacity.
“This workshop is different.
It’s impossible here!”
“The gap is due to different
skill levels, so there’s
nothing we can do about it.”
“So let’s tell the previous
process to ease up a little.”
In-line layout (flow production)
Processes where workpieces
accumulate are like large
islands, apart from the rest of
the line. They need to be
brought back into a closely
linked line.
“This machine is stuck here,
so we can’t have an in-line
layout!”
“I’ve never seen a small
machine that can do this
process.”
“If we do that, we’ll lose
efficiency.”
“They don’t make machines
like that.”
“We’ll have to spend a
fortune buying new equipment!”
Capacity
Capacity
2. Accumulation/
dispersion of processes
This occurs when workpieces for the same product
are gathered at certain
processes and spread out
at others.
PROCESS WAITING
218
Use smaller equipment
Smaller machines that fit more
easily into a closely linked
line can be built inexpensively.
Large
island
Materials waiting
3. Operations delayed by
missing materials or
parts
Process
Operation method waiting
4. Caravan operations
The factory is understaffed
and workers are processing
lots at more than one
process station.
Process
Process
Process
Parts from outside vendors
Vendor guidance
Need to provide guidance and
training in JIT and re-evaluate
the vendor’s delivery system.
Reorganization
Need to reorganize based on
number of orders and vendor
evaluation.
Parts from outside vendors
Address the ultimate cause
Address the improvement to the
ultimate cause—defects, machine
breakdowns, insufficient capacity,
or whatever.
“No, the vendor is a bigger
company than we are.”
“Sure, we can try to help
them, but it won’t do any
good.”
“It’ll cost us more if we ask
them to deliver more often.”
There’s no way to avoid
havind those few defectives.”
“Machines break down
beacuse they’re machines
—it’s inevitable.”
In-line formation
Redesign the scattered
processes into an in-line
formation.
Multi-process handling
Develop operations into multiprocess handling.
One-piece
Switch from shish-kabob
production to one-piece flow.
“We have no choice—we’re
short of workers right now.”
“One-piece flow sounds like
one big hassle. It wouldn’t
work.”
Figure 3.40A Ways to Remove Waste from Retention Points (Process Waiting).
“Wastology”
Cause
1. Process is separated
Previous
Mass
production
LOT WAITING
Expected Resistance
In-line
Line up the equipment
according to the process
sequence.
One-piece flow
Switch to one-piece flow.
“That machine can’t be
moved over here.”
“That is a very high-precision
machine. It shouldn’t be
moved.”
“One piece at a time? What
are you talking about?”
Cycle time
One-piece production must be
in accordance with cycle
time.
One-piece production
Don’t gather workpieces into
batches for processing,
always process just one at a time.
Use smaller equipment
Smaller machines that fit more
easily into a closely linked
line can be built inexpensively.
“Making things one at a
time had got to result in
lower efficiency.”
“I’ve never even heard of
a machine built for
one-piece processing.”
Next
2. Mass-production
equipment
Equipment is mainly designed
for high output and cannot
handle one-piece flow.
3. Product changeover
takes too much time
Changeover
4. Operations are hard
to balance
Figure 3.40B
Improvement (Waste
Elimination) Point
Assembly
Changeover within cycle time
Changeover of parts, jigs, and
so on should be able to be
finished within the cycle time.
Sequence feed or
marshalling
Parts should be fed to the line according to the assembly sequence.
Processing
Changeover
Improve changeover to enable
single changeovers or even zero
changeovers.
SOS system
Balance the line immediately
and without further planning.
Baton touch zone
method
Perform each operation at a
prescribed pitch, then move
directly on to the next one.
Multi-process handling
Train workers to handle all
processes on the line, from
start to finish.
“It’ll get expensive if we start
changing the equipment.”
“There are just too many
parts. It can’t be done.”
“If we do that, we’ll need
too much labor on the line.”
“Changeover time can’t be
made any shorter than this.”
“Stop the line? You must be
crazy!”
“If we ever forget to touch
the baton, there’ll be lots
of defectives.”
“Frankly, I don’t think I
could learn to handle so
many processes.”
Ways to Remove Waste from Retention Points (Lot Waiting).
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Improving actions
IMPROVING
OPERATIONS
Improving the point
of the operation
Figure 3.41
Improving Actions and Improving the Point of the
Operation.
repeatedly ask “Why?” We also need to switch from small
islands to one closely linked line. This gets rid of the major
waste involved in conveyance by getting rid of the conveyance points themselves.
Thus, there are two ways to approach operations improvement. The first is “improving the actions” by removing waste
from within the motions that comprise the operation and
the second is “improving the point of the operation” by
re-evaluating the entire operation to possibly find a more
sweeping improvement that serves the same purpose. In JIT,
we always put primary emphasis on the latter, more radical
approach. (See Figure 3.41.)
The “principles of economy of motion” can be a good tool
for improving the motions of workers to remove waste from
human actions. These 17 principles are grouped into three
sets of principles relating to (1) use of the body, (2) layout of
the workplace, and (3) jigs, tools, and machines.
Principles Relating to the Use of the Body
Apply these principles when attempting to eliminate or minimize body motions.
◾◾ Principle 1: Start and stop manual operations
using both hands at once. When a manual operation
requires the use of both hands, both hands should move
in unison to start and stop the operation.
◾◾ Principle 2: Keep arm motions simultaneous and
symmetrical. Arm motions should follow the principle
“Wastology”
of the breast stroke in swimming: Move with the same
timing but in opposite directions, symmetrically.
◾◾ Principle 3: Minimize leg and torso motions. At the
assembly line, if the parts are kept behind the assembly
workers, the workers must move their legs to get them.
If kept at their sides, they need to move their hips to
twist aside for them. If kept in front of them but up on a
shelf, they need to move their shoulders to reach up for
them. If kept at chest level in front and just to the right
and left of the shoulders, they only need to move their
arms, wrists, and fingers. We need to minimize movement beginning with the largest motions (feet) and then
gradually work down to smaller motions, going from
hips, to arms, wrists, and finally fingers. We begin by
standing alongside each worker and carefully observing
his or her motions to understand what kind of motions
the worker is making in performing the operation.
◾◾ Principle 4: Use gravity instead of muscle power.
The more we use our muscles, the more tired we get.
Whenever possible, put the force of gravity to work in
moving things.
◾◾ Principle 5: Avoid motions that zigzag or turn sharply.
Try to keep motions smooth along continuous curves.
Avoid “hairpin turns” and complicated z­ igzag patterns.
◾◾ Principle 6: Make motions rhythmic. Motions without an easy, natural rhythm often lead to defects or injuries. Find a rhythm that fits the cycle time and that is
easy to steadily maintain.
◾◾ Principle 7: Ensure easy posture and easy motions.
Having to bend over a work table that is too low or
strain the arms and shoulders to work at one that is
too high will only make work uncomfortable, which can
only lead to waste.
◾◾ Principle 8: Use the feet, too. The feet can also be put
to work without strain, such as in pressing foot switches.
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Normal range for left hand
330
660
Normal range for right hand
Maximum range for right hand
Maximum range for left hand
330
1080
1680
Height of worker: 1700
Length of forearm: 260
Figure 3.42
Length of upper arm: 320
Torso length: 780
(Unit: mm)
Range of Motion in Manual/Operations.
Principles Relating to Workplace Layout
◾◾ Principle 9: Keep all materials and tools in front
and close (maximum proximity of use points). The
points at which the worker must reach to pickup and/or
replace materials and tools should be kept in front and as
close to the worker as possible to minimize the w
­ orker’s
motions. (See Figure 3.42.)
◾◾ Principle 10: Lay out materials and tools in their
order of use. Place all materials and tools within easy
reach and arrange them to follow the sequence of the
­manual operation. This will not be possible unless we
make the parts layout as compact as possible by feeding only a few parts at a time to the work table and by
thoroughly implementing the 5S’s to keep things neat
and orderly.
◾◾ Principle 11. Use inexpensive types of power. Use
inexpensive types of mechanical power to extract and
feed materials to processes.
◾◾ Principle 12: Keep the work tables and equipment
matched to the worker’s height. Make sure that the
“Wastology”
work tables and other equipment are not too high or too
low, as this will cause undue stress and fatigue.
◾◾ Principle 13: Make the work environment as comfortable as possible. Operations will go more easily
and smoothly if such environmental factors as lighting,
ventilation, and temperature are controlled for maximum
possible comfort.
Principles Relating to Jigs, Tools, and Machinery
◾◾ Principle 14: Let the feet work, too. Many switching
operations can be comfortably handled by the feet, thus
freeing the hands for other work.
◾◾ Principle 15: Integrate tool functions to minimize
tool variety. Sometimes, a single tool can cleverly combine the functions of two or more other tools. This saves
space and simplifies tool organization and handling.
◾◾ Principle 16: All materials and parts should be
easy to pickup. Keep all materials and parts in front of
the worker and lower than chest level, so that they can
be picked up easily. All containers should also be within
easy reach.
◾◾ Principle 17: All handles and knobs should be in
convenient places and in an easy-to-use shape. If
possible, the operator should be able to reach all handles
and switches without having to shift or bend his or her
torso. The position and shape of these things should be
designed for maximum operability and efficiency.
Removing Waste in the Way People,
Goods, and Machines Are Combined
The basic work of eliminating waste from operations is to
remove waste from each of the “3M” factors involved: man,
materials, and machines.
However, some of the waste that these three factors include
may not be so easy to identify. Therefore, it is wise to look
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also at the way the three factors are combined as another
possible source of waste. Our objective is to combine these
factors in the way that is most efficient and “flows” most
easily­, much like the harmonic parts that make up a pleasant
piece of music. In a sense, we are removing everything that
does not harmonize with the operations flow, and the result
should be a pure combination of harmonic resonances.
Combination charts for standard operations are the best
tools to use for grasping the “surface waste” in this combination. The more waste we can find and remove from this combination, the more standardized the operations will become.
First use these combination charts to find the “surface waste”
in just the combination of people and machines. Make a
complete and careful observation of how manual operations
(indicated by solid bars in the chart) relate to auto feed operations (indicated by broken lines).
The two ways in which people and machines can work
together are serially and in parallel.
Serial Operations
In serial operations, the worker and the machines take turns
adding value to the product. Ordinarily, we begin with the
worker’s standard operations and when those are done, it is
the machine’s turn to begin working. (See Figure 3.43.)
Parallel Operations
In parallel operations, the worker and the machine work
alongside each other, which is to say that they work together
Worker’s operations (manual operations)
Machine’s operations (auto feed operations)
Figure 3.43
Worker’s operations
Machine’s operations
30
seconds
40
seconds
Serial Operations.
Completion time:
70 seconds
“Wastology”
Machine’s operations
40
seconds
Worker’s operations
Completion time:
40 seconds
30
seconds
Figure 3.44
Full Parallel Operations.
Machine’s operations
40
seconds
Worker’s operations
Completion time:
50 seconds
30
seconds
Figure 3.45
Partial Parallel Operations.
to add value. Sometimes the worker and machine are able
to work completely in parallel, which is called “full parallel
operations,” and sometimes the worker is in parallel with
the machine only part of the time (usually during standard
operations), which is called “partial parallel operations.” (See
Figures 3.44 and 3.45.)
We need to pay attention to different things depending upon
whether we are trying to remove waste from serial or parallel
operations. In serial operations, we should try to mechanize
the overall operation to simplify and facilitate the worker’s
share of it, while in parallel operations we should try to keep
the worker as separate from the machine as possible.
To do the latter, we need to carefully observe the parallel operations and continually ask, “Why can’t that worker
be separate from the machine right now?” We should then
start brainstorming ways in which the machine can take over
more and more of the worker’s tasks, especially simple tasks
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such as pressing switches. This is the kind of thing that JIT
refers to as “human automation.”
Next, we must address the need to separate workers
from the materials. No matter how completely we separate workers­from the machines, it will do no good if the
worker is still tied down to handling the workpieces. The
way to do this is by having machines handle single workpieces by themselves and automatically send them to the
next process.
Figure 3.46, found on page 228, shows how a wood products manufacturer used combination charts to remove waste
from production operations.
Secrets for Not Creating Waste
Waste is something that tends to gather around us and remain
there. In factories, we can never even hope to be permanently rid of waste. But if factory people take that as an
excuse for accepting waste as inevitable, they are only sending their factories down the tubes. The successful f­actories
will be those whose workers strive day in and day out to
eliminate waste.
In general, there are two “secrets” for not creating waste
in the first place. One is to take preventive measures against
waste by thoroughly implementing standard operations and
developing the discipline to maintain such operations. In
other words, we need to consistently deal with waste at its
very source.
The other “secret” is to follow up on these source-deep
measures by looking out for abnormalities and problems that
occur whenever there are gaps or loopholes in our antiwaste
measures. Recognizing such abnormalities and p
­ roblems is
just one short step away from recognizing the waste that led
to their creation. We can use them as “symptoms­” pointing
us back to the source of waste in order to enact further
“Wastology”
◾
Before Improvement
Standard Operations Combination Chart
Item name: Door jamb (lintel)
Cycle time: 89" (54" needed)
1 Pull out workpiece
3
2 Process S101 gain (small) at
circular saw bench
3 Process S102 gain (large) at
circular saw bench
4 Finish B101 hinge fastening
at multi-spindle drilling
5 Insert edge (using cutter) at
work table
6 Cut edge (using cutter) at
work table
15 10
7 Set up new workpiece
2
23 18
12 7
13
7
Analysis No.: 1of 1
Walking
Description
Manual
Time
Auto feed
Sequence
Manual operations Entered by: Kawano
Auto feed
Walking Date: 1/17/89
No. required: 303 (600)
Process No.: 391-3637
Operation times (in seconds)
5 10 15 20 25 30 35 40 45 50 55 65 70 75 80 85 90
Why is the worker kept busy
by the machine?
2
2
2
2
2
2
Why is the worker doing that
and not the machine?
2
After First Improvement
Standard Operations Combination Chart
No. required: 303 (600)
Process No.: 391-3637
Time
1
Pull out workpiece
3
2
Process S101 gain (small)
at circular saw bench
Process S102 gain (large)
at circular saw bench
Finish B101 hinge fastening
at multi-spindle drilling
Insert edge (using cutter)
at work table
Cut edge (using cutter) at
work table
15 10
Set up new workpiece
2
3
4
5
6
7
23 18
12
13
7
7
Analysis No.: 1of 1
Walking
Description
Manual
Auto feed
Sequence
Item name: Door jamb (lintel) Cycle time: 89" (54" needed)
Manual operations Entered by: Kawano
Auto feed
Walking Date: 1/31/89
Operation times (in seconds)
5 10 15 20 25 30 35 40 45 50 55 65 70 75 80 85 90
Attach feed roller
2
2
Standard operations
using single units
2
2
2
2
2
NOTE: Implement secondary improvements
to further remove waste
Figure 3.46 Wood Products Manufacturer’s Combination Charts for Standard Operations: Before and after First Improvement.
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waste-removing measures. To ensure that such checking
up occurs, we must make abnormalities and other problems ­visible and obvious to everyone. This will make us
­better able to address the true causes of these problems and
prevent their recurrence. The chief tools for doing this are
visual control, auditory control, and the 5W1H approach to
problem-solving.
In this section, we will be covering the following topics as
we discuss the “secrets” for removing waste:
◾◾ Thorough standardization and standards maintenance
◾◾ Visual control and auditory control
◾◾ The 5W1H sheet
Thorough Standardization
Standardization is a very important thing for factories. Why?
Mainly because factories are operated by large numbers of
people, and if each worker is left to his or her own methods
(or even his or her interpretation of the standards), product­
quality and production efficiency are bound to suffer. To
avoid this, we must have standards that are precisely followed
to ensure consistency in product quality and manufacturing
methodology. This is what we mean by “standardization.”
The key word to remember when standardizing operations is
“anyone.” Anyone should be able to understand and use the
standard operations.
Factories require a wide variety of standardization. The
major types include:
◾◾ Machine standardization: Enabling anyone to operate
the machines in the same way.
◾◾ Operation standardization: Enabling anyone to perform
operations in the same way.
◾◾ Control standardization: Enabling anyone to tell the difference between normal and abnormal conditions.
“Wastology”
◾◾ Clerical standardization: Enabling anyone to carry out
clerical procedures in the same way.
◾◾ Procurement standardization: Enabling anyone to perform procurement tasks in the same way.
Thus, standardization basically means establishing procedures so that anyone assigned to carry them out can easily
understand and do them in a consistent manner. These series
of procedures must then be recognized as the particular
­factory’s standards, which means what is to be expected as
the normal way of doing things. This makes it much, much
easier for anyone to identify the abnormalities and problems
that are the first symptoms of waste. As such, we can think of
such problems as the “buds” from which waste unfolds.
While recognizing the importance of the “anybody can do
it” concept in standardization, we should also be well aware
of the major advantage such standardization brings: the ability to identify abnormal conditions and other problems.
Naturally, standardization is not a one-time goal; standards
must be meticulously maintained for waste to be minimized.
This is where training and discipline come in. Each and every
worker must have both if waste is to be continually nipped
in the bud.
At all factories, training and discipline contain the seeds
of toil and trouble. No matter how thoroughly we implement
the 5S’s, there is going to be some backsliding. No matter
how clear and simple the rules of standard operations are,
they will soon be broken. People will also tend to “bend” the
rules of standardization toward their own idiosyncratic way
of doing things. The more they do this, the harder it will be
for them to identify abnormalities and other problems. If this
trend goes unchecked, more and more waste will accumulate until it adversely affects the quality and character of the
entire factory.
There are various tools for establishing and maintaining training and discipline, including classes and periodic
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check-ups. However, the foundation for strong training and
discipline will always be to “catch them in the act.”
Once anyone finds the 5S’s being ignored or standard
operations being bent toward personal inclinations, he or she
must alert the supervisor and have the transgression dealt with
immediately. There is no other way. This means, of course,
that supervisors need to be immediately accessible and not
hidden away in some office. No supervisor—not even one
who can draw the entire factory layout from memory—can
deal with factory problems from anywhere but the factory.
Supervisors need to be in the factory regularly in order to
keep a regular watch on current conditions. Each supervisor
should make a complete inspection tour of the factory (or his
part of the factory) twice a day, at the very least. Any supervisor who does not maintain at least this minimum inspection routine does not deserve to be a supervisor. All factory
work happens at the factory, using real materials and real,
observation-based facts.
Visual Control and Auditory Control
Visual and auditory control will be taken up in detail in
Chapter 9. For now, let us note that no matter how thoroughly
we implement standardization, the standards will sooner or
later become obsolete. Any number of factors can cause such
obsolescence, such as switching to a new product, or adjusting output to match changing sales and price trends. If we
get right down to it, we must admit that producing even a
single defective product will send a minor tremor through
the foundation of the current standards.
It cannot be repeated often enough that the factory should
be regarded as a living thing. Even when everything is being
operated according to the latest standards, abnormalities and
problems will inevitably crop up occasionally. In view of this
fact, we must bring such problems to the surface and immediately devise improvements to correct them before they
“Wastology”
first develop into habits, and then into an established part of
“how we do things here.” The best methods for doing this
are visual and auditory control.
Instead of finding problems through statistical analysis
and other management data, we use our own eyes and ears
as measurement instruments that alert us to problems immediately so we can make an immediate response.
Very often, visual and auditory control use the tools known
as kanban and andon. However, we must recognize that these
are just the tools that alert us to problems, and that we need
other tools—our own energy and ingenuity—to actually solve
the problems.
Many people tend to forget this basic fact about visual and
auditory control and instead rush headlong toward setting up
kanban and andon systems as if they were the whole answer.
Needless to say, such systems are absolutely worthless until
they are followed up by problem-solving measures.
With that in mind, we are ready to view a summary of
tools and procedures that can be used as part of a system for
visual and auditory control of the factory.
Red Tagging
Red tag teams take a cold, hard look at the factory and stick
red tags on everything they judge to be currently unnecessary. This enables anyone to recognize unnecessary items.
Signboards
We use signboards to clearly indicate what things are, where
they belong, and how many of them there should be.
Outlining
Putting outlines around the standardized places for keeping
things—from tools to work-in-process, machines, carts, and
so on—shows anyone exactly where they belong. Outlining is
especially useful for indicating the place and amount of unprocessed and processed workpieces at each production station.
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Andon
Andon are alarm lights (usually accompanied by buzzers or
bells) that immediately inform us when an abnormality or
other problem occurs on the production line.
Kanban
Kanban are small signs that we use to maintain Just-In-Time
production. When these signs are still attached to work-inprocess, they are referred to as kanban. As soon as they have
been removed from the work-in-process, they serve as order
forms, work instructions, or some other kind of voucher.
Pitch and Inspection Buzzers
Pitch buzzers or pitch horns can help maintain the pitch of
assembly operations, and so forth. During inspection, inspection buzzers or horns sound whenever an inspector finds a
defect, and this auditory recognition helps reinforce visual
recognition of defects.
The 5W1H Sheet
The 5W1H sheet is a very good tool to use for following up
on problems we have discovered through visual and auditory
control. Our follow-up is to continually ask “Why?” until we
find the problem’s root cause. Then we can ask “How?” to
correct the problem. The 5W1H (five “Whys” and one “How”)
sheet provides a format and procedure for performing these
follow-up tasks.
If we neglect to make good use of 5W1H sheets, chances
are that whatever improvement we make will only scratch
the surface of the problem and will not be a lasting improvement. Installing devices that will automatically stop the line
whenever a defective is produced will do nothing but create
a place where known defectives can accumulate—unless we
take the 5W1H approach.
“Wastology”
In the previous example, we need to ask, “Why are defectives
being made?” over and over again until we find the root cause
whose elimination will prevent the defective’s recurrence.
Figure 3.47 shows an example of the 5W1H sheet being
used to follow up on line stops.
As it turned out, the root cause in this case was inadequate
drill bit storage. The improvement was to solve the root cause
of the line stops by modifying the drill bit drawer with vertical
felt ridges, as shown in Figure 3.48.
As you can see, the 5W1H sheet is a very important tool for
preventing the recurrence of waste. When trying to use this
sheet themselves, managers must be sure to keep the f­ollowing
five key concepts about 5W1H in mind.
Key Concept #1: Look with the Eyes of a Child
Never cease to look at machines, people at work, material on
the move, and everything else in the factory with the pure
and unclouded eye of a child. The first “Why?” should always
be lurking in the back of your mind. Never let it out of mind;
all improvements begin with that initial “wondering why.”
Key Concept #2: Remember the
Three Essentials for 5W1H
Each workshop reflects the character of the entire factory.
When investigating any kind of factory-related abnormality or
problem, the problem can best, most quickly, and most reliably be understood only at the particular workshop(s) where
it originated. So, managers must know that the first thing to
do is get up and go to the workshop, see the abnormalities
and problems first-hand, then confirm the facts based on
their own observations. The best-run workshops take their
strength from observing these three essentials.
Key Concept #3: Be a Walker
As we all know, many managers typically spend all day at
their desks. Sometimes they sit with a calculator in hand
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5W1H SHEET
Improvement target:
List stops
Why No. 1: (analysis)
Why did the line stop occur?
Current status:
Current status:
Line stopped when dimensional defect was found
in processed item.
Current status:
Why No. 2 or improvement
proposal (HOW):
Why No. 2:
Why did the dimensional
defect occur?
Why No. 2 or improvement
proposal (HOW):
Current status:
Current status:
Two workpieces got
processed at once.
Why No. 3:
Why did two workpieces
get processed at once?
Current status:
Why No. 3:
Why No. 3:
Current status:
Current status:
Two workpieces got stuck
together.
Current status:
Improvement proposal:
Why No. 4:
Why did two workpieces
get stuck together?
Why No. 4:
Current status:
Current status:
Due to inadequate drill bit
storage (drill bits are kept in
a casual pile), the drill was
able to drill two workpieces
together.
Current status:
Improvement proposal:
Improvement proposal:
Device storage improvement
and reinforce the 5S’s.
Improvement proposal:
Figure 3.47
5W1H Follow-Up after Line Stops.
“Wastology”
Before Improvement
After Improvement
Ridges
Felt
Piled in unorganized heap
Figure 3.48
Vertical placement
Improvement of Drill Bit Storage Method.
busily­developing data. They believe (or assume) that all these
figures and analytical data will afford them an understanding
of what is happening in some workshop. But no matter how
much data they develop, its total sum of meaning can be
correctly calculated as zero. First, managers must get up on
their atrophying feet. Next, they need to write WALKING in
capital letters in their job descriptions, then they must head
to the factory for a walk around. Once in the morning and
once again in the afternoon—at the very minimum. Taking
their time. Weight-conscious managers say it is also good for
their health.
Key Concept #4: Break Down the Walls of Fixed Thinking
Everyone carries these types of walls in their mind to channel
and confine perception and thinking. When we ask “Why?”
over and over about the same phenomenon, we reach a
point where we run out of “known” answers. That dead end
is where we meet a wall that protects and defines our fixed
ideas and taught assumptions about things.
Earlier in this chapter, I described a question-and-answer
dialogue about conveyance. As you may recall, the gist of the
conversation was:
“Why?” #1: “Why do you carry these workpieces over there
when you’re done with them?”
Response: “Huh? Oh, because I’m taking them to the next
process,”
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“Why?” #2: “But why are you carrying them to the next
process?”
Response: “Well. I guess it’s because this process is over here
and the next process is way over there. Does that
answer your question?”
“Why?” #3: “Why are the two processes so far apart?”
Response: “I wonder why, too. It’s been this way since I started
working here…
That is where the worker being questioned ran into his
own wall of fixed ideas. When the “way of doing this here”
becomes firmly established, people stop wondering about
other ways to do it. None of us will reach the root cause and
the optimum improvement unless we face that wall head-on,
and keep pounding on it until it tumbles down.
Key Concept #5: Do It Now
In working toward the root cause or the appropriate improvement, once you know, “I’ve got it,” head straight for the workshop and put your idea into practice. First realize the form
and once that is in place, the content will naturally follow.
Chapter 4
The “5S” Approach
What Are the 5S’s?
There is a curious JIT axiom that says, “Good workshops
develop beginning with the 5S’s. Bad workshops fall apart
beginning with the 5S’s.” The first part of the axiom refers to
the thorough implementation of the 5S’s that we need in order
to lay the groundwork for subsequent improvements. The
5S’s are our foundation blocks, upon which we can lay flow
production, visual control, standard operations, and various
other JIT building blocks. All of this long, hard block-laying
will in a few years turn the factory into a close approximation of the JIT production system.
On the other hand, it only takes a moment for a workshop
to begin falling apart. This process also begins with the 5S
foundation block, even though all those other blocks have
been placed on top. Like a skyscraper whose bottom floor
is suddenly demolished, the proud edifice of JIT production
can also be destroyed from the bottom up.
The strength of the 5S foundation is a reliable sign of how
strong the entire JIT edifice is. There is no such thing as a
factory that manufactures things well without a strong 5S
foundation. On the contrary, any virtually waste-free factory
is bound to be in top condition as far as the 5S’s are concerned. In fact, thoroughness of 5S implementation is directly
proportional to production strength.
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This chapter is devoted to this essential foundation for
improvements and corporate survival. It also includes the
following sections:
◾◾ Benefits of the 5S’s
◾◾ Meaning of the 5S’s
◾◾ The Visible 5S’s
◾◾ Keys to Success with the 5S’s
Benefits of the 5S’s
Once, when entering a certain factory for the first time,
I encountered a big sign posted a little above eye level emblazoned with two words “seiri, seiton” (Proper Arrangement and
Orderliness), written in very large characters. When I took a
quick look around the factory, though, I could see that the
sign was a big lie.
That magic pair of words—seiri and seiton—can be found on
factory walls all over Japan. I guess they are in fashion now.
Just the same, it is amazing how few of these factories
are actually properly arranged and orderly. For almost all of
them, these magic words are just powerless incantations. At
best, they are statements of hope: “Wouldn’t it be great if we
could have proper arrangement and orderliness here?”
Some factories are more insistent on these two concepts.
Their signs read “Proper Arrangement and Orderliness Now!”
They line up everything in a neat grid of parallel vertical
and horizontal rows with 90-degree intersections, and then
declare, “We’ve done it!”
As popular as the magic duo “Proper Arrangement and
Orderliness” is, there are precious few factories where people
actually understand what seiri and seiton mean and put them
into practice. Most people interpret them as arranging things
into orderly rows.
This is where the 5S’s come in. The 5S’s are five Japanese
words whose romanized renderings all begin with the letter
The “5S” Approach
“S”: seiri, seiton, seiso, seiketsu, and shitsuke. Their respective
English counterparts are Proper Arrangement, Orderliness,
Cleanliness, Cleaned Up, and Discipline.
Some people add yet another Japanese “S” word—shukan
(Habit)—to get 6S’s instead of 5S’s. However, the 5S’s are
enough to communicate the basic concepts, and the most
basic of these 5S’s is the popular pair of seiri and seiton
(Proper Arrangement and Orderliness). These lie at the root
of other JIT basics, such as zero defects, cost reduction, safety
assurance, and zero breakdowns.
For example, most factory workers have simply grown
accustomed to “searching” as part of their jobs. They search
for parts, carts, tools and jigs. The more searching they do,
the lower their productivity sinks, and the more obsolete their
factory becomes in today’s era of product diversification.
People take little notice of the five minutes they spend
searching for jigs, tools, dies, and carts during an hour-long
changeover procedure. But when the factory switches to single
changeovers, those five minutes of searching time suddenly
become an obvious waste.
The facts are simple:
◾◾ A neat and clean factory will have higher productivity.
◾◾ A neat and clean factory will turn out fewer defective
products.
◾◾ A neat and clean factory will make more on-time deliveries.
I have gathered the essential benefits the 5S’s afford into a
chart that shows their various interrelations. Figure 4.1 shows
this chart.
Benefit #1: Zero Waste Bringing Lower Costs and Higher
Capacity
−− Eliminate “stand-by waste” in in-process inventory
and warehouse inventory.
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Product
diversification
Improved
safety
Lower
costs
Higher
quality
Strict delivery
schedules
Zero
changeovers
Zero
waste
Zero
delays
Zero
defects
Easy-to-understand
workshops
Workshops where
all defects are
made obvious
Proper storage of
inspection gear
Eliminating
unnecessary inventory
Eliminating
unneeded equipment
Proper
Arrangement
(seiri)
Figure 4.1
Clean workshop
environment
Eliminating
pick up/set down
waste
Orderliness
(seiton)
5S
Better understanding
of equipment conditions
Establishing places
to put things
Eliminating
“searching waste”
Zero
breakdowns
Distinguishing
dangerous places
from safe ones
Eliminating
defects
Eliminating
unnecessary
in-process stock
Eliminating errors
in jig and part selection
Zero
injuries
Higher possible
operation rate
Cleanliness
(seiso)
Discipline
(shitsuke)
Longer
equipment life
Preventing
breakdowns
Low absenteeism
Cleaned Up
(seiketsu)
5S
The Eight Benefits of the 5S’s.
−− Eliminate unneeded storage places (such as warehouses, shelves, cabinets).
−− Eliminate “stand-by waste” in waiting for conveyance
equipment (such as pallets, carts, forklifts).
−− Eliminate waste arising from unneeded allocation of
space and equipment.
−− Eliminate wasteful motion in searching, sidestepping,
and so forth.
−− Eliminate actions that do not add value (such as picking up, putting down, counting, carrying).
The “5S” Approach
Benefit #2: Zero Injuries—Bringing Improved Safety
−− When the equipment is kept in spotless condition, you
are able to discover mechanical failures and hazards
immediately.
−− Maintain well-defined places to put things and make
sure there are plenty of uncluttered aisles and rest
areas.
−− Things should be placed in a safe manner to prevent
breakage and so on.
−− Fire-extinguishing equipment and emergency exits
should be clearly marked in case of fires, earthquakes,
or other emergencies.
Benefit #3: Zero Breakdowns—Bringing Better Maintenance
−− Trash, dirt, and dust can all lead to major equipment
breakdowns and much shorter equipment life.
−− Get rid of shavings, filings, oil leakage, and keep the
workshop sparkling clean to make it easier to see
how the equipment is running.
−− Maintain and check the equipment daily to nip breakdowns in the bud.
Benefit #4: Zero Defects—Bringing Higher Quality
−− Defects are harder to discover when the workplace is
a mess.
−− Pickup things from their proper places and put them
back properly. This will help eliminate part- and toolselection errors.
−− A clean and well-organized workplace makes workers
more conscious of the way they are making things.
−− Proper maintenance and storage of quality-assuring
inspection tools and measuring instruments is a prerequisite for zero defects.
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Benefit #5: Zero Changeovers—Bringing Product Diversification
−− Proper arrangement of dies, jigs, and tools eliminates
a major form of waste: “searching waste.”
−− Sparkling clean equipment and a neat and clean workplace help raise operational efficiency.
−− Thorough implementation of the 5S’s makes workshops simple and transparent enough for observers to
understand with ease.
−− Just say “NO” to using nonspecified jigs for the sake
of convenience.
Benefit #6: Zero Delays—Bringing Reliable Deliveries
−− When defects are gone, deliveries go out on time!
−− We need good work environments and smooth
operations.
−− Absenteeism is lower at 5S workshops.
−− Operational efficiency is higher in waste-free workshops.
Benefit #7: Zero Complaints—Bringing Greater Confidence
and Trust
−− Products that come from a neat and clean workshop
have no defects.
−− Products that come from a neat and clean workshop
cost less to make.
−− Products that come from a neat and clean workshop
are not delivered late.
−− Products that come from a neat and clean workshop
are not dangerous.
Benefit #8: Zero Red Ink—Bringing Corporate Growth
−− People who work in 5S workplaces earn more respect
and trust in their community.
−− Customers are happy to buy from manufacturers that
have rid themselves of waste, injuries, breakdowns,
and defects.
The “5S” Approach
−− Factories that have mastered the 6S’s (proper arrangement, orderliness, cleanliness, cleaned up, discipline,
and habit) are growing factories.
Meaning of the 5S’s
A factory superintendent once proudly informed me, “When
it comes to proper arrangement and orderliness, we don’t
fool around.” But when I looked around, I saw chaos in the
parts warehouse, things piled directly onto the factory floor,
and various parts piled here and there.
As I said earlier, seiri and seiton are a very popular pair
of words in Japanese factories. You can find them on signboards and banners everywhere. In fact, I cannot think of
a slogan that is more popular than this one in Japanese
­factories today.
Ironically, it is these same two words that are probably the
least understood. “Seiri and seiton,” or “Proper Arrangement
and Orderliness,” does not mean “Let’s start arranging things
properly and being orderly.”
The true meaning of these words cannot be written down
anywhere, not on signboards, papers, or banners. As written­
words, these concepts are sometimes counterproductive:
People write them on signs, post the signs, and then rest on
their laurels, feeling proud and confident that the factory is
moving in the right direction. Therefore, we should not even
teach workers to look at such signs. These two most basic
concepts are not about looking at signs and thinking—they
are about doing.
With that in mind, let us once again confirm the meaning
of the 5S’s.
Seiri (Proper Arrangement)
How often this simple term is misunderstood! People say, “Let’s
get things arranged right!” and then they busily line everything
up in neat rows and declare, “We’re finished. Great job!”
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Proper arrangement has very little to do with lining
things up in rows or piling them into neat stacks. All that is
just line-forming.
When proper arrangement is done correctly, it is broad­ranging enough to include proper arrangement of job assignments, proper arrangement of outside orders, and so on. When
the factory experiences a lull in orders, managers­should be
able to easily determine which workers are still needed and
which are not and make the necessary personnel­changes. Only
when it comes to factory hardware does proper arrangement
basically mean arranging things in neat rows and stacks.
Please take a moment to be sure you know the full meaning of this word. And remember:
Proper arrangement means clearly distinguishing between
what is needed and kept and what is unneeded and thrown
out.
It is surprising that such a simple concept can be so ­easily
misunderstood. At first, it is hard to distinguish between what
is needed and what is not. At this point, my suggestion is:
If in doubt, throw it out.
People tend to be pack-rats. They hang onto parts thinking,
“We can use this for the next order.” They look at an inappropriate machine and say, “Well, let’s use it anyway.” Meanwhile,
inventory and machinery continue to pile up and start getting
in the way of everyday production activities.
Naturally, this leads to a mass buildup of waste that spreads
far and wide through the factory.
The following are a few types of waste that contribute to
errors and defects.
◾◾ Unneeded inventory incurs extra inventory-related
expenses.
◾◾ Suddenly, the factory needs more warehouse space and
shelving, and space becomes scarce.
◾◾ When unneeded conveyance occurs, it requires extra
pallets and carts.
The “5S” Approach
◾◾ More shelving means more purchasing costs and other
management and labor expenses.
◾◾ It becomes more difficult to tell what is needed and what
is not.
◾◾ Stocked items become obsolete due to design changes,
limited shelf life, and so forth.
◾◾ Unneeded in-process inventory leads to quality defects
and machine breakdowns that can nip improvements in
the bud.
◾◾ Unneeded equipment is a daily hindrance for production
activities.
◾◾ Having extra stuff around makes equipment layout design
that much more difficult.
Visible methods of proper arrangement (such as red tagging) make identifying waste easier.
Seiton (Orderliness)
Once again, we have a term that is used all the time but is
rarely understood. Orderliness means much more than an
orderly appearance.
Moreover, orderliness always goes hand in hand with proper
arrangement. When we have arranged everything properly, the
only things that remain around us are the necessary things.
The next step is to clarify where these things belong so that
anyone can immediately understand where to get them from
and where to put them back. In this sense, orderliness means
standardizing the places where we keep things.
Orderliness means organizing the way we keep necessary
things, making it easier for anyone to find and use them.
I would like to emphasize the idea that anyone at all
should be able to easily understand the order of things in the
factory. This is very important. Having to “learn the ropes” or
“become a veteran” before understanding where things go is
nothing but bad news for everyone.
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The signboard strategy is a visible orderliness method that
helps anyone understand where things go and thus helps
make operations run more smoothly.
Seiso (Cleanliness)
This is the kind of cleanliness most people like to maintain in
their own houses. Unfortunately, for some people, cleanliness
stops at home and they tend to be litterers in public. Even at
the workplace—where many of us spend more time than we
do at home—people ironically tend to ignore cleanliness.
Cleanliness means sweeping floors clean and keeping
things tidy.
Cleanliness in a factory is closely related to the ability to
turn out quality products.
The basics of cleanliness are simply sweeping floors and
wiping off machinery. As a labor-saving device, we also need
to find ways to prevent dirt, dust, and debris from piling up
in the workshop. The two main targets for improvement are
debris from cutting and drilling machines and oil leakage.
Cleanliness should be integrated into everyday maintenance
tasks. The equipment operator should be the person who best
understands how the machine or other equipment is running.
Often, it is only when we are wiping dirt from a machine
that we notice, “Hey, this thing is leaking oil!” or “It smells
like something’s burning in this control panel!” We need to
demolish the distinction between the operator’s work and
the maintenance technician’s work and instead get ­everyone
involved in developing better maintenance activities.
Seiketsu (Cleaned Up)
“Cleaned up” differs just enough from proper arrangement,
orderliness, and cleanliness to warrant a separate description
among the 5S’s. Unlike cleanup, these other three can be
seen as activities, as something we “do.”
However, cleaned up does not refer to an activity, but to a
state. Therefore, we define it as follows.
The “5S” Approach
Litter-producing
fingernail clippers
Litter-preventive
fingernail clippers
Cover keeps clippings from
falling out of clippers
Figure 4.2
Device to Prevent Fingernail Clipping Debris.
Cleaned up means that the first three S’s (seiri, seiton, and
seiso) are being maintained.
Although “cleaned up” relates to all three of the first three
S’s, obviously it is most strongly linked with seiso or cleanliness.
Cleanliness means keeping the machinery and its environs
free of debris, oil, and dirt; cleaned up is what we get when
we perform cleanliness consistently over a period of time. We
can take the state of being “cleaned up” one step farther by
devising ways to prevent dirt and the like from occurring in
the first place. Workshops that have accomplished this are well
on their way to being top-notch 5S workshops.
For example, Figure 4.2 shows how some ingenious person found a way to keep fingernail clippings out of the
workshop. Figure 4.3 shows another example involving
a drill press. In this example, workers placed a cover to
­prevent drill shavings from being scattered onto the floor.
The debris was stopped near its source. The closer we can
get to the source of the debris, the easier it will be to maintain a “cleaned up” workshop.
Shitsuke (Discipline)
The first four S’s can be implemented thoroughly without
major difficulty if the workshop is already one where the
employees maintain certain habits—such as friendly hellos
and goodbyes among co-workers at the start and end of
their shifts, work uniforms, name tags, and helmets—that
help maintain good safety, a clean shop, and a positive work
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Figure 4.3
Litter-Preventive Device for Drill Press.
attitude. Such workshops are probably already characterized
by high productivity and high quality.
The Chinese character that Japanese uses for the word
shitsuke (discipline) is a combination of two characters. One
of these component characters means “body” and the other
means “beauty” or “beautiful.” The sound of the character
also associates it with careful and precise craftsmanship,
such as in sewing.
As such, discipline is seen as the most important of the
5S’s, and is indeed a pivotal factor for the production system
as a whole.
Discipline means making a steady habit of properly maintaining correct procedures.
The time and effort involved in establishing proper arrangement and orderliness will all be in vain if we do not have the
discipline to maintain them. Factory supervisors work their
tails off establishing the first four S’s, only to discover that the
workers lack the discipline to maintain the new procedures.
The “5S” Approach
The managers can organize as many “5S Campaigns” and
“5S Contests” as they want, but the 5S’s will not last for long
without discipline in the workshop.
The key to discipline lies outside of any specific tool, such
as the 5S checklist. The seeds of workshop discipline need
to be planted by factory bosses and managers who are themselves deeply committed to establishing and maintaining the
5S’s. The foreman should be called to the workshop if even
just one screw is left lying on the floor. The foreman needs to
use strong language to emphasize the importance of the 5S’s
and to condemn, not the particular worker at fault, but the
attitude that it is OK to leave debris on the floor. The person
who is ultimately responsible for any 5S backsliding is not
any particular worker, but rather the relevant top manager,
such as the factory superintendent.
Managers who are not willing to accept responsibility for
maintaining the 5S’s do not have the right to complain if their
workers feel the same way. For managers, discipline means
maintaining the heartfelt conviction that workers’ transgressions
against established procedures are a rebuke to their authority
as the person most responsible for workshop discipline.
This concludes our introduction to the 5S’s: proper arrangement (seiri), orderliness (seiton), cleanliness (seiso), cleaned
up (seiketsu), and discipline (shitsuke). Figure 4.4 summarizes
their meaning and primary results.
The Visible 5S’s
Every factory is more or less concerned with the company’s
survival and is undertaking various rationalization and costcutting measures to improve the company.
Many factories are full of enthusiasm for such improvements,
but still make no real progress. Usually, the managers at these
companies wonder, “Is the JIT production approach really
being taught throughout the company?” or “Are people really
learning what they need to know to make improvements?”
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on
er q
ua
lit
y
Seiri
Seiton
(proper
(orderliness)
arrangement)
Always keep
Clearly distinguish
needed items in the
needed items from
correct place so that
unneeded items
anyone can
Shitsuke
and get rid of
immediately
(discipline)
the latter.
find them.
Make a constant
habit of
Seiketsu
maintaining
(cleaned up)
established
Seiso
This is the
procedures. (cleanliness)
condition we
Keep the
support when we
workshop swept
maintain the first
and clean.
three S’s.
S
eli
ry
ve
s
edule
s ch
Impr
ove
d
saf
et
y
Figure 4.4
High
td
p
her
Hig
ti
ifica
Lower cost
utilization r
ossible
ate
uc
od
r
P
rs
ive
td
ic
tr
250 ◾
Meaning of the 5S’s.
This questioning often prompts them to decide on such
“positive measures” as more training and outside s­ eminars for
key people.
But still no progress. This leads to further wondering,
“Is there something wrong with the way we’re promoting
JIT?” or “Do the project members really know what they are
doing?” Then more positive responses, but still no progress.
The real problem at such companies is that the managers do
not know how to look for the real problems. The real problem
seldom concerns improvement methods or a weak promotional organization. It usually concerns a failure to ask what
forms of waste or other problems remain in the workshops.
Once people have learned to spot waste and other problems as they are in the workshop, they are already well on
their way to success. All they need to do next is put their
experience and knowledge to work in devising and implementing improvements. The easiest way to do this is to make
The “5S” Approach
the whole array of waste, abnormal operations, and other
problems­as explicit and visible as possible so that anyone­
observing the workshop can quickly spot them.
There is no such thing as a problem-free factory!
The world is full of companies and factories. There are
some excellent factories and some abominable ones. But all
factories have one thing in common: problems, problems, and
more problems. What makes the excellent factories different
is that when they find a problem, they move immediately to
solve it. Once they solve the problem, they follow up by dealing immediately with any problem that occurs subsequently.
The worst factories do not even recognize the problems as
such. They just do what they can to get around them. Since
avoiding problems does nothing to solve them, the problems
soon take firm root as part of the factory’s “way of doing
things.” This is happening all the time—new problems crop
up, get ignored, and take root.
All factories are full of problems. The difference between
the good factories and the bad ones lies in whether or not
they recognize the problems as such and do something to
solve them. To put it differently, the good factories have
discovered a “trick” that enables them to recognize various
problems as they occur.
In JIT production, there is a “trick” that enables anyone to
recognize various types of waste, problems, and abnormalities, whether they are in the warehouse, factory equipment,
or production operations.
The trick is called “visual control.” While the 5S’s stand as
the foundation for improvement, the “visible 5S’s” are what the
5S’s must become in order to be preserved. (See Figure 4.5.)
Visible Proper Arrangement
Almost all factories contain more stuff than they need for current production purposes. There are many materials, parts,
and even numerous machines, jigs, and other equipment that
are not currently needed. There is so much superfluous stuff,
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Proper Arrangement
(seiri)
Red tag strategy
Red tag inventory
Red tag machines
Red tag unused space
Orderliness
(seiton)
Signboard strategy
Location indicators
Item indicators
Amount indicators
Color code organization
Outlining organization
Discipline
(shitsuke)
5S badges
5S mini motto boards
5S stickers
5S checklists, 5S contests
5S patrol reports
5S photo exhibits
5S maps
Cleaned Up
(seiketsu)
5-point “Cleaned Up
Checklist”
5-point check for proper
arrangement
5-point check for orderliness
5-point check for cleanliness
Figure 4.5
Cleanliness
(seiso)
Cleanliness inspection
checklist
The Visible 5S’s.
in fact, that it tends to obstruct production activities, lower
efficiency, and create waste.
Once everyone decides to get rid of all this useless stuff,
they are still not able to do anything until they learn how to
tell what is actually needed from what is not. This is where
the red tag strategy comes in. Red tag teams know how to
make this distinction. They inspect the factory and attach red
tags to all items they deem unnecessary. This enables anyone
to see what must be disposed.
The red tag strategy is an effective means of turning the first
“S” (seiri, or proper arrangement) into the first visible “S.” (The
red tag strategy is described more fully later in this chapter.)
Visible Orderliness
If proper arrangement has been implemented thoroughly,
there should be nothing left in the factory that is not needed
for current production. Now is the time to start asking all the
The “5S” Approach
“Where?” “What?” and “How many?” questions that will lead
us toward an orderly arrangement of these necessary items.
To make all this organization planning more visible, we
should use the signboard strategy. (The signboard strategy­is
described more fully later in this chapter.)
All the various types of signboards, such as “standing
signboards” and “display signboards,” serve the same important purpose: to make the establishment and maintenance of
orderliness more visible.
Other handy tools for making orderliness more visible
include color coding of items to make different types of items
easier to spot at a glance, and outlining jigs and tools in
their correct positions so that they can be easily returned to
exactly the right place. (Color coding and outlining will also
be described more fully.)
Visible Cleanliness
Cleanliness refers mainly to the daily cleaning tasks that
should go hand in hand with basic daily maintenance tasks.
Figure 4.6 shows an example of how “cleanliness inspection
checklists” can be used to verify how well the daily cleaning
tasks are being carried out.
Visibly Cleaned Up
As mentioned earlier, “cleaned up” is a condition that can
only be established by maintaining the first three S’s (proper
arrangement, orderliness, and cleanliness) on a daily basis.
Figure 4.7A shows an example of the “five-point cleaned up
checklist” that we can use to rate how cleaned up the workshop really is.
As can be seen in Figure 4.7B, the checklist includes separate sections for rating the state of the cleaned up condition
in terms of the first three S’s (proper arrangement, orderliness, and cleanliness). Each of these sections has five levels
for scoring, as shown in the figure.
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Workshop name
CLEANLINESS INSPECTION
CHECKLIST
Cleanliness Inspection Points
Mfg. Dept. 2, Shop No. 1
Machine name
Month
Drilling line
November
Date
254 ◾
Inspect
1
2
3
4
5
6
7
1(T)
MB01
(1) Daily cleaning
(2) Drill section:
Clean dripping
oil and add more
oil if needed.
2(W)
3(Th)
4(F)
5(Sa)
6(Su)
7(M)
8(T)
(3) Check pneumatic cylinder section:
If needed, pour one half cup of turbine
oil (ISOVG 32) into the oiler section.
Check daily, oil once a month.
9(W)
10(Th)
11(F)
MB02
Figure 4.6
Cleanliness Inspection Checklist.
Visible Discipline
One cannot tell simply by looking at the workers whether or
not discipline is in force. This is because discipline has its
source deep in the hearts and minds of the workers, and thus
is not so obvious to the casual observer. However, there are
certain types of behavior that we can expect if discipline is
truly there. Therefore, we should look at the workers’ actions
and the results those actions bring to determine whether or
not discipline is being maintained.
In other words, how well the workshop has done with the
first four S’s is itself a good gauge for determining how well
discipline has been established. This means we can put the
five-point check for cleanliness and other forms to work for
us as tools for evaluating discipline.
Since discipline is a mental and spiritual phenomenon, we
cannot be too critical of workers who have not yet managed
to develop it. As in the oriental martial arts, we first have
to practice the forms and, while doing that, we gradually
develop the psychological and technical aspects of the art.
The “5S” Approach
5-point
“Cleaned Up Checklist”
Factory name:
Date:
Division:
First assembly div.
Entered by:
Page:
Yamaguchi
1 of 1
Proper
Orderliness Cleanliness
Arrangement
Total
Previous
total
12345
7
6
12345
12345
8
6
12345
12345
12345
6
5
Line A: operation at process 4
12345
12345
12345
7
7
5
Line A: operation at process 5
12345
12345
12345
10
6
6
Line A: operation at process 6
12345
12345
12345
12
8
Line A: overall (average total)
2.8
12345
2.8
12345
2.8
12345
54
38
No.
Process and checkpoint
1
Line A: operation at process 1
12345
12345
2
Line A: operation at process 2
12345
3
Line A: operation at process 3
4
Figure 4.7A
Five-Point Cleaned Up Checklist.
Likewise, with the 5S’s, we begin by establishing and practicing the first four S’s, and by doing this we develop the fifth S:
shitsuke, or discipline.
The following are some of the things we can do to make
this process of developing discipline more visible.
◾◾ 5S badges
Figure 4.8 shows an example of a 5S badge that graphically portrays the 5S’s centered on discipline as a means
of encouraging the development of discipline.
◾◾ 5S mini motto boards
We can use small signboards for posting 5S-related mottoes­
invented by the company’s own workers to help heighten
awareness and participation. Figure 4.9 shows a 5S mini
motto board that was posted in the men’s restroom. This
company changed its motto boards every week. The
­mottoes and illustrations should always be simple enough
to be read and understood in about a minute.
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(1) 5-point check for proper arrangement
Description
Points
1
2
3
4
5
Needed and unneeded items are mixed together in
the workshop.
Needed and unneeded items are basically separated.
It is easy to see what is not needed.
All unneeded items are kept somewhere away from
the workshop.
All completely unnecessary items have been
disposed of.
(2) 5-point check for orderliness (warehouse and in-process inventory)
Description
Points
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
Can’t tell what things belong where and in what
amount.
Can basically tell what things belong where and
in what amount.
Workshop is using only place indicators and
item indicators.
Workshop is using place and item indicators and
outlining to make item organization visible.
Input and output from workshop are clearly indicated and amount indicators are also being used.
(3) 5-point check for orderliness (for jigs and tools)
Points
Description
Can’t tell what things belong where and in what
amount.
Can basically tell what things belong where and
in what amount.
Workshop is using only place indicators and
jig/tool indicators.
Measures have been taken to make item placement
more visible (color coding, outlining, etc.)
Jigs and tools have been streamlined by combining
functions, etc.
(4) 5-point check for cleanliness
Description
Points
Workshop is left dirty for a long time.
Workers clean up the workshop occasionally.
Workers clean up the workshop daily.
Daily cleaning tasks and maintenance have
been integrated.
Workers have devised ways to prevent messes.
Figure 4.7B
Detail of Cleaned Up Checklist.
The “5S” Approach
PROPER
ARRANGEMENT
ORDERLINESS
DISCIPLINE
CLEANLINESS
Figure 4.8
CLEANED UP
5S Badge.
Proper arrangement means
getting rid of unneeded things.
The point is to throw away
whatever we don’t need,
even if we hate to see it go!
JIT Promotion Headquarters
Figure 4.9
Mini Motto Board.
◾◾ 5S stickers
No matter how frantically busy a factory is, there is still
one place where people are not busy working. In fact,
workers tend to spend a good five minutes there, just
sitting. The place is the restroom. At one household electronics manufacturing plant, I saw 5S stickers (shown in
Figure 4.10) pasted on the walls of the toilet stalls. When
people are too busy to read anything else, these stickers
still get read.
◾◾ Five-point check for “cleaned up” status
We can use this checklist to help maintain cleanliness
by posting the various scores for proper arrangement,
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5S Sticker
PQCDS: Key to Success
PQCDS stands for:
Making the Products our customers want, with built-in high Quality,
manufactured at low Cost, with timely Delivery, and assured Safety.
Manufacturing is no longer just the business of making things.
Today, manufacturing is a service industry.
By thoroughly implementing the 5S’s, we can improve our service
and raise our productivity.
What are the 5S’s?
Seiri (Proper arrangement)
This means clearly distinguishing what is needed from what is not,
then throwing out the latter.
Seiton (Orderliness)
This means placing needed items where they can be spotted,
retrieved, and replaced most efficiently and easily by anyone.
Seiso (Cleanliness)
This means always keeping the workshop floors and equipment
swept and wiped clean.
Seiketsu (Cleaned up)
This is the state of the workshop when we successfully maintain the
first three S’s.
Shitsuke (Discipline)
This means cultivating the habit of doing things the right way.
Figure 4.10
5S Sticker.
orderliness, and cleanliness on workshop walls as a
means of stirring up concern in problem-plagued workshops. These checklists are powerful tools for making
the “cleaned up” status more visible.
◾◾ 5S checklists and 5S contests
Figure 4.11 shows a completed 5S checklist. This particular list was compiled during this company’s “5S Month,”
which emphasized the 5S theme. The company conducted checks once a week during this month. They
also carefully conducted an “overall workshop check” at
each workshop, and posted the total points at the end of
the month to find out which workshop would win the
Excellent Workshop Award in a “5S Contest.”
◾◾ 5S patrol score sheet
Once a month, a “5S Patrol Team” should wander
through the factory, filling out the 5S Checklist shown
The “5S” Approach
259
◾
Year and month:
Check item
Check description
1
2
3
4
5
T
Are there clearly distinguished paths?
Are the operations areas and paths clearly separated?
0
1
0
1
0
2
Do the operators at work and those walking on the
paths ever get in each other’s way?
Does the factory use white and yellow tape to mark
floor areas?
Are there any exposed wires or pipes?
0
2
0
2
0
4
0
2
0
2
0
4
0
3
0
3
0
6
1
3
1
3
1
9
verall)
Overall factory
Location
Outdoors (overall)
Clerical (overall)
1
3
1
3
1
9
Are there flowers or other ornaments in the factory?
1
1
1
1
1
5
Are the item names and addresses shown on the
shelves?
Are shelf partitions clearly distinguishable?
Scoring: 3 = Very good 2 = Good
1 = OK
0 = Not good
2
Year and month:
2
3
2
3
2 12
1
2
3
4
5
T
0
1
0
1
0
2
0
2
0
2
0
4
0
2
0
2
0
4
Are traffice signs being used?
0
3
0
3
0
6
Are there any exposed wires or pipes?
1
3
1
3
1
9
1
3
1
3
1
9
1
1
1
1
1
5
2
3
2
3
2 12
2
3
2
3
2
2
3
2
3
2
8
Do tables, desks, and chairs have designated locations?
2
1
2
1
2
8
Do desks have ashtrays or are there ashes on the floor?
Are there any unneeded signs on the wall?
Are the names of meeting participants displayed
somewhere?
Are there any unneeded items?
0
1
0
1
0
2
0
1
0
1
0
2
0
1
0
1
0
2
Are soap and paper towel dispensers kept stocked?
1
1
1
1
1
5
Are the floor and sink areas kept clean?
1
1
1
1
1
5
Is there any graffiti in the stalls?
1
1
1
1
1
5
Check item
Are there any unneeded
items?
Are storage areas clearly
determined?
Have paths been clearly
defined?
Shelves and other
storage spaces
5S Checklist
(for factories)
Factory: Takai plant
Checked by: Nishiro kaibe
Location
Are any desks, shelves, or machines jutting out into
the paths?
Are any boxes left lying around?
Check description
Outdoors (overall)
Areas for: parking, pallets, temporary materials storage,
delivered goods reception, trash processing, and boxes
Have white and yellow lines been laid down?
Are ashtrays, trash cans, gardens, entrance areas,
Are outdoor areas kept
windows, and paths kept clean?
clean?
Are there any unneeded Are signboards, copy machines, and pathways
arranged properly?
items?
Have fire-extinguishing equipment and emergency
Have temp. storage
areas been clearly defined? exits been established?
Are the walls dirty?
Are office areas being
kept clean?
Are there any unnecessary items?
Restrooms
Figure 4.11
5S Checklist.
in Figure 4.11. After scoring each workshop according to
the checklist, it should enter the workshop scores onto
a “5S Patrol Score Sheet,” such as shown in Figure 4.13.
The 5S Patrol Team must be sure to enter improvement
deadlines when filling out this score sheet.
2
5
5
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Figure 4.12
5S Photo Exhibit (seiri and seiton).
JIT 5S Patrol Score Sheet
Patrol date:
Manufacturing 3
Improvement deadline:
Manufacturing 4
Overall 2
Parts 2
Manufacturing 1
Overall 1
Materials 2
Materials 2
Materials 1
Parts 3
Manufacturing 5
HIC
Manufacturing 6
Parts 4
Materials 5
Parts 5
Manufacturing 2
Parts 1
Materials 3
Materials 6
Area
Score
Area
Score
Area
Score
Area
Score
Overall 1
50
Materials 1
46
Manufacturing 1
49
Parts 1
47
Overall 2
44
Materials 2
42
Manufacturing 2
45
Parts 2
55
Materials 3
44
Manufacturing 3
56
Parts 3
46
Materials 4
45
Manufacturing 4
61
Parst 4
46
Materials 5
37
Manufacturing 5
46
Parts 5
44
Materials 6
54
Manufacturing 6
38
Manufacturing 7
60
HIC
59
Average
Figure 4.13
47
44.7
5S Patrol Score Sheet.
51.8
47.6
The “5S” Approach
5S Map
Please make note of any 5S improvement suggestions
you may have.
1st Manufacturing Div.
Press Dept.
Diecast
MEMO
storage area
Press A1
Press A2
Press A3
Transfer line A
Toilet
Press B1
Press B2
Press B3
Transfer line B
Toilet
MEMO
MEMO
Rest area
MEMO
Office area
Blanking 1
Press 4
Press 4
Parts
storage area
Blanking 1
Press 4
Press 4
Transfer line C
Parts
storage area
MEMO
Cellophone
tape
Memo
sheets
5S MEMO
Pencil
Figure 4.14
DATE: Nov. 10
BY: Tagawa
MEMO:
Parts are not being
stored properly.
5SMap.
◾◾ 5S photo exhibit
In addition to the monthly inspection by the 5S Patrol
Team, a 5S Photographers Team should also be sent out
once a month to inspect the factory and take pictures
of both good and bad examples of 5S workshops. The
photos should have comments added below and ought
to be posted in a common space, such as the company
cafeteria. (See Figure 4.12.)
◾◾ 5S Maps
Maps showing each workshop’s layout should be posted,
as shown in Figure 4.14. Whenever someone tours the
factory or even just passes through, he or she should be
able to glance at these maps. If they notice areas where
enforcement of the 5S’s can be improved, they can make
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a note of it on memo pads that are provided with the
map. They should check up on the improvement every
morning or evening and write further improvement
memos if necessary.
Keys to Success with the 5S’s
After the big push to establish 5S workshops, we may succeed
in getting rid of unneeded items, setting up clearly defined
places for keeping things, and cleaning floors and machines
until they shine.
But all this means nothing unless we also establish a ­system
for maintaining all of these 5S improvements. This is why we
should be sure to organize a “5S Promotion Team” that will
be responsible for the maintenance and further improvement
of 5S conditions in the factory.
The following are eight main points that can serve as keys
to success in establishing and maintaining 5S workshops. We
call them the “Eight Keys to 5S Success.”
Key #1: Get everyone involved
−− The 5S’s cannot be the responsibility of a concerned
few. Everyone must get into the act.
−− All levels of factory management should take part in
the decision-making.
−− Carry out 5S activities as part of the factory’s small
group activities.
Key #2: Get company authorization
−− 5S activities should not be performed in secret or disguised as overtime work. Get management approval
for all 5S activities.
−− Make signs and posters to explain the 5S’s to everyone. (See Figure 4.15.)
−− Have a general monthly meeting where company and
factory managers can address 5S issues and themes.
The “5S” Approach
Figure 4.15
Sign Proclaiming the 5S Strategy.
Key #3: Final responsibility rests with the president
−− The 5S’s will not be taken seriously until the factory
superintendent and even the company president take
personal responsibility and interest regarding their
implementation.
−− Nothing could be worse for 5S success than to have
managers who “pass the 5S implementation buck” to
their subordinates.
−− Company managers must take a strong leadership role
in 5S promotional meetings and other 5S events.
Key #4: Make yourselves understood
−− Don’t leave people wondering, “Why are we sticking
red tags on things?” or “Is all this 5S stuff really necessary before we can make improvements?”
−− Hold 5S promotional meetings to clearly explain the
5S’s and to answer all questions from all participants.
−− When explaining the 5S’s, present actual examples of
successful 5S implementation, or take the participants
on tour of successful 5S workshops.
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Key #5: Do it all the way
−− When establishing proper arrangement, be sure to
carry out red tag campaigns and be sure to use the
correct red-tagging formats and procedures.
−− When establishing orderliness, use signboards. Make
sure the signboards have the proper format, descriptions, and locations.
−− Make up your factory’s own 5S (or 6S) manual, complete with all the necessary details.
Key #6: The president should inspect the factory personally
−− The president should personally inspect factories and
point out their various positive and negative conditions.
−− The president should help out by pointing out specific improvement items and proposing improvement
themes at 5S promotional meetings.
−− Workshops should work individually and in groups to
study and report on improvement methods taken in
response to improvements suggested by the president.
Key #7: Don’t stop halfway in establishing the 5S’s
−− Don’t do things halfway. Once the 5S promotional
organization and methods have been established, get
started and stick with it.
−− When developing red tagging and signboards throughout the factory, make sure everyone gets involved.
−− Once you have laid the foundation by establishing
proper arrangement and orderliness, start developing
“discipline” habits to keep the foundation strong.
Key #8: The 5S’s are a bridge toward other improvements
−− Don’t stop with the 5S’s: Follow through with zero
defects, cost reduction, and other improvement activities.
−− Once the factory has been cleaned up, start putting
casters on machines to make them easily movable.
−− Eliminate defects as close to their source as possible
and implement flow production.
The “5S” Approach
Red Tags and Signboards:
Proper Arrangement and
Orderliness Made Visible
In JIT production, everything in the factory should be made
as clearly visible as possible. This means that the flow of
goods, the appearance of abnormalities, and everything else
that exists or occurs in the factory should be readily apparent at a glance. As the very foundation for improvements, the
5S’s must be made visible. This is all the more true for the
most basic of the 5S’s, proper arrangement (seiri) and orderliness (seiton).
It is therefore only natural that we should want to further enhance and emphasize these two most basic factors as
“visible­proper arrangement” and “visible orderliness.” The
two tools we should use to make them more visible are red
tags (afakuda) and signboards. We use “red tag strategy”
to make proper arrangement more visible and “signboard
­strategy” to make orderliness more visible.
Invariably, the situation in the factory prior to 5S implementation can be characterized by two shortcomings: We
cannot easily tell what is necessary from what is not, and,
walking around the factory, we cannot tell what things are,
where they belong, and in what quantities. Red tagging and
signboards are two strategic tools that identify and clarify
factory waste and other problems.
No matter how attractive the design and execution of the
factory’s “Proper Arrangement and Orderliness” signs are,
things are not going to become better arranged or more
orderly on their own.
The first thing to do is clearly distinguish between what
is needed and what is not. The best way to do this is to
have a company-wide red tag campaign aimed at visible
proper arrangement. Red tagging clearly marks the unneeded
items, which we can then move over to a temporary pile of
“red-tagged” items for subsequent disposal.
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This leaves only the needed items in the factory. Now we
are ready to look at these necessary items and start asking
“Where?” “What?” and “How many?” A factory in which both
red tagging and signboards have been implemented this way
is a factory where anyone can readily see what is necessary,
where each type of thing belongs, and in what amount.
Figure 4.16 shows the overall procedure for implementing
red tagging and signboards. Each step in this procedure is
described below.
Step 1: Separate Needed Items from Unneeded Items
Factories are full of all kinds of things: machines, parts, dies,
jigs, and so on. However, not all of those things are needed
for whatever type of production is currently being done.
There are usually some items sitting around to be available
for future orders or items that were scheduled to be used but
got canceled by a design revision.
These unnecessary items are mixed in with the necessary
ones. So the first thing to do is separate them. The most visible and simplest way to do this is by attaching red tags to all
items that are deemed unnecessary. Use brightly colored red
tags that are easy for anyone to see.
Step 2: Move Out the Unneeded Items
Once the unneeded items have been marked with red tags,
we can remove them from the factory and temporarily store
them somewhere else. Suddenly, the factory is much less
cluttered; only the really necessary things remain.
Step 3: Throw Out Whatever Is Really Not Needed
Now we need to go through the piles of unneeded items,
figure out which are truly superfluous, and dispose of them.
Step 4: Intensive Improvement
Carrying out a red tag campaign will remove the unnecessary
items from the factory, leaving only what we need for current
The “5S” Approach
Before Red Tagging and Signboards
Needed items were mixed with unneeded items
and no one could tell them apart.
EP
ST
Separate needed items from
unneeded items.
Red Tag Strategy
(visible proper arrangement)
Needed items
EP Intensive improvement
ST
Unneeded items
EP Move the unneeded items
out.
ST
EP Need to indicate where,
what type, and how many
Red Tag Pile
ST
Signboard Strategy
(visible orderliness)
After Red Tagging and Signboards
EP Throw out whatever is
really not needed at all.
ST
Disposal
Only needed items are left, and
all are arranged in an efficient
and readily visible manner.
Figure 4.16
Overall Procedure for Red Tagging and Signboards.
production purposes. This generally means that red tag campaigns lower in-process inventory to one-half or one-third
the previous amount. However, since inventory, especially
in-process inventory, is part of the factory’s basic way of doing
things, it reflects the ability of the factory to produce things.
Figure 4.17 shows how simply removing unneeded items is
soon betrayed if we maintain the same way of doing things.
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Red tag campaign
Inventory level
(conventional factory
system)
50-66% reduction
Red tag campaign
Inventory level
(conventional factory
system)
Back to prior inventory level
New inventory level
Intensive improvement
Figure 4.17 Timing of Red Tag Campaign and Intensive Improvement.
The conventional way of doing things will cause inventory to
creep back up to its former level.
Therefore, just as soon as we finish a red tag campaign,
we need to carry out intensive improvements—working all
night if need be—to change the production set-up over to
flow production. This will keep inventory from climbing
back to its previous level. Such intensive improvement attests
to greater production ability, while the reduction in inventory
affords a proportionate reduction in waste.
Step 5: Indicate Where, What Type, and How Many
Naturally, we will need to change the equipment layout as part
of our intensive improvements. Once we have changed the
equipment layout, we need to change the production set-up
by placing things in the most efficient way. Furthermore, we
need to clearly indicate what goes where and in what amount.
This labeling of items is the signboard strategy.
The Red Tag Strategy for Visual Control
The red tag strategy has become very popular among Japanese factories in recent years. The 5S’s have also gained
The “5S” Approach
wide recognition as the foundation for improvement. Both
have been praised as tactics that cost little yet produce good
results in terms of reducing inventory, raising productivity,
and so on. Another reason for the red tag strategy’s wide
acceptance in Japan is that attaching red tags to unneeded
items is a simple procedure that anyone can perform.
In fact, the red tag strategy has become popular not only in
Japan, but also in faraway France and neighboring Korea. The
red tag strategy is a new wave in visual control and “visible
proper arrangement” that is gradually becoming a global trend.
This section describes the following red tag strategy topics:
◾◾ What is the red tag strategy?
◾◾ Steps in the red tag strategy
◾◾ Red tag computers
◾◾ A red tag episode: laughing and learning
◾◾ Case study: red tag strategy at Company S
◾◾ Case study: spreading the news about red tag implementation
What Is the Red Tag Strategy?
The following is something that happened just the other
day. I was invited to a ribbon-cutting ceremony to mark the
completion of a factory that would be staffed by about 100
people. Everything in the brand-new factory was sparkling
clean—walls, floors, pillars, and so on. Not a speck of dust
anywhere. It was refreshing just to look at such a bright and
shining place.
Give that factory a year or two, and it will become just as
dirty as any other typical factory. The dirtier it gets, the more
hospitable it becomes for the archenemy “Waste.”
Some people will argue that anywhere you have people
you’ll have dirt. People perspire and pickup dirt and germs
where ever they go, which is how disease is spread. How
could it be any different in a factory? But I would argue that
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people do know how to wash off the dirt that they carry. Just
take a shower or bath.
I have never seen a factory take a shower or bath, though.
The question is, can we find some kind of shower/bath substitute for the factory?
The best “factory bath” I have ever run across is the 5S’s:
proper arrangement, orderliness, cleanliness, cleaned up, and
discipline.
People are used to treating all the unnecessary things in the
factory—vouchers, operations, equipment, and all the inventory
those things require—as if they were their proud, personal possessions. That is why it is so important that we look all around
us and determine what is really needed and what is not.
This is where the red tag strategy comes in. Every strategy is aimed at conquering a certain “enemy.” Obviously, the
enemy we use red tagging against is waste and the other “evils”
we create.
Even for workshop workers, it is not always easy to identify the “evils” of the factory. They seldom have any notion
of how to separate items needed for current production from
other unnecessary items. Conservative-minded factory managers can look at factory evils right in the face and still not
recognize them as such.
We need a simple method for bringing such evils to the
surface and for enabling even the most tunnel-visioned factory manager or company president to tell the difference
between what is needed and what is not. The red tag strategy just happens to fit the bill. (See Figure 4.18.)
Steps in the Red Tag Strategy
Once red tagging gets underway, we suddenly find red tags
all over the place! But there is no such thing as too many red
tags. Neither is a factory full of red-tagged items anything
to be ashamed of. When red tagging is carried out well at a
typical factory, the whole factory starts looking red.
The “5S” Approach
RED TAG
Figure 4.18
RED TA
G
Examples of Red Tag Forms.
Why do we use the color red? The reasons are many.
First of all, red is a bright and conspicuous color. Second,
red is the color of stop signs and stop lights. Third, in Japan,
the word for red (aka) is a homonym with another aka that
means “dirt.” The criteria for attaching red tags on items
­differs from factory to factory. If the factory is typical, red
tags are attached to all items that will not be needed for the
next month’s production schedule. At the stricter factories,
the “need period” for items is the next week’s schedule.
Sometimes, no one in the factory can tell for sure whether
or not a particular item will be needed during the next week
or month. In such cases, some factories use yellow tags for
these items. Personally, I am not fond of using any yellow
tags, since that opens the door to vagueness and indecisiveness, resulting in a factory that may soon be full of nothing
but yellow tags. I prefer to use only red tags and keep things
cut-and-dried. Figure 4.19 shows the steps for carrying out a
red tag strategy.
Step 1: Launching the Red Tag Project
Optimally, red tagging is something that happens every day.
But even factories that devote a few minutes each day to red
tagging still need to carry out factory-wide red tag campaigns
at least once or twice a year.
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What is the red tag strategy?
The red tag strategy is a means of implementing proper arrangement
by labeling all unneeded items with conspicuous red tags.
STEP 1 Launching the red tag project
Members: Employees in manufacturing, materials, management, and
accounting divisions
Period: One to two months
Key point for JIT consultant: Help the factory employees understand
how to identify what items are not needed.
STEP 2 Identifying red tag targets
Inventory: Raw materials, parts, in-process inventory, and products
Equipment: Machines, miscellaneous equipment, jigs, tools, carts, desks,
chairs, dies, vehicles, fixtures, etc.
Space: Floor and shelving
STEP 3 Setting red tag criteria
Set the criteria for determining what is needed and what is not. Example:
All items that will be needed for the next month’s production schedule
are not to be tagged, and all other items are to be tagged.
STEP 4: Make the red tags
The red tags should be about as large as a standard (8 1/2" × 11") piece
of typing paper to ensure eye-catching prominence.
For inventory items, the red tag teams should write down the item’s name,
quantity, retention period, reason for retention, and other related information.
STEP 5: Attach the red tags
People from indirectly related divisions should come to the workshop,
listen to a description of the current conditions, and use their objectivity
to attach red tags on all unneeded items.
Look with a cool, critical eye.
Do not let the workshop’s own workers decide where to stick the red tags!
The workshop workers tend to think that everything is necessary.
Show no mercy when attaching red tags!
If in doubt, red tag it!
Red tagging should be done intensively over a short period of time.
STEP 6: Evaluate the red tag targets
Divide red tags into two types: one for “dead stock” and the other for
“retained stock.”
Set the “need period” for service parts according to the product life of
corresponding products. Keep service parts in the warehouse for the
appropriate need period.
Create and execute a schedule for disposing of dead stock. The schedule
should indicate the quantity, value, and disposal period.
Write up a list of all unneeded inventory to facilitate understanding of the
unneeded inventory and for use in accounting.
(Equipment:)
Basic principle: Whatever gets in the way during improvement activities
should either be disposed of or moved.
Follow the company’s disposal application procedure to dispose of
unneeded equipment.
If the equipment that is in the way during improvement activities is an
off-the-book asset, simply get rid of it, since there are no applications to fill.
Make signboards (visible orderliness)
Figure 4.19
Steps in Red Tagging Strategy.
The “5S” Approach
Implement each campaign as a distinct red tag project. The
person who takes final responsibility for the project should
be a top manager, such as the company president, the manufacturing division chief, or factory superintendent.
Project members should come from almost every division
in the company. It is especially important that accounting
division members get actively involved in the disposal of
unnecessary warehouse stock and equipment.
Step 2: Identifying Red Tag Targets
In the manufacturing division, the main targets for red tags
include inventory, equipment, and space.
Inventory can be divided into warehouse inventory and
in-process inventory. Warehouse inventory has its own subdivisions: material warehouse, parts warehouse, product warehouse, and so on. We need to be especially careful to target
all inventory that does not have a specified location, such as
inventory that gets piled up alongside aisles or on shelves in
the factory. In the management division, we need to target all
the unnecessary paperwork, along with superfluous desks,
lockers, and the like.
The point is to make immediately obvious what is needed
and what is not. That is what the red tag strategy is all about.
When red tagging is carried out thoroughly, it gets to the
point where we even can begin red tagging superfluous staff.
This is a rather inhumane way to treat people, however, and
it would be better to address surplus labor in other ways.
(See Chapter 7 regarding manpower reduction.)
Step 3: Setting Red Tag Criteria
The most difficult thing about red tagging is knowing how to
tell what is needed from what is not.
If a red tag team member asks someone who works in the
workshop whether a particular item is needed, the answer is
almost always, “Yes, we need that!” Even items such as parts
and machines that get used no more often than once every
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two or three years will be judged “necessary” by the workshop staff. They will look at parts that have been rendered
obsolete by equipment changes and say, “Let’s hang onto
those. We’ll find some way to use them sooner or later.”
All too often, we will run into people who exclaim, “Throw
it away? What a waste!” This sentimental attachment to things
waxes especially strong when the things were built or customized by the workshop staff themselves.
We must face it: People are naturally reluctant to throw
familiar things away. So how do we get around this? Generally,
we need to establish clear-cut criteria for deciding what is
needed and what is not. The most common criteria is the
next month’s production schedule. Whatever is needed for
that schedule is needed. Whatever is not required for the
schedule is superfluous and can be hauled away.
Some factories may be able to take on a stricter criterion by
using next week’s production schedule instead of next month’s.
But at the average factory, this one-week criterion would result
in almost everything being red-tagged. Usually, it is best to
stick to the one-month production schedule criterion.
Step 4: Make the Red Tags
It does not matter what you make the red tags out of. Use
red paper, thick red tape, or whatever else that works. The
key is to make sure the red tags call attention to themselves.
(See Figure 4.20.)
We need to laminate whatever material we use with plastic
or something that will protect the red tags during repeated
use. Red paper is usually the easiest thing to use for red
tags. In any case, the whole purpose is to make eye-catching
memos. The types of things we should write down on the
red tags are:
◾◾ Category: This provides a general idea of the type of
thing the tag has been attached to, such as a warehouse
item, machine, or whatever. The major categories include
The “5S” Approach
Plan H
Measure H
Category
1. Raw material
7. Quasi products
2. In-process stock
8. Finished products
3. Idle equipment
9. Quasi materials
4. Unneeded tools and fixtures 10. Office products
5. Other
11. Paper, pens, etc.
Item name
Manufacturing
No.
Quantity
Units
Value
$
Reason
1. Not needed
7. Inappropriate destination
8. Other
2. Defective
3. Late (missing items, old technology)
4. Surplus (Surplus or marginal surplus)
5. Destination unknown
6. Inappropriate destination
Disposal by:
Department/Division/Section
Disposal method:
1. Discard
2. Return
3. Move to red tag storage site
4. Move to separate storage site
5. Other
Today’s date:
Posting date:
Disposal
completed
(signature)
Disposal date:
Red tag file number
Figure 4.20
Example of a Red Tag.
raw materials, in-process inventory, products, equipment,
jigs, tools, dies, and fixtures.
◾◾ Item name: Write the name or number of the item to
which the red tag has been attached.
◾◾ Quantity: Indicate the number of items included under
this red tag.
◾◾ Reasons: Describe why you attached a red tag. If the
item is an inventory item, give only the main reason
(“unneeded,” “defective,” or “not needed soon”).
◾◾ Division: Write the name of the division responsible for
managing the red-tagged item.
◾◾ Date: Enter the red-tagging date.
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Step 5: Attach the Red Tags
Make sure the entire red-tagging team thoroughly understands the criteria for telling the unneeded items from needed
ones, then send the team to the workshops.
It is better if the people attaching the red tags are not from
the workshop being tagged. The people who work there are
likely to hate seeing red tags being attached to their stuff and
will protest, “Hey, we need that in case we get a big order!”
or “But we’ll probably use that next month!”
Instead, let managers or other people from outside the workshop do the red tagging. They will be better able to red tag
items unhindered by sentimental resistance or regret. In fact,
these outsiders should be encouraged to take devilish delight
in their work as red taggers. Such a game-spirited attitude has
led to a popular nickname for red taggers: “red devils.”
The best way to carry out red tagging is to do the whole
factory in as short a time as possible. Stringing the red tag
project period out any longer than necessary tends to put a
damper on morale. It is important to regard red tagging as a
swift and powerful event.
Step 6: Evaluate the Red Tag Targets
The final step in red tagging—evaluation of red tag targets—
is a very important step.
First, we need to examine the targets in the inventory
categories. We need to clarify the types of unneeded warehouse items and how they were being warehoused. That will
help us decide what to do with the items. Figure 4.21 shows
the major types of unneeded warehouse items and the corresponding disposal methods.
After we have analyzed the unneeded items and have better understood them, we are ready to apply the “unneeded
inventory items list,” which is the basic tool for reducing
unneeded items. Figure 4.22 shows an example of this list.
The “5S” Approach
Unneeded
warehouse
items
TYPE
DEFECTIVE ITEMS
Defective stock
Discard
Dispose by
discarding
Dead stock
Move to site for
retained goods
Retained stock
Determine what is
needed and what is
not, then dispose of
unneeded items.
Marginal items
(off-the-book items)
Figure 4.21
Types and Disposal Treatments of Unneeded Ware-
house Items.
Unneeded Inventory Items List
Division
Item
Date:
Code Quantity Unit Value Disposal Supply Comments
value
category category
Cash value of unneeded items
Disposal value
Other
Measures and improvement points:
Figure 4.22
Unneeded Inventory Items List.
As a target for red tagging, equipment is just as important as
warehouse inventory. We should move all red-tagged equipment away from the areas where daily production activities
take place. However, large equipment and equipment that is
firmly attached to the floor may be quite expensive to move.
To avoid undue expenses, it is sometimes better not to move
such equipment unless it really gets in the way of daily production activities or prevents workshop improvements. Until
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Unneeded Equipment List
Division
Date:
Equipment Asset
name
No.
Quantity Unit Trade-in Date of
Total
Book Installation Comment
value value trade-in depreciation value
site
Cash value of unneeded
equipment:
Measures and improvement points:
Figure 4.23
Example of Unneeded Equipment List.
such a time, the unneeded and unwieldy equipment should
be marked with a “freeze” red tag.
Figure 4.23 shows an example of the “unneeded equipment list” that we need to draw up and use for deciding how
to dispose of red-tagged equipment.
Red Tag Computers
Wide-variety, small-lot production with short delivery deadlines. We have all heard, spoken, and dreamt of this kind of
production for years now. And all this time, this new wave of
wide-variety small-lot production has grown stronger, as have
the demands for shorter delivery schedules and lower costs.
The day of large volume production is long gone, and a
new day of production centered on small lots of many product models has dawned. This new day has dawned over all
The “5S” Approach
manufacturing industries, and these industries must find a new
production system that will provide the key for changing from
volume-oriented production to model-oriented production.
This radical change is what is known as the “factory
revolution.”
“Making things” remains the foundation of production.
But everything above that foundation—wide-product variety, short delivery schedules, information-intensiveness, and
overall speed—has changed dramatically.
During the era of volume-oriented production, factories
had only a handful of products to manage, and they could
afford to take their time in deliveries. Many shipped products
only once a month, on the regular “shipping day.”
In today’s era of wide variety and small lots, factories
must handle a much wider assortment of product models,
all of which have increasingly short life cycles. This trend
has caused a rapid surge in the amount of information that
factories­need to have about each of their products.
Unlike the corner grocery store, when the variety of products increases in a factory, the factory must deal with hundreds or even thousands of additional parts. Wider product
variety also means an exponential increase in the variety and
volume of order-related data and parts management data.
In this light, how can factories still manage to shorten their
delivery times?
Even when factories ship only once a month, they must
manage the shipments in two ways: as dealer-based deliveries and as time-based deliveries. This alone requires a
vast volume of information. In other words, the switch to
wide-variety, small lots, and shorter delivery schedules has
engendered both a factory revolution and an information
management revolution.
With further expansion of information expected in the
future, people are rightfully concerned about how they are
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going to handle it all. This trend is making computers an
indispensable part of every factory.
This brings us to our current subject: red tag computers.
When managers see all kinds of items being red-tagged
and disposed of, they want to know all the details: “We need
specific accounts of how parts and products are affected by
all this reduction of inventory!” or “We need to know how
these things are being disposed of in each factory division!”
How can we come up with all of these analytical reference
data? Red tags are themselves a very important type of data since
they indicate the factory’s superfluous items. But how can we
put these data to good use? I would propose the following.
One way is to remove the red tags from items just before
they are disposed of, then enter the data written on the red
tag into a computer. To facilitate computerized data processing, data such as the item category, item name, reasons for
red tagging and company division should be converted to
codes before being entered.
Figures 4.24 and 4.25 show examples of red tag-related
data lists output by a computer, a general red tag list, and a
more detailed reason-specific red tag list.
*** RED TAG STRATEGY: Red Tag List ***
Number of
Category
red-tagged items
1. Equipment
11
2. Jigs and tools
11
3. Measuring instruments
10
4. Materials
10
5. Parts
1,022
6. In-process items
6
7. Quasi products
97
8. Finished products
19
9. By-product materials
60
10. Office materials
1
11. Documentation materials
4
(Total)
1,251
Figure 4.24
Total units covered
by red tags
12
18
10
8,431
6,692,659
126
201,238
7,655
645
1
21
Value
Example of a Computer-Operated Red Tag List.
The “5S” Approach
*** RED TAG STRATEGY: Reason-specified Red Tag List ***
Number
Item name
Standard
Unit value Quantity
PP adjustment of standby material
110.00
Pressure blade
2.00
Straight bevel gear (front)
M 134−007
48.00
M 135−003
HP die 1 gear
169.00
Cup ring B
M 139−002
53.00
M 139−003
Cup ring A
43.00
Gate amateur attachment
M 143−085
30.00
Feed roller bearing holder
M 150−003
69.00
Upper case box
1.00
Setting gear
2,000.00
N-8 mescellaneous parts
80.00
N-8 platen roller
4.00
N-8 mainframe
3.00
N-8 motor bracket
30.00
TM300 box
1.00
Gear cover
13.00
Sheet steel guide
3.00
Sheet steel mat
24.00
Power supply assembly
15.00
Cover stand assembly
23.00
Relay board
1.00
Logic board
8.00
TT joint
3.00
TT axis
M 106−006−0 TT pulley assembly
M 106−006−1 Hopper ring primary molding
133−001 Cover
34−001 HP motor
HP switch
E L motor P630CN
Figure 4.25
Cash
value
Implement
Date
Division
Reason
Standby
Dept.
Unneeded item11/29
Mfg.
Dept.
Defective
item
12/07
11/29
12/07
11/29
Standby
Dept.
S (comments)
E
E
E
E
E
E
E
E
E
E
E
E
E
E
1921
1923
1963
1962
1958
1959
1957
1938
2331
2336
2567
2570
2565
2581
2332
1917
1919
1930
1907
1956
Example of a Computer-Generated, Reason-Specific
Red Tag List.
Red Tag Episodes: Laughing and Learning
When people operate a factory year after year, dirt and grime
gradually accumulate without anyone noticing anything. The
red tag strategy is a direct battle against such dirt. Many humorous “war stories” have been born of these battles against dirt.
The following eight red tag episodes offer ­lessons that you
may find applicable to your own situation.
Episode 1: Twenty Years of Inventory
One plant supervisor recalls how bad the inventory situation
had been at his factory: “It was nothing to be proud of. I was
shocked by what we found. For instance, we found a part
that had been sitting in the warehouse for 20 years!”
In hindsight, it seems that somehow the wrong part name
was assigned for the part when it was ordered. For 20 years,
until the factory carried out a red tag campaign, the part sat
unnoticed in the warehouse. Apparently, even the person
who originally ordered the part failed to notice the mistake.
The factory superintendent reflected, “We were not especially concerned with superfluous parts in the warehouse. As
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long as there were no missing parts, we felt that all was well.
The red tag strategy showed us where we were wrong.”
Lesson 1—Just as we keep an eye out for missing parts,
so must we watch for excess inventory!
Episode 2: Twice Red Tagged
Another factory established March as “Red Tag Month.”
Unexpectedly, though, their red tag project lingered on into
April. I asked someone at the factory what happened. He told
me, “March is also the audit month at our company. People
thought the factory would look horrible to the auditors if red
tags were stuck all over the place, so we took the tags off.”
The audit was completed at the end of March. In April, the
factory workers put the red tags back on again. Obviously,
people at that company do not really understand what red
tagging is all about.
Lesson 2—Check twice to make sure that everyone completely understands the red tag strategy!
Episode 3: Red Tagging People, Too?
One factory had already carried out red tagging of targets
such as unneeded inventory, equipment, and space.
The red tag project leaders exhorted everyone, “Don’t hold
back. Tag everything that deserves to be tagged.”
Later, it was discovered that someone stuck a red tag on
the desk belonging to the chief of the manufacturing department! It was not clear whether or not this was meant as a
joke. The department chief in question took it as a bad joke.
I would venture to suggest that red tagging desks may indeed
be called for in certain situations, but never, even in jest,
should we stick a red tag on someone’s back, where it would
seem like the proverbial “kick me” sign.
Lesson 3—Don’t red tag people unless you want to be
red-tagged yourself!
The “5S” Approach
Episode 4: Now We Have Too Many Pallets!
This factory was suffering a pallet shortage, and so it sent out
an order for another 300 pallets to fill the gap. However, a
red tag project was carried out before the new pallets arrived.
The project achieved inventory cutbacks that resulted in a
300-pallet surplus!
The factory superintendent asked everyone, “Now what are
we going to do when we get those 300 pallets we ordered?”
With a wry smile, he answered his own question: “I know.
We’ll turn this place into a pallet factory!”
Lesson 4—An appetite for more pallets is a sure symptom of a gluttonous production system.
Episode 5: A Yellow Tag Flop
Factories are mysterious entities. It is not always easy to tell
what will be needed for next month’s production and what
will not. One factory sought to appease peoples’ reluctance
to red tag certain items by allowing yellow tags to be used
for items having doubtful necessity. When the red tag campaign was completed, the factory was full of yellow tags and
nary a single red tag could be seen. As a result, the whole
campaign was one big flop.
Lesson 5—If you go halfway with yellow tags, you won’t
have any red tags!
Episode 6: Red Tag Stickers
When red tag project members at a major household electronics manufacturer discussed how to make the red tags,
they decided it would be convenient to have red tag forms
on adhesive-backed paper and eliminate the need for rolls of
cellophane tape. However, these large red tag stickers were
not cheap: Each one cost over a dollar. When the factory
superintendent saw these fancy stickers, he called a worker
over, saying, “Hey, bring me some of those red tag stickers!”
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A curious group of people gathered around and watched in
amazement as the superintendent placed one red tag sticker
onto a bunch of other ones. He then announced, “I’m putting
a red tag on these needlessly expensive red tag stickers!”
Lesson 6—Improvement—including red tagging—should
not be expensive. The more money we spend, the less we
use our own ingenuity to find solutions.
Episode 7: Each Person Should
Attach at Least Four Red Tags
I once visited a factory that was disappointed with the results
of its red tag project. I figured that since the factory employs
about 300 people, each person should have found at least four
things to tag, which adds up to about 1,200 red-tagged items.
When I got to the factory, I asked the superintendent how
many items were red-tagged.
“Oh, I guess about 40 or 50,” was his reply.
No wonder they were disappointed!
Lesson 7—A red tag project is not a red tag project unless
each member attaches at least four red tags.
Episode 8: Showing No Mercy
This factory had set-up its red tag project, had made the red
tags, and was all ready to start attaching them to unneeded
items. The red tag team distributed red tags to workshops
throughout the factory and instructed the workers there to
stick red tags on everything not needed.
A week later, the red tag team received almost all of the
red tags back from the workshops. Every workshop had the
same excuse for returning them: “There aren’t any unneeded
items in our workshop.”
Lesson 8—Everyone must understand and use the same
criteria for deciding what is needed and what is not needed.
The people who work in the target workshop will all say,
“We need that!” about everything. Instead, let managers or
other people from outside the workshop do the red tagging.
The “5S” Approach
And it’s better to avoid the production engineering staff. It
knows the workshops too well and tends to have sentimental
attachments to them.
Lesson 9—When red tagging a workshop, we must be as
cold-hearted as the Devil!
As these episodes illustrate, red tagging reaches right
down into the hearts of factories and can be expected to
bring major results. It is indeed a very important strategy.
About the only thing that produces greater results and
boosts improvement higher than red tagging is “visual
orderliness”—in other words, the signboard strategy.
Case Study: Red Tag Strategy at Company S
The following is a case study of red tag strategy implementation at a company we shall call Company S.
Finding Oneself Amid the Waste
Company S’s production division sponsored a meeting of the
production management subcommittee on February 24. Its
main concern at this meeting was to concentrate on the 5S’s
to lay the foundation for improvements. It realized it needed
the top manufacturing managers’ complete understanding
and backing, but so far no progress had been made to secure
that support.
The production division chief addressed the meeting in
a loud, authoritative voice: “Right! Let’s get the 5S’s done so
we’ll be ready to start really improving the factory. I say we
should make March our 5S Month.”
Naturally, the production division chief’s suggestion was
taken as a command. Company S inaugurated “5S Month” by
kicking off its red tag strategy. On March 1, the production
division chief had a notice sent to all manufacturing departments in the company. (See Figure 4.26.)
The production management division should be active only
in the overall promotion and organization of the red tag project­.
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MEMORANDUM
To: All Manufacturing Divisions
Re: 5S Implementation
Date: March 1
Issued by: Production management
division chief
1. Main Objectives
(1) To lay the groundwork for flow production
(2) To reduce inventory and raise efficiency in capital turnover
2. 5S Month
March has been established as the 5S Month.
3. Main 5S Activities
(1) Attaching red tags (proper arrangement)
By March 10, red tags must be attached to the following target
items if they have not been used for one month or their status
has otherwise remained unchanged.
(2) Red tag target items
Empty space
Equipment (carts, dies, etc.)
Shelved items (materials, in-process inventory, quasi
products)
Other unneeded items (desks, shelves, other
furnishings, etc.)
Figure 4.26
5S Implementation Memo at Company S.
All of the details should be handled by the f­actory people
themselves, using their hands-on know-how and ingenuity.
At one of the company’s factories, they figured they
would use about 500 red tags. However, once they started
tagging things, they soon found themselves running out of
red tags. They ended up using about 1,500—three times
their original estimate.
Through red tagging, the factory staff finally came to realize just how much dirt and waste they were working amid.
Anticipatory Large Lot Production
Company S was founded in 1954, and is currently one of
Japan’s top manufacturers of stainless steel sinks and other
kitchen fixtures and furnishings.
The key to survival in today’s highly competitive manufacturing world is to produce a wide variety of products in small
lots and with short delivery times. And that is not all—the
products must also be built with high quality, but at low cost.
The “5S” Approach
To help motivate employees toward this challenge, Company S’s president came up with the “SS” strategy. SS stands
for Company S’s “survival.”
As part of this SS strategy, Company S set-up a comprehensive computer-based sales/production system that helps
it promptly identify current market needs and distribute this
information to the proper manufacturing divisions.
The company was trying to beef up its information-related
strengths by putting more information into its “brains” and
making that information more accessible.
However, it is not enough to have a lot of “brains” in the
company. Any brain needs a healthy body to survive. In other
words, a powerful brain and a frail body makes it difficult for
the whole body to function well. Companies need to have
quick and agile bodies that can provide prompt “hardware”
responses to the “software” (information) they receive from
the computer system.
What this all boils down to is a radical change in the character of the old large lot-oriented factories. Obviously, making­
such a change is a very big project. It requires more than
incremental improvements in the factories. A lot of people
will not like the idea and will be reluctant to follow along.
Such radical improvement will require improvement teams to
put in long hours after work, day after day. They must begin
by re-educating the workers, then they must overhaul the
­factory layout and change the production methods.
This Is Nothing Short of a Factory Revolution
Factory improvement is an underlying assumption of the
­factory revolution. Carrying out the 5S’s is the only way to lay
the foundation for factory improvement and to set the stage
for the factory revolution.
It is not difficult to find manufacturing people in Japan
who are familiar with the 5S’s. In fact, as mentioned earlier,
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many Japanese factories post signs and banners showing the
first two (and the two most basic) of the 5S’s, seiri (proper
arrangement) and seiton (orderliness). But very few factory
people have any clear idea of what actually needs to be done
to establish those first two S’s!
Company S understood what red tagging meant, and adopted
the following basic policy points concerning it: Properly arrange
items by removing currently unneeded items, then make them
orderly in every direction—horizontal, vertical, perpendicular,
and parallel.
This humble statement is all a company needs to ignite the
sparks of an awareness revolution in its factories.
We Are Ready for JIT Improvement: Our Inventory Is
Now One-Third What It Was Just Six Months Ago
Company S not only got its larger and smaller factories involved
in red tagging, it also enlisted the participation of several
subcontractor factories. As a result, some factory managers
were reporting that thoroughly implementing the 5S’s was
apparently enough to boost productivity about 20 percent.
This productivity rise was most likely due to the 5S effect
on eliminating the need to search for parts and tools and in
removing conveyance-related waste. Another reason was that
factories were rendered conducive to visual control.
Company S’s factories now had too many pallets and carts
and their inventory levels had dropped dramatically. In the
case of the one large factory that received the most attention from the company, red tagging resulted in a one-third
inventory reduction over the level recorded just six months
before. (See Figure 4.27.) Everyone was amazed at how spacious their factories had become after red tagging. In fact,
people felt disoriented without all that familiar clutter all over
the place.
If we can get this far, we are halfway there. The stage is all
set for factory improvement. Everyone is excited and anxious
for the curtain to rise and for the improvements to begin.
The “5S” Approach
Total value
Inventory
reduction:
33%
100
35
33
33
28
28
20
In-process
inventory
50
Raw
materials
65
65
65
68
58
47
Nov*
Dec
Jan
Feb
Mar
Apr
* Total value and inventory value for November were assigned 100 points
Figure 4.27
Achievement of a 33-Percent Inventory Reduction.
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Case Study: Spreading the News
about Red Tag Implementation
Figures 4.28 through 4.31 show the notice that Company A
sent out to employees in all divisions regarding the implementation of their red tag strategy.
MEMORANDUM
TO: All divisions (division chiefs and department chiefs)
RE: Implementation of Red Tag Strategy
As you all know, the operations division and other divisions have already gained
some success in carrying out red tag strategies. However, we still have a lot of
space-wasting, unneeded items in various workplaces and, in order to lay the
foundation for JIT improvement, we are undertaking the following additional red
tag strategy. We hope we can count on your cooperation in this effort.
Signed,
1. Objective
To remove space-wasting unneeded items from workplaces and to lay the
foundation for JIT improvement
2. Implementation period
February 13-24: Red tag strategy period
February 28: Report on red tag strategy results
3. Red tag targets
Equipment, productions, inventory items, etc.
4. Criteria for red tagging
Attach red tags to all equipment, inventory items, and other items that will
not be required under the March production schedule.
5. Organization
(1) Head office
Chief executive officer for overall red tag strategy: President
Vice-chief executive officers for overall red tag strategy: Managing
director and factory superintendent
(2) Operations division and other divisions
Chief executive officers for red tag strategy: Each division chief
Vice-chief executive officers for overall red tag strategy: Each
department chief
Division and department chiefs will set up a red tag strategy promotional
organization within each division.
6. Implementation method
(1) Members of the red tag strategy promotional organization will individually
attach red tags to items they judge unneeded, based on reasons other than listed
in the red tag criteria used by the division concerned. They will notify the relevant
departments of the number of items that have been red-tagged in this way.
(2) While waiting for an investigative team to study the red-tagged items,
the people in the division concerned will sort the items out and start
arranging for their disposal.
(3) As for shelving or other immovable assets, separate the items for
which disposal applications have already been made, then clear as
many of them out of the workshop as possible.
Figure 4.28
Company A’s Memo to All Employees.
The “5S” Approach
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291
(4) Main tasks in red tag strategy
Development of
red tag strategy
Chief executive officer
Vice-chief executive
officer
(head office)
Issue general
instructions for
red tag strategy.
Secretarygeneral
Red tag strategy
executive officers
in each division
Red tag
promotion team
Consult with chief
and vice-chief
executives, then
issue more detailed instructions.
Act as person
responsible within
operation division
based on executive
instructions.
Act as the team
Investigate disposal
which carries out
of red-tagged items.
specific red tag
activities (one
person will be given
responsibility as
team leader).
Make sure everyone
understands the red
tag strategy and
then establish the
strategy’s general
direction.
Review their own
Dispose of red-tagged
workplaces, related items from their own
workplaces, and
division. For items from
various warehouses. other divisions, consult
Use appended
with division staff first,
checklist for reviews. then attach white tags
to items that cannot be
disposed of or that
must be moved to
temporary storage.
Determine disposal
method for all other
items.
Fill out appended
report form.
Report
results
Main tasks
same
Division
members
7. Long-term storage
Contact the secretary-general’s office to receive instructions regarding storage sites for parts that
cannot be discarded. Store items to be disposed of during this business term separately from
items to be disposed of after this term.
8. Disposal of administrative materials
Consult with the general affairs department before disposing of administrative materials.
9. Other
The red tag strategy promotion team should work with the head office in dealing with any
problems that arise after the red tagging has been completed.
Figure 4.29
Main Tasks in Red Tag Strategy.
◾ JIT Implementation Manual: Volume 2
Red Tag Strategy Checklist
WORKPLACE
CLERICAL
TARGET
WAREHOUSE
292
CHECK POINTS
File cabinets,
books, documents
Dispose of all books and documents for which the specified storage period
has expired. Bundle up all documents that require incineration. Leave
necessary files alone or put them into storage.
Signs and other
posted items
Remove and dispose of all outdated or otherwise old items.
Desks, tables, etc.
Organize what is on top of, inside or underneath, and next to all desks.
Leave only items that are necessary to the current operation on top of the desk.
Minimize the number of documents, tools, and other small articles kept on the desk.
Fixtures and
machines
Dispose of all unneeded items.
Inventory items
All quasi products, finished products, in-process inventory, testing materials,
and other items that fall outside of the red-tagging criteria.
Equipment
Items that fall within the red-tagging criteria and that are not expected to
be needed, off-the-book items, etc.
Work tables
Items that fall outside of the red-tagging criteria or that are rendered
unnecessary by a layout revision or other reason.
Jigs and measuring
instruments
Unneeded shared or individually used items and defective items
Tools
Unneeded items stored in boxes or on shelves
Wires, cables,
etc.
Return all materials that cannot be disposed of to the distribution department
or store them in a common storage site.
By-products
materials
Store or dispose of unneeded bolts, nuts, clamps, chemicals, etc.
Shelving and
boxes
Dispose of all shelving and boxes that are unnecessary and/or detract from
productivity.
Drawings
Check what is not being used currently and what is being stored in duplicate.
Other
Be sure to dispose of whatever does not seem to be needed.
Retained goods
Items related to management or design that are of questionable need in
schedules, off-the-book items, items that are removed from equipment and
stored, items that have never been used, etc.
Books, files, wires,
steel plates,
metal fittings, etc.
Review all of these and dispose of all unneeded items.
Equipment
Dispose of all items not expected to be used, old and worn items, and
outdated items.
Figure 4.30
Red Tag Strategy Checklist.
The “5S” Approach
TO: Operation Division Chief
Red Tag Strategy Report Form
Date:
Department name:
Signature:
Machines,
devices, etc.
Name and processing number
Remove
inventory items
from workplace
Disposed of,
filed, or placed
in library
Other
Make space, include
areas with equipment
for which a current-term
removal application
has been made
Figure 4.31
Note the factory name and the number
of floors in the factory.
Red Tag Strategy Report Form.
The Signboard Strategy:
Visual Orderliness
The signboards we use in the signboard strategy are sometimes confused with the well-known kanban system in
which signs are used as tools for maintaining Just-In-Time
production. Signboards are a different kind of tool, though.
We use these signboards to make orderliness more visible.
The ­kanban system may use some signboards, such as for
indicating item names and quantities, operation instructions,
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or delivery instructions. But just the same, we should think
of the signboard strategy as a modest “visible orderliness”
strategy that may serve as part of a comprehensive kanban
system that functions as a full-fledged “autonomic nervous
system” for the factory.
This section addresses the following topics concerning the
creation and use of signboards in the signboard strategy.
◾◾ What is the signboard strategy?
◾◾ Steps in the signboard strategy
◾◾ Orderliness beyond signboards
What Is the Signboard Strategy?
A simple, two-step procedure is all it takes to lay the foundation for achieving zero defects and eliminating waste: Clearly
separate what is needed from what is not, and remove all
unneeded items from daily production activities.
After that, all that remains is needed items, and the natural thing to do is arrange and use these needed items in
the most efficient way. While we are at it, we need to post
signboards that indicate just what kind of machines we are
using and “where,” “what,” and “how many” inventory items
are to be kept. In other words, make everything obvious and
visible­. The signboard strategy is a tool that makes the whole
organizing process more visible.
Figure 4.32 gives an overview of visible orderliness using
the signboard strategy.
Of these signboards, the most important ones are the
inventory signboards that should clearly indicate where each
inventory item belongs and in what amount, allowing anyone to understand the inventory layout. Signboards should
only be used for items that are needed for current production
purposes. Therefore, the signboard strategy should always be
preceded by the red tag strategy, or we will end up wasting
time posting signboards over unneeded items.
The “5S” Approach
WHERE:
Place indicators
Section
indicators
Address
indicators
INVENTORY
S
I
G
N
B
O
A
R
D
Item
indicators
HOW MANY:
Amount indicators
S
T
R
A
T
E
G
Y
Figure 4.32
WHAT:
Item indicators
Item
placement
indicators
MACHINES
Large
amount
indicators
Small
amount
indicators
Machine/equipment
indicators
Overview of Visible Orderliness Using the Signboard
Strategy.
(Hanging)
Machine name
Process
name
Operator
Acquisition
date
Machine name
Process
name
Figure 4.33
Operator Acquisition
date
(Posted)
Examples of Machine/Equipment Signboards.
Before getting into a closer look at how to apply the signboard strategy to inventory items, let us turn to the machine/
equipment signboard example shown in Figure 4.33.
We simply write down the name of the machine, the process name, the operator or other person-in-charge, and the
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machine’s acquisition date. Then we hang the signboard from
the ceiling or post it against a wall or on the machine itself.
Steps in the Signboard Strategy
After we have carried out the red tag strategy, the factory
should contain only items that are needed for current production. Now, the question is what to do with those remaining items. We should remember that the items needed for
current production are not necessarily the most efficient
types of items.
After red tagging, factories suddenly have a lot of open
floor space and empty shelving. Now is the time to consolidate what is left and change the equipment layout or
production flow pattern. Once operations have been thus
redesigned, we are ready to move the remaining inventory
and in-process items to the most efficient and orderly sites.
Figure 4.34 illustrates the signboard strategy procedure.
Step 1: Determine Locations
As soon as the red tag strategy has been completed, we need
to make improvements that will consolidate the equipment
layout and the production flow. Then we are ready to ask
where things should be placed to best suit the new layout.
When determining locations, make sure to place oftenused items as close as possible to the operator’s position and
place seldom-used items farther away from the line. Keep
easily portable items about waist-high on the shelves and
keep harder-to-carry items on the upper and lower shelves.
Step 2. Prepare the Locations
Once we know where we want to place something, we still
need to prepare the site. We can use some of the cabinets,
shelving, boxes, pallets, or other containers that were rendered superfluous by the red tag strategy.
The “5S” Approach
What is the signboard strategy?
The signboard strategy is a method for clearly indicating where
(location), what (item names), and how many (quantity) necessary
items go as we make the factory more orderly.
STEP 1 Determine locations
After consolidating the remaining items, decide where to place them
to best suit the way operations will be done.
Note: Be sure to put frequently-used items as close as possible to the
operators.
STEP 2 Prepare the locations
Organize shelving and cabinets in their specified places.
Note: Use your ingenuity, such as by making parts easier to remove
from shelves and cabinets or by setting up a “first-in, first-out” stocking
system.
STEP 3 Indicate locations
Make and post or hang signboards that clearly indicate where each
item belongs.
Note: Use either a place name/diagram signboard or an address
signboard to indicate where things belong.
STEP 4 Indicate item names
Make and post or hang signboards that clearly indicate the names of the
items and the name/number of the shelf or cabinet where the items are
to be kept.
Note: Use a shelved item signboard or some other place-specific item
signboard.
STEP 5 Indicate amounts
Indicate the amount of inventory items covered by each signboard.
Note: Indicate both the maximum and minimum amounts.
STEP 6 Make orderliness a habit
Make orderliness a habit so that it does not lapse into disorder.
Notes:
(1) Make orderliness easy to maintain.
(2) Maintain discipline.
(3) Make the 5S’s an everyday habit.
Figure 4.34
Signboard Strategy Procedure.
While doing this, if we find that there are not enough cabinets or shelves or whatever, we do not need to rush out and
buy more. Instead, we should take this golden opportunity
to reconsider the containers we are using and try to think
of smaller containers that will do just as well. We should
also consider whether lot sizes can be shrunk or whether
unneeded items can be customized to serve as the kind of
cabinet or shelf that we need.
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We might also want to set-up a system that lets us extract
items in first-in first-out order, or use labor-saving roller conveyors or other clever devices.
Step 3: Indicate Locations
Once we have decided where to put things, we need to make
location indicators—in other words, signboards that show
the place and address of the item concerned.
Location indicators can be modeled after the postal s­ ystem’s
address system. No matter where in the world we send a
letter, if that letter indicates our return address, it can be
returned to us. The factory’s address system should be at
least as comprehensive as the postal address system. Like
the postal address system, the factory address system should
include both a “town address” and a “street address.” This
means there should be an indication of where in the factory
the item belongs, and also what specific address within that
area. Address numbers are often duplicated within different
areas, so we must be sure to specify the area and not just
the number.
An address system and a map are all anyone should need
to find anything in the factory.
Section and address indicators can be separate signboards,
as shown in Figure 4.35. In this example, the section signboards indicate which set of shelves (A, B, C, and so on) the
items are on and the address signboards show the part of the
shelf (1, 2, 3, and so on).
In the example shown in Figure 4.35, the address consists
of a vertical address number and a horizontal address number. Once we set-up a system like this one, we can give an
item to a brand-new employee in the factory and simply say,
“Here, this goes to address A32 on the shelves,” and trust
that the item will get put in the right place. This is what we
mean by making things visible so that anyone can understand them.
The “5S” Approach
Section signboards
(unique in factory)
B
1
2
3
A
1
Address
signboards
(not necessarily
unique in factory)
1
2
Horizontal
address
Figure 4.35
2
3
Vertical
address
(A32)
(Section A,
vertical
address 3,
horizontal
address 2)
Location Indicators.
Step 4: Indicate Item Names
After we have finished setting up the shelf addresses, we still
need to indicate what kinds of items go there. For this we
use item indicators.
Examples of such indicators abound among high-rise
apartment complexes and parking lots. Figure 4.36 shows
a comparison between a well-managed parking lot and a
poorly managed one.
Let us assume that a new parking lot attendant has arrived
for his first day of work at the lot. He finds that all of the
parking spaces have people’s last names on them. He sees
that a car with license plate number 90R 3G56 is in the space
marked as Mr. Smith’s, but he cannot tell whether or not that
car is parked in the right space. The “old hand” who managed the parking lot before knew which car belonged to
whom and could tell. But the new guy is at a loss.
If the lot were organized and managed as shown in the
bottom half of the figure, the new guy could tell right away
if any cars were parked in the wrong spaces. In this lot,
all parking spaces include item placement indicators that
show what specific item belongs in each space. In this case,
the items (automobiles) are identified by their license plate
numbers. The license plate number on the car parked in
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Can you tell whether or not this car is parked in the right space?
Poorly-managed parking lot
Rosen
Smith
Lennon
Well-managed parking lot
Item placement indicators
Rosen
AHNO 870
Smith
90R 3G56
Lennon
IGU1 994
Location indicators
Item indicator:
90R 3G56
(license plate)
Figure 4.36
Well-Managed and Poorly-Managed Parking Lots.
Mr. Smith’s space matches the number shown on the item
placement indicator in that space, so the new guy knows
immediately that the car is parked in the right space. All over
the lot, one glance is enough to see whether the cars’ license
plate numbers match the license plate numbers shown in the
parking spaces.
The same goes for factories. Figure 4.37 shows how item
placement indicators and item indicators can be used similarly for shelf slots in factories.
The item placement indicators show exactly what item
belongs in what place, while the item indicators identify each
item. If we take this item indicator and include various other
data (such as data used to maintain the “pull production”
­system, operation instructions, and/or delivery instructions),
this simple signboard becomes a full-fledged kanban.
The “5S” Approach
1
1
Item indicator
5963
5963
2
Item placement indicator
2640
2640
Item Indicators.
Figure 4.37
Step 5: Indicate Amounts
Unless we keep tabs on the amount of inventory items, they
tend to pile up. The best reason to have amount indicators is
that they limit the number of shelves and other storage space
to be used for inventory items. When exact amounts cannot
be indicated, we should at least indicate the minimum and
maximum amounts. Color coding is a good way to distinguish between minimum and maximum amount indications.
(See Figure 4.38.)
This system enables anyone to spot misplaced items
right away. Again, this brings us back to a basic tenet of JIT:
Maximum inventory amount
Minimum inventory amount
1
2
3
4
1161
0321
3111
2213
2166
0419
1919
2314
1
2
Figure 4.38
Amount Indicators.
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Abnormalities, waste, and all other problems in the factory must
be made so visible that they can be recognized at a glance.
Step 6: Make Orderliness a Habit
Orderliness means standardizing the new way we place things
as a result of seiri (proper arrangement). Orderliness should
clarify what goes where and in what amount. It should also
make all abnormalities and problems immediately obvious to
everyone. The key to maintaining orderliness is to respond to
problems as soon as they arise by identifying the causes and
making the appropriate improvements.
The three most important things to do to prevent backsliding on orderliness are to make orderliness easy to maintain
to begin with, stick to discipline, and make the 5S’s a daily
habit. The following sums up the concepts behind the three
main types of indicators used in the signboard strategy:
◾◾ Location indicators: “at the specified location”
◾◾ Item indicators: “the specified item”
◾◾ Amount indicators: “in the specified amount”
Orderliness beyond Signboards
Although signboards are the major tool for bringing orderliness to inventory items, there are a few other methods
worth noting.
First-In/First-Out (FIFO)
It is not hard to find inventory items piling up here and there
in factories. The worst kind of inventory stack is when different types of inventory items get mixed up in the same stack,
as shown in Figure 4.39. Such stacks often require that we
move some of one type of item out of the way so that we
can get to another type. This activity should be considered a
major form of waste.
Generally, items are accumulated and retrieved in one of
two opposite ways: first-in/first-out (FIFO) or last-in/last-out
The “5S” Approach
Different types of
items in stack
Same types of
items in stack
Order of
placement
Order of
retrieval
E
5
A
1
D
4
3
2
A
A
A
2
3
4
1
A
5
C
B
A
To be retrieved
Must pull all items off
of stack to reach item A
Figure 4.39
LIFO order makes it difficult
to reach the bottom items
Inventory Stacks.
Insert
side
Insert
parts tray
Extraction
side
Pull out
parts tray
(FIFO)
Roller conveyor
(for easy
movement)
Shelf slanted
(improves visibility and
facilitates extraction)
Figure 4.40
Example of FIFO Method for Storing Inventory Items.
(LIFO). FIFO means that whatever gets put in earliest is the
first to be taken out. This method is easy to implement on
shelves that are accessible from both front and back, as shown
in Figure 4.40. The FIFO method is a good way to prevent
age-related deterioration of inventory items.
Inventory Liveliness Index
Conveyance-related waste occurs whenever inventory items, inprocess stock, or other items are retained. Obviously, it is best
to get rid of all waste arising from retention and conveyance,
but when this is not possible, we should at least make sure that
conveyors are being used efficiently to move such items.
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Le
f
Liveliness
Index
tp
Lo iled
ad o
e n
M d o floo
ov n
ac r
e
ar
Un d
t
lo
ad
Lo ed
ad
on
e
M d o to fl
ov nt
oo
o
e
pa r
Le d
ft
lle
o
t
M np
ov al
ed le t
Lo
ad
e
M do
ov nt
ed o
ac
ar
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In transit
Loaded on cart
Loaded in bin
Average
Total liveliness index points
liveliness =
Number of steps
index
(0+3+4+0+2+4+2+4+3+4)
=
10
Loaded in box
set on floor
= 2.6
Piled directly
on floor
See if items piled on floor
(0 index points) can instead
be kept in a box (1 index point)
or in a bin (2 index points).
1
Figure 4.41
2
3
4
5
6
7
8
9
10
Conveyance Liveliness Index.
Figure 4.41 shows how the “liveliness” of a factory’s conveyance system can be indexed and evaluated.
When items are simply piled on the floor (zero index
points) and then are loaded into a box or other container to
be moved, this creates a lot of waste related to loading and
unloading items. Higher index totals and averages indicate a
reduction of waste.
Lined Up Inventory Placement
When materials, parts, or other items are delivered, they are
first “inserted” into an inventory pile. When the factory needs
to use them, they are “extracted” from the pile and sent to the
The “5S” Approach
Function-specific method
Machine
screws
(Extraction)
Product
A
Product
B
Washers
Machine
screws
Machine
screws
Washers
Washers
Machine
screws
Machine
screws
Washers
Washers
Machine
screws
Machine
screws
Washers
Washers
(Insertion)
A B
Washers
Product-specific method
(lined up)
(Insertion)
Washers
Product
A
Product
B
Machine
screws
Washers
Machine
screws
Washers
Bolts
Nuts
Bolts
Nuts
Terminals
Wires
Terminals
Wires
(Extraction)
Product
A
Figure 4.42
Product
B
Function-Specific Method and Product-Specific Method
of Inventory Management.
factory. Therefore, inventory always includes the two actions
we refer to here as “inserting” and “extracting.”
Inventory items can be managed using a function-specific
management method that emphasizes easy insertion or using
a product-specific management method that emphasizes easy
extraction. This latter method is also known as the “lined up
inventory placement method.” Both methods are illustrated
in Figure 4.42.
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Supplied parts
Products
Parts storage site
Figure 4.43
Marshalling.
The function-specific method enables centralized management of orders and deliveries, and is thus an easy method
to use. However, it also requires warehouse workers to walk
deep into the homogeneous stacks of goods to collect everything needed for a particular product. This method is better
suited for unit production systems.
On the other hand, the product-specific management method scatters similar items among mixed piles of items needed
for certain products. While this makes orders and deliveries
more difficult to manage, it makes collecting parts for products very easy and helps minimize waste when the same
groups of items are frequently sent to the factory. We call this
warehouse organization of parts into product-specific groups
“marshalling.” Marshalling is commonly done at the start
of assembly lines, so that parts can be sent in pre­arranged
groups for assembly. (See Figure 4.43.)
The advantages of marshalling are that assembly w
­ orkers
do not have to move sideways or turn around to pickup
parts, and there will be fewer defects due to missing parts or
errors in selecting parts.
Marshalling also has at least one disadvantage: Either the
supplier or an operator must take the trouble to arrange the
parts into their respective groups, which creates an extra set
of unloading and loading steps.
The “5S” Approach
Orderliness Applied to Jigs and Tools
One of the important ways that jigs, tools, blades, and dies
differ from materials and parts is that jigs, tools, and the like
have to be put back after being used. Parts and other m
­ aterials
go into products and are shipped out with the products, so
we do not need to put them back.
Orderliness tends to collapse into disorder. But if we can
find some way to make jigs and tools easy to put back, the
chance of backsliding on orderliness can be cut in half. This
section discusses the following points concerning orderliness
as applied to jigs and tools:
◾◾ Easy-to-maintain orderliness for jigs and tools
◾◾ Orderliness applied to cutting tools
Easy-to-Maintain Orderliness for Jigs and Tools
Almost all materials and parts go into products and are
shipped as part of those products, so they do not have to be
put back. Jigs and tools, on the other hand, must be put back
after they are used so they can be used again. The key to
preventing orderliness from lapsing into disorder lies in this
distinction between putting back jigs and tools and not putting back materials and parts.
Obviously, we need to store jigs and tools in a way that
makes them easy to retrieve and use, but we should also
make them just as easy to put back. We must never forget
that making jigs and tools easy to put back is a vital part of
orderliness as applied to jigs and tools.
There are several stages involved in making orderliness for
jigs and tools easy to maintain. We call this progress of stages
the “evolution of orderliness for jigs and tools.” The following
describes the stages in this evolution.
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Stage 0: No Sense of Orderliness; Complete Disorder
In workshops where the people have not yet developed a
sense of orderliness, jigs and tools can be found laying in
highly unpredictable places, and this causes workers to waste
a lot of time searching for them. After the workers find the
jigs and tools they are looking for and use them, they just
leave them by the machine or wherever else seems convenient. Sometimes, they try to “hoard” the jigs and tools by
keeping them close by them, which makes it hard for other
workers to use them.
Stage 1: Jigs and Tools Are Kept in Groups;
Easy-to-Understand Orderliness
First, the workers put all jigs, tools, blades, and even garbage
and various parts together into one big pile. Then they select
groups of items, such as a group consisting only of tools, a
jig group, a blade group, and so on. This makes finding and
replacing these items a little easier.
Stage 2: Visual Confirmation of Where to Put Back
Jigs and Tools; Easy-to-Confirm Orderliness
The following devices and methods can be used to make it
easier to confirm where jigs and tools should be put back
when we are through using them.
◾◾ Indicators
Label stickers and other indicators are good devices for
showing everyone where to put back which jig or tool.
Figure 4.44 shows examples of such indicators.
◾◾ Color-coded orderliness
Color coding of jigs and tools according to their use is
another good way of enabling easy confirmation. We
call this method “color-coded orderliness.” For instance,
if different jigs and tools are used for different machines,
the machines and the jigs and tools they use can each
The “5S” Approach
Tool Storage Site A13
1
Screwdriver
1
2
Screwdriver
3
Tool sticker indicator
Screwdriver
2
Place indicator
3
Figure 4.44
Indicators Showing Where to Put Back Tools.
be marked with a certain color, which makes it easy for
anyone to match jigs and tools with the right machine.
◾◾ Outlined orderliness
If the place where we are supposed to return jigs and
tools is vaguely defined, it becomes difficult to maintain orderliness. “Outlined orderliness” is a good way to
solve this problem. “Outlined orderliness” means using
markers or tape to show the outlines of the tools that
belong in each place. Matching jigs and tools to their outlines is perhaps the simplest way to confirm that we are
putting them back in the correct places. It is especially
helpful to combine outlining with indicators, and even
with color coding.
Some family restaurants use the same idea by providing
children with place mats that have knife, fork, and spoon
outlines to show where these utensils properly belong. (See
Figure 4.45.)
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Figure 4.45
Outlined Orderliness.
Stage 3: Knowing It by Heart; Orderliness so Simple
That Workers Can Maintain It with Their Eyes Closed
People tend to be lazy. They would rather be able to replace
something without having to look to see what they are doing.
The following devices are therefore worth developing.
◾◾ Bring return points to within arm’s length.
When busy with their work, operators generally do not
feel like putting something back in the right place if the
right place is out of reach. That is why it is best to make
those places as close to the operator as possible. This
is especially true of jigs and tools used for changeover
tasks. The operator should be able to remain in the same
spot throughout the changeover procedure. Better yet,
he or she should be able to reach over to pickup jigs and
tools and put them back without even having to look at
the jig/tool storage place.
The “5S” Approach
Operator moves his arms, but not his legs
Machine-specific tools
M11 Tools
Arranged in order of use
Figure 4.46
Machine-Specific Tools and Close Tool Storage Site.
If there are several tools, they should be arranged in
their order of use during the changeover procedure.
Figure 4.46 shows an example in which a changeover
process has been simplified and made orderly using
the 5S’s.
◾◾ Enlarging dimensions
Everyone knows how hard it can be to thread a needle.
The thread starts bending or the tip of the thread frays
and we have to keep wetting and twisting it to restore
the point. Likewise, if maintaining orderliness applied to
jigs and tools is as nerve-wracking as threading a needle,
you can be sure orderliness will not last long.
Threading a needle is so difficult because of the small
needle hole we must work with. The small needle hole
requires that we use a very thin thread, and thin threads
tend to bend and fray.
Let us suppose, for example, that we need to pour
some salad oil from one bottle to another, as shown in
Figure 4.47. If we try to pour directly from one narrowmouth bottle to another, chances are we will end up
spilling some of the oil. We can get around that problem
by enlarging the dimensions we must deal with. We all
know which device to use for this—a funnel.
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Small
dimensions
Figure 4.47
Large
dimensions
How to Keep the Salad Oil from Spilling.
STAGE
STAGE
STAGE
Lean it against
the wall
Hang it on
a hook
Hang it on a hook
using a loop
STAGE
Hang it without having
to pay much attention
larger
dimension
small
dimension
larger
dimension
small
dimension
Figure 4.48
larger
dimension
larger
dimension
Four Stages in the Evolution of Orderliness: Brooms
and Mallet.
There is no reason why we cannot apply to the factory
the same sort of everyday ingenuity that brought us the
funnel for pouring. Figure 4.48 shows four stages in the
evolution of orderliness applied to a broom and a mallet.
As can be seen in the figure, the larger the dimensions
The “5S” Approach
get, the more we are able to put the items back without
even looking at what we are doing. Orderliness becomes
progressively easier to maintain.
Stage 4: “Just Let Go” Orderliness;
We Don’t Even Have To Return It
When it comes to convenience, if you give people an inch
they will take a yard. Even when we have made it so easy
to put tools back that the operators do not even have to pay
attention to how they do it, some operators will still think it
is too much trouble. Perhaps the only thing to do with such
people is devise a way in which they can simply let go of the
tools when they are done with them.
Believe it or not, ways have been found to do just that. At
produce stalls or fish stalls in Japanese marketplaces, it is a
common practice to hang the money basket from the ceiling
using an elastic cord. The merchant reaches up to grab the
basket, makes change for the customer from it, then simply
lets go of the basket and the rubber cord lifts the basket back
up and out of the way. The merchant does not even have to
think about returning the basket. This can serve as a prime
example for factories.
Assembly factories have already developed a wide array
of such “auto-return” devices. Figure 4.49 shows how most of
the tools used in an automotive component assembly factory
are hung above the assembly workers. We can see the same
kind of device used in home electronics or electrical equipment manufacturers where electric screwdrivers are hung by
cords. Generally, it is best to hang the tools at points closest
to where they will be used.
Stage 5: Orderliness That Eliminates Some of the
Jigs and Tools; We Don’t Even Have to Use Them
If you give lazy people a whole yard, what will they take
next? Even when they can just let go of the tool when they
are through with it, they may still think, “Why must I bother
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Figure 4.49
“Just Let Go” Orderliness Applied to Tools.
to use that tool, anyway?” The question is, can we come up
with a way to eliminate the need for certain tools?
◾◾ Combining jigs and tools
By combining the functions of several jigs and/or tools
into just a few, we can reduce the amount of jigs and tools
to be managed. Figure 4.50 shows how two pneumatic
or electric tools used for assembly can be combined into
one. Naturally, some parts redesigning was needed for
this combination.
◾◾ Transferring tool functions
The best kind of orderliness removes the need for orderliness. If the items to be kept orderly are eliminated,
we also eliminate the practice of orderliness for those
items. Orderliness that no longer exists can hardly lapse
into disorderliness.
The “5S” Approach
A
Figure 4.50
B
B
Combination of Electric Screwdrivers.
The essential method for eliminating the need for orderliness is to find some way of performing a particular operation
with fewer tools. To do this, we need to look at each tool and
ask ourselves three simple questions:
1. “Why must I use this tool?”
2. “What is this tool’s basic function?”
3. “Is there some other way to perform that function without this tool?”
Sometimes we can find answers for all three questions and
eliminate some of the need for orderliness. (See Figure 4.51.)
The above questions will help us learn what the basic
functions of the tools are. If we have a wrench whose basic
function is to turn something, we may be able to think of
a way to turn that something without needing a wrench or
other hand tool. Figure 4.51 shows two such improvements:
screw rods whose tops have been replaced by hand-turnable
devices. These devices serve the same basic function as the
monkey wrench and the alien wrench, but the operator does
not have to pickup a tool to do the job.
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JIT Implementation Manual: Volume 2
“How can I do this task without this wrench?”
“How can I do this task without this wrench?”
Figure 4.51 Device for Eliminating Tool by Transferring Tool Functions.
As you can see, there are many ways we can make orderliness easier to maintain. Below is a summary list of the points
discussed above in the evolution of orderliness for jigs and
tools, or ways to keep orderliness from becoming disorderly.
Stage 0: No sense of orderliness; complete disorder.
Stage 1: Jigs and tools are kept in groups; easy-to-understand orderliness.
Stage 2: Visual confirmation of where to put back jigs and
tools; easy-to-confirm orderliness.
Stage 3: Knowing it by heart; orderliness so simple that
workers can maintain it with their eyes closed.
Stage 4: “Just let go” orderliness; we do not even have to
return it.
Stage 5: Orderliness that eliminates some of the jigs and
tools; we do not even have to use them.
Orderliness Applied to Cutting Tools
So far, we have talked about how to apply orderliness to materials and parts used in the factory, as well as to inventory and
in-process stock. There are still some tools, however, that we
The “5S” Approach
have not covered. Factories generally include a wide assortment of drill bits, saw blades, measurement tools such as calipers, and various other tools that are required for production.
This section looks at how orderliness can be applied to
these tools, too.
Orderliness for Cutting Tools
Figure 4.52 shows a few examples of cutting tools. The following are some of the ways we can apply orderliness to tools
like these.
◾◾ Layout of cutting tools
Cutting tools can be laid out in either a centralized or a
decentralized arrangement. A centralized arrangement,
in which the cutting tools are all kept in one place, is best
suited for tools that are not used very often. A decentralized arrangement, in which cutting tools are set out near
the machines that require them, is best suited for cutting
tools that are only used by certain machines.
◾◾ Placement of cutting tools
After deciding where to keep the cutting tools, we need
to determine how we will place them there. As with parts
placement, the two basic placement methods are the
function-specific method and the product-specific method.
Drill bit
Tap bit
Milling cutter
Saw blade
Figure 4.52
Types of Cutting Tools.
Bite
Grindstone
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JIT Implementation Manual: Volume 2
Ridged
sheet
Anti-rust
Felt
Figure 4.53
Storage of Cutting Tools.
Using the function-specific placement method, we
group together cutting tools that have similar functions
and place them in the same group. This method is better
suited for unit production systems.
With the product-specific placement method, we group
cutting tools according to which ones are needed to
manufacture which products. These groups of tools can
then be set as part of the production line. This method
is better suited for repetitive production.
◾◾ Storage of cutting tools
Cutting tools are no good without sharp edges. When
we store drill bits and tap bits, we must be sure they do
not rattle around against each other, which dulls their
edges. Figure 4.53 shows how cutting tools can be stored
in a manner that prevents such deterioration. The tools
should also be oiled to prevent rusting.
Orderliness for Measuring Tools
Figure 4.54 shows several types of measuring tools. We must
take extra care in handling and storing these tools, since they
are high-precision instruments. We must at least ensure that
they remain free of dirt, dust, and rust.
Orderliness for Oil
Since factory machines need routine oiling, oil containers
make certain regular routes through the factory, just like
migratory birds. The best way to manage these oil containers
is to color code them according to route.
The “5S” Approach
Ruler
Figure 4.54
Micrometer
Dial gauge
Calipers
Types of Measuring Tools.
Obviously, we first need to find out just how many types
of oil are used in the factory. Next, we observe which types
of oil take which routes through the factory. Then we can
color code the containers. We can then apply the same color
coding to the areas where each type of oil is supplied. An
example is shown in Figure 4.55.
1
1
1
2
2
2
Oil drums
3
3
Small
oil drums
3
Oil cans
Oil inlets in
machines
Figure 4.55
Machines.
Color-Coded Orderliness for Oil Containers and Oiled
◾
319
About the Author
Hiroyuki Hirano believes Just-In-Time (JIT) is a theory and technique to
thoroughly eliminate waste. He also calls the manufacturing process the
equivalent of making music. In Japan, South Korea, and Europe, Mr. Hirano
has led the on-site rationalization improvement movement using JIT production methods. The companies Mr. Hirano has worked with include:
Polar Synthetic Chemical Kogyo Corporation
Matsushita Denko Corporation
Sunwave Kogyo Corporation
Olympic Corporation
Ube Kyosan Corporation
Fujitsu Corporation
Yasuda Kogyo Corporation
Sharp Corporation and associated industries
Nihon Denki Corporation and associated industries
Kimura Denki Manufacturing Corporation and associated industries
Fukuda ME Kogyo Corporation
Akazashina Manufacturing Corporation
Runeau Public Corporation (France)
Kumho (South Korea)
Samsung Electronics (South Korea)
Samsung Watch (South Korea)
Sani Electric (South Korea)
Mr. Hirano was born in Tokyo, Japan, in 1946. After graduating from
Senshu University’s School of Economics, Mr. Hirano worked with Japan’s
largest computer manufacturer in laying the conceptual groundwork for the
country’s first full-fledged production management system. Using his own
I-321
I-322 ◾
About the Author
interpretation of the JIT philosophy, which emphasizes “ideas and techniques for the complete elimination of waste,” Mr. Hirano went on to
help bring the JIT Production Revolution to dozens of companies, including Japanese companies as well as major firms abroad, such as a French
automobile manufacturer and a Korean consumer electronics company.
The author’s many publications in Japanese include: Seeing Is Understanding: Just-In-Time Production (Me de mite wakaru jasuto in taimu
­seisanh hoshiki), Encyclopedia of Factory Rationalization (Kojo o gorika
suru jiten), 5S Comics (Manga 5S), Graffiti Guide to the JIT Factory Revolution (Gurafiti JIT kojo kakumei), and a six-part video tape series entitled
JIT Production Revolution, Stages I and II. All of these titles are available
in Japanese from the publisher, Nikkan Kogyo Shimbun, Ltd. (Tokyo).
In 1989, Productivity Press made Mr. Hirano’s JIT Factory Revolution:
A Pictorial Guide to Factory Design of the Future available in English.
Business Improvement
JIT Implementation Manual
The Complete Guide to Just-in-Time Manufacturing • Second Edition
Volume 2
Waste and the 5S’s
HIROYUKI HIRANO
“It is a book for manufacturing companies that are fighting desperately for survival and that will go
to any length to improve their factories and overcome the obstacles to success. One could even call
this book a ‘bible’ for corporate survival.”
—Hiroyuki Hirano
Known as the JIT bible in Japan, JIT Implementation Manual — The Complete Guide to Just-inTime Manufacturing presents the genius of Hiroyuki Hirano, a top international consultant with vast
experience throughout Asia and the West. Encyclopedic in scope, this six-volume practical reference
provides unparalleled information on every aspect of JIT— the waste-eliminating, market-oriented
production system. This historic, yet timeless classic is just as crucial in today’s fast-changing global
marketplace as when it first published in Japan 20 years ago.
Volume 2: Waste and the 5S’s provides a comprehensive overview of the concepts of waste in
manufacturing and methods of discovering, removing, and preventing the creation of waste. It also
teaches the 5S system, a method for organizing the workplace to eliminate waste, demonstrating how
to use red tags for visual control and signboards for visual orderliness. The book also illustrates how
to organize jigs and tools.
PP9024
ISBN: 978-1-4200-9024-6
90000
www.taylorandfrancisgroup.com
9 781420 090246
w w w. p r o d u c t i v i t y p r e s s . c o m
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 3
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 3
Flow Manufacturing –
Multi-Process Operations and Kanban
HIROYUKI HIRANO
Originally published as Jyasuto in taimu seisan kakumei shido manyuaru copyright © 1989 by JIT Management Laboratory Company, Ltd., Tokyo, Japan.
English translation copyright © 1990, 2009 Productivity Press.
CRC Press
Taylor & Francis Group
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© 2010 by Taylor & Francis Group, LLC
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Version Date: 20140812
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Contents
Volume 1
1
Production Management and JIT Production Management....... 1
Approach to Production Management................................................... 3
Overview of the JIT Production System................................................ 7
Introduction of the JIT Production System...........................................12
2
Destroying Factory Myths: A Revolutionary Approach............ 35
Relations among Sales Price, Cost, and Profit......................................35
Ten Arguments against the JIT Production Revolution.........................40
Approach to Production as a Whole....................................................44
Volume 2
3
“Wastology”: The Total Elimination of Waste..........................145
Why Does Waste Occur?....................................................................146
Types of Waste.................................................................................. 151
How to Discover Waste..................................................................... 179
How to Remove Waste......................................................................198
Secrets for Not Creating Waste...........................................................226
4
The “5S” Approach..................................................................237
What Are the 5S’s?.............................................................................237
Red Tags and Signboards: Proper Arrangement and
Orderliness Made Visible...................................................................265
The Red Tag Strategy for Visual Control............................................268
The Signboard Strategy: Visual Orderliness.......................................293
Orderliness Applied to Jigs and Tools................................................307
v
vi
◾
Contents
Volume 3
5
Flow Production......................................................................321
Why Inventory Is Bad........................................................................321
What Is Flow Production?..................................................................328
Flow Production within and between Factories.................................332
6
Multi-Process Operations....................................................... 387
Multi-Process Operations: A Wellspring for Humanity on the Job......387
The Difference between Horizontal Multi-Unit Operations and
Vertical Multi-Process Operations......................................................388
Questions and Key Points about Multi-Process Operations................393
Precautions and Procedures for Developing Multi-Process
Operations.........................................................................................404
7
Labor Cost Reduction..............................................................415
What Is Labor Cost Reduction?.......................................................... 415
Labor Cost Reduction Steps............................................................... 419
Points for Achieving Labor Cost Reduction........................................422
Visible Labor Cost Reduction.............................................................432
8
Kanban.................................................................................. 435
Differences between the Kanban System and Conventional Systems....435
Functions and Rules of Kanban........................................................440
How to Determine the Variety and Quantity of Kanban...................442
Administration of Kanban.................................................................447
9
Visual Control......................................................................... 453
What Is Visual Control?......................................................................453
Case Study: Visual Orderliness (Seiton)..............................................459
Standing Signboards..........................................................................462
Andon: Illuminating Problems in the Factory....................................464
Production Management Boards: At-a-Glance Supervision................. 470
Relationship between Visual Control and Kaizen.............................. 471
Index.............................................................................................. I-1
About the Author.......................................................................... I-31
Contents
◾ vii
Volume 4
10 Leveling...................................................................................475
What Is Level Production?................................................................. 475
Various Ways to Create Production Schedules...................................477
Differences between Shish-Kabob Production and Level Production.....482
Leveling Techniques..........................................................................485
Realizing Production Leveling............................................................492
11 Changeover............................................................................. 497
Why Is Changeover Improvement (Kaizen) Necessary?.....................497
What Is Changeover?.........................................................................498
Procedure for Changeover Improvement...........................................500
Seven Rules for Improving Changeover.............................................532
12 Quality Assurance.................................................................. 541
Quality Assurance: The Starting Point in Building Products..............541
Structures that Help Identify Defects.................................................546
Overall Plan for Achieving Zero Defects............................................561
The Poka-Yoke System.......................................................................566
Poka-Yoke Case Studies for Various Defects.......................................586
How to Use Poka-Yoke and Zero Defects Checklists.......................... 616
Volume 5
13 Standard Operations.............................................................. 623
Overview of Standard Operations.....................................................623
How to Establish Standard Operations..............................................628
How to Make Combination Charts and Standard Operations Charts.....630
Standard Operations and Operation Improvements...........................638
How to Preserve Standard Operations...............................................650
14 Jidoka: Human Automation.................................................... 655
Steps toward Jidoka...........................................................................655
The Difference between Automation and Jidoka...............................657
The Three Functions of Jidoka..........................................................658
Separating Workers: Separating Human Work from Machine Work.....660
Ways to Prevent Defects.................................................................... 672
Extension of Jidoka to the Assembly Line.......................................... 676
viii
◾
Contents
15 Maintenance and Safety......................................................... 683
Existing Maintenance Conditions on the Factory Floor......................683
What Is Maintenance?........................................................................684
CCO: Three Lessons in Maintenance.................................................689
Preventing Breakdowns.....................................................................683
Why Do Injuries Occur?....................................................................685
What Is Safety?.................................................................................. 688
Strategies for Zero Injuries and Zero Accidents..................................689
Volume 6
16 JIT Forms................................................................................711
Overall Management......................................................................... 715
Waste-Related Forms.........................................................................730
5S-Related Forms............................................................................... 747
Engineering-Related Forms................................................................777
JIT Introduction-Related Forms..........................................................834
Chapter 5
Flow Production
Why Inventory Is Bad
Why Does Inventory Accumulate?
Every year, when heavy rains hit the forest, the streams
and rivers suddenly swell and sometimes overflow. Most
river flooding is caused by localized downpours. The rivers
become wider and sometimes adjacent forks are reunited as
a single large river.
In factories, goods and materials should flow in the factory much as water flows in a river. But things tend to accumulate. We could say that the “river”—the flow of in-process
inventory—tends to “flood.” Needless to say, it would be
­better if this river of in-process inventory flowed smoothly
and briskly. The following are some of the main reasons for
such “flooding­” in factories.
Reason 1: Inventory flow is behind the times
It has been a long time since large lot production gave
way to the era of wide-variety, small lot production, but
some manufacturers still have not caught up. They try to
use the old “shish-kabob” production schedules to turn
out orders for a wide assortment of product models in
small lots and, not surprisingly, “floods” often occur at
certain processes.
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Reason 2: Old habits are hard to change
Some factory managers understand quite well that this
is the era of wide variety and small lots. But they do not
have the energy and courage to let go of old familiar ways
and make the necessary changes. Rather than t­rying to
“go with the flow,” they are just trying to stay afloat for
the years remaining until their retirement age.
Reason 3: Unbalanced capacity brings unbalanced inventory
Inventory shoots through the “rapids” of high-capacity
processes, but it naturally gets backed up when it reaches
processes having lower capacity.
Reason 4: Inventory is sometimes gathered from several
processes
Some processes, such as painting and rinsing ­processes,
often use large equipment that can handle in-process inventory sent from several processes. Naturally, the in-process
inventory from several processes accumulates at such
large equipment before being processed by it.
Reason 5: Inventory must wait to be distributed from large
processes
This is what happens at the downstream side of the large
equipment described under Reason 4. Each kind of processed inventory must wait its turn to be sent on to one
of several downstream processes.
Reason 6: Inventory must wait for a busy operator
Sometimes operators work sequentially on a number of
machines. We call this “caravan” operations. In-process
inventory tends to gather at each machine until the operator gets a chance to process it. In other words, inventory
gathers wherever the operator is not.
Reason 7: Inventory accumulates when operators dislike
changeovers
Inventory tends to gather at presses and other processes
where changeover is regarded as arduous work. The
operators would much rather do fewer changeovers by
handling large lots.
Flow Production
Reason 8: Inventory accumulates in factories that have
“end-of-the-month rushes”
This tends to happen at factories that have monthly
volumes to meet. The assembly line is especially busy
during the last five days of the month. In fact, workers
from all over the factory are called over to the assembly
line for the end-of-the-month rush. By the middle of the
month, the factory is chock-full of in-process inventory,
lined up to be assembled during this rush period.
Reason 9: Inventory accumulates due to faulty production
scheduling
Sometimes production planners are not knowledgeable
enough about inventory and include some noninventory
items as inventory. Such misunderstandings can lead to
incorrect inventory distribution planning when drawing
up production schedules.
Reason 10: Inventory accumulates when people forget to
revise standards
Once standards are set for lead-time, lot sizes, or acceptable defect rates, people forget to revise them. Soon
workshops start producing extra goods in anticipation
of a certain percentage of defectives. Surplus production
means surplus inventory.
Reason 11: People tend to store up “ just-in-case” inventory
Things do not always go as planned. Sometimes, new
developments in a company’s business activities will
require a sudden change in production scheduling. All
company divisions—from sales to management, purchasing, and manufacturing—like to keep a “safety margin”
of extra inventory around just in case a sudden change
of plans occurs. “Safety” is a misleading term here. What
these inventory buffers provide is not safety, but security
for the people in charge.
Reason 12: Inventory accumulates due to seasonal adjustments
No product sells at the same rate all year-round. Some
sell in cycles, and others have distinct seasons. No one in
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factories likes to deal with sudden and dramatic changes
in production. Instead, they try to smooth out the seasonal transitions by producing ahead of time in anticipation of extra orders when the product’s season arrives.
Obviously, this requires some stockpiling of inventory.
Thus, there are at least a dozen major reasons why inventory tends to accumulate in factories and throughout entire
companies. Unless the company’s various departments come
to grips with these reasons, inventory will keep on building
until it begins to sap the company’s strength.
Why Is Inventory Bad?
Most people regard inventory as a “necessary evil.” They feel
especially strong about an inventory’s necessity when sales
are brisk, but when sales sag inventory starts looking evil. So
it is a necessary evil—necessary today and evil tomorrow.
While most Western companies tend to look upon inventory as a necessary evil, most Japanese companies emphasize its wickedness. In fact, attitudes toward inventory is one
key characteristic of the difference between Western and
Japanese manufacturing systems.
In Japan, inventory is regarded as being so evil that it is
often called “the company’s graveyard.” Japanese managers
tend to view inventory as the root of all evil and a likely
cause of poor performance in any business activity.
But why is inventory so evil? Again, there are several
reasons:
Reason 1: Inventory adds to the company’s interest payment
burden
Inventory solidifies a lot of capital (as inventory assets) that
could otherwise be turned over for a profit. It puts pressure on operating capital and raises the interest payment­
burden. Therefore, it is clearly an obstacle to successful
business management.
Flow Production
Reason 2: Inventory incurs maintenance costs
Inventory is an investment of capital that does not of itself
contribute to profits. Moreover, inventory has to be managed and maintained, which adds to costs: warehouse
lease fees, insurance premiums, property tax, and so on.
Reason 3: Inventory means losses due to hoarded surpluses
and price cutting
When there is excess inventory, unused items undergo
age-related deterioration. They get hoarded up due to
their obsolescence or they are sold off at rock-bottom
prices, both of which hurt corporate profitability.
Reason 4: Inventory takes up space
Naturally, any inventory we have takes up a certain
amount of space. Eventually, the piles of inventory start
spilling over into the warehouse aisles, which leads to
building new shelves and even a new warehouse.
Reason 5: Inventory causes wasteful operations
Inventory causes goods to be retained. Retained goods
always require some kind of conveyance. Conveyance never
adds value to the product. Warehouse operations include
picking up, setting down, counting, and moving—none
of which add value (therefore, all of which are wasteful).
Reason 6: Inventory requires extra management
Warehouse operations need to be managed. Managers
have to keep track of when items are received at the
warehouse, when they are shipped out, and the current
amount of each item in the warehouse.
Reason 7: Inventory requires advance procurement of ma­
terials and parts
Companies that keep large warehouses make it a practice to order materials and parts even before client orders
come in. These parts and materials, however, do not
always match what is actually required by the orders.
Reason 8: Inventory incurs wasteful energy consumption
Building, operating, and managing warehouses means
greater energy costs incurred by electric, pneumatic, and
hydraulic equipment.
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These eight are just the more obvious reasons why inventory is bad. We have not even begun to consider other reasons
related to capital turnover, hoarding surpluses, and the like.
What, more than anything else, makes inventory evil? This
question deserves some sober contemplation. Let us look at a
few of the reasons that we have not yet covered.
First, there is the greater interest payment burden incurred
by inventory. Let us assume that a certain company has
plenty of money, and does not need to worry about paying
interest­. The managers at this company see no harm in having
­several warehouses for its factory. “Hoarding up ­surpluses”
is a problem at these warehouses, but the ­managers think
the way to solve this problem is by making products that
tend to sell briskly.
Let us reconsider the problems caused just by taking up
space. In a huge warehouse, wasted space is rarely noticeable.
If anything, we would get the feeling that not making use of the
immense warehouse is somehow wasteful. But the real waste
lies in having such a large facility to begin with. No matter­
how much capital a company has, no matter how quickly its
products sell, and no matter how much space its factory sites
include, inventory remains just as evil a thing as ever.
So what might we say is the real reason why inventory is
bad? I have found this most basic reason is: Inventory conceals all sorts of problems in the company.
There are a countless number of factories in the world.
Each factory must deal with a wide variety of problems every
day. Problems pile up even at the best factories, and there is
no such thing as a problem-free factory.
Let us compare problems in factories to rocks that pile
up at the bottom of a pond. When the pond is full of water,
we do not see any of the rock piles, but if we empty the
pond, they suddenly become obvious. Figure 5.1 illustrates
this analogy.
Keeping a large inventory of finished products in the warehouse enables the company to deal with the demands of
Flow Production
◾
Capacity
gaps
Late
deliveries
Equipment
breakdowns
Occurrence
of defects
Schedule
revisions
Product
diversification
High water volume (inventory volume) conceals the rocks
(problems)
Figure 5.1
How Inventory Conceals Various Problems Affecting the Company.
product diversification without having to address the problem
of why it takes so long to switch production from one product
model to another. It also enables the company to keep up with
schedule changes without having to question why schedule
changes are so hard to keep up with in the first place. Plentiful
warehouse supplies can also help fill in the production output
Capacity
gaps
Late
deliveries
Equipment
breakdowns
Occurrence
of defects
Schedule
revisions
Product
diversification
Low water volume (inventory volume) reveals the rocks
(problems)
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JIT Implementation Manual: Volume 3
gaps caused by equipment breakdowns, again without having
to take preventive action against the problem.
In short, a “well-stocked warehouse” gives people the illusion that they are solving these kinds of problems. Instead of
solving problems, they are just avoiding them.
As long as the company avoids problems by keeping a
large inventory, the problems continue to grow and lay down
deeper roots. The more unsolved problems there are, the
more inventory the company needs to compensate for them.
Eventually, the company becomes visibly weaker.
Today’s highly competitive era is no time to waste money
and energy on covering up problems. Challenging trends,
such as product diversification and shorter delivery d
­ eadlines,
create new problems every day. The successful companies
are the ones who not only learn how to respond rapidly
to today’s fast-changing marketplace, but also know how
to apply the same swiftness in dealing with problems—not
avoiding them.
What Is Flow Production?
Differences between Shish-Kabob
Production and Flow Production
I mentioned earlier that the factory “river”—the flow of inprocess inventory—tends to “flood.” A main reason for such
flooding is conventional lot production, which we might also
refer to as “shish-kabob production.” The shish-kabob image
is a natural one—workpieces move along in little clumps. In
other words, they are grouped into batches for batch processing at each workshop along the line. We can look at the
differences between shish-kabob production and flow production in various ways (see Figure 5.2). Let us look at some
of these in more detail.
Flow Production
Type of production
Point
of comparison
Shish-kabob production
1
Flow production
2
1
Approach
to
processing
Adds processing only
Press
workshop
Drill
workshop
Adds processing and raises
added value
Product A workshop
Press
Equipment
layout
Press
Drill
2
Product A
Drill
Product B workshop
Product B
Press
Job shop type
Flow workshop type
In-process
inventory
Approach
to
rationalization
One worker handle several
similar machines
Press
One worker handles several
different machines
Press
Press
Operators
Press
Bender
Bender
Press
Proficiency
Single-skilled operator
Multi-skilled operator
Worker repeats the same operation Worker repeats a group of operations
In-process inventory
A lot
Almost none
Lead-time
Long
Short
Equipment
High-speed, general-purpose,
Slow, specialized, small, inexpensive,
large, costly, emphasis on capacity emphasis capacity utilization
utilization
Production orientation Narrow variety and large lots
Space
Takes up a lot of space
Emphasis on efficiency within
Approach to efficiency processes
Conveyance
Quality
Figure 5.2
Wide variety and small lots
Does not take up as much space
Emphasis on efficiency throughout
the company
Required
Not required
Quality problems discovered only
after the lot is produced
Minimization of defects that cause
quality problems
Comparisons of Shish-Kabob Production and Flow
Production.
Difference 1: Approach to processing
Shish-kabob production uses large groups of workpieces at each processing point within a process station.
These groups (lots) are retained at the process until all
of the units in the lot are completed. By contrast, flow
production means that once each workpiece has been
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processed, it is sent to the next process for immediate
processing. This continuous moving flow continues until
each workpiece is completed as a finished product. There
is little or no retention of workpieces at the processes.
Difference 2: Equipment layout
For shish-kabob production, the equipment layout
usually has equipment grouped into rows of machines
that serve the same function. This is the “job shop” type
of equipment layout. Typical press workshops and lathe
workshops are two examples of this. Since flow production means processing and sending along one workpiece
at a time, there should be very little material handling
required, and preferably none at all. That is why flow
production requires that equipment be laid out according to the sequence of processes. Workshops are no
­longer “press workshops” or “lathe workshops.” Instead,
the equipment is laid out according to the product being
made. We call the equipment layout in such flow production workshops a “flow shop” or a “line” layout.
Difference 3: Approach to rationalization
In conventional job shops, rationalization often means
increasing the number of equipment units operated
by one worker. For example, in a press workshop,
rational­
ization might mean assigning three presses to
a worker who has been operating only two. In a flow
shop, we ­cannot assign several units of the same type
of equipment to a single worker, since that would interrupt the one-piece flow of workpieces from process
to process. Instead, individual workers learn to operate several d
­ ifferent kinds of equipment corresponding
to the different processes along the line. We call this
“multi-process operations.” (For a more detailed description of multi-process operations, see Chapter 6.)
Difference 4: Operators
No matter how many equipment units each worker operates in conventional job shops, the worker sticks to a
Flow Production
single set of skills as a press operator, a lathe operator,
or whatever. In flow shops, workers learn several sets of
skills needed to operate a series of different processes,
such as press → drilling → bending. We call such workers “multi-process workers.”
Difference 5: In-process inventory
In the shish-kabob production system, in-process inventory is found as lots retained between processes and
between machines. In flow production, where workpieces continually flow from one process to another,
there is rarely any in-process inventory retained between
processes or machines.
Difference 6: Lead-time
Shish-kabob production tends to create long lead-times
because of the many times when lots are retained while
waiting for the previous lot to be processed or for the
rest of the same lot to be processed. When flow production keeps workpieces moving all the way until the final
process, the lead-time can be reduced to the level of the
total processing time.
Difference 7: Equipment
Shish-kabob production lacks any kind of overall flow
from raw materials processing to final product assembly.
This makes it very difficult to sense rhythm in the ­factory
operations. The only kind of rhythm that might be e­ vident
is the pitch at which individual workers operate individual machines. This is called the “individual rhythm.”
Shish-kabob production managers seek to improve f­actory
operations via greater speed, which requires ­
general
­purpose machines that can quickly process various types
of workpieces. However, general purpose machines tend
to be large and expensive. When large and costly machines
are installed, the factory managers naturally become concerned with maintaining a high capacity utilization rate
by turning out more and more products. Meanwhile,
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the factory becomes one that is more concerned with its
equipment than with its customers.
Flow production takes an almost completely opposite
approach by emphasizing a smooth production flow all the
way from materials processing to final product assembly.
There is a clear overall rhythm to production, and the tempo
of this rhythm is set by customer orders. Each machine along
the production line is like a bar of music. There is no need to
hurry the tempo. Production should always be slow enough
to remain in the overall flow. There is also no need to hurry
when changing over to other product models. Each machine
should serve only one main function, operating like a bar of
music in the symphony of production. Each machine should
be a specialized machine that emphasizes quality over speed.
These specialized machines should serve only the minimum
required function and should be compact enough to fit right
into the production line. Naturally, these slower, more specialized machines are inexpensive and therefore do not invite
concern over capacity utilization rates. Instead, the major
maintenance concern is to ensure a high possible utilization
rate (that is, high serviceability) to prevent disruptions in the
production flow.
Flow Production within and
between Factories
“Flow” can mean the gurgling flow of tiny brooks amid the
rocks or the quiet majestic flow of a wide river spanned by
long bridges. In the factory, the smaller parts lines are like the
brooks and the large final assembly lines are like the wide
rivers. The streams eventually converge into rivers, and the
flow (of goods) ultimately reaches the sea (the marketplace).
Factories need to have a smooth flow of operations, and
the basic method for creating such a flow is by making
Flow Production
individual improvements. These improvement “points” add
up until they form a “line” of improvements. This line is the
flow between processes.
Eventually, we also need to have a smooth flow of production operations between manufacturers and the vendors, subcontractors, and wholesalers or distributors that they work with.
This kind of flow is a vertical flow between factories, and the
­corresponding improvements are called vertical improvements.
Therefore, when we discuss flow production, we must be
aware of the kind of flow production we are talking about.
The main distinction to make is between flow production
within a factory and flow production between a factory and
another factory or business.
1. Flow production within a factory. To establish this kind
of flow production, we must eliminate the in-process
inventory that accumulates at and between processes as
“flood water” or “shish-kabob clumps.”
2. Flow production between factories. We must also establish
a smooth flow of operations between our own factory
and the various subcontractor factories, vendors, distributors, and other businesses that our factory deals with.
Flow Production within the Factory
Eight Conditions for Flow Production
Making things requires various techniques. Many of the techniques used in manufacturing are based on two engineering
technologies: pressing and drilling (or punching).
So we might ask whether JIT improvement is meant to
also improve these essential engineering technologies. The
answer is yes. JIT improvement means radical improvement,
which means it goes into the very basic engineering technologies. But that is not the main point of JIT improvement.
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Products
Linked technologies (technologies
that raise the degree of
Bending
processing) in
JIT production
Punching
Pressing
Shearing
Painting
Engineering technologies
(technology that adds
processing)
Materials
Figure 5.3
Linked Technologies in JIT Production.
The engineering technologies, such as pressing and drilling
(or punching), are technologies for processing workpieces.
Of course, no matter how many times a press adds processing to a workpiece, it will not be enough to turn out a
finished product. Manufacturing products requires an assortment of materials plus several engineering technologies,
among which pressing is just one.
The main work of JIT improvement is to link these engineering technologies in a production system that is attuned
to customer needs. (See Figure 5.3.)
While engineering technologies add processing to workpieces, linked technologies raise the degree of processing.
Accordingly, the basic aim of JIT production is to make things
one at a time, in a smooth flow, to prevent defects.
The following is a list of eight conditions that must be met
to establish one-piece flow production.
Condition 1: One-piece flow
Condition 2: Lay out equipment according to the sequence
of processes
Condition 3: Synchronization
Condition 4: Multi-process operations
Condition 5: Training of multi-process workers
Condition 6: Standing while working
Flow Production
Condition 7: Make equipment compact
Condition 8: Create U-shaped manufacturing cells
Condition 1: One-Piece Flow
One-piece flow is the most basic of all eight conditions; it
is where flow production starts and ends. One-piece flow
refers to the condition in which each workpiece must be
processed and passed along the production line by itself,
and that includes assembled quasi products. One-piece flow
sounds simple enough in theory, but putting it into practice
can be very difficult indeed.
Whenever we inspect the production line and find places
where “shish-kabob clumps” of in-process inventory have
accumulated, we need to find out why it happened. Perhaps
the equipment units are not lined up according to the processing sequence, or perhaps the processes are not synchronized.
There is always some reason, and it usually includes a human
factor: resistance to change. That is why it is so important
that everyone understands what JIT is about from the outset.
Without prior understanding, things are bound to fail.
JIT Production
(Ideas and Techniques for the Total Elimination of Waste)
Uncovering
One-piece flow (ideas and
techniques for the total
uncovering of concealed waste)
Conveyance
waste
Defect production
waste
Movement
waste
Observation
waste
Large equipment
waste
Inventory
waste
Movement
waste
Capacity imbalance
waste
Idle time
waste
Inspection
waste
Overproduction
waste
Waste inherent
in processing
Concealed waste
Figure 5.4
One-Piece Flow.
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JIT production means ideas and techniques for the total
elimination of waste. We must begin by uncovering all of the
deeply rooted concealed waste in the factory. Switching to
one-piece flow is the best way to do this. If I may p
­ araphrase
the JIT definition: One-piece flow means ideas and techniques
for the total uncovering of concealed waste. (See Figure 5.4.)
Unfortunately, one-piece flow is not something we can
achieve simply by rearranging the equipment according to
the processing sequence and retraining the workers in new
operation procedures. Rather, it is a first step in a process
that includes uncovering concealed waste in the factory. That
is why we should begin by switching over to one-piece flow
using the current equipment layout and operation procedures.
This will show us where the hidden waste is, such as conveyance waste, waste caused by having large equipment, and so
on. Once we have uncovered all of this waste, we are more
than halfway there since we have learned how to redesign
the layout to eliminate the conveyance waste (by eliminating
conveyors), large equipment waste (by using only compact
equipment), and other waste.
The key to success in all of this is whether or not we are
truly resolved to implement one-piece flow production.
Condition 2: Lay Out Equipment according
to the Sequence of Processes
After we have started giving one-piece flow a try, we first
notice conveyance waste staring us in the face. If the line
was conveying workpieces between processes in lots of 100,
it suddenly becomes obvious that 100 units of conveyance
waste had been concealed in each lot.
One-piece flow changes all of that. Once a process is
completed, the workpiece is immediately moved along to
the next process. Under current conditions, that means each
workpiece must be moved along via the existing conveyance
system. The amount of time and trouble built into that system
suddenly becomes 100 times greater. That makes it obvious
Flow Production
enough for the workers to notice the tremendous amount of
waste involved. With that awareness, they are ready to start
changing the equipment layout.
In redesigning the equipment layout, they now know the
idea is to minimize conveyance or, better yet, eliminate it altogether. They can do this by lining up the equipment according
to the processing sequence. This kind of line up is the standard for all flow shops and flow-oriented production lines.
Condition 3: Synchronization
Once we have set-up the equipment for flow production, we
need to consider how fast the flow should be; in other words,
at what pitch the processes should be operated. Unless we
have a common pitch among processes, workpieces will accumulate at the slower processes and cause the flow to “flood.”
Synchronization means maintaining the same pitch among
the various processes. In the final analysis, the pitch should
be determined (as so many minutes and seconds) by the
amount of orders from customers. This time figure is called
the cycle time. The cycle time sets the rhythm for the “music”
of manufacturing. (Cycle time is discussed in more detail in
Chapter 10 of this manual.)
Condition 4: Multi-Process Operations
One-piece flow production can be achieved without any
multi-process operations. (See Chapter 6 for further description of multi-process operations.) Instead, we can simply
assign one worker to each process and have them process
and hand along workpieces according to the established
pitch. Figure 5.5 illustrates this kind of arrangement, which
we might call “hand-transferred one-piece flow.”
One problem with the hand-transferred one-piece flow
arrangement is that requiring one worker at each process makes
it difficult to add or subtract workers to adjust for changes
in scheduled output. Such adjustments are the aspect of JIT
known as “manpower reduction” (described in Chapter 7).
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Hand-transferred one-piece flow
One-piece flow using multi-process operations
Figure 5.5
Two Types of Flow Production.
The idea is to have just the minimum amount of manpower
needed to produce the scheduled amount of output.
Another problem with the hand-transferred one-piece
flow arrangement is that it encourages workers to think of
themselves in strictly defined job roles, such as press operator, drill operator, or inspector. This reduces manpower flexibility and makes it hard for the idea of “building quality in
at each process” to take hold among the workers.
These are two reasons why JIT production calls for flow
production using multi-process operations. Multi-process operations move vertically along the production line by h
­ aving
workers operate as many processes as possible. This is quite
different from multi-unit operations, in which workers­expand their work horizontally in the production line by operating several of the same type of machines performing the
same process.
Flow Production
Condition 5: Training of Multi-Process Workers
Multi-process workers are workers trained to handle several
processes together. Conversely, we call workers that handle
only one process “single-process workers.” (See Chapter 6 for
a detailed description of multi-process workers.)
Training multi-process workers is a key step toward achieving
JIT flow production. This training can be extended company­
wide over the short term to include:
◾◾ Thorough standardization of machines and other equip­
ment so that anyone can more easily learn to operate them;
◾◾ Equally thorough standardization of operations, eliminating special or exceptional cases;
◾◾ Company-wide multi-skill training as an important part
of company-wide improvement.
Condition 6: Standing While Working
In most machining workshops, workers traditionally stand
while working. However, assembly lines such as at home electronics and electrical equipment manufacturers are usually
operated by workers who sit while working. The s­ witchover
to standing while working can create serious problems at
such places. It may take a long time indeed before such
assembly workers are convinced of the need to stand while
working. (One wonders if it might even take as long as it
took our primeval ancestors to switch from walking on all
fours to walking on their legs only!)
About the only way to succeed in this difficult transition
and overcome workers’ reluctance to stand is by getting the
entire company deeply involved—including the president
and other top managers—in pointing out the advantages that
standing while working brings, i.e., easier movement, helping each other out when necessary, correction of unbalanced
operations, multi-process operations, and much more.
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Condition 7: Make Equipment Compact
If one workpiece is about as big as a fist, then a lot of ten
workpieces would be about the size of a bread box and a
100-workpiece lot would be as large as a washing machine.
To handle lots of 100 workpieces each, we need a conveyor that can easily move washing machines. Likewise, the
processing machines and other equipment must also be able
to handle washing machine-size lots.
In other words, the equipment has to be big, so big that
much of it will not fit into a small production line. In most
cases, we must set such large equipment aside somewhere as
a processing “island.”
Sometimes, those expensive general purpose machines
advertised as being able to do just about anything end up
doing nothing well. JIT production has no use for machines
like these. Instead, we should try to use only compact
Straight-line flow production
Input
Output
Walk
ing w
a
ste (r
eturn
trip)
U-shaped manufacturing cell flow production
Input
Output
Figure 5.6
Flow Production Examples.
Flow Production
machines that can be arranged and rearranged into the line
at a moment’s notice and that are not so expensive that we
have to worry about their capacity utilization rates.
Condition 8: Create U-Shaped Manufacturing Cells
This is another topic that does not directly relate to one-piece
flow production. In some cases, it is fine to have a straight
line for flow production. However, if we have one-piece flow
production using multi-process operations, it is wasteful to
require a worker who operates a series of processes along a
straight line to walk all the way back from the final process
to the starting one to get the next workpiece. This is where
U-shaped manufacturing cells come in. (See Figure 5.6.)
What Is the Best Way to Eliminate This Kind of Waste?
We should try to arrange the input and output points as close
together as possible. For short, we call this the “I/O matching
principle.” The closer the input and output points are, the less
walking waste we will create.
These curved lines are called U-shaped manufacturing
cells because they usually end up having a shape like the
letter “U.” However, they can just as well be arranged like
circles or triangles if that works better. The exact shape of
the cell should be determined based on such factors as the
overall flow of goods in production, elimination of waste,
and available space.
Of the above eight conditions, the most important by far
is the first: one-piece flow. If we think switching to one-piece
flow is too difficult and give up on it, we may end up
­handling lots of ten workpieces without ever realizing how
much waste those breadbox-size lots create. People will start
assuming that ten-unit lots are the smallest lot size possible
in flow production.
But if we hang in there and manage to establish onepiece flow, we will hold the key to great success in eliminating waste.
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The other seven conditions are like walls that protect the
fortress of one-piece flow. Among these, Condition 4 (multiprocess operations) would take prominence as the front
wall and Condition 2 (lay out equipment according to the
sequence of processes) would form the rear wall.
We can group these eight conditions according to the production factors they relate to most directly.
1. Equipment
a. Condition 7: Make equipment compact
2. Equipment layout
a. Condition 2: Lay out equipment according to the
sequence of processes
b. Condition 8: Create U-shaped manufacturing cells
3. Operation methods
a. Condition 1: One-piece flow
b. Condition 3: Synchronization
c. Condition 4: Multi-process operations
d. Condition 6: Standing while working
4. Operators
a. Condition 5: Training of multi-process workers
Let it be clear from the outset that we can expect to run
into many obstacles—equipment problems, capacity imbalances, and the like—as we work to establish these eight
conditions in factory workshops. But the biggest obstacle is
human resistance. We have to get people to drop all those
tired old ideas, such as “This equipment can’t be moved,” or,
“We’ll lose money if we don’t have lot production.”
The best way to ensure success in establishing these eight
conditions for one-piece flow production is to first get the
people to “go with the flow” of JIT production.
Flow Production
Create
U-shaped
manufacturing
cells
Synchronization
Multi-process
operations
Lay out
(line up)
equipment
according to
sequence of
processing
Establish
one-piece flow
Standing
while working
Train multi-process
workers
Compact
equipment
(One-piece) Flow Production
Preparation:
Production analysis
Install casters on equipment
Select a model line
Groundwork:
Awareness revolution
The 5S’s
Figure 5.7 Interrelationship of Factors in (One-Piece) Flow Production.
Figure 5.8
In-House Seminar on JIT Production.
Steps in Introducing Flow Production
In establishing flow production—a basic part of JIT production—we need to rearrange the production equipment, but
we do not have to find the perfect arrangement the first time.
Instead, we should follow a series of experimental steps that
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well help us get closer to success. Figure 5.7 illustrates how
various factors interrelate in flow production.
Let Us Look at Each of These Factors, Starting from
the Groundwork—Two Types of Groundwork Must Be
Laid before We Can Start Introducing Flow Production
1. The awareness revolution
Everyone at the company should be taught to discard
long-established notions about everything from lot sizes
to inventory and conveyance and to understand and support the JIT production philosophy. JIT study groups and
in-house seminars are useful means of establishing the
JIT awareness revolution. (See Figure 5.8.) (The awareness revolution is described in detail in Chapter 2.)
JIT production can be described and discussed in
study groups and seminars. To really learn it, however,
we have to practice it. After we have practiced the various
procedures and steps for a while, we begin to develop
a “feeling” for JIT; only then are we truly learning it in
both heart and mind.
2. The 5S’s
The 5S’s are described fully in Chapter 4. The S’s are the
first letters in the Japanese words seiri (proper arrangement), seiton (orderliness), seiso (cleanliness), seiketsu
(cleaned up), and shitsuke (discipline). The first two
S’s are the most important, and use two indispensable
tools: the red tag strategy and the signboard strategy. All
improvement activities should start with reinforcing the
5S’s, particularly by using these two strategic tools.
Preparation for Flow Production
Once we have made some headway in establishing the awareness revolution and the 5S’s, we are ready to enter the preparation
stage for flow production. We can facilitate making improvements for flow production by analyzing the production data
needed for building a model line, then selecting a model line.
Flow Production
Analysis by: J. Smith
P-Q Analysis List
Analysis Period:
No.
Item (part number) Quantity
Total
%
Total %
1
RA1103
15,900
15,900
17.5
17.5
2
RB0121
12,500
28,400
13.7
13.7
3
RC1631
11,700
40,100
12.9
12.9
4
RD1911
9,450
49,550
10.4
10.4
5
RE0314
9,400
58,950
10.3
10.3
6
RF1213
9,000
67,950
9.9
9.9
Figure 5.9
Date:
11/16/89
10/1/89 to 10/31/89
Management category
A
B
C
P-Q Analysis List.
As a third preparatory step, we need to install casters on equipment units to facilitate their rearrangement into new layouts.
Preparatory Step 1: Production Analysis
Three types of analyses will help us understand flow production: P-Q analysis, arrow diagrams, and process path tables. We
can use these three tools to eliminate waste and pave the way
for lining up equipment according to the processing sequence.
P-Q analysis. The P stands for products and the Q for quantity (production output). By analyzing the relation between
products and quantity, we can make a distinction between
“flow of quantity” and “flow of product models.” This will
help us line up processes for flow production. The steps in
P-Q analysis are described below:
Step 1: Obtain three or six months’ data on product (or
parts) and production output.
Step 2: Figure the total production output from the obtained
data, list products in order of highest quantity to lowest
quantity, then find their proportionate percentages. Write
these on a P-Q analysis list, such as the one shown in
Figure 5.9.
Step 3: Create a P-Q analysis table based on the P-Q list.
(See Figure 5.10.) The vertical axis on this table indicates
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P-Q Analysis Chart
Creation date: 11/16/89
Created by: J. Smith
R-x related items
100
%
90
82.4% (75,000)
80
74.7% (67,950)
Total: 90,940 units
70
20,000
60
54.5% (49,550)
50
15,000
40
10,000
30
20
5,000
Figure 5.10
850
1,140
900
1,450
1,550
3,200
6,850
7,050
9,000
9,400
9,450
RM &
RA RB RC RD RE RF RG RH RI RJ RK RL RM others
Empty
Part (P)
11,700
Quantity (Q)
12,500
10
15,900
346 ◾
Total
P-Q Analysis Table.
the production output (quantity) and the horizontal axis
shows the products. Then we can use the output amounts
to make an analysis of product groups A, B, and C.
Step 4: Design a line of processes based on the P-Q analysis
list. As shown in Figure 5.11, the A group is a specialized
line for building quantity, while the B group and C group
lines are ordinary lines that build product models.
Flow Production
A group: about 70%
B group: about 70% to 95%
C group: about 95% to 99%
A
“Quantity-building line”
Specialized line
“Product model-building line”
Ordinary line (GT)
B
C
No line
Q
Other
P
Figure 5.11
Line Design Using P-Q Analysis.
Factory:
Tokai Plant
Process Path Table
Entered by:
Shin’ichi Yamagawa
Process name Cutting Drilling Punching Punching Press
Machine no. M1
M2
M3
M4
M5
No. Item
1 110931 (side board)
1
2
3
2
130106 (side board)
1
2
3
3
161137 (side board)
1
3
4
1316171 (top board)
1
2
5
1315021 (top board)
1
Figure 5.12
2
Press
Press Bending Bending Bending
M6
M7
4
M8
4
4
M9
5
M10
6
5
5
3
2
Date:
January 10, 1989
6
4
3
4
Process Route Table.
The key factors in ordinary lines are Group Technology
(GT) lines and changeover. GT lines are lines that turn out
different products (or parts) that have similar process paths
and can therefore use the same line configuration. We group
such lines together as one line in the process path tables. We
can improve GT lines by combining tool functions into fewer
tools and by establishing simple changeover procedures.
Arrow diagrams. Before establishing flow production in
the factory, we need to clarify how goods will flow and
remove major forms of waste from retention and conveyance
points. Arrow diagrams are tools for doing just these things.
(Arrow diagrams are described in Chapter 3.)
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Process route tables. Process route tables enable us to see
what kind of machines and other equipment are needed for
processing a certain workpiece and what path these processes
should take. As such, they are indispensable aids for creating ordinary lines and grouping workpieces. These grouped
lines are called GT lines. (See Figure 5.12.)
As can be seen in Figure 5.12, machines and other equipment are listed horizontally on the table and names of parts
or other items are listed vertically. This provides a clear indication of which parts are handled by which machines and in
which order. Once we can see this, we can more easily find
the parts that use the same or similar machines in the same
or similar order and group those parts together in a GT line.
The main purpose of this type of GT line is to eliminate or
greatly simplify the changeovers needed when switching to
new product models.
Preparatory Step 2: Select a Model Line
Start this step by finding the most enthusiastic workshop in
the factory, then make that workshop the model line. You
can choose the model line based on the workshops involved
in making a certain product, or based on specific processes
or workshops. The important thing is to establish a model
that clearly shows to everyone in the company how flow production works in a line and what kinds of things it involves.
The first thing to inquire about when selecting a model is
the enthusiasm of workshop-level leaders, such as the foremen.
Workshops that have weak leadership are much more likely to
fail than those with strong leadership. Strong, energetic workshop leaders are a good sign of a highly active workshop.
Once you select a model line, put up a large sign with the
words “JIT Model Line” and the target date for completion
of the line. This will help cultivate the seeds of awareness
and generate enthusiasm among the workshop staff for being
chosen as leading examples for their factory. It will also help
draw attention to what is happening in the model line.
Flow Production
Figure 5.13
The Caster Strategy.
Preparatory Step 3: The Caster Strategy
It has always been a good idea to make equipment as movable as possible so that it can be easily rearranged into the
most efficient layout for the particular product model being
manufactured. However, many equipment units are bolted
to the floor, the usual reasons being that they are either too
bulky and heavy to move, or their high-precision mechanisms are too fragile to be moved. Once equipment gets
bolted down, we must move the workpieces to the equipment rather than vice-versa. This makes one-piece flow production too difficult, encouraging factories instead to opt for
shish-kabob production. Bolted-down equipment can make
layout improvements difficult indeed. We need to put casters
on as many equipment units as possible, so that we can rearrange machines, work tables, and other equipment whenever
the need arises. In JIT, this is called the “Caster Strategy.”
A word of caution about the caster strategy: Be sure to
install casters on machines and work tables in such a way that
they do not significantly change the height of the equipment.
The photo in Figure 5.13 shows a “caster dolly” device that
avoids having to install casters directly underneath the equipment. This device raises the equipment’s height only slightly.
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There should be about 10 millimeters of clearance between
the frame and the floor to ensure smooth movability.
Procedure for Flow Production
We have finished the preparation for introducing flow production: We have launched the awareness revolution establishing the 5S’s, and put various tools and strategies to use,
such as production analysis, model line selection, and the
caster strategy. Now it is time to follow the steps for introducing flow production.
Introductory Step 1: Use One-Piece
Flow to Flush Out Waste
Flow production has two stages. The first stage comes before
establishing JIT production and is concerned primarily with
using one-piece flow to reveal concealed waste in the f­actory.
The second stage is where we must establish the various
conditions needed for full-fledged flow production, in which
one-piece flow can be maintained without creating waste.
Let us have a closer look at each of these stages.
◾◾ Stage 1: Revealing concealed waste with one-piece
flow.
At this stage, we need to “force” one-piece flow onto
the current set-up, which means the current equipment,
layout, and operation methods. This can be for just two
processes, if you wish. Even if the workshop staff is reluctant and uncooperative, this “experiment” in one-piece
flow production must be carried out.
At this point, it is best if we can train single workers
to handle all of the processes that have been switched
over to one-piece flow, but it can be done with a worker
at each process, if necessary. It does not matter how
odd or unorganized things look: Just carry out one-piece
flow under the current conditions. This alone will flush
Flow Production
out waste related to conveyance, large equipment, and
unbalanced operations.
When waste has been revealed in this way, we confirm the waste and then eliminate it. This should not cost
money. All we need is our wits and our muscles. This is
what making improvements is all about.
This experimental switchover to one-piece flow for
flushing out waste is also very important as a vehicle for
teaching the spirit of JIT right from the start, before people have come to understand JIT fully. In other words,
they are learning the form first to get a feeling for JIT. In
this way, JIT improvement is an art similar to the oriental
martial and aesthetic arts, such as karate, judo, flower
arrangement, and the tea ceremony.
Figure 5.14 shows two diagrams of a diecast deburring
line. This line includes two processes—a pressing process and a drilling process, each in a different workshop.
The current set-up is for lot production; workpieces are
handled in 500-unit lots.
Under this lot production set-up, no one notices the
waste involved in conveying 500-unit lots along a distance of 120 meters. However, when we switch this
over to flow production, each individual unit must be
conveyed the 120 meters, and the waste becomes quite
­obvious. Once everyone has been impressed by how
much concealed waste there was in conveyance alone,
we can make an improvement to eliminate that waste.
Obviously, this first switch to one-piece flow will mean
considerably lower productivity. But making improvements involves more than simply raising productivity.
Lowering productivity by revealing waste is a “teaching
tool” that enables us to clearly recognize the waste.
◾◾ Stage 2: Maintain one-piece flow so as not to create waste.
Once we have understood where waste lies in our
conveyance system and operational imbalances, we
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Before revealing waste
with one-piece flow
After revealing waste
with one-piece flow
Press
Press
500 units
500 units
120 m
500 units
500-unit lots conceal
120 meters of
conveyance waste
(120m/500 units)
Figure 5.14
1 units
120 m
Multi-spindle
drilling
machine
500 units
500 units
Multi-spindle
drilling
machine
1 units
500 units
When each of 500 units
needs to be conveyed
120 meters, the conveyance
waste becomes obvious.
Using One-Piece Flow to Reveal Waste.
can change the equipment layout into a closely-linked
one-piece flow line to prevent this waste from being
created again.
Figure 5.15 shows a line of cutting processes for automotive parts. Before making improvements, this line
included widely separated workshops, was operated by
four workers, and had multi-process operations only for
some of the cutting processes.
Flow Production
After improvement
Cutting
Cutting
Cutting
Drilling
Cutt
ing 3
Cutting
NC
machine
Drilling
NC
machine
Cutting 1
Manual
work
procedure
Cutting 4
Cutting
2
ing
Cutt
Cutting
5
ing
Cutt
Before improvement
200 units
After
processing
(products)
Workpieces moved among processes in
200-unit lots (operated by four workers)
Figure 5.15
Before
processing
(materials)
One-piece flow without waste
(operated by two workers)
Maintaining One-Piece Flow without Creating Waste.
Then came the improvements. The scattered equipment
units were brought together into a flow-oriented line from
start to finish, and everything was set-up for one-piece
flow production. This enabled the total elimination of
in-process inventory, made the overall flow clearly v­ isible
and comprehensible to everyone, and enabled early detection of defects. Moreover, human work was separated
from machine work, and this enabled a manpower reduction from four workers to just two.
Introductory Step 2: Arrange the
Equipment in the Order of Processing
So far, we have pointed out conveyance waste, eliminated the
conveyance system, set-up a way to move workpieces with
a minimum of material handling, and rearranged the equipment layout. At this point, we are still faced with several
problems. Many equipment units do not have casters and are
difficult to move. And some of the larger equipment units are
too big to fit directly into the line, which creates bottlenecks
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Input port
Waiting tray
Output port
Figure 5.16
Compact Shotblaster.
at the isolated equipment units. Therefore, our next step is to
find ways to make the equipment more movable­and compact. Again, we should be using our wits and not spending
much money to make these improvements.
There is no need to use large and expensive general purpose machines that can quickly process various kinds of
workpieces in large lots. Instead, we need to be only as fast
as the cycle time, and we must stress the need for compact,
inexpensive machines that specialize in reliable, high quality­
processing of certain types of workpieces. To do this, we
must develop skills in grasping the basic function of each
process and selecting or designing equipment that serves
precisely that function.
Figure 5.16 shows a newly developed compact shotblaster.
Previously, lots of 500 units each were divided into large
batches and loaded onto pallet containers for shotblasting.
Flow Production
They used a large shotblaster which can handle large batches,
but cannot prevent the diecast units from colliding and denting each other. About 10 percent of the units were rendered
defective by this shotblaster. The shotblaster’s batch processing also meant that there were large piles of in-process
inventory on either side of the shotblaster.
To eliminate dent defects and in-process inventory while
reducing manpower, this company worked with the equipment’s manufacturer in developing a compact shotblaster that
could fit into the flow-oriented line.
Figure 5.17 shows an example of a compact washing unit.
This washer is used to wash flax from soldered motor parts
on a motor assembly line. Prior to this improvement, the
parts were conveyed to a larger washer. This became quite
impractical under one-piece flow production, especially since
the previous system used lots of 200 workpiece units. The
company made this compact washer, which was able to be
inserted into the conveyor line, and this rearrangement alone
eliminated the conveyance waste, retention waste, and manpower waste created by the large washing unit.
Preparatory Step 3: Standing While Working
We have gathered two or three processes into a line and
have left the operators on their stools to operate one process
each using one-piece flow instead of shish-kabob lots. The
seated operators can hand-pass the individual workpieces
down the line. Once this set-up starts working smoothly,
we are ready for the first step in multi-process operations:
standing while working. The operators should first learn to
handle one process at a time on their feet. Standing while
working has different characteristics depending upon the
type of line involved. Let us look at how standing while
working can be established first for an assembly line and
then for a processing line.
Standing while working at an assembly line—Most
assembly operations use conveyors to produce an even
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Before improvement
Isolated “island”
Large
washing unit
In-process inventory from
several other processes
accumulates at the
washing unit.
40 meters of conveyance
are created here.
Final
assembly
Finished
products
Motor
assembly line
200 units
After improvement
Compact
washing unit
In-line layout eliminates waste
created by conveyance and
in-process inventory, and also
enables manpower reduction
of three workers.
Motor
assembly line
Finished products
Figure 5.17
Compact Washing Unit That Fits into the Production
Line.
production flow. Figure 5.18 shows workers standing while
working at a VCR assembly line.
The photo in Figure 5.18 shows a free-floating assembly
line that is 90 meters long. The workers in this photo had
been seated while working until just a few days before the
photo was taken. When the workers were seated, they tended
to wait until workpieces were directly in front of them before
Flow Production
Figure 5.18
Standing While Working at an Assembly Line.
they picked them up to assemble them. Because the assembly­
workers were not balanced well (that is, they worked at different speeds), some workers spent a lot of time just waiting­
for the next workpiece to arrive.
Figure 5.19 shows a line balance analysis table that we can
use to record the operation times for each worker. This table
helps us understand how to rearrange labor at bottleneck-prone
processes and achieve an overall balance in line operations.
However, such “analytical line balancing” does not always
work well when put into practice. There are three main
­reasons why this can happen.
Reason 1: Rapid product diversification prompted the f­ actory
to switch product models while operation time analysis
was still in progress.
Reason 2: At long last, we have finished the analysis. But
by the time we are ready to put the results into practice,
the corresponding product’s life cycle has ended and the
factory has switched to a new product.
Reason 3: The workers are part-time workers (such as working mothers) and the turnover rate is high. Absenteeism
is also rather unpredictable.
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Line Balancing Analysis Chart
Product name:
PCB-01-03
Lot size:
300
Line name:
Line A
Units per day:
300
Conveyor No.:
Operating time:
480 seconds
Line balance loss
= 32%
Item processing
interval:
Date:
November 16, 1988
Total processing time
Number of workers
Conveyance workers:
8
Relief workers:
Pitch = 96 seconds
Total pitch = 768 seconds
Time
60’ 72 56 75 82 57 69 52
Process
name
Insert 2
Insert 3
Insert 4
Inspection
Soldering
Inspection
Assembly
Net time: 523 seconds
Insert 1
Process times
ST (m)/unit
By:
Yamagawa
Time pitch:
Line
Total of worker operations times
balance =
Pitch time × number of workers
efficiency
= 100 – line balance efficiency
110
100
90
80
70
60
50
40
30
20
10
COV.S s/m
NO
1
2
3
4
5
6
7
8
Figure 5.19
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
Line Balancing Analysis Table.
In the old days of high-volume lot production, product life
cycles were longer, which made analytical line balancing a
handy tool. In today’s fast-paced world, there is not always
time for this slow, analytical approach.
There are two alternative methods to analytical line balancing.
Method 1: “Practical line balancing.” Here, we do not
carry out any kind of analysis but instead simply start the
product assembly operations, then take an ad hoc approach
to changing the configuration of assembly workers whenever the need arises. This approach has two common names:
“practical line balancing” and “the SOS system.”
Specifically, we begin this approach by running the assembly line at a relatively slow pitch. Then we gradually accelerate
the pitch until assembly workers who are not able to keep up
Flow Production
sound an “SOS” alarm. The workshop leader then responds
immediately by making a balance-improving adjustment to
the assembly worker configuration.
This goes on repeatedly until the workshop members
finally arrive at the best pitch and configuration for that particular product. At this point, things go much easier if the line
uses forced conveyor rather than a free flow conveyor.
Method 2: “Baton passing zone method.” Other names for
this system are the “nonbalancing system” or the “cooperative
system.” This system avoids line balancing altogether.
In conventional conveyor operations, each worker is
assigned a predetermined and fixed workload. This rigidity
in worker responsibilities helps give rise to imbalances.
By contrast, the baton passing zone method gives each
worker at each process a set of basic tasks to perform, as well
as a set of overlapping tasks that are shared with the previous
and/or next process. When each worker is finished, he or she
can “pass the baton” to the person at the next process.
To recapitulate, the traditional “defensive” or “reactive” type
of assembly operations, in which workers sat to work and held
rigidly defined job duties, no longer works as well in today’s
manufacturing world. Instead, we need more “offensive” or
“proactive” operations in which operators do more on their
own to balance operations and ensure progress on the line.
The latter type of operation is all the more necessary in view
of today’s ongoing trends toward production diversification,
shorter product lives, and more and more part-time workers.
Standing while working at processing lines—Standing
while working is much more common at processing lines
than at assembly lines, and today almost all factories have
processing line workers standing to work.
If anyone wonders why processing workers must stand
while working, the answer is simple: They need to stand for
multi-process operations. Standing should not be required just
because it suits the conveyance system or because the equipment is too large to operate while sitting. When processing
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Figure 5.20
Work Table Raised by Concrete Blocks for Standing
While Working.
workers sit while working, they are like isolated little islands.
We have to connect these little islands into an integrated line
that follows the sequence of processes, and get workers to
stand while working to enable one-piece flow and help build
quality into products at each process.
Figure 5.20 shows how concrete blocks were used in one
factory to raise the level of the work table to comfortably
accommodate standing while working.
Preparatory Step 4: U-Shaped Manufacturing Cells
Flow production that includes two processes can be arranged in
a straight line or an L-shaped line, as shown in Figure 5.21.
Straight line
Pressing
L-shaped line
Cutting
Pressing
Cutting
The operator moves from side to side
while handling these two processes.
The operator turns sideways (90°)
while handling these two processes.
Figure 5.21
Two Types of Two-Process Flow Production Lines.
Flow Production
When the processing machines are small enough, they
can be lined up side by side and the operator can move
“crab-like” while operating both processes. If the machines
are too large for this, they can be set at right angles to each
other, and the operator can merely turn sideways to move
the other machine. Either layout helps minimize the amount
of “motion waste” created by the operator.
When there are three or more processes in one line, it is
usually best to arrange them into a U-shaped layout. Although
these sets of processes are called “lines” in Japanese, the
name “cells” better conveys their function as a unit within the
overall production line. We can minimize motion waste in
these U-shaped cells by laying out the cell’s input and output
sites as close together as possible. Operators should always
work on the inside of the cell, since this will enable them
to get to each machine with fewer steps than if they were
on the outside of the cell. It also makes it easier for teams of
operators to help each other out whenever necessary. (See
Figure 5.22.)
No matter what shape these cells take, the layout should
work to minimize wasteful motions. Figure 5.23 shows how
the layout does not have to be U-shaped, but instead can be
Processed
items
(output)
Press
in
Pressing
Input and output sites are
arranged in close proximity
Figure 5.22
U-Shaped Cell.
Cutting
Unprocessed
items
(input)
g
Operators
work on the
inside of
the cell.
in
Cutt
g
Drilling
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Cell shaped like an equal sign (=)
S-shaped cell
Cutting
Cutting
Cutting
Cutting
Drilling
Pressing Part B
Pressing
g
g
Dr
ill
ing
Drilling
sin
es
Pr
Part A Pressing
lin
Dril
362 ◾
Cut
ti
ng
= Before processing
Cutting
= After processing
ng
hi
as
W
Figure 5.23
Cutting
“Equal Sign” and “S-Shaped” Cells.
other shapes, such as a parallel line arrangement—like an
“equal” symbol ( = ) or an “S” shape.
Preparatory Step 5: Multi-Process Operations
Once we give up the “one worker per machine” system and
arrange the processing equipment according to the processing
sequence, all sorts of new possibilities arise for worker operations. Most significantly, it lets us switch from single-process
operations to multi-process operations. At first, the workers
will have to get used to doing things a completely new way.
Naturally, this will result in lower daily output for a while.
There must be no half-hearted changes. We cannot claim
to have implemented multi-process operations if we are still
handling workpieces in “shish-kabob” lots or “caravan-style.”
Multi-process operations is not multi-process operations
unless it is done under one-piece flow conditions.
Figure 5.24 shows how multi-process operations were set-up
for a sensor assembly line.
Before the improvement, this sensor assembly line had
one sitting worker per process and used a conveyor to “push”
finished lots toward the next group of processes. The manufacturing lead-time for products on this line was about
Flow Production
Before improvement
After improvement
Work table
Work table
U-shaped cell
Soldering
Electrical
inspection
Soldering
Sitting
Aisle
Sensor
installment 2
Sitting
Work table
Sensor
installment
Holder
assembly
Sitting
Harness
assembly
4
Electrical
inspection
5
Holder
assembly
Standing while working,
multi-process operations
Sitting
Work table
1
3
Work table
Harness
assembly
Sitting
Harness
All operators are sitting while working.
When they have finished a lot, the lot
is loaded onto a conveyor to be sent
to the next group of processes.
Figure 5.24
All workers are now standing and carrying
out multi-process operations. The layout was
changed to a U-shaped cell. This brought
about a reduction in manufacturing
lead-time, elimination of in-process inventory,
and a manpower reduction from five
workers to three.
Multi-Process Operations on a Sensor Assembly Line.
two days. The operators sat at work tables in cramped areas
handling the lots that were passed to them at the upstream
processes’ convenience. These workers sat amid piles of
in-process inventory.
After the improvement, the layout is a U-shaped cell, in
which all workers are standing while working and handling
multi-process operations under one-piece flow conditions.
This arrangement reduced the lead-time and completely eliminated the in-process inventory. The cell only takes about a
third as much space as it used to, and they were able to lower
the cell’s manpower requirement from five workers to three.
Preparatory Step 6: Synchronization
Synchronization means synchronizing both processes and
workers so that the entire line and, eventually, the entire production system become synchronized. To do this, we must
calculate the cycle time required for level production, after
which we must match this up with the appropriate number
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of workers and the correct operational procedures. We must
first build up a smooth rhythm within sections of the production line, then we can build these up into an overall
p
­ roduction rhythm.
However, this is often much easier said than done. There are
many obstacles that can stand in the way of achieving an overall
rhythm. The five main types of obstacles are described below.
Obstacle 1: Several upstream processes bottleneck into
one downstream process, resulting in inventory pile-ups at
the downstream process. (Solution: in-line layout.)
Most factories have many “exceptions” to whatever rules
exist, and special processes or procedures are created to
accommodate these exceptional cases. We must recognize,
though, that making exceptions and accommodating them
with special handling does not solve any problems. There
need not be any exceptions in the factory.
In many factories, people regard processes such as forging, casting, painting, washing, and calcination as “special
processes.” As a result, these processes get special treatment,
and become self-involved little islands in the factory.
Figure 5.25 shows one such little island, a washing unit.
Workpieces are conveyed from three cutting lines and piled up
before this washing unit as in-process inventory. Before entering
this washing unit, the workpieces are loaded by two workers
into washing containers. Two other workers unload the containers and send the workpieces on their way downstream.
To solve this problem, we must remove the waste created
by consolidating production flow at the large washing unit
and then dispersing it again downstream. We can do this by
incorporating small, inexpensive washers at the end of each
processing line that formerly converged on the large washing
unit. This in-line layout allows this factory to eliminate both
the need for the four workers attached to the large washing
unit and also the in-process inventory.
Obstacle 2: The “push” method, in which goods produced
at one process are automatically sent to the next process, is
Flow Production
Before improvement
The washing process was set apart as a little island in the factory. Two workers were
needed to load parts into washing containers and two others were needed to unload
the containers and send the parts to the next processes. This arrangement still
resulted in large piles of in-process inventory.
Processing line A
Cutting
Loaders
Island
Washing
process
Processing line B
Cutting
Processing line C
Cutting
Unloaders
In-process inventory
To
assembly
line
In-process inventory
Forklift conveyance
After improvement
Processing line A
Cutting
One-piece
washing
unit
Processing line B
Cutting
One-piece
washing
unit
Processing line C
Cutting
One-piece
washing
unit
Retire the large washing unit and install small one-piece washers at the end of each
processing line. This removes the need for a large washing unit and also eliminates
the in-process inventory around the washing process.
Figure 5.25
In-Line Layout of Washing Units.
resulting in pile-ups of goods at certain downstream processes. (Solution: the full work system.)
The “push” method makes it hard to achieve a smooth flow
of goods because automatically sending goods to the next
process does not consider whether or not the next p
­ rocess
is ready for the goods. The “pull” method is therefore highly
recommended as a means to ensure a smooth flow of goods.
We call the “push” method “the push system” and the “pull”
method “the pull system.”
There are various tools for implementing the pull system,
such as kanban, hand delivering, and the full work system.
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Before improvement
Final
assembly
After improvement
Parts
assembly
Large
work table
Flood
(shish-kabob)
In-process inventory piled up between
operators at the final assembly line and
the parts assembly line. The parts
assembly line operated at its own pitch.
Figure 5.26
Final
assembly
Parts
assembly
Small
work table
Hand-delivery site
(one-hand delivery)
A single-hand delivery site was
established between the final assembly
line and the parts assembly line. As long
as the hand delivery site is not used for
final assembly, the parts assembly line
will not produce goods.
Pull Production Using Hand Delivery.
Here, we shall look at hand delivering and the full work
system. (The full work system is explained in more detail in
Chapter 14.)
Figure 5.26 shows how the number of hand deliveries
were calculated between two operators. Before the improvement, in-process inventory filled up the entire space between
the final assembly and parts assembly lines and no one could
find any way to synchronize the two lines. They responded
instead by making the work tables smaller and reorganizing
the physical space to make more room. They also set-up a
place where goods could be hand-delivered, which meant
there was one hand delivery. The improvement reduced
all of the in-process inventory to this one hand-delivery.
Furthermore, if the hand delivery can be eliminated, this
improvement will enable implementation of the pull system
and will make any imbalance between the final assembly line
and the parts assembly line readily obvious. This improvement led to the following improvement.
Figure 5.27 illustrates the synchronization of a “pull s­ ystem”
involving a printed circuit board (PCB) assembly line and a DIP
Flow Production
Before improvement
PCB assembly line
Flood
(shish-kabob)
Correction line
DIP vat
The PCB assembly line and DIP vat process did not operate at
the same pitch, and this resulted in chronic accumulation of
in-process inventory between them.
After improvement
PCB assembly line
Limit
switch A
Limit
switch B
Correction line
DIP vat
The conveyor for the PCB assembly was moved closer to the DIP vat,
and use of two limit switches (A and B) enabled achievement of a
pull production using a full work system. This eliminated the
in-process inventory between the PCB assembly line and the DIP vat
and enabled a reduction of one worker at the DIP vat process.
Figure 5.27
Pull Production Using a Full Work System.
vat. Before this improvement was made, the DIP vat process
tended to lag behind, and there was a chronic accumulation of
in-process inventory between the PCB assembly line and the
DIP vat. The improvement included moving the two processes
closer together and installing two limit switches (A and B) to
enable implementation of a full work system. This improvement eliminated in-process inventory between the PCB assembly line and the DIP vat and led to manpower reduction on
both the PCB assembly line and the DIP vat process.
A full work system controlling points A and B proved
necessary for achieving pull production and synchronization
with downstream processes, as shown in Figure 5.28.
Obstacle 3: Variation in work procedures among different workers causes delays or idle time. (Solution: cooperative operations.)
Whether it be a processing line or an assembly line, balanced operations among workers within the line is a key
prerequisite for maintaining a smooth flow of goods. Such
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Point A
Point B
Line
CONDITION
Condition for sending
workpieces
Point A
Point B
1
Yes
Yes
2
Yes
No
3
No
Yes
4
No
No
CONDITION
If there is a workpiece at point A
but not at point B, the conveyor
can be moved without causing
problems.
Conveyor moves only under this condition
CONDITION
CONDITION
Figure 5.28
If there are workpieces at point A
and B, moving the conveyor
would cause a pile-up at point B.
If there is a workpiece at point B
but not at point A, moving the
conveyor would cause a gap in
workpiece flow while leaving a
workpiece at point B.
If there are no workpieces at
points A and B, moving the
conveyor would simply cause
a gap in workpiece flow.
Devices Enabling a Full Work System.
balancing of operations takes a lot of training and practice,
but these days more and more factory workers (in Japan) are
part-time workers, which makes it harder to achieve and maintain such a balance. As a result, maintaining a constant tact
time for operations such as fine-tuning electronic products­is
difficult indeed; delays or idle time often occur, upsetting the
balanced flow of goods.
The solution that will keep balanced operations and
smooth flow of goods from being upset is to have workers
consider their operations flexible rather than rigid. In other
words, they should be trained to help other workers when the
flow starts becoming unbalanced. This approach is known as
“cooperative operations” or the “baton passing method.”
Figure 5.29 illustrates the steps to take in carrying out
cooperative operations on an assembly line.
◾◾ Step 1: Standing while working.
This step starts with having all of the workers on the
assembly line stand up. They should perform their operation whenever a workpiece arrives in front of them. This
means abandoning their old “reactive” way of working
Flow Production
Before improvement
Assembly line
Parts put beside
operator
Parts put behind
operator
Sitting operator
After improvement
Proactive operations
Step 1: Standing while working
Step 2: Place parts in front of workers.
Smaller amounts
of parts
Step 3: Reduce the gap between operators.
Operators should be able to see previous and next operations
with peripheral vision.
1m
Step 4: Establish cooperative operation zones.
Worker Worker Worker
A
B
C
Worker A’s operations
Worker C’s operations
Worker B’s operations
Cooperative zone
(baton touch zone)
Step 5: Start vocal pull production.
I‘ve done up to 10.
Figure 5.29
Right. Starting from 11.
Improvement Steps for Cooperative Operation.
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and adopting a “proactive” method that emphasizes the
value each worker adds to the product.
◾◾ Step 2: Place parts in front of workers.
When the workers were sitting, they made little use of
the area directly in front of them. Standing while working enables workers to eliminate the stacking of parts
on their left and right and instead have all parts in front
of them. To do this, we have to decrease the amount
of parts placed before each worker and increase the
­frequency of supplying parts to the workers.
◾◾ Step 3: Reduce the gap between operators.
By placing all of the parts the operators will be using in
front, we are able to get rid of the parts that had been
piled up on the left, right, and in back of the operators.
This newly created open space makes it obvious that the
operators are too far apart from each other. In reducing
the gap between operators, we should figure that the
operators should be close enough to reach each other’s
outstretched hands (about 80 centimeters to 1 meter). In
assembly operations for home electronics products and
electrical equipment, the operators should be even closer;
about 60 centimeters apart. Once we have reduced the
gap between operators, each operator is able to keep an
eye (using peripheral vision) on what is going on at the
previous and next processes. This creates an environment that is more conducive to cooperative operations.
◾◾ Step 4: Establish cooperative operation zones.
Now that we have established a layout that supports
cooperative operations, we need to establish cooperative
operation zones. To calculate these zones, we need to list
each of the assembly operations and assign a number to
each. Then we can set-up cooperative operation zones
that can cover some of the operations at the previous and
next processes. Each cooperative operation zone should
be expressed as starting from one operation number and
ending at another operation number, as in the cooperative
Flow Production
Cooperative Operation
Zone Checklist
Factory: Chiba
Product: PCB 1013
Section: 1st Assembly Dpt., By: Yamagawa
Date: 1/4/1989
Line A
Process No. 1
2
3
4
5
6
7
8
Opera
tor nam
e Tucker Engle North Brown Meyer Kline Jones Black
No. Parts input
1
11-1640-20
2
16-1311-31
3
19-2931-16
4
20-2131-16
5
14-1923-61
6
36-3111-21
7
63-1416-41
8
27-2131-51
9
32-8136-24
Figure 5.30
Establishment of Cooperative Operation Zones.
operation checklist shown in Figure 5.30. The zones of
cooperative operations among operators at adjacent processes is reminiscent of the zones on the running track
within which relay runners must pass their batons. That
is why cooperative operations are sometimes called the
“baton passing method.” In track relays and in cooperative zones on the assembly line, the “baton pass” can be
made anywhere within the baton passing zone.
◾◾ Step 5: Start vocal pull production.
In this case, “vocal pull production” means that the
worker—who is “passing the baton” by turning the rest of
the process’s operations in a cooperative operation zone
over to the next worker—should vocally confirm which
operation number he or she has finished. This helps prevent any misunderstanding between workers that might
result in the repetition or omission of an operation.
Obstacle 4: When we have shish-kabob production on
the assembly line, it is not possible to synchronize the assembly line with the process line, which also means that the
flow of goods cannot be synchronized. (Solution: establish
specialized lines.)
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Many factories have assembly lines that are used to put
together a variety of product models. When asked why they
do it this way, the managers of such lines always have some
excuse, such as: “We don’t have any other equipment,” or
“There’s no room to do it otherwise,” or “These are our most
efficient workers.”
When several different product models are assembled on
the same line, the many equipment changeover operations
are bound to be a haphazard affair, and the line will likely
adopt shish-kabob production to minimize the number of
required changeovers. This reinforces all the old conventional
notions about manufacturing and creates a vicious cycle.
Figure 5.31 shows how a mixed-product assembly line can
be changed into three specialized assembly lines. Before this
improvement, one assembly line operated by ten workers
would handle three product models per day. This resulted
in a lot of waste created by changeovers and by unbalanced
operations following each changeover. Also, because the line
was using the shish-kabob production method, it was quite
difficult to synchronize the assembly line with the processing
Before improvement
After improvement
Shish-kabobs
Product model changeover (shish-kabob
supply method)
One day
A
A
B
C
Specialized lines
Line A
Line B
B
C
Product
10 line workers
storage
sites
To assemble three different product models
on one line, they opted for shish-kabob
production, which meant they were not
able to synchronize processes and product
flow.
Mixed model
delivery
Line C
Zero product
model
changeovers
Establishing specialized assembly lines
eliminated product model changeovers
and facilitated level production. As a
result, they were able to eliminate
surplus inventory and synchronize both
processes and product flow.
Figure 5.31 Improvement to Establish Specialized Assembly Lines.
Flow Production
line and to synchronize the flow of goods. This led to large
amounts of inventory.
After the improvement, the workers were divided into the
numbers needed for the required output of each of the three
product models (A, B, and C) to enable level production.
This also completely eliminated the need for changeovers,
prevented disruption of balanced operations, and made for
easier and smoother synchronization of the assembly and
processing lines, and of the product flow. Finally, it enabled
the elimination of surplus inventory.
Obstacle 5: Attempts to reduce the number of changeovers in the processing line results in large lots, which disrupts
the smooth flow of goods. (Solution: improve the changeover
procedures.)
When changeovers for different product models occur in
the assembly line, they usually also take place in the processing line. To avoid the hassle of frequent changeovers,
the lines naturally tend toward handling large lots, which
disrupts the flow of goods and makes it hard to synchronize
upstream and downstream processes.
We might think that the same advantages can be realized
by also setting up specialized processing lines for different
product models. However, unlike assembly lines, processing
lines require various expensive types of machines. It is therefore necessary to make each processing machine handle several different product models. In such cases, the appropriate
improvement is to improve the changeover procedures.
Changeover improvements are described in Chapter 11.
Case Study: Flow Production within the
Factory—Improvement at a Diecast
Factory for Automotive Electrical Parts
The factory in this case study, a subcontractor to an automobile manufacturer, makes diecasts for automotive electrical
parts. Before making improvements, this factory operated
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entirely on the shish-kabob production system, using lots of
500 to 700 units loaded into containers and conveyed between
processes by forklift. The factory was operating slightly in
the red, but the company somehow managed to balance
its accounts at the end of each term. The factory managers
decided to adopt JIT improvement as a way to revolutionize
their tired old factory management system.
Before Improvement
Figure 5.32 shows this factory’s processing sequence and production flow prior to improvement.
Processing sequence
Raw materials (forging)
Pressing
Multi-spindle drilling machine 1
Multi-spindle drilling machine 2
Reaming
Shotblasting
Inspection
Shipment
Layout and flow pattern
Forklift conveyance
Raw materials
(forging)
Container
Inspection 5
6
Loading
for
shipping
Shipping
2
Large
shotblaster
Press
1
4
Figure 5.32
Staff: 12
In-process inventory:
3 day’s worth
Lead-time: 3 days
Multi-spindle
drilling
machines
3
Conveyor operations
Processing Sequence and Production Flow for Diecast
Product A (before Improvement).
Flow Production
The major characteristics of this factory are:
◾◾ Layout: Job shop layout; similar tasks are grouped within
the same workshops.
◾◾ Production flow: Shish-kabob production using lots of
500 to 700 units.
◾◾ Operators: Single-skilled workers, each assigned to a
specific process.
◾◾ Machines: Large machines capable of handling large lots.
Under this arrangement, it takes 12 workers to operate the
line for product model A, and it takes three days for each
workpiece to go all the way from the forging process to shipment. The factory contains three days of in-process inventory
and the lots are conveyed between processes via forklifts
requiring full-time forklift drivers.
The biggest obstacle to improvement was the large shotblaster, shown in Figure 5.33. Every workpiece that this
factory­handled had to be shotblasted by this big machine,
and naturally this led to large piles of in-process inventory
on the upstream and downstream sides of the shotblaster. In
addition, the fact that workpieces were shotblasted in large
batches meant that the workpieces got jostled around in the
shotblaster. Inspectors were needed to sort the damaged
diecasts from the undamaged ones.
Figure 5.33
Large Shotblaster.
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Processing sequence
Raw materials (forging)
Pressing
Multi-spindle drilling machine 1
Multi-spindle drilling machine 2
Reaming
Shotblasting
Inspection
Shipment
Layout and flow pattern
Raw materials
(forging)
Container
500 units
Inspection
and loading
Shipping
ll
Sma ster
tbla
o
h
S
6
7
5
4
Figure 5.34
2
ss 2
Pre
s1
1
er
am
Re
Forklift
conveyance
Pr
es
376
3
Multi-spindle
drilling
machine 1
Mu
ltid spi
ma rillingndle
chi
ne
2
Processing Sequence and Production Flow for Diecast
Product A (after Improvement).
After Improvement
We got right to work by selecting a model line for manufacturing product A. We abandoned the job shop layout and switched
over to a flow shop (line) layout that emphasizes the flow of
goods. At this point, we also abandoned all of the manual
deburring processes and switched over to machine operations
using a press, multi-spindle drilling machine, and other equipment. This enabled us to eliminate all manual processing.
Figure 5.34 shows the processing sequence and production flow following the improvement.
The major characteristics of this factory are:
◾◾ Layout: Flow shop layout (in-line); emphasizes the flow
of goods.
◾◾ Production flow: Workpieces exit the forging process in
500-unit lots and move in one-piece flow from the pressing process to shipment.
Flow Production
Figure 5.35
Compact Shotblaster for In-Line Layout.
◾◾ Operators: Multi-skilled workers, trained to handle seven
processes, from pressing to shipping.
◾◾ Machines: Eliminated large shotblaster and built a small shotblaster conducive to in-line arrangement. (See Figure 5.35.)
As a result of this first improvement, the model line
was able to manufacture product model A using only two
­workers instead of 12. To reduce the former lead-time of
three days, this improvement brought about a cycle time
of 10 seconds for one-piece flow. Naturally, the inventory
was also drastically reduced, reaching zero except for seven
workpieces of inventory at the pressing processes and three
at the drilling machines.
In addition, this improvement meant that forklift conveyance was no longer needed within the line. Furthermore, the
elimination of the large shotblaster did away with the chronic
problem of shotblast-damaged diecasts.
After their initial success with this model line, the factory
managers extended the improvement laterally to other lines.
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Within two years, the company’s business accounts were in
the black.
Flow Production between Factories
Applying the Flow Concept to Delivery
When we take a successful model of flow production, such
as the model line described above, and extend that clearly
visible example to other lines in the same factory, we call it
“lateral development.”
Once we have carried out lateral development and have
established a firm footing for flow production within the
factory­, we are ready to take on the challenge of extending
these improvements outside of the factory. In so doing, JIT
production begins to take on greater height and depth as
well as breadth.
Obviously, this vertical development of JIT improvements
is centered on the factory where the improvements began
and is generally extended in two directions: the “delivery”
direction, which means from the factory to its vendors and
subcontracted suppliers, and the “shipment” direction, which
means from the factory to its customers or wholesalers. Once
we understand these two directions, we must also understand that the most important direction is that between the
vendor and/or subcontractors and the factory.
JIT’s basic approach is to reduce the amount of each delivery
and to compensate by increasing the frequency of deliveries­.
Obviously, if the deliveries are more frequent, they will also
be more costly if current methods are used.
Let us suppose that deliveries are increased from once a day
to twice a day and the per-delivery amount is correspondingly
cut in half. This means the deliverer’s cost will be approximately double.
When people hear this, many are quick to conclude that
the JIT production system bullies the subcontractors. But this
Flow Production
is not so. The general trend toward diversification and shorter
delivery deadlines has affected the distribution industry, the
manufacturing industry, and the transport industry. Right now,
the transport industry is confronting this challenge. Meanwhile, manufacturers are struggling to meet market needs for
product diversification and short delivery scheduling.
Several clever new delivery methods have been developed. These methods concern three main aspects of delivery operations: loading methods, frequency of delivery, and
transport routes.
Loading Methods
The product diversification trend has radically changed loading methods. Cargo loads used to be mainly all the same type
of products. Today we not only have mixed-product loads,
but also mixed-product loads that are loaded in the sequence
of their use on the client’s production line. (See Figure 5.36.)
Single-product load
A
A
Mixed load
C
B
A
Sequential mixed load
C
B
A
C
B
A
Effects of the product diversification trend
Figure 5.36
Loading Methods.
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Once per day
Factory 1
Factory X
8 times per day
Factory 2
Factory Y
32 times per day
Factory 3
Factory Z
Response to need for less inventory and shorter delivery times
Figure 5.37
Frequency of Deliveries.
Frequency of Deliveries
Product diversification can easily lead to greater inventory. To
keep inventory levels down and lead-times short, we must
have more frequent deliveries. Sometimes we must switch
from just one delivery per day to eight per day, from eight to
16, or even from 16 to 32. (See Figure 5.37.)
Transport Routes
One way to hold down the higher costs caused by product
diversification is to improve transport route planning. Instead
of simple point-to-point deliveries, it may be more economical
to make circuit or compound deliveries. (See Figure 5.38.)
Thus, there are three main areas of improvement the
transport industry must concern itself with: improved loading methods in response to product diversification, more frequent deliveries in response to lower inventory levels and
shorter lead-times, and improved transport route planning in
response to the need for cost reduction.
Flow Production
Point-to-point delivery
Factory 1
Factory X
Factory 2
Factory Y
Factory 3
Circuit delivery
Factory 1
Factory X
Factory 2
Factory Y
Factory 3
Compound delivery
Factory X
Factory 1
Distribution
center
(transport
company)
Factory 2
Factory Y
Factory 3
Response to cost reduction needs
Figure 5.38
Transport Routes.
It follows that the best combination of improvements is
when the transport company manages to implement sequential loading, 32 deliveries per day, and compound deliveries.
The transport industry is witnessing a major shift away from
large-scale container deliveries and toward smaller packages
delivered door-to-door. In big cities, we can even find small
package deliveries being made via motorcycle. Whenever
there are new needs, the transport industry is obliged to
respond with new methods.
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Factory:
Delivery Company
Evaluation Chart
Main
product
No.
Company
1
M Company Resistors
2
Y Company
A1 units
3
K Company
C materials
4
F Company
Packaging
5
T Company
Coils
Figure 5.39
Tohoku Plant
Name/Dept. of evaluator:
Anderson, Purchasing dept.
Date:
November 16, 1988
Manager Loading Frequency of deliveries Transport
Manager
method
route
(delivery
(in-house)
company) 1 2 3 1 2 3 4 5 6 7 1 2 3
Off
Total
382
Jones
1
Lennon
Sandler
6
Lennon
McTighe
4
Off
Rosen
10
Smith
Amick
2
Delivery Company Evaluation Table.
Figure 5.39 shows a delivery company evaluation table.
Factory managers can use this table to evaluate how well
each delivery company responds to their needs and to help
improve their own factory’s policy on deliveries.
Applying the Flow Concept to Delivery Sites
In JIT production, the secret for success in deliveries is not
the conventional wisdom of delivering larger loads in fewer
trips. It is just the opposite: smaller loads and more trips.
For instance, assuming there are 20 workdays in a month,
consider the following two monthly delivery schedules:
A. Deliver once a month, 100 units per delivery (= 100
units total).
B. Deliver 20 times a month (daily), 5 units per delivery
(= 100 units total).
In JIT production, we choose the latter. Even though the
delivered units add up to the same total, the delivery ­methods
are as different as night and day. Method B calls for 20 times
more deliveries than Method A.
Next, we need to consider another very important issue:
Which part of the factory should take in the delivered items?
Flow Production
Exactly where and how these deliveries are made can
have a big impact on the handling of materials and parts in
the factory.
The following are five points to remember for setting up
delivery sites that will help prevent goods from accumulating and will make for a smooth flow of goods with little or
no waste.
Point 1: Self-Management by Delivery Companies
In principle, the delivery company should be responsible
for managing the delivery site it uses. In other words, the
delivery company should bring the cargo all the way to the
delivery site, keep the site properly arranged and orderly,
and manage its general condition.
I strongly suggest that signboards be used to clearly indicate who brings what to where and exactly when. (See
Figure 5.40.)
Location:
Where A1-1-3
Item name:
131 plank
When Quantity:
100 planks × 3
Next process:
Trimming
Signboard
Location:
A1-1-3
Item name:
131 plank
Quantity:
100 planks × 3
Next process:
Trimming
Delivery
Company:
Yamagawa Ind.
Delivery
Evaluation:
Company:
A
Yamagawa Ind.
Who
Evaluation:
A
What
Where
(it will
be used)
Periodic site evaluation
A : Good
B : Fair
B : Poor
White placement line (outline)
Figure 5.40
Establishment of Delivery Sites and Signboards for
Delivery Site Management.
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Line display board
Line A
Line B
1
Same
color
The color of the line display board and the
parts storage rack are the same.
Figure 5.41
Line-Specific Method of Color Coding.
Point 2: Color Coding for Orderliness
Color coding is a good way to clearly show the relationship
between things and processes—that is, what things are used
in which processes. One good way to color code this relationship is to select a different color for each line and use that same
color for the parts and materials that will be used in that line.
Color coding in this way will help prevent parts mix-ups
when parts are supplied to the various lines at the factory. At
the same time, it will also help parts and materials flow more
smoothly to the lines with less waste, thereby contributing
to an overall smooth flow of goods. (See Figure 5.41.) (Color
coding is described in more detail in Chapter 4.)
Point 3: Product-Specific Delivery Sites
There are basically two ways to sort parts: according to similar types of parts that serve similar functions, or according
to the products in which the parts will be used. These are
respectively called “function-specific” and “product-specific”
sorting methods. The product-specific method helps minimize waste and makes for a smooth flow of goods when the
parts are to be used in products manufactured frequently.
Point 4: FIFO (First In First Out)
Whenever goods are put somewhere, there is always a process of placing and retrieving. If the most recently placed
Flow Production
product is the one to be retrieved, we call it a LIFO (Last In
First Out) arrangement. The problem with this arrangement
is that the oldest item (the one placed there first) is also the
last one to be retrieved. Delays in retrieving stored products
can make these older items grow very old indeed.
Obviously, this is not a desirable situation. Therefore, we
should be sure to have the opposite arrangement—FIFO (First
In First Out)—whenever possible, to keep items moving as if
they were on a conveyor belt and to help prevent inadvertent
long-term storage.
Point 5: Visible Organization of Containers
Another important means of making the flow of delivered
items smoother is to make the containers used for such items
as clearly distinguishable as possible. We call this “visible
organization of containers,” which is part of the general idea
of “visual control.”
Figure 5.42 shows two examples of visibly organized containers, a parts tray and a parts box. These containers make
it much easier for workers who select parts from them to
understand which parts are which. They also make obvious
which part has been overlooked, since the container should
be empty when parts selection is finished. This also helps
improve defect detection.
Visible organization of
parts tray
Shows outline shapes of parts
Figure 5.42
Visual organization of
parts box
Part name
and quantity
Mini signboard
Visible Organization of Containers.
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Chapter 6
Multi-Process
Operations
Multi-Process Operations: A Wellspring
for Humanity on the Job
Eliminating defects, raising the operating rate of workers and
machines, and improving productivity are all matters of great
importance in any factory. It is no exaggeration to say that
higher productivity is the key to survival for companies today.
However, even “survival” is not reason enough to treat
workers like machines. When you come right down to it, it
is people—not machines—that make products. Productivity
is important indeed, but not as important as respecting the
humanity of our workers. Productivity and humanity must
coexist in the factory. Sometimes, the two have conflicting
purposes. If we raise productivity at the expense of humanity, we are doing ourselves a disservice in the long run.
For example, let us suppose that the workers in our factory
each have very specific and specialized job tasks. One person hammers in bolts all day while another glues on labels.
They have been doing this for five or ten years. How much
pleasure do you suppose these workers derive from their
work, and what sense of achievement or satisfaction have
they gained after all those years?
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Productivity and Humanity in the Factory
Productivity
Humanity
Lack of respect for workers
Minutely specialized job tasks
“Human robots”
Lack of concern over
economic matters
Selfish production
Corporate deterioration
The joy of constructive activities
Multi-skilled workers handling
several processes
Corporate development
Figure 6.1
Relationship between Productivity and Humanity.
Now let us consider the opposite situation: a factory where
humanity is respected even to the point where productivity is no longer important. When taken to such an extreme,
humanity takes on shades of arrogance and, eventually, selfishness. Factories that take this path lose their vitality and
ultimately fail.
Obviously, we need to find a way to satisfy both productivity and humanity (See Figure 6.1.)
The Difference between Horizontal
Multi-Unit Operations and Vertical
Multi-Process Operations
Building up one-piece flow production is the best way to
get rid of defects, waste, and production delays. The basic
concept in one-piece flow production is to send workpieces
along the processing sequence one at a time, adding processing (value) to the workpieces at each process. As such, flow
production is a very basic ingredient in JIT production. (For
further description of flow production, see Chapter 5.)
Multi-Process Operations ◾
The following are the main things we must have in order
to establish flow production.
◾◾ Equipment. We need specialized machines that include
only the essential required functions, are inexpensive, and
are small enough to fit right in to the production line.
◾◾ Equipment layout. Equipment must be arranged according to the processing sequence. Workshops should be of
the “flow shop” type (as opposed to the “job shop” type)
and should preferably consist of U-shaped manufacturing cells.
◾◾ Operational procedures. We must give up “shish-kabob”
production and learn one-piece flow in which workpieces are fed to and from processes one at a time. All
workers must stand while working and learn to handle
several processes in order to synchronize their work with
the cycle time.
◾◾ People. We must train workers in the multiple skills they
will need to handle several processes.
Multi-process operations are the key that opens the door
to one-piece flow production. Without multi-process operations, there can be no JIT production system.
We are not likely to find much worker enthusiasm for
multi-process operations if we introduce such operations in
conventional “job shop” type workshops (workshops laid
out according to function). Multi-process operations can be
achieved in such workshops, but the amount of conveyance
the workers would have to do themselves by walking and
carrying workpieces makes it hard to find time for processing the workpieces. Therefore, we first need to change the
equipment layout to the “flow shop” arrangement (equipment
arranged according to the product). This changes the workshop from being a multi-unit process station to being a multiprocess production line.
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Obviously, we cannot change a multi-unit process station
to a multi-process production line unless we change the
equipment. A group of presses are only good for pressing
and a group of drilling machines are only good for drilling.
There is no way we can arrange multiple press units or drilling machine units into a multi-process production line. That
is why we need to make the distinction between the grouping of machines that all serve a certain processing function
(multi-unit process stations) and the grouping of machines
that provide a sequence of processing functions needed to
build a certain product (multi-process production line).
Figure 6.2 illustrates this distinction.
The concept behind multi-unit operations (that is, operations at multi-unit process stations) is to have one worker
handle several processing machines that perform the same
type of process. By contrast, the concept behind multi-process
operations is to have one worker handle several processes
(arranged according to the processing sequence).
No matter how many machines multi-unit operators handle,
they only need one skill to operate them since the machines
are all similar (presses, drilling machines, or whatever). Since
multi-unit operations all take place at the same processing
stage in the overall production line, we refer to multi-unit
operations as “horizontal operations.”
Conversely, operators who handle multi-process operations
must have skills in several types of processes, such as presses,
drilling machines, bending machines, and so on. We therefore refer to such workers as “multi-skilled workers.” Since
multi-process operations occur along a sequence of processes
that include several stages along the overall production line,
we refer to multi-process operations as “vertical operations.”
Once we have established flow production that uses
multi-process operations, we can be sure to expect higher
quality­. Almost all surface defects on products—such as dents,
cracks, or missing parts—will disappear. One-piece flow will
ensure that when the occasional defect does occur, the line
Multi-Process Operations ◾
Horizontal operations
Process
Product
A
B
C
D
1
2
3
4
5
Multi-unit operations
(horizontal)
1
1
2
2
Multi-process operations
(vertical)
2
1
3
1
2
2
1
One worker handles four similar
machines.
5
4
One worker handles five
different processes.
Quality
(Q)
Dented, damaged, or
missing items
Defective lots
Causes of defects remain
a mystery
“I make the products, you
inspect them.”
Inspectors are responsible
for sorting out all the
defective products.
Zero dented, damaged, or
missing items
Zero defective lots
Causes of defects are tracked
down and arrested.
Production workers do their
own inspecting.
Quality is built in at each
process.
Cost
(C)
Creates lots of waste
related to in-process
inventory, space, manpower, and conveyance
Costs vary depending
upon volume.
Workshops try to save
labor.
Zero waste
Costs are steady regardless
of volume fluctuation.
Workshops try to reduce
manpower.
Delivery
(D)
Long lead-times
Chronically late deliveries
Not very adaptive to
schedule revisions
Short lead-times
Zero late deliveries
Adaptive to schedule revisions
Figure 6.2
Difference between Multi-Unit Process Station and Multi-
Process Production Line.
can be stopped before an entire lot of defective products is
turned out.
Best of all is the fact that this improvement enables us
to track down the causes of defects and take appropriate
counter­
measures. In conventional shish-kabob production,
anywhere from 500 to 1,000 defective units are produced
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before anyone notices the defect. Since the people who discover the defects are usually several stages down the line
from the operators at the defect-causing process, it is very
difficult to trace where that process is, and therefore it is very
likely the defect will occur again.
By contrast, flow production using multi-process operations usually includes self-inspection by the multi-process
operators. These operators not only turn out products, they
objectively inspect them for defects. The inspection results
reflect directly on their work and remind the operators that
quality is built into products at each process.
In conventional shish-kabob factories, the general attitude
among line workers is: “I just make them. It’s up to the
inspectors to inspect them.” When we stop to think of the
way the quality “buck” gets passed to the inspectors, we can
recognize just how flawed the conventional approach is. The
inspectors do what they can to sort out defects, but they do
little or nothing to stop them from recurring.
We have been comparing shish-kabob production and flow
production using multi-process operations only in terms of
their quality aspects. But there are other important aspects,
such as costs and punctual delivery. The cost impact of these
two very different approaches includes the cost of in-process
inventory waste, space-related waste, conveyance waste, and
waste caused by putting things down and picking them up
again. Flow production using multi-process operations can
completely eliminate all of these kinds of waste.
One way to eliminate these kinds of waste is the practice of manpower reduction. (Chapter 7 describes manpower
reduction in detail). Manpower reduction means using the
minimum number of workers needed to produce the amount
of products ordered by the client. When work is divided into
single-skill tasks, more workers are needed to operate a production line and it is more difficult to reduce the number of
workers when client orders shrink. Multi-process ­operations
Multi-Process Operations ◾
enable us to easily determine the minimum number of workers needed for any particular amount of output.
As for the delivery aspect, the lead-time for multi-process
operations is remarkably shorter than for conventional shishkabob operations. The former method not only prevents
delivery delays, but reduces lead-time to where it is much
better able to adapt to schedule revisions than the latter conventional method.
Questions and Key Points about
Multi-Process Operations
Questions from Western Workers
Whenever I begin explaining JIT production to Europeans,
Americans, and other Westerners, they usually look at me
with a baffled expression, since their way of making things
is so different from the way I am describing. After I describe
multi-process operations to them, they pose questions that
invariably include the following.
Question 1: Don’t Multi-Process Operations
Present Problems with the Labor Unions?
Yes. As a matter of fact, we can expect to have problems
with the labor unions whenever we attempt to introduce
multi-process operations in Western countries. In Japan, labor
unions are “enterprise unions” in that each company has its
own union. This means that companies can changeover
to multi-process operations without having to change the
union organization.
In the West, most unions are “craft unions.” There are
press workers’ unions and lathe workers’ unions and so on.
The press workers’ unions include people who specialize in
operating presses, and this specialization makes it difficult,
if not impossible, to introduce multi-process operations.
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Japan
Company
A
The West
Company
B
Company
C
Company
D
Union 1
Company A’s
union
Company B’s
union
Enterprise unions
Figure 6.3
Union 2
Union 3
Craft unions
Enterprise Unions and Craft Unions.
When Japanese automakers build plants in the West, they
generally try to hire all nonunion labor in order to facilitate the
introduction of multi-process operations. (See Figure 6.3.)
Question 2: Do Workers Get a Raise in Pay after They
Have Learned to Handle Multi-Process Operation?
There is a strong belief among Western workers that a worker’s pay should correspond to the level of his or her skills. It
would follow that someone who takes the trouble of learning
the multiple skills needed for handling multi-process operations should expect a pay raise. In Japan, raises are generally
tied to seniority in the company and not so much to specific
skills. Very few Japanese workers or managers think that
learning to handle multi-process operations should directly
affect pay scales.
Question 3: If All Company Workers Need to
Learn to Handle Multi-Process Operations,
Wouldn’t That Incur a Tremendous Amount
of Training Costs for the Company?
In the West, it takes about three months of basic training to
teach an unskilled worker how to operate factory equipment.
Training the entire factory workforce to handle multi-process
operations would indeed mean colossal training costs. But
there are other, less expensive ways to train workers. In Japan,
companies provide very little in the way of basic training
Multi-Process Operations ◾
courses for equipment operators. Instead, starting workers
are given unskilled jobs and are required to spend about one
hour of overtime each day just watching the skilled workers
do their work. Another way Japanese companies keep training costs down is by thoroughly standardizing equipment so
that few machines require a lot of specialized knowledge for
their operation.
When seen from the perspective of the Westerners who
typically ask the previous questions, it becomes obvious
that JIT production is a very Japanese type of production. In particular, multi-process operations makes superb
use of the flexibility in job assignments that characterizes
Japanese companies.
Eight Key Points about Multi-Process Operations
Let us take a closer look at multi-process operations and the
answers given to those three questions by examining the
following eight key points about multi-process operations.
Point 1: Establish U-Shaped Manufacturing Cells
The first thing to do in preparing for multi-process operations
is to abandon the “job shop” type of layout, which is appropriate only for shish-kabob production, and set-up a “flow
shop” arrangement where the equipment is laid out according to the processing sequence. In other words, the various
machines are lined up in a closely linked processing cell.
In this kind of cell, U-shaped lines are better than straight
lines. Straight lines create waste by making operators walk
farther when going back to get another workpiece at the end
of each set of processes.
Figure 6.4 shows an automotive electronic parts assembly
line. Before improvement, this line included about four or five
cases of 24 parts each as in-process inventory between each
set of processes. After improvement, they built a U-shaped
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Before improvement
In-process
inventory
After improvement
Ha
(sm rden
all ing
ov
en
)
7
8
6
Soldering
3
Setting up
Silicon
filling
10
Press
filling
Unit
assembly
Inspection
4
11
2
1
12
13
k
Pac
Unit
assembly
Packaging
9
Inspection
Press
fitting
5
Setting up
Caulking
Caulking
Silicon
filling
Resin
filling
Resin
filling
ing
en n)
rd ve
Ha ge o
r
(la
Hardening
(large oven)
Soldering
396
ing
ag
In-process inventory gathers at each
proces and gets conveyed in carts.
Workpieces move smoothly in a
U-shaped cell.
The number of production days
needed for this shish-kabob production
system comes close to a full week.
There is no in-process inventory except
during hardening
Figure 6.4
Lead-time has been reduced to a matter
of minutes.
Creation of a U-Shaped Manufacturing Cell for Automotive
Electronic Parts Assembly.
manufacturing cell using a smaller hardening unit that could
fit into the cell. This new layout eliminated cart conveyance
and enabled a smooth one-piece flow of workpieces. The
operators learned how to handle all 11 processes in the cell
and, as a result, a smaller number of workers could produce
the same output.
Point 2: Abolish Processing Islands
Manufacturing should have a steady rhythm to it, but who
should determine the rhythm? The customers, of course.
The rhythm that customer orders dictate is dictated first to
the assembly stage, then to the processing stage, and finally
Multi-Process Operations ◾
Before improvement
Stem process
(Small processing “islands”)
Line A
Line B
Line C
Line D
Must carry
in-process
inventory
between
processes
Inventory used for keeping pace with assembly processes
After improvement
Effects
Saves 4.59 square meters
of space
Reduces lead-time by half
a day
Eliminates 4,000 units of
in-process inventory
Enables manpower reduction
of four workers
Stem processes
arranged in-line
Line A
Figure 6.5
Line B
Line C
Line D
In-Line Arrangement of Watch Stem Processes (Eliminate
Processing “Islands”).
to the basic materials processing stage. However, at many
­factories, some processes exist independently as isolated little
islands that run at their own rhythm. These little islands are
full of waste—waste caused by their independent rhythms,
by the resulting idle time for workers, and by their less obvious operating methods.
It is imperative to eliminate such processing islands and
bring them directly into the line or cell. Figure 6.5 shows how
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a watch factory’s winding stem process was brought into an
integrated line. Before this improvement, the stem gear process was an isolated “island” that was operated at its own
pitch by four workers, each of whom had to carry armfuls of
inventory. They had to keep this little island well-stocked with
workpieces in order to keep pace with the assembly lines.
After the improvement, they were able to balance this line
with the assembly lines by including a stem process in each
assembly line. As a result, they freed up 40.59 square meters
of floor space, cut lead-time by half a day, eliminated the
4,000-unit stem inventory, and reduced the number of workers by four. (See Figure 6.5.)
Point 3: Make the Equipment Smaller
Usually, when a factory brings in new machinery, the major
concern centers on how efficiently that machinery can be
used. Even more important than the efficient use of any individual machines is the overall efficiency of the entire production system. (The concept of overall efficiency is discussed
further in Chapter 2.) The equipment only needs to work fast
enough to keep up with the cycle time. Therefore, we do
not need fast, large, and expensive general-purpose equipment when the job can be done perfectly well using slower,
smaller, and cheaper machines that perform only specialized
tasks. Getting the right kind of equipment is the first step in
bringing all equipment into a single line.
Figure 6.6 shows how a smaller shotblaster for automotive
parts was developed. Before this improvement, this factory­
was using a shotblaster that was as tall as three people and
was installed in its own room. Naturally, this machine lent
itself to processing large lots, and the piles of in-process
inventory in front of the shotblaster room took up twice as
much space as the room itself. The shotblaster handled minimum lots of 500 units, and the units often banged into each
other while being shotblasted, producing a defective rate of
Multi-Process Operations ◾
Before improvement
Large shotblaster unit
The large shotblaster was
as tall as three people and
had its own room. It
processed lots of 500
units or more. Almost
one-tenth of the shotblasted
parts became defective
due to collisions during
shotblasting. Inspectors
had to sort the defective
units from the good ones
after each shotblasting
operation.
After improvement
Small shotblaster unit
The small shotblaster is
one meter wide, one meter
deep, and two meters high,
it fits into the processing line
and produces zero defects.
The total equipment costs
related to the large
shotblaster—cranes, conveyors, maintaining a
separate room, and so
on—were cut in half.
Figure 6.6
Shotblaster for Automotive Parts.
nearly 10 percent. Inspectors were kept busy sorting out the
defective parts after each lot was shotblasted.
The factory worked with the shotblaster manufacturer to
develop a smaller machine that measured one meter wide,
one meter deep, and two meters high. They called it the
“one-piece shotblaster” Not only was this new shotblaster
small enough to bring directly into the processing line, but it
eliminated shotblast damage-related defects and removed the
need for a shotblasting room, cranes, conveyors, space for
in-process inventory, inspector manpower, and other forms
of waste. (See Figure 6.6.)
Point 4: Standing While Working
At most home electronics or electronic component assembly
plants, we can find rows of female workers seated alongside
conveyors, busily assembling products.
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Standing while working is a basic requirement for multiprocess operations. Workers need to learn how to work
on their feet. Once they are standing, they can more easily
help their neighboring workers and thus eliminate idle time.
Simply standing can do wonders.
Think about how the typical housewife fixes dinner. Can
you imagine her seated at the kitchen counter or the stove,
calling, “Dinner’s almost ready,” to her family as she busily
prepares the food?
Point 5: Multiple Skills Training
Multiple skills training is an obvious necessity if we are going
to have workers capable of handling multi-process operations. Multi-process operations occurs when a worker takes
individual workpieces through the processing sequence,
operating a variety of processing equipment. This differs
from being an expert on any particular machine, such as
thoroughly understanding the machine’s design, retooling,
operation, and maintenance.
The key to success in multi-process operations is simplifying the machines so that they perform only the essential
processing function and do not require frequent fine-tuning.
After that, we need to make certain that the workers learn
how to systematically and confidently use the skills needed
to operate those machines.
Figure 6.7 shows an example of multi-process operations
at an auto parts machining line. This line is centered on
numerically controlled machine tools and includes seven processes altogether. The operator is a 19-year-old woman. The
key training points for multiple skills in this case included
standardizing the machines, work procedures, and various
other forms.
Point 6: Separate Human Work from Machine Work
This means making a clear distinction between work done
by people and work done by machines, then separating the
Multi-Process Operations ◾
This multi-skilled worker operates a machining line
for automotive parts.
This operater, a 19-year-old woman, has learned
to handle seven different processes.
Figure 6.7
Multi-Skilled Worker in a Machining Line.
people from the machines whenever possible. (Separating
human work from machine work is described further in
Chapter 14.)
Usually, equipment operators stay close to their machines
while the machines do their work. The fact is, however, that
the worker and the machine each have separate tasks to do.
Obviously, labor costs and equipment costs are both costs
the company must pay.
If we can clearly distinguish between human work and
machine work, the worker can leave the machine alone
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Pneumatic cylinder
(presses workpiece)
ON switch
Before the pneumatic cylinders were installed, the operator
had to hold the workpiece in position for drilling.
After the improvement, the operator only needs to press the
ON switch, and can then leave the machine alone.
Figure 6.8
Separating Human Work from Machine Work at a Drilling
Machine.
to do its work while he or she goes on to the next human
task. To make this possible, we must often develop devices
and techniques that fall under the categories of “human
automation­” and “poka-yoke.”
Figure 6.8 shows how human work was separated from
machine work at a drilling machine. Before the improvement, the worker would press the ON switch and stand there
holding the workpiece on the drilling machine with both
hands. This meant that the worker was not free to do other
work until the workpiece had been drilled.
After the improvement, pneumatic cylinders were installed
on the right and left sides of the drill. When the worker
presses the ON switch, these cylinders hold the workpiece
in the correct position, enabling the worker to be completely
separate from the machine.
Point 7: Human Automation and Poka-Yoke
Once the operator is able to let the machine do its own work,
he or she is free to turn to the next human task. But what if
Multi-Process Operations ◾
Before improvement
After improvement
Press
Press
Workpiece
Die
Die
Workpiece Connected
to power
circuit
Limit
switch
Figure 6.9 Use of a Poka-Yoke Device to Prevent Press Set-up Errors.
the machine starts producing defects without anyone there to
notice? Does that mean we have to keep the operator there
just to watch out for abnormalities? If we do that, we have not
really separated the human work from the machine work.
Instead, we must come up with ways to prevent defects by
having the machines automatically detect them and then stop
operating. This is where human automation and poka-yoke
come in. (Human automation and poka-yoke are described
further in Chapter 14.)
Figure 6.9 shows a poka-yoke device that prevents set-up
errors in a press. Before the improvement, the operator had
to set-up the workpiece and then confirm correct set-up.
Sometimes, however, the operator still made set-up errors,
which resulted in defective products.
After the improvement, the machine was equipped with
a limit switch that prevented the machine from operating
unless the workpiece was set exactly right. This enables the
operator to leave the machine without having to worry about
the possibility of producing defective goods.
Point 8: Safety First
Once we have begun multi-process operations, we need to
pay more attention than ever to safety matters. Everyone
should remain mindful that “safety takes precedence over
everything else.”
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One safety point is to keep start buttons separate from the
machine themselves so operators will be at a safe distance at
the instant the machines start working. Other useful safety
devices include machine covers and electric eyes that shut
off the machines when anything or anyone approaches them.
Even when there are several operators working in the same
U-shaped manufacturing cell, everyone must be very careful
to maintain safety.
Precautions and Procedures for
Developing Multi-Process Operations
Seven Precautions for Developing
Multi-Process Operations
Single-skill workers are incapable of handling several types
of processing machines and/or procedures. Therefore, we
cannot have multi-process operations until we have taught
the operators the wide range of skills they will need for the
job. When training these operators, please note the following
seven precautions.
1. Make work procedures as simple as possible
There will inevitably be some cases where operators will
need to learn certain procedures that take a long time to
master or involve special skills. This is especially true of
retooling and fine-tuning procedures.
We can minimize these difficulties by simplifying work
procedures so that anyone can easily understand how
to perform them. In addition to simplification, thorough
standardization can go a long way toward making multi­
ple skills for multi-process operations easier to learn.
2. Factory leaders should provide proper guidance
Effective leadership from factory managers and foremen
is essential for ensuring swift progress in multiple-skill
training.
Multi-Process Operations ◾
After all, the operators are not the ones who best understand how the factory’s various processes fit together and
what procedures are involved in each process. Managers,
foremen, and other supervisors have this knowledge and
should put that knowledge to use in helping operators
learn multiple skills for multi-process operations.
3. Transparent operations
When teaching work operations to a novice, we must
explain the various operations and steps as clearly and
fully as possible. This is what I mean by “transparent
operations.” (Chapter 13 explains the difference between
transparent operations and standard operations.) To
make our explanations transparent, we must uncover
and elucidate all the little details that are usually considered “givens” and left unexplained. These “transparent
operations” will ensure that even a completely unskilled
worker will have all the information he or she needs to
perform the job correctly.
Nothing should be left up to the factory’s “oral tradition­”
of know-how that gets passed from person to person­.
Everything must be explicit and by the book. Job guidelines and operations manuals must contain clear descriptions of thoroughly standardized operations.
4. Implement multi-process operations throughout the factory
Multiple skills will soon deteriorate if they are only taught
for certain processes or workshops. Company presidents
and/or factory supervisors should put their full authority into promoting factory-wide multiple skills training.
They should use whatever vehicles of communication
are available to them (such as in-house news­letters and
speeches) to issue progress reports on multiple skills
training. They should also periodically hold “­multiple
skills contests” to present awards of recognition to the
best trainees.
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5. Promote perseverance and set successive goals
Multiple skills training needs perseverance like a car
needs gasoline. Trainees have to be constantly encouraged to “hang in there” no matter what problems they
encounter. There is no rush—the key is to take all the
time you need to accomplish the training.
It is also very important to be systematic by clearly scheduling the various steps in multiple skills training. Draw
up reference charts, such as a “Multiple Skills Training
Schedule” or a “Multiple Skills Score Sheet,” so that you
can have an at-a-glance display of each trainee’s progress.
6. Make prompt equipment modifications
Sometimes we need to modify equipment to make it
easier for anyone to use or to enable the separation of
human work from machine work.
Sometimes workshop employees get let down when
production engineers or the equipment maintenance staff
refuse to make the desired equipment improvements. It
would be nice to have a team of equipment experts who
specialize in JIT-related equipment improvements and
are ready to work at a moment’s notice. If the desired
equipment improvement is simple enough, equipment
operators or factory floor supervisors may be able to
make the improvement themselves.
7. Absolute safety
Since multiple skills training requires novices to learn to
operate various kinds of processing equipment, we must
make sure the training is not hazardous. If even one
accident or injury occurs during the training, it will likely
have an adverse impact on morale and willingness to
learn. We must therefore do everything we can to avoid
all possible hazards.
Basically, two things can ensure absolute safety: careful
safety checks during the design and operation of the equipment, and safety-minded discipline.
Multi-Process Operations ◾
Five-Step Procedure for Training
Multi-Process Workers
A few examples of multiple skills training can be found at
just about any Japanese factory. Some factories proudly display banners or signs that announce their commitment to
multiple-skills training.
However, almost all of these factories that promote multiple-skills training do not train workers to use these skills
in a flow production system. Instead, they are mainly interested in having “pinch hitters” who can readily substitute for
absent workers. These factories continue to operate shishkabob production systems, and the multiple-skill workers are
trained to move batches of workpieces from one process to
the next in what I call “caravan style” operations.
They do not understand the true meaning of multiple-skill
training and multi-process operations. Flow production forms
the very foundation for JIT production. Factories must focus
on the need to cultivate true multiple skills, which means
the ones that are required for flow production using multiprocess operations.
Multiple-skills training is a lot like small-group a­ctivities
because it vitally depends on the involvement of the entire
factory and on the encouragement provided by factory
­leaders. Many workers need to be prodded along—they are
not fond of new adventures. They are snuggled safely into a
cozy nest made up of work habits and the single set of skills
they have practiced for years and years. They know their job
perfectly and need not fear any unpleasant surprises. In fact,
they can be confident and proud knowing that no one can
perform their particular job as well as they can.
Multiple-skills training asks these seasoned “veterans” to
throw away their single-skill achievements and start all over
as amateurs. No wonder they resist so much.
We must use strong medicine to rid factories of this addiction to traditional work methods. We must go over the heads
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of section and division chiefs and include the company president and other top managers in the effort to encourage workers to accept the challenge of learning multiple skills.
I recommend following the steps described below when
promoting multiple-skills training.
Step 1: Create multiple-skills training teams
It is usually best to follow the familiar format of small
group activities by creating multiple-skills training teams.
If the factory has already established a small-group activities program, it can simply set-up “multiple-skills training”
as a new major theme within the program. The important
thing is to help put trainees at ease and to set the stage
for the challenge of developing multi-process operations.
Step 2: Clarify what the trainees’ current skills are for each
process
Before beginning the multiple-skills training, find out what
skills and strengths the operator trainees already have
and explicitly describe them. This can generally be done
by entering the trainees’ names on a chart and marking
“skilled” or “unskilled” next to each process to indicate
whether or not each trainee has the skills required for each
process. You may need to make separate current ability
marks when special skills are required in the process.
If possible, it would be even better to evaluate current
skills using multiple levels instead of just the two ­levels of
skilled and unskilled. A five-level skills evaluation might
be organized as:
a. Level 1: Unable to do the operation.
b. Level 2: Able to do the operation if someone else
does the set-up.
c, Level 3: Can generally do the operation, but needs
minor guidance.
d. Level 4: Can do the operation well, except under
unusual conditions.
e. Level 5: Can do the entire operation well.
Multi-Process Operations ◾
Step 3: Use a “multiple skills training schedule”
We are now ready to set separate targets for each trainee
whose current skills we just evaluated in Step 2. We
should keep it simple by displaying person-specific lists
of current conditions and targets, rather than p
­ rocessor skill-specific lists. Also, we should avoid numerical
indicators if more easily understood graphic ones can
be used. Popular graphic display formats for this include
“multiple skills score sheets” and “multiple skills maps.”
Figures 6.10 A, B, and C show three examples of multiple
skills training schedules.
Step 4: Create a multiple skills training schedule that makes
effective use of overtime hours and other opportunities
Once we have set specific targets for every worker, we
need to set-up a multiple skills training schedule tailored
to each worker’s objectives. We should try to avoid using
the noon hour, since that tends to disrupt production
activities. It is better to use evening overtime hours.
Multiple Skills
Training Schedule
Unable to do operation (LOSS)
Can generally do operation (TIE)
Can do operation well (WIN)
Factory name:
HIC
Foreman:
Yamasaki
By:
Date:
11/20/88
Yamasaki
6
Worker F
Figure 6.10A
Packaging
Worker E
Electrical char.
5
Tie bar card
Worker D
External view insp.
4
Sealing
Worker C
Curing
3
Powder coating
Worker B
Soldering
2
Corrections
Worker A
Visual inspection
1
Cleaning
Operator
name
Reflow
No.
Printing
Process
name
Mounting
Process
no.
Current
date
Target
date
(11/30/88) (3/31/89)
5 wins
7 losses
2 ties
6 wins
7 losses
1 ties
4 wins
7 losses
3 ties
7 wins
5 losses
2 ties
3 wins
11 losses
12 wins
2 losses
3 wins
10 losses
1 ties
6 wins
8 losses
Examples of Multiple Skills Training Schedule.
12 wins
2 losses
9 wins
5 losses
11 wins
3 losses
7 wins
7 losses
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Multiple skills score sheet
WIN
TIE
LOSS
Multiple Skills Score Sheet
Period: 4/1/88 to 6/30/88
Gyochu Dept. 1, Section 2
Process
Pressing Punching Bending Bending Drilling Finishing
Operator name
(1)
(2)
name
Wins and Losses
4/1
6/30
5 wins
1 loss
6 wins
0 losses
Worker C
3 wins
2 losses
1 tie
4 wins
2 losses
Worker D
3 wins
3 losses
4 wins
1 loss
1 tie
4 winss
2 losses
1 tie
4 wins
2 losses
Worker E
2 wins
4 losses
3 wins
3 losses
Worker F
1 win
5 losses
2 wins
4 losses
Worker A
Worker B
Monthly check
Multiple skills score sheet
Multiple Skills Score Sheet
Period: Dec.–Jan. 1988
Manufacturing Dept. 1, Section 2
Process
Coater Coater
Operator name
1
2
name
DB
PL
MJ
BP
CD
Section chief’s check
1 2 3 4 5 6
7
8
9
10 11 12
Progress
100%
50%
Worker A
Worker B
Worker C
Worker D
Worker E
Worker F
Evaluation criteria
Unable to do operation
Able to do the operation if
someone else does the set-up
Can generally do operation,
needs minor guidance
Color coding
Can do the operation well,
except under unusual
circumstances
Black..................................1987 results
Red shading....................... Estimated
1988 results
Red.....................................1988 results
Can do entire operation
well
Figures 6.10B,C
For training in U-shaped manufacturing cells, it is
best to pair up trainees with experienced workers and
have them work together until they can keep pace with
the cycle time. During this time, we will likely see the
Multi-Process Operations ◾
trainee and experienced worker develop a cooperative
operations approach on their own.
Step 5: Periodically announce score sheet standings to raise
worker awareness
At regular intervals, such as once or twice a month,
factory supervisors should announce the trainees’ current score sheet standings to make everyone aware of
recent progress and to identify cases of delayed progress that need special attention. It is better to report the
multiple-skills progress of trained teams rather than individual trainees.
If you choose to give progress reports for individuals,
it is best to report their current status as “X percent of
the way to the target,” or in terms of “wins” and “losses”
regarding specific skills (as shown in Figure 6.10).
And let us not forget the very important role the workshop leaders play in fostering multiple skills training. When
learning a completely new skill, the trainee should begin by
just watching an experienced operator or workshop leader
do the job. These leaders in training have a direct and vital
impact on the trainees. The trainees will learn the correct
things, as well as any incorrect things, their more e­ xperienced
­colleagues demonstrate.
On-the-job training is clearly the best way to learn multiple skills for multi-process operations. Pulling a particular set
of processes out of the production line to make an isolated
island for training is not worth the time and trouble, since the
training can be done within the production line.
In other words, training should be within the flow production system. This puts more pressure on performance. If
we are just a little too slow, it causes problems for the next
process. This keeps the trainees on their toes and aware of
what is going on in the line. We call this method of training
“multiple skills flow training.”
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Multiple skills flow training should take the following steps.
Step 1: Have the workshop leaders do the job first
Equipment operators learn quickly if given a chance to
watch others do the job first. That is why it is best to start
just by having them watch an experienced workshop
leader do the job.
Step 2: Explain the operation points
Seeing is not enough. We also need to explain the procedures and main purposes of each job and make sure the
trainees understand them thoroughly. At the very least,
the teacher should explain the particular cycle time,
operation sequence, standard operations, quality check
points, and safety points.
Step 3: Hands-on practice
The trainee has seen and heard what he or she needs to
know, it is time for some hands-on practice. The trainee
should be allowed to attempt the entire set of operations
for the process. If he or she starts lagging behind the
cycle time, the trainer can step in to help. After repeated
practice, the trainee will be able to perform the job
according to the particular standard operations.
For example, let us suppose that a certain job includes
five processes. The operator will start at the first process,
and then in succession move on to the four others. If, at
the third process, the trainee starts lagging behind the
cycle time, the trainer should step in to help with processes 4 and 5. (See Figure 6.11.)
This works better than having the trainee just practice
process 1 until he or she has learned it. The one-processat-a time approach is too much like having isolated processing islands. The trainee will not gain a feel for flow
production unless the training uses a flow production
line of closely linked processes.
Multi-Process Operations ◾
2
1
3
“I’ll step in to help
you if you start falling
behind the
cycle time.”
Trainer
Figure 6.11
Trainee
Trainer Helping Trainee during Multiple-Skills Training.
Step 4: Review the training immediately.
It is important to reserve a little time immediately after
each training session to review the session. This is the
perfect time to have another look at the key points in
the operation and to resolve any confusion over what
has been covered in that session. This should not be a
purely negative review by the trainer. The trainer should
always remember to praise the trainee. Beginners naturally feel uncomfortable around veteran operators, and
the t­rainee’s self-confidence is easily damaged. Harsh
criticism is therefore often counterproductive. The trainer’s responsibility is to bolster the trainee’s confidence
and enthusiasm. This is important.
In short, my advice to trainers of multiple skills for flow production is: show them, tell them, have them do it, then praise
them. You need all four steps to get multiple-skill workers.
413
Chapter 7
Labor Cost Reduction
What Is Labor Cost Reduction?
The Approach to Labor Cost Reduction
Improvements in both productivity and humanity have long
been major themes at factories everywhere. The market envi­
ron­ment and needs differ from one era to the next, and factories must always attempt to make improvements in productivity
and humanity that match the current market conditions.
Until recently, the general supply of products lagged behind
demand, which in many cases meant, “If you can make it,
it will sell.” Factories sought to expand output volume, and
looked at productivity-boosting measures as a means of doing
just that. Human labor became more and more specialized,
and factories tried to give workers simple tasks that they could
master quickly. This simplification of worker roles as little cogs
in a big machine tended to rob workers of the joy of creating
things, but it served the factory’s objective, which was to have
a stable and highly regimented workforce that could turn out
increasingly greater volumes of products. The following equation describes this volume-oriented approach to productivity.
PRODUCTIVITY ↑ =
PRODUCTION OUTPUT ↑
PRODUCTION INPUT →
Eventually, the overall supply of goods overtook demand,
leaving more room for diversification based on consumers’
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individual preferences. Manufacturers began to notice that
their large production runs of identical products were no
longer selling as briskly. Sales forecasts heralded the dawn of
a new era, in which high volume output could no longer be
assured of high volume sales.
Manufacturers began searching for a better way of making products that would sell. This was the advent of today’s
wide-variety, small-lot era. The soil was right for the JIT production system to take root. In contrast to the large-volume
production approach that emphasized production and was
thus a “product-oriented” or “product-out” approach, the new
approach for the wide-variety, small-lot era emphasized the
customers (that is, the market) and was a “market-oriented”
or “market-in” approach.
Naturally, this new era saw growth in production volumes
slow to a trickle. Manufacturers reckoned that the only feasible way to raise productivity in such a sluggish market c­ limate
was to reduce labor costs and other product input costs. They
sought to cut labor costs by investing in greater mechanization and automation, but such improvements require a lot
of investment funds and cannot ensure steady productivity
because of rapidly changing market needs. Eventually, p
­ eople
started talking about building products more economically
by matching production input to customer orders. This is the
basic idea behind the labor cost reduction approach described
in the following equation:
PRODUCTIVITY ↑ =
PRODUCTION OUTPUT →
PRODUCTION INPUT ↓
Thus, we can define labor cost reduction as meeting the
needs (changes) of the next process (ultimately, the market)
while incurring as few personnel costs as possible.
Let us suppose, for instance, that a factory employs ten
people to produce 1,000 units per month of product A.
However, a recent slowdown in sales has shrunk customer
Labor Cost Reduction
orders to just 800 units a month. The traditional response to
this situation is expressed in the following equations. The
equation expressing the previous order level is:
1000 UNITS
(Number of products
(Monthly output)
= 100 UNITS produced per month
10 PERSONS
by each person)
(Labor cost)
The equation expressing the new order level is:
800 UNITS (Monthly output)
= 8 PERSONS
(Labor cost)
(Number of products
100 UNITS produced per month
by each perso
on)
The arithmetic is quite simple; assuming each worker can
produce 100 units per month, the factory simply needs to
reduce its workforce from 10 persons to 8 persons. However,
it may not be so simple to reduce a ten-person workforce by
two persons, especially if each of the ten workers specializes
in handling just one type of machine.
This problem has forced some manufacturers to discard
the concepts of single-process operations and strictly defined
job roles and to instead embrace the new notions of multiprocess operations and flexible job roles.
The realization of this kind of labor cost reduction is not without its technical obstacles, and the chief obstacle is a psychological one: giving up the fixed idea of large lot production.
The Difference between Labor Cost
Reduction and Labor Reduction
Terms such as “labor reduction” and “labor savings” are familiar to all of us. We tend to think in these terms when confronted with the following types of situations.
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Let us suppose that a factory has been using a singlespindle drill that required some manual assistance in drilling. Then the factory managers decide to buy a numerically
controlled (NC) drill to automate more of the drilling work.
However, the NC drill still requires a human operator, and so
the factory is unable to reduce its manpower even after purchasing it. Whereas the worker used to be busy with manual
drilling, now he or she simply sets up the workpiece, presses
a start button, and watches the NC drill do the drilling. The
NC drill has realized a labor savings (that is, the worker has
less work to do), but not a labor cost reduction.
This case illustrates the meaning of the familiar term “labor
savings.” The investment in the NC drill has raised the plant
investment cost without bringing a reduction in labor costs,
so overall costs are actually higher than before.
Another familiar term is “staff reduction.” Staff reduction means responding to demand fluctuations by simply
reducing the number of workers without making any wasteeliminating improvements. However, if we just reduce the
number of workers without making such improvements, the
result will be labor intensification—in other words, more
work to do for the remaining workers. Obviously, this kind
of labor cost-cutting cannot go on for long. The following
short definitions should help clarify the distinctions we need
to make among labor reduction, staff reduction, and labor
cost reduction.
◾◾ Labor reduction: Reducing the workload without cutting
labor costs.
◾◾ Staff reduction: Reducing the workforce without removing waste (which means a heavier workload for remaining workers).
◾◾ Labor cost reduction: Removing waste, then using the
minimum required workforce.
Labor Cost Reduction
Labor Cost Reduction Steps
To be able to respond flexibly to changes in customer orders,
we must have flexibility throughout our production system.
Hence, the concept of “flexible production.”
But exactly what needs to be made flexible? Everything—
meaning every main element of production, from people and
materials to machines, operating methods, and management.
Let us look at these elements one by one.
◾◾ People: We can increase human flexibility by training
single-skilled workers to become multi-skilled workers.
◾◾ Materials: We can improve flexibility in materials by moving from diverse specifications to shared specifications.
◾◾ Machines: Machines can in several ways be made more
flexible by:
1. Making nonmovable equipment movable.
2. Switching from large machines to smaller ones.
3. Switching from expensive machines to cheaper ones.
4. Switching from costly “do-it-all” machines to cheaper
specialized machines.
◾◾ Operation methods: Again, flexibility may be enhanced
in several ways by:
1. Abandoning lot production in favor of one-piece
flow production.
2. Switching from strictly defined job roles to flexible
job roles.
3. Switching from separate job responsibilities to cooperative job responsibilities.
4. Giving up idiosyncratic operations and enforcing standard operations.
5. Switching from “push production” to “pull production.”
◾◾ Management: We can increase management flexibility
by de-emphasizing statistical control and emphasizing
visual control.
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Thus, we need to make all sorts of changes to make
the factory conducive to flexible production. Below, I have
arranged some of these into a sequence of changes needed
for realizing labor cost reduction.
Step 1: A Change in Philosophy
It is not possible to give up lot production and strictly defined
job duties without also giving up the whole conventional “way
of doing things.” Even when someone decides, “OK, I’ll give
up all my preconceived notions about how things should be
done,” it is much easier said than done. Often, the old way
of doing things is very old indeed; some workers have been
doing things the same way for ten or even 20 years! The
old way has become a deeply ingrained habit and cannot
­simply be cast aside. Workers who cannot bring themselves
to admit the need for a change in philosophy might as well
start preparing for retirement. Labor cost reduction requires
flexibility, and flexibility must begin in the mind.
Step 2: Make Production Equipment
Easy to Move Around
Large units of production equipment tend to have an imposing presence, as if they were standing with arms crossed
and chest thrust forward, proclaiming, “I make widgets and
I make them right here.” We tend to lose our enthusiasm for
making layout improvements when we come face to face
with such huge machines that have usually been bolted to
the floor. At such times, let us remember the following:
1. Whenever possible, install casters on equipment and work
tables to make them movable. We must install the casters
in a way that does not raise the height of these units.
2. If the machine has an oil pan under it, find out what is
causing the oil leakage, fix it, then remove the oil pan
and install casters.
Labor Cost Reduction
3. Some machines have air ducts or power cords that limit
their movability. In such cases, try lengthening the cord
(make sure the length still meets safety specifications)
and install flexible air ducts if possible.
Step 3: Get Rid of Processing Islands and
Integrate Equipment into a Line
Labor cost reduction is not possible if workers are assigned to
their own little isolated processing stations. We have to begin
by bringing all those little islands together into one “land
mass” so that workers can be grouped in one place. Once
we have grouped our line workers, we can make a ­better
line layout and start making improvements for one-piece
flow production.
Step 4: Train for Multi-Process Operations
Instead of Simple, Specialized Operations
The more we break production operations up into little pieces
to be handled by different workers, the farther we get from
labor cost reduction. Instead, we need to train workers­in
the multiple skills they need to handle multi-process operations. At each step of the way, we also need to implement
thorough standardization.
Step 5: Standardize Equipment and Operations
Thorough standardization of equipment and operational
procedures is essential for promoting multiple skills t­raining.
This training will progress much more rapidly if we can make
the equipment easy enough for anyone to operate and the
operations easy enough for anyone to perform.
Step 6: Level Out Production and
Assign Appropriate Workloads
Find an average spread for product models versus volume,
then divide this up by the cycle time and use the result as a
basis for establishing standard operations. Use the cycle time
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to calculate the daily production output per person, then find
the number of required workers depending upon how much
each worker can do. (This procedure is described in detail
in Chapter 10.)
When carrying out the above procedures, we must be careful to avoid putting too many workers on the line just because
the workers are available. We must not ignore how much
work each worker can comfortably handle. Workers are easily
tempted to think, “Let’s just take it easy since things are slow
now.” Managers tend to get lax about standards. Implement
the 5S’s and improvement activities to find out how much
slack there is in the workforce and tighten up operations.
Points for Achieving Labor
Cost Reduction
We must not make compromises when carrying out the above
steps for achieving labor cost reduction. These steps include
five salient points, which I list and describe below in the
order of their appearance in the labor cost reduction steps.
◾◾ Develop flow production
◾◾ Cultivate multi-process workers
◾◾ Work in groups: no isolated workers
◾◾ Cooperative operations
◾◾ Separate people (from machines)
Develop Flow Production
Here are some typical characteristics of factories that are not
conducive to flow production:
1. Equipment layout and operational methods are set-up
according to the “job shop” model.
2. Equipment units are bolted in place and cannot be moved.
Labor Cost Reduction
3. Each worker has distinct and strictly defined job duties.
4. People generally think large lots are better than small ones.
5. At processes where there is a lack of workers, workers
are moved around “caravan style.”
To begin changing from lot production (shish-kabob production) to one-piece flow production, we must do away
with all of these obstructive characteristics.
Figure 7.1 shows an example of flow production on an
assembly line for medical equipment. Before improvement, this
line used eight workers, each of whom had a separate set of
assigned tasks. This rigidity in task assignments made it nearly
impossible to juggle operations when order levels fluctuated.
As part of the improvement, the layout was changed to
accommodate flow production and operations were switched
Mechanical assembly
Electrical assembly
Inspection
and
packaging
Electrical assembly
Overall assembly
Electrical assembly
After improvement
Standing while working
Multi-process operations
Flexible job duties
Mechanical assembly
Before improvement
Sitting while working
Fixed job duties
One-piece flow
Inspection
Packaging
Rest area
Figure 7. 1
Chairs and space freed by standing
while working used for rest area
Manpower Reduction through Flow Production (Medical
Equipment Manufacturer).
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from shish-kabob production to one-piece flow. The switch
to multi-process operations not only enabled a labor cost
reduction of two workers, but also made the line adaptable
to ups and downs in order levels.
Before improvement, all of the workers sat while working.
The improvement changed this to standing while working,
which freed a lot of space. The extra space and unneeded
chairs were used to make a rest area, which the assembly
line had previously lacked.
Multi-Process Operations
To reduce the manpower required for a certain amount of production output, we first need to establish flexible job duties.
Second, we must establish multi-process operations. This
second step is the key to success in labor cost reduction.
If we were to try to reduce manpower without first establishing multi-process operations, we would have to follow
these steps:
1. Removing one or more workers from the line.
2. Reassign job duties to the remaining workers.
3. Balance the line.
4. Set the conditions achieved after operational balancing
as standard operations.
Each time the line changes to a new product model or
the required production output goes up or down, we would
have to go through all four of these steps all over again.
Given today’s frequent fluctuations in product models and
volumes, this time-consuming process of reassigning job
duties and b
­ alancing the line after each adjustment of the
manpower makes this kind of labor cost reduction more
trouble than it is worth. What factory managers are really
wishing for is the kind of flexibility that enables them to
easily reduce manpower one day to meet that day’s output
Labor Cost Reduction
needs and to just as easily add manpower the next day. Only
multi-process operations can make this wish come true, and
that is why I call multi-process operations the key to successful labor cost reduction.
The three most important factors in establishing multi-process
operations are:
1. Line workers must stop sitting and instead stand while
working.
2. Lay out processes according to the processing sequence
and make each worker take individual workpieces
throughout the entire set of processes.
3. Set-up a company-wide multiple skills training program.
Once we have established one-piece flow using multi-process
operations, the lead-time will be much shorter, and the shorter
the lead-time, the lower the amount of in-process inventory.
Figure 7.2 shows how multi-process operations were established at a wood products factory’s processing/assembly line.
Before improvement
Router
Gluing
Input port
same as
output port
Finishing
Packaging
Finishing
Dowe
l
fitting
Gluing
Figure 7.2
r
Sma
lle
d
r
y
i
n
g ma r
chin
e
Dowel
fitting
Skilled
worker
te
Rou
Multi-spindle
drill
Island
Multi-process
operations
Drying
chamber
Island
Multi-spindle
drill
After improvement
Homemade small drying machine
is used only for drying glue.
Multi-Process Operations for Processing Assembly Line
at a Wood Products Factory.
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Before this improvement, almost all work done by the line
workers required special skills, and workers skilled in one
process were rarely able to handle other processes. To
change that, they first dramatically altered the layout, then
trained their workers in multiple skills, and finally established one-piece flow using multi-process operations. They
also made a very clever improvement in the drying process.
Before, they had used a large drying chamber for drying
glued parts. But since this chamber was too large for multiprocess operations, they instead opted for a smaller machine
that uses ordinary hand-held hair dryers and an auto-return
device that returns the glued workpieces to the input site
after they have been dried.
Not only did this improvement make the flow of goods
on the line much more visible, it also made it easy to adjust
the manpower to suit changing output requirements. It also
helped get rid of waste, such as conveyance waste, caused by
having isolated process stations.
Work in Groups: No Isolated Workers
We can distinguish among three types of “islands”—small
medium, and large—at which workers do their jobs with no
direct relationship to other workers.
◾◾ Small islands: Small islands are isolated areas where
one or more workers are kept busy doing simple tasks,
such as bagging items or mounting washers. Often, such
islands are used to prepare parts for assembly.
◾◾ Medium islands: Usually, medium islands consist of
medium-sized equipment, such as drills or lathes, that
are used apart from the processing line and that move at
their own pitch. As such, they are common in processing
sections of factories.
◾◾ Large islands: Large islands generally include large
equipment units, such as cleaning, coating, or welding
Labor Cost Reduction
machines, all of which are designed for large-lot processing. Most common in processing sections, large
islands are like dams that hold back the flow of goods.
Sometimes, large islands require their own room or even
their own factory facility.
If we have a large island, the most important point is to
develop and make smaller equipment. If we have a medium
island, we need to overhaul the layout and arrange the equipment according to the processing sequence. Finally, if we
have a small island, our first step is to group the workers and
assign cooperative tasks.
Figure 7.3 shows an improvement that was made at a
household electronics assembly plant. Before the improvement, each worker worked separately at his or her own pace.
Naturally, this imbalance resulted in a lot of waste caused
mostly by operations, in-process inventory, and conveyance.
If we look at each worker involved in a small processing
island, we can see the waste that is caused. But since the
workers are separate, it seems there is nothing that can be
done to improve the situation.
At the household electronics assembly plant, they began
by setting up a conveyor and grouping all of the workers
together. A conveyor can be valuable not only as a tool for
maintaining a certain pitch, but also as a tool for grouping
workers together.
After grouping their workers together, they laid out the
various processes in order, then used the cycle time as a
basis for assigning tasks. This helped eliminate the waste
caused by having separate workers and also enabled a labor
cost reduction of one worker.
Cooperative Operations
It is not at all unusual to have workers stand while working
if they are working on processing tasks and using a lot of
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Before improvement
Preassembly
Packaging
Belt conveyor
Finished
Packaging
product
Packaging
Overall
rhythm
6
7
8
1
2
Connect wires (1)
Connect wires (2)
Attach cover
Basic assembly
Inspection
Packaging
Soldering (1)
Soldering (2)
Eight workers
3
4
5
6
7
Packaging
5
Assembly & inspection
4
Assembly (1)
3
Connect wires (2)
2
Cycle time
Connect wires (1)
1
Soldering (2)
Individual rhythms
Seven workers
(Manpower reduction)
Final pitch
Figure 7.3
Assembly & inspection
Assembly (1)
Connect wires (2)
Solder
(2)
Solder
(1)
Connect wires (1)
Connect
wires (2)
Soldering (1)
Connect
wires (1)
(1) Group separate workers together
(2) Balance the lines
Balance soldering (2) and wire
connecting (1)
Balance cover installation and basic
assembly
Balance basic assembly, inspection,
and packaging
Basic
assembly
Soldering (2)
Attach
cover
After improvement
Soldering (1)
428 ◾
Manpower Reduction at Household Electronics Assem-
bly Line.
machines, tools, and other equipment. In fact, it is hard to
find seated workers doing this type of work. In assembly line
work, however, the situation is almost the opposite.
Assembly line workers tend to plant themselves on their
stools or benches and seem to believe they can get their jobs
done perfectly without having to take one step. About the
only time they use their legs is to join or leave the assembly
Labor Cost Reduction
Before improvement
After improvement
PCB assembly line
s
art
rt p
e
(Fixed job duties)
s
In
VCR assembly line
A
B
Manpower reduction to suit
output reduction
(Flexible job duties)
C
DIP
Cu
t
lea
ds
er
Ins
So
Ins
lde
pe
r
pe
Pac
k
ct
ag
ing
Ins
Ins
tal
lb
ac
Pac
k
er
ov
kc
ing
Ins
pe
ct
Ass
Ad
I
ju nsta
ble st ba ll
ck
cov
er
4
5
em
As
sem
ble
pe
ct
Process
2
3
4
5
6
7
1
A
B
B
Worker
Worker
ag
ut
A
C
D
2
3
6
7
C
D
Operation method: Separate job duties
Figure 7.4
t
ads
r
de nspec ut le
C
I
DIP
js
Ad
Process
1
Sol
A B C
ct
Main unit assembly line
Ins
s
art
tp
Operation method: Cooperative
operations
Cooperative Operations on a VCR Assembly Line.
line at the start or end of each shift and to get up for meals
and breaks.
As long as work procedures are that rigidly established,
labor cost reduction is impossible and it is even difficult
to raise productivity. Before we can make any significant
changes, we must establish the fundamental elements of
cooperative operations, which are “standing while working”
and “offensive (proactive) operations.”
Figure 7.4 shows how cooperative operations and labor
cost reduction were both realized at a VCR assembly line.
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Before the improvement, the rigid task assignments made
even slight increases in output something that required overtime work. Reductions in output were addressed by slowing
down the pitch.
Because each line worker had his or her own strictly
defined, separate tasks to perform, the line was not easily
adaptable to model changes or fluctuations in daily output
needs. If the managers were to remove just one worker (out
of 61) in response to lower output requirements, they would
have to take the time and trouble of balancing the remaining
60 workers on the line.
The answer, then, is to broaden the sphere of work that
each line worker is responsible for, so that job duties overlap between neighboring workers and therefore workers can
help their neighbor when he or she lags behind. This makes
the line more adaptable to model changes and production
output changes that occur from day to day. This improvement also helped get rid of the waste related to imbalances
and made the line easily amenable to manpower adjustments
in accordance with output changes.
Separate People (from Machines)
Most factory equipment operators are only rarely able to
physically separate themselves from their machines and do
other productive work while the machines are operating. The
reasons for this unfortunate situation include:
1. Some of the processing activity requires assistance from
the operators’ hands or feet.
2. Operators have to set-up and retrieve workpieces manually from the machines.
3. Even when the operators do not have to touch the
machines during their operations, they still must use
their eyes and ears to detect defects or other problems.
Labor Cost Reduction
4. Occasionally, operators are able to leave the machines
completely alone, but only for a few seconds, so there is
no significant separation.
5. Even when operators are able to leave the machines
alone for significant lengths of time, there is nothing else
at hand for them to do.
If the reason is any of the first three listed above, we need
to develop some kind of device that will enable the operators
to separate themselves completely—including their eyes and
ears—from their machines. If the reason is the fourth or fifth
one, we need to find them something more productive to do
than just standing and watching the machines do their work.
(Separating human work and machine work is described in
detail in Chapter 14.)
Figure 7.5 shows how human work was separated from
machine work in a printed circuit board (PCB) washing process. Before the improvement, the operator of this process
had to insert the PCB manually into the washer and extract
it manually after it was washed. Depending upon the timing
The operator used to insert
and extract each PCB
manually. The factory
developed a human automation device that
automatically extracts
PCBs and sends them onto
a conveyor. Now the
operator only insert the PCBs.
Figure 7.5
Separation of Human Work and Machine Work at a
Compact PCB Washer.
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of the insertion, it could take several seconds until the PCB
was ready to be extracted, during which time the operator
was just standing by.
After the improvement, a human automation device was
applied to the extraction step so that the operator no longer
had to extract the PCB manually. Now, a shooter automatically moves the washed PCBs onto a conveyor line. After setting up each PCB in the washer, the operator can leave the
machine alone and do other work.
Visible Labor Cost Reduction
Multiple Skills Training Schedule
Multi-process operations are the most decisive factor in
achieving labor cost reduction. Once all workers have been
trained for multi-process operations, it is a cinch to move
workers around and to add or subtract workers to suit current
manpower needs.
While this method known as multi-process operations is
vital to such flexibility, it is the operators themselves who
make it a reality. In other words, the key point for labor cost
reduction is to have all workers trained in the multiple skills
needed for multi-process operations.
Multiple skills training schedules, multiple skills maps, and
multiple skills score sheets (all described in Chapter 6) promote progress in multiple skills training by making the training more visible.
The following are five steps we should take in training
workers for multi-process operations. At each of these steps,
we need to reaffirm a positive attitude that should include
the three “P’s”: Painstaking care, Patience, and Perseverance.
◾◾ Remember the three “P’s”: Painstaking care, Patience,
and Perseverance.
Labor Cost Reduction
◾◾ The five steps in multiple skills training are:
1. Find a way to describe and/or illustrate the workers’ current skill levels so that anyone can understand them.
2. Once or twice a year, evaluate and display progress in
multiple skills training.
3. Make up a schedule of skills achievement targets.
4. At weekly, biweekly, or monthly intervals, mark the
results that indicate progress toward achieving skill
targets, and announce these results at meetings or
other appropriate occasions.
5. Some trainees may find certain processes difficult to
master. This is when the workshop leaders need to step
in and provide moral support and extra training.
Labor Cost Reduction Display Board
In assembly lines, the first parameter to keep track of is the
pitch time (otherwise known as the cycle time). We must at
least keep track of the line’s rhythm: How many units are we
turning out per day and does this match the current volume
of orders? This information is so vital that it should always be
available to us at a glance.
If we want to improve the range of immediately available
information, we should also include an up-to-date display of
labor cost reduction parameters. In other words, how many
workers does the line currently require? It is helpful to have
that information around to check at any time.
Figure 7.6 shows a “labor cost reduction display board”
that can serve just this purpose.
Once we know how many units each worker can reliably turn out in a day, we divide the day’s total output by
that number of units to obtain the minimum number of
workers needed for the day. For instance, let us suppose
that each worker on the assembly line can assemble 100
units a day:
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Labor Cost Reduction Display Board
Dec. 1
Today’s output:
1200
units
Today’s cycle time:
24
seconds
Number of units
per worker
100
Indicates how many units to
be produced per workday
Figure 7.6
Section chief
J. Black
Minimum
required manpower
12 persons
Indicates the minimum
number of workers needed
for that day’s output
Labor Cost Reduction Display Board.
1. If the total output is 1,000 units, the number of required
workers is 10, and the pitch time is 28.8 seconds per unit
(based on an eight-hour workday).
2. If the total output is 1,200 units, the number of required
workers is 12, and the pitch time is 24 seconds per unit
(based on an eight-hour workday).
It is good to keep a labor cost reduction display board
(such as the one shown in Figure 7.6) posted in a conspicuous place so that everyone at the assembly line can quickly
refer to it at any time.
Chapter 8
Kanban
Differences between the Kanban System
and Conventional Systems
The Reordering Point Method
and the Kanban System
Many people think the kanban system comprises the central
technique around which JIT production is built. Let it be
understood, however, that kanban are just one of several
tools used to maintain JIT production and are by no means
a central aspect of the JIT production system.
It has been said, “Wherever there are kanban, there is
in-process inventory.” Kanban and in-process inventory are
indeed very closely related to each other. We can find k­ anban
circulating here and there all over many Japanese factories.
Because the kanban are in such conspicuous use, the f­actory
workers imagine they have established JIT production in
their factory. From the perspective of true JIT production,
one might ask, “Why use kanban?” There is no reason why
kanban should be absolutely necessary for every JIT production system. Rather, the essential thing in JIT production is
a healthy flow of goods. The kanban system is not even an
original idea, really. It is something that grew out of a statistical inventory management method known as the reordering
point method.
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As its name suggests, the reordering point method enables
factories to reorder the same volume of parts or products
each time. When the inventory amount drops to a certain
level (the reorder point), another order is issued for the same
amount as before to replace the depleted inventory.
Let us examine a list of the reordering point method’s
chief characteristics:
◾◾ It enables inventory to be managed without having to
pay attention to demand fluctuations.
◾◾ It is not suitable when sharp demand fluctuations are
typical.
◾◾ It helps keep inventory management costs down.
◾◾ It is conducive for use in an automated reordering system.
◾◾ It helps lighten the clerical workload.
In view of the above characteristics, we can conclude that
the reordering point method is a good inventory management method when the inventory consists of products having
the following three characteristics:
1. A stable consumption volume
2. Easy to purchase and easy to store
3. Relatively inexpensive
We should regard the reordering point method’s unsuitability for products whose market demand fluctuates sharply
as the method’s most important characteristic. This means, of
course, that this method is only suitable for managing inventory of products that have stable demand.
We should also note that the exact same problem exists
for the kanban system: If demand has large and unpredictable ups and downs, even the kanban system will not prevent
product shortages or gluts. At the production planning stage,
we can spread out the various product models and ­volumes
Kanban
Reordering Point Method
Differences
Similarities
1. Enables inventory to be managed without paying attention
to demand fluctuations
2. Not suitable when sharp demand fluctuations are typical
3. Helps keep inventory management costs down
4. Conducive to use in an automated reordering system
Information
and goods
Information (kanban) and
Information and goods are
kept separate from each other goods are kept together.
(inventory [= goods] is
managed according to the
warehouse entry/exit vouchers
[= information]).
Management
Requires constant inventory
management (warehouse
entry/exit management)
Does not require
management
Visual control
Does not enable visual control
Enables visual control
Relationship
with factory
Managed separately from the
factory
Closely related to the factory
and factory operations
Relationship to None
improvement
activities
Figure 8.1
Kanban System
Decreasing numbers of
kanban indicate a need for
improvement.
Similarities and Differences between the Reordering
Point Method and the Kanban System.
and average them out. This is called “level production.” (Level
production is described further in Chapter 10 of this manual.)
If we use level production to help minimize waste, we are
no longer able to manufacture products in large batches or
lots. Therefore, factories that rely mainly on lot production or
batch production need to use a rather strict production method.
Figure 8.1 lists some of the similarities and differences between
the reordering point method and the kanban system.
Conventional Production Work Orders
and the Kanban System
Conventional production work orders indicate the type of
production to be carried out at each process based on process-specific operation plans that have been developed as
part of the overall production schedule. This means that each
process relates vertically to the production schedule and not
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Push system
Flow of information
Flow of goods
Procurement
schedule
Processing
schedule
Inventory
preparation
Vendors
Materials
warehouse
Assembly
schedule
Inventory
preparation
Production
schedule
Inventory
preparation
Vouchers
◾
Vouchers
438
Product
warehouse
Customers
In-process
inventory
Pull system
Parts
Assembly
Kanban
Vendors
Kanban
Materials
warehouse
Products
Kanban
Kanban
Customers
Kanban
Figure 8.2 Differences between Conventional Work Orders and
Kanban.
horizontally to other processes. Nevertheless, production is
still a series of processes.
Usually, factories that use conventional production work
orders also use the “push system” in which the upstream
processes take priority over downstream ones in terms of
how goods are moved and controlled between processes. By
contrast, the “pull system” is a basic principle of the kanban
system. As shown in Figure 8.2, the pull system means that
downstream processes fetch from upstream processes only
the goods that are needed, only when they are needed, and
only in the required amounts. Naturally, as an upstream process is depleted of its products, it “pulls” more workpieces
Kanban
from the previous process, and this gets repeated as a chain
reaction all the way up the line.
Figure 8.2 illustrates some of the differences between the
push system and the pull system. The push system emphasizes
the flow of information in that it “pushes” or “imposes” the
production schedule and the in-process inventory onto downstream processes. In the pull system, kanban are attached
to in-process inventory, so that when goods are pulled from
a process by the next process, the item indication on the
­kanban can serve as a work order for the previous process.
The biggest difference between the push system and the pull
system is the way information relates to actual goods. While the
push system deals primarily with general production-related
information first, after which production flow occurs as a result,
the pull system deals with process-specific information and the
transfer of goods. The pull system therefore makes it easy for
changing conditions in downstream processes to impact upon
upstream processes. The push system tries to stubbornly fulfill the original production s­chedule no matter what is going
on downstream. This rigidity is reflected in the unchangeable
nature of the typically “confirmed” production­schedule for
the next week and the “estimated” production schedule for the
following three weeks. Even if the flow of goods in the f­actory
should change drastically from what was envisioned when the
production schedule was created, the inventory brought in
for that schedule is still imposed upon downstream processes
regardless of its actual value under the changed situation.
By contrast, the pull system dictates that as soon as clients
order certain products, work orders for those products are
sent to the assembly line, which in turn orders the parts
it needs for those products from the processing line. The
processing line then orders from the materials procurement
people, and so on. This means that order information (that is,
kanban) travels upstream from sales to assembly, instead of
downstream from planning to materials procurement. This
makes for a very flexible production system.
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Functions and Rules of Kanban
Functions
As I said earlier, kanban comprise a tool for establishing and
maintaining Just-In-Time production. As such, it is similar to
the autonomic nervous system. When some kind of problem
occurs at a downstream process, the system has a function for
alerting upstream processes and stopping the production line.
In other words, kanban have two main functions.
Function 1: To Act as an Autonomic Nervous
System for Just-In-Time Production
Kanban pass along information about downstream conditions to upstream processes, just as the autonomic nervous
system notifies the brain of stimuli encountered by the body’s
peripheral nerves. This function can be broken down into
two main roles.
1. To provide pickup and work order information. In this
role, kanban provide two types of information: data
about which items have been used and in what amounts,
and also instructions on where and how certain items
are to be manufactured.
2. To eliminate overproduction waste. In the kanban system,
production occurs when goods are pulled from upstream
processes. Otherwise, no production occurs. This is what
makes the kanban system a “pull system.”
Function 2: To Improve and Strengthen the Factory
As long as kanban are used as information, they remain
attached to the goods that they give information about. As
such, kanban serve beautifully as a visual control tool. This
function of kanban also plays two roles:
1. A tool for visual control. Conventionally, productionrelated information is issued first, and the actual goods
Kanban
come into play later on. In the kanban system, though,
the information arises as a result of the consumption of
goods. Therefore, kanban are always used with actual
goods. And the way (including the order) in which
­kanban are eventually detached from goods shows us
an obvious indication of how factory operations are proceeding and which goods in the flow of goods are receiving the highest production priority. This makes kanban
an excellent tool for visual control.
2. A tool for promoting improvement. Inventory tends to
conceal problems in the factory. Similarly, an overabundance of kanban indicates there is too much slack in the
in-process inventory. Reducing the number of circulating
kanban can help reveal the problems that can remain
hidden under such slack conditions.
Rules
As mentioned above, kanban are the factory’s autonomic
nervous system and are a tool for building a stronger,
healthier factory. The following six rules must be observed
if we intend to make the most of kanban’s potential for
­factory improvement.
Rule 1: Downstream Processes Withdraw
Items from Upstream Processes
Rule 2: Upstream Processes Produce
Only What Was Withdrawn
Upstream processes must always produce in direct relation to
downstream production. In other words, the previous process
should produce only what was needed by the next ­process,
only when needed, and only in the amount needed.
Rule 3: Send Only 100 Percent
Defect-Free Products
Quality is built in at each process, and processes should never
send any defective goods downstream. Passing the quality
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buck not only creates confusion at downstream processes,
it also conceals problems at the defect-producing process and
ultimately brings disorder to the entire factory.
Rule 4: Establish Level Production
Production leveling is a method that eliminates variation in
flow at different processes and helps maintain stable, smooth
production. (See Chapter 10 for a detailed description of production leveling.) This is different from the kind of balancing
of load that occurs in a shish-kabob production system when
using a planning method called Capacity Requirements
Planning (CRP). Rather, it is the thorough balancing of
­product models and volumes within the framework of the
production schedule.
Rule 5: Workshop Indicators
Kanban should also move with the goods to ensure visual
control.
Rule 6: Use Kanban to Discover
Needs for Improvement
By gradually decreasing the number of kanban in circulation, we can better reveal missing items and line-stopping
problems, which we need to follow up with causal analyses
and improvement measures.
How to Determine the Variety
and Quantity of Kanban
Types of Kanban
First of all, let us be sure we understand the distinction between
kanban and the signboards that describe where things are
placed in the workshop. The latter are the manifestations of
the “signboard strategy” that serve to make orderliness—one
Kanban
Supplier
Kanban
Transport
Kanban
Kanban
(overall)
These kanban are used to
indicate when numerous
parts are to be moved to
the production line.
These kanban are used as
orders to outside suppliers.
In-factory
Kanban
These kanban are used
between processes in the
factory.
Production
Kanban
Production
Kanban
These kanban are used to
indicate operation
instructions at specific
processes.
Figure 8.3
These are the type of
kanban routinely used
at processes that do not
require changeovers.
Signal
Kanban
These kanban are used at
presses or other processes
that require changeovers.
Types of Kanban.
of the 5S’s—more visible. (See Chapter 4 of this manual for a
description of the signboard strategy.)
Since the Japanese word kanban corresponds to “signboard” in English, kanban and signboards can be easily confused. In this manual, we use the English word “signboard”
when discussing the signs used in the signboard strategy
and the Japanese word “ kanban” when discussing the signs
attached to in-process inventory that comprise the factory’s
autonomic nervous system.
There are as many types of kanban as there are types of
kanban applications. Figure 8.3 classifies these kanban types
according to their functions.
Let us look at these kanban types in more detail.
Type 1: Supplier Kanban
Also known as “parts-ordering kanban,” these kanban are
used to order large numbers of parts that need to be delivered
to assembly lines. Often, such kanban are sent to outside
suppliers who deliver the parts on demand (see Figure 8.4).
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2S
313-26-161
(abbreviation
for factory
receiving parts)
84212-24110-003
134
ASSY
20
Assembly line
receiving gate:
25
Post No. 114
Yamagawa
Industries, Ltd.
(outside supplier)
Store shelf no. 121
Figure 8.4 Example of Supplier Kanban for Outside Supplier.
913-3117
F3 model PC BL
PCB
B03-4
L-3
B line
5
Control site
Quantity in box
B-line position code
Part number and name
2/3
Previous
process
Current
process
This means this box kanban
is the second of a total of
three box kanban.
Figure 8.5 Example of In-Factory Kanban.
Type 2: In-Factory Kanban
Assembly lines also use parts that are processed and delivered
from within the same factory. In-factory kanban are used to
order such parts from upstream processes. Thus, they are
also known as “pickup kanban” or “withdrawal kanban.”
(See Figure 8.5.)
Sometimes, in-factory kanban are used even when only
one part is being withdrawn, or they can be used as “sequential
withdrawal kanban” for when parts must be supplied in a
certain order for assembly. The types of in-factory kanban
Kanban
Previous
process
Process
Control no.
Figure 8.6
L-2
Current
process
Plating
(ME-47)
Coating
(TO-13)
Part
name
51341-162600-00
Tail lamp rim
Capacity
20
No.
issued
6/10
Example of Production Kanban.
can range from ordinary plates to “box kanban” (attached to
boxes) and “cart kanban” (attached to carts).
Type 3: Production Kanban
Production kanban are used for in-process inventory within
processes. These are the type of kanban most people think
of first when kanban are mentioned in an overall sense.
Usable in either specialized or nonspecialized lines, production kanban give instructions on operations at each process
that does not require any (or hardly any) changeover time
(see Figure 8.6).
Type 4: Signal Kanban
Moving some types of equipment (such as presses) directly into
the production line can be difficult due to the costs involved.
In addition, when model changes occur, the changeover procedures for such equipment can be quite time-consuming. As
a result, lot production is sometimes unavoidable, at least at
processes using these kinds of equipment. Signal kanban are
used for such lot-production situations. (See Figure 8.7.)
How Many Kanban Do You Need?
Kanban help maintain level production. They also help
maintain stable and efficient operations in which the same
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1531-1520
Top plate
3S-110
Capacity
20
Location code
Figure 8.7
SUS
108
Lot size
120
Standard
number
80
Material
Item number and name
Example of Signal Kanban.
Number of kanban =
Daily output =
Daily output × (lead-time + safety margin)
Pallet capacity
Monthly output
Workdays in month
Lead-time = Manufacturing lead-time (processing time + retention
time) + lead-time for kanban retrieval
Safety margin: Zero days or as few days as possible
Pallet capacity: Try to keep pallet contents small and instead
increase the number of deliveries
Figure 8.8
How Many Kanban Do You Need?
procedures are repeatedly performed: in other words, standard operations. Before kanban can help maintain these
things, however, we must establish an even spread of product­
models and volumes at the production planning stage.
At factories that include mostly standard, repeated operations, the number of kanban can be determined as shown below
(see Figure 8.8), based on the premise of level production.
If the factory specializes in custom-order products, each
order will need one kanban as the work order kanban.
However, this kanban should also indicate when to produce
the ordered item. And if, for example, the finished products at
a certain process are placed into two or three different places,
the kanban should also indicate from which site or sites the
Kanban
next process will withdraw the product. Even in this case
of a custom-order factory, the kanban serves not only as a
placement kanban, but also as an indicator of when the next
process may come to withdraw items under a pull system.
Administration of Kanban
Kanban Administration in Processing
and Assembly Lines
At one time, kanban was a big fad in Japan. It seemed that
every factory was adopting the kanban system. But nine out
of ten companies that adopted it found it did not work for
them as they had expected. What was the problem?
Usually, the problem was that the factory tried to reap
some benefits from the kanban system alone, without bothering to change its “shish-kabob” production system or its
“push” system for moving goods through the line.
From the perspective of eliminating waste, it is best not to
use any kanban at all. After all, for a factory to have kanban,
it must have in-process inventory, and in-process inventory is
itself a form of waste.
Unfortunately, the use of kanban can become a counterproductive fixed idea, just like any other firmly established
practice. People eventually delude themselves into believing
that their factory could not possibly operate without kanban.
Before adopting kanban, it is best to take on the challenge
of establishing thorough flow production.
Figure 8.9 shows an example of how kanban are used in
assembly and processing operations. In this case, the transport
kanban are the pallets themselves and the production kanban
are hung on the “dispatch board” used for work scheduling.
After the improvement, this factory had sharply reduced
its inventory levels compared to its previous days of production determined by the operations schedule. The factory was
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Assembly
Line A
Line B
L
Assembly inventory
1. Completes production by
assembling pallet items
Pallet kanban
(Transport kanban)
2. Empty pallets withdrawn
from assembly line and
materials supplied
F
Processing inventory
In-process kanban
4. Supply in the order
withdrawn
Front
5. Withdrawn pallets
replenished via forklift
3. Kanban put into
box on post
Post
Kanban post box
8. Kanban posted on work schedule board
when each process is completed
Work Schedule Board
Today’s
TFM
Today’s
frames
Next
frames
6. Kanban collected
at regular intervals
7. Detached Kanban lined up for
next use on work schedule
Framing process
Back
Materials inventory
Frame transformer
I : Hand lift
F : Forklift
: Flow of goods
: Flow of kanban
Figure 8.9
9. Once the pallet is completed,
a kanban is attached and the
pallet is sent to the processing
inventory storage area.
Use of Kanban in Processing and Assembly Lines.
also able to greatly reduce its lead-time for manufacturing
scheduling and boosted productivity to about double its prior
level. In addition, the flow of goods was made much more
visible, which made problems easier to discover. Even when
the required output rises, the factory is able to respond with
faster turnover instead of larger lots, so it can maintain fairly
steady inventory levels.
Kanban
Processing (Plywood warehouse)
Site: P-278-001
Item category: 6210346
Item name: 7SE5+6
Company: Yamagawa Ind.
1. Detached kanban put on post
6. Kanban attached to corresponding items
and delivered to storage site
Post
5. Exchange delivery
list and kanban
2. Kanban returned at specified times
Delivery
list
(empty)
Supplier
Delivery
list
Control division
Ka
n
Ka ban
nb
an
Ka
nb
an
an
nb
Ka
an
nb
Ka
an
nb
Ka
3. When kanban reach
the reorder point,
a new order
sheet is filled out.
Delivery
list
Ordered items and
corresponding kanban
Kanban already used for
numbers telefaxed to supplier
ordering are placed here
Order
sheet
FAX
4. Order sheet issued and telefaxed to supplier
Figure 8.10
Example of Purchasing Kanban.
Administration of Purchasing-Related Kanban
Figure 8.10 shows an example of purchasing kanban that
indicate information about withdrawn items. In this ­example,
the kanban are not passed to the purchasing agent, but
instead are used only in the factory. To make this possible, the
­factory counts the number of kanban to obtain the number
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of orders, then fills out an order sheet and telefaxes it to the
purchaser, along with the individual kanban numbers.
When items are delivered, the kanban having those numbers
are picked up and attached to the items on the way to the
storage site. This means the kanban are also used in place of
delivery vouchers.
Before making this improvement, the person in charge of
ordering had no clear idea of how goods were flowing in
the factory, and in fact had to come to the factory every day
to find out what needed to be ordered. This situation led to
larger and larger inventories, missing items, and a general lack
of stability. After the improvement, inventory was reduced
sharply, the problem of omitted orders was eliminated, and
materials processing became much smoother thanks to the
stable supply situation.
A Novel Type of Kanban
Figure 8.11 shows a rather exceptional and interesting example in which kanban in the shape of golf balls are sent back
from the assembly line to the processing line via a pneumatic
chute and gutter.
This “golf ball” kanban system eliminates the need for
manually retrieving and issuing kanban. When an assembly
line worker starts using a new box of parts, he or she removes
Pneumatic chute
Assembly line
Figure 8.11
Example of Golf Ball Kanban.
Processing line
Kanban
the golf ball kanban that comes with the box and sends it
through the chute back to the processing line.
These golf ball kanban indicate output amounts and use
different colors to indicate different product models. The
pneumatic chute places the balls onto a gutter that carries
them across a distance of 200 to 300 meters. They are then
“plunked” right in front of the processing workers. Since the
golf balls come in the order in which the parts boxes are
used on the assembly line, it is easy to maintain that same
order on the processing line.
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Chapter 9
Visual Control
What Is Visual Control?
Why Aren’t Improvements Happening?
Many factories that are rich in improvement activities are
poor in actual improvements. It is not so much that they
do not know how to go about implementing improvement
activities; it’s just that they have failed to identify the factory’s
current problems and the various forms of waste that inhabit
the place.
There are some excellent factories around, and there are
some wretched ones. But the former do not necessarily have
fewer problems than the latter. Every factory has lots of problems—not one is problem-free. So what separates the good
factories from the bad ones? The answer is seen in the way they
respond to problems: Good factories respond promptly and
effectively, bad ones respond slowly (if ever) and ineptly. Good
factories are good at revealing hidden problems. They are also
good at getting the whole company behind finding the root
causes of problems and making corrective improvements.
But things are never the same from one day to the next.
No sooner have we solved yesterday’s problems than we find
today’s problems staring us in the face. The question is, do
we continue to jump at the opportunity of analyzing and
solving the steady flow of problems as they arrive? If we do,
our improvement activities are going somewhere.
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Keeping up with problems as they occur is where bad
factories fail. First of all, current problems and waste are
often not easy to identify. The reasons why certain defects
occur or why certain deliveries tend to run late are hidden or
extremely vague. Factories tend to overlook such problems
or “let them slide.” Obviously, such an attitude will not bring
success in solving problems and eliminating waste.
Even when a factory is successful in solving a set of problems, the world keeps changing. Before they know it, the
factory employees have a new, perhaps more difficult, set of
problems on their hands. The longer they are kept busy with
those problems, the more time new problems have to accumulate. Eventually, the factory finds itself overwhelmed by
the crush of problems and is no longer able to navigate the
treacherous road to survival.
How can factories keep pace with the daily onslaught of
problems? The answer is threefold:
1. By learning to distinguish promptly between what is
normal and what is not.
2. By making abnormalities and waste obvious enough for
anyone to recognize.
3. By constantly uncovering needs for improvement.
“Visual control” begins with making the factory’s myriad
abnormalities and forms of waste so clear that even a rookie
will recognize them.
All too often, factory management becomes a desktop
activity centered on statistics and number-crunching. Only
the specialists understand what is going on with all those
numbers. For example, let us consider what many factories do
with their inspection results and other quality-related information. They take the numbers and plot them on various
types of charts. And that’s it. Rarely do they use such information as ammunition in improvement campaigns.
Visual Control ◾
Types of Visual Control
Visual control is what JIT production offers as a means of turning specialist-knowledge management into plain and transparent management by everyone. We might even go as far as to say
that visual control is JIT’s way of “standardizing” management.
Visual control includes many application methods, each
suited to a different type of management problem. Some
visual control methods help identify waste while others help
bring latent problems to the surface.
Figure 9.1 lists visual control’s main tools and methods,
which are described below.
1. Red tag strategy
The “red tag strategy” refers to the red tags that are used
when establishing the “5S’s”: proper arrangement (seiri),
orderliness (seiton), cleanliness (seiso), cleanup (seiketsu),
and discipline (shitsuke). The red tag strategy helps lay the
foundation for improvement by making obvious which
items are not needed for daily production activities.
2. Signboard strategy
The signboard strategy is another visual control tool for
establishing the 5S’s. Signboards clearly show where tools
and other items belong in the workshop so that anyone
can find his or her way around easily.
3. White demarcators
White tape or paint can be used effectively to enforce
orderliness by marking off pathways, inventory storage
sites, and other areas.
4. Red demarcators
We use red demarcators on warehouse shelves, in-­
process inventory storage areas, and other inventory
storage sites to indicate the maximum allowable amounts
of inventory. In addition to using red marks to indicate
maximum levels, we might also use green tape or paint
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Description
No.
Name
Illustration
1
Red tag strategy
2
Signboard
stragety
3
White line
demarcators
4
Red line
demarcators
5
Andon
(alarm lamps)
6
Kanban
Kanban are administrative tools that
help us maintain Just-In-Time production.
The two main types of kanban are
transport kanban and production kanban.
7
Production
management
boards
These are display boards that indicate
current conditions on production lines.
Data shown on these boards include
production results, operating conditions,
and causes for line stops.
8
Standard
operation
charts
9
Defective item
displays
The red tag strategy helps us distinguish
needed items from unneeded items in
the workshops. Red tag teams use red
tags to mark unneeded items for removal.
Red tag
In the signboard strategy, we set up signs
that indicate what belongs where and in
what amount, so that anyone will be able
to understand where things belong.
When organizing workshops in an orderly
condition, marking out pathways and
in-process storage sites with white tape
makes it easy for anyone to keep the
workshop neat.
Red line demarcators form part of the
signboard strategy. We set up poles next
to inventory (warehouse or in-process
inventory) stacks and mark the maximum
allowable stack height with a red line to
show when excess inventory exists.
Andon immediately alert factory
supervisiors to abnormalities that
occur in the factory.
Assembly
Standard operation combination chart
Error prevention board
10
Error prevention
Figure 9.1
We use these charts to find the work
methods that use the best combination
of people, machines, and materials. One
of these charts should be on display at
each line in the factory.
Set-up at workshops where defects have
occurred, these displays exhibit defective
items along with graphic data urging
workers not to allow the same defects
to recur.
Error prevention boards help promote
independent management to reduce
human errors.
Visual Control Tools and Methods.
to show minimum levels. The idea is to make inventory
shortages or surpluses obvious for everyone.
5. Andon
As the “front line” leaders in the factory, supervisors such
as foremen and section chiefs need to keep a close and
steady watch on workshops to make sure the workers and
the machines are doing the job right. When an abnormality
Visual Control ◾
occurs at a certain process, andon (alarm lamps) will alert
the supervisors to the problem immediately.
6. Kanban
Kanban are an administrative tool that helps maintain
the “pull” system and Just-In-Time production. The two
main types are transport kanban, which are withdrawn
whenever in-process inventory is withdrawn, and production kanban, which provide operation instructions at
various processes.
7. Production management board
These boards show the current production line conditions. Besides showing estimated and actual output
results, they indicate causes for line stops and various
operation-related data. This keeps the line leaders constantly informed of the line’s pace relative to estimated
output. In other words, they always know if their line is
going too fast or too slow.
8. Standard operation chart
Standard operation charts help us create easy-to-read
graphical representations of process layouts, work procedures, and the like. In a sense, they serve as guide maps
for those who prefer illustrations over descriptions.
Standard operation charts are rarely used by themselves. Usually, they are used with “standard operation
combination charts,” which help us find the most efficient combination of people, machines, and materials.
9. Defective item display
Quality control statisticians use Pareto diagrams to illustrate data on defective items and defect causes. Most
factory workers, however, find it difficult to read Pareto
charts. Defective item displays solve this problem by
exhibiting actual defective items along with the Pareto
diagram or other charts describing defect trends. (See
Figure 9.2.)
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Defective items and
Pareto diagram
Category-specific
defect totals
Data compiled
in two-hour
increments
Poreto Diagram of Defectives
Category-specific Defect Totals
Defective
items
Defective
items
Item
categories
Figure 9.2
Defective Item Display.
Let’s reduce downstream defect/error reports to zero!
Error Prevention Board
December
Date 1 2 3 4 5 6 7 8 9
Hour
29 30 31 Tot.
9–10
10–11
11–12
12–13
13–14
14–15
15–16
16–17
17–18
Total
= No abnormality
Figure 9.3
= Caution
= Abnormality
Error Prevention Board.
10. Error prevention board
Instead of remembering that “to err is human” and shrugging it off as inevitable, we can utilize error prevention
boards to keep us more aware of our past errors so that
we are less likely to repeat them. As such, error prevention boards are a tool for independent management. (See
Figure 9.3.)
These boards usually have the hours of the day on the
vertical axis and the days of the month on the horizontal
Visual Control ◾
axis. When workers receive feedback on defects or human
errors from the next process, they mark the error prevention board under the hour and day when the defect
occurred. They use one of three symbols to describe the
type of defect or error: A circle indicates an error that
does not cause an abnormality, an “X” indicates an error
that does cause an abnormality, and a triangle serves as
a caution symbol. At regular meetings, workshop leaders
and workers review their errors and compare them to
error prevention board results from previous months.
Case Study: Visual Orderliness (Seiton)
In Chapter 4 of this manual, we provided a detailed description of 5S-related visual control tools, such as the red tag
strategy and the signboard strategy. Now we will examine
a case study of how “Visual orderliness” (seiton) tools have
been put to work.
First, let us reaffirm that orderliness means “standardizing
where things go.” In this case, standardizing means “­making
it clear to everyone what is normal and what is abnormal.”
With this in mind, let us see how well the 5S’s were established in a parts storage area of a household electronics
­factory. (See the photo in Figure 9.4.)
On a scale of one to 100, these shelves rank about 25 for
orderliness. Points were taken off for several reasons:
Reason 1: The shelves include place indicators, but no
address indicators. What do the boxes’ vertical arrangement signify? Their horizontal arrangement?
Penalty: 15 points.
Reason 2: The boxes have item indicators but the shelves
do not. How do people know where boxes should go
on the shelves?
Penalty: 15 points.
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Figure 9.4
Establishing Orderliness in an Electronics Parts Storage
Area.
Reason 3: The boxes give no indication of volume contained.
Penalty: 15 points.
Reason 4: There is not enough space above the boxes for
us to easily see what is inside them. Perhaps the boxes
are bigger than they need to be.
Penalty: 10 points.
Reason 5: The most serious reason is that the boxes can
only be identified by the person who stocked them. This
invites misplaced and lost items. It marks the beginning
of the end of 5S conditions.
Penalty: 20 points.
Thus, by looking critically at the parts shelves and evaluating them based on the 5S’s, we can more easily see where
improvement needs exist.
Figure 9.5 shows a group of parts shelves at an auto­mobile
assembly plant. Let us compare these shelves with those
shown in Figure 9.4 and note their differences.
Visual Control ◾
Figure 9.5
Parts Shelves at an Automobile Assembly Plant.
Difference 1: The shelves at the auto plant are lower and
thus accessible to shorter workers. Since the household
electronics assembly plant hires more female workers
than the auto plant, one would think it should have the
lower parts shelves.
Difference 2: The parts boxes at the auto plant are smaller.
This indicates that the turnover of parts boxes on the
shelves is probably more frequent at the auto plant than
at the household electronics plant.
Difference 3: The auto plant’s shelves clearly show where
each box goes, making them much easier to use than the
other plant’s shelves.
Difference 4: The location indicator signs at the auto plant
are within the space marked off by white line demarcators, but they stick out beyond this boundary at the
household electronics plant, which can be dangerous
when tall items are being moved alongside the shelves.
Difference 5: Unlike at the household electronics plant, the
parts boxes at the auto plant are easy to look into.
Difference 6: The biggest difference lies in how items are
placed onto and retrieved from the shelves. At the auto
plant, workers go to one side of the shelves to stock
boxes and the other side to retrieve them. This results
in parts being used in FIFO (First In, First Out) order.
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The arrangement of shelves at the household electronics
plant does not allow for FIFO stocking.
At first glance, one would not notice such differences
between the two sets of shelves in the photos. After looking at them from the perspective of the 5S’s, however, it is
obvious that the auto plant’s shelves are much more orderly
than the household electronics plant’s. With practice, we
should all be able to make equally revealing evaluations at
our own factories.
Standing Signboards
Kaizen Boards
Improvements tell the history of the factory and must keep pace
with fast-changing market needs. Once we make an improvement, however, we begin to forget how conditions were before.
It would be helpful indeed to keep track of improvements, so
we can see how some improvements lead to other ones.
Figure 9.6 is a kaizen board that contains an “improvement results chart.” Charts such as these can provide before
and after displays for each improvement. By the way, it helps
to take before and after photographs of the workshop from
exactly the same camera position. Another way to enhance
visibility is to choose a different “improvement color” each
year and paint each improved workshop area using the
improvement color designated for the year.
It is also good to include information such as improvement
expenses and improvement descriptions in the displays.
Process Display Standing Signboards
Signboards are needed not only to show where things go, but
also to describe machines and other equipment and show which
processes are contained in processing and assembly lines.
Visual Control ◾
Improvement Results
Before improvement
After improvement
Date: Oct. 4, 1986
Effects
Distance between No. 1 and No. 2 fasteners was shortened from
6 meters to 0.5 meters. Manpower was reduced from three
workers to two workers.
Costs (external charges)
Cylinders, boosters, etc. Total cost: ¥149,000
Description of improvement
Shortened distance between No. 1 and No. 2 fasteners on the
brake assembly line. Made one new fastening machine and
remodeled another one. Also moved the annealing vat to
minimize transport waste and prevent creation of in-process
inventory. (Saved space formerly needed for in-process inventory.)
Figure 9.6
Kaizen Board with Improvement Results Displays.
Figure 9.7 depicts a signboard that describes the processes
in a VCR assembly line. The signboards are posted alongside
andon that alert supervisors to parts supply problems. In
this case, the signboards serve a basic function in helping to
ensure a smooth supply of parts to the assembly line with
minimal errors or waste.
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Figure 9.7
Signboards Indicating Processes in Assembly Line.
Andon: Illuminating Problems
in the Factory
Workshop leaders must be kept abreast of how smoothly things
are going in their workshops. The sooner they can be informed
of abnormalities or other problems in their workshops, the
sooner they can analyze the situation and correct it.
Andon (alarm lamps) make a useful tool for alerting workshop leaders and other supervisors to problems on the f­actory
floor. The purpose of lamps in general is to shed light on dark
areas. Andon are special lamps that illuminate problems in
the factory.
Basically, there are four types of andon: “paging andon”
that light up when supplies of parts are needed, “emergency
andon” that notify supervisors of abnormalities, “operation
andon” that indicate the equipment’s operation status, and
“progress andon” that confirm the progress of operations.
(See Figure 9.8.)
Visual Control ◾
Paging andon
These are lit to request parts supplies.
There are two types of paging andon:
“hire andon” and “taxi andon.”
Emergency andon
Andon
(overall)
Visual control tool
that alerts supervisors
to factory floor
problems
These andon alert supervisors to
abnormalities on the line.
Operation andon
These andon indicate the machines’
current operation rates.
Operation andon
Especially useful for lines having long
tact times, progress andon help us
monitor the progress of line
operations.
Figure 9.8
Types of Andon.
Paging Andon
Paging andon are often used to request supplies of parts
for the production line. When parts are about to run out
at a process, the operator sends out a signal that lights the
andon. This notifies the people who operate the parts supply
system. In Japan, the parts suppliers’ quick movement around
the factory in collecting and supplying parts has earned them
the nickname “mizusumashi” or whirligig beetle.
Actually, there are two types of “whirligig beetle” techniques. One is the “hire” method, in which a group of andon
page the carts used for supplying parts. The other technique is
the “taxi” method in which dispersed andon page the carts.
Figure 9.9 illustrates the “hire” method for paging andon.
In this case, the andon operate as follows:
Step 1: Operator confirms the shortage of parts and presses
parts request button.
Step 2: The paging andon lights up.
Step 3: The parts supply cart operator (whirligig beetle)
goes to the process where the parts request was issued.
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JIT Implementation Manual: Volume 3
A1
A2
A3
A4
A5
B1
B2
B3
B4
B5
Parts supply cart operator
sees lit andon
3
2
1
4
466 ◾
5
Parts request button
Figure 9.9
The “Hire” Method for Using Paging Andon.
Step 4: The parts supply cart operator takes the processes’
empty pallets to the empty pallet storage area.
Step 5: The parts supply cart operator supplies the requested
parts.
Step 6: The parts supply cart operator switches off the parts
request button.
Warning Andon
Warning andon are mainly used on assembly lines and may
differ depending upon the length of the line.
On short assembly lines, people tend to use “airplane
andon.” Like the flight attendant call buttons on passenger
seats in commercial airplanes, each process in the assembly line has an emergency call button. When one of these
buttons is pressed, the andon board for the assembly line
lights up and shows which process’s button was pressed.
(See Figure 9.10.)
The following is a step-by-step description of how “airplane
andon” are used.
Visual Control ◾
4
Process-specific
andon
3
Call button
2
1
Process number
Yellow lamp
(lights when call button is pressed)
Figure 9.10
Red lamp
(lights when line stops)
Warning Andon for Short Assembly Lines.
Step 1: When a line operator gets behind due to parts
shortages, defects, machine trouble, or whatever, he or
she presses the “call button” (which lights up a yellow
andon lamp).
Step 2: If the line is equipped with human automation
devices for automatic stopping, the operators continue
working for the time being. If it is not so equipped, a
line operator must press the line stop button to stop the
line, at which point a red andon lamp goes on.
Step 3: A workshop leader and/or a parts supply cart operator comes immediately to find out what the problem is,
resolve it, and turn off the andon lamps.
The above type of warning andon configuration works
well enough when the assembly line is short enough so that
all of the andon, processes, and operators can be seen from
one place. Longer lines, however, make it impossible to see
the whole line and all of its operators. In this case, the andon
are lined up in a centralized board (as in the “hire” method
described earlier), as shown in Figure 9.11. These andon are
used in three ways:
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Assembly Line A
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Red
Green
Figure 9.11
Abnormality
Missing parts
Emergency
Finished
Yellow
Warning Andon for Long Assembly Lines.
1. When line A is operating normally, the name “Line A” is
lit up on the andon board.
2. When an abnormality occurs, an operator presses a call
button, at which time the process number where the
call was issued lights up on the andon board (usually a
­yellow lamp).
3. Once a warning call button is pressed, if the line is
equipped with a device that automatically stops the line
at a certain point, the line will continue until that point
is reached or until the problem is resolved (whichever
comes first). If the line is stopped, the yellow andon
indicating the process number goes out and is replaced
by a red andon that also indicates the process number.
Operation Andon
Operation andon indicate machine operating statuses. When
the machine has been stopped, the operation andon shows
the reason for the stoppage. (See Figure 9.12.)
Operation andon can be used as follows:
1. The green “IN OPERATION” lamp is lit whenever the
machines are operating normally.
2. The yellow “CALL” lamp is lit when an emergency call
button has been pressed.
3. A red lamp (“BREAKDOWN,” “BLADE CHANGE,” or
“WIDTH ADJUST”) is lit when a corresponding button
has been pressed.
Visual Control ◾
IN OPERATION
Green
CALL
Yellow
BREAKDOWN
BLADE CHANGE
Red
WIDTH ADJUSTMENT
CYCLE TIME OVER
Figure 9.12
Operation Andon.
4. The red “CYCLE TIME OVER” lamp is lit when one of
the cycle time pacemakers installed in the equipment
indicates the cycle time has been exceeded.
Progress Andon
Many assembly lines have short pitch times, such as 1- or
2-minute tact intervals. When a line has such a short tact
time, the progress of operations is easy to observe simply by
monitoring the rhythm.
It is more difficult to sense delays in lines that have longer
tact times, such as 10 or 20 minutes. Progress andon enable
line operators to gauge the progress of their own operations.
(See Figure 9.13.)
Paging
andon
Line A
12
Progress
stage
Call button
1
2
3
4
5
6
7
8
9
3
6
Beep
Figure 9.13 Progress Andon in Manual-Conveyance Assembly Lines.
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Most progress andon are divided into 10 equal sections, but
the main idea is to have the various stages of the operations
correspond in a level manner to the various andon sections.
In the case of conveyor lines, limit switches can detect
when the progress stage number on the progress andon
board has changed. In lines where workpieces are passed by
hand, a timer is used instead.
Production Management Boards:
At-a-Glance Supervision
Many factories rush feverishly into production based on the
production schedule and resort to overtime hours if it turns
out they cannot keep up with the scheduled output. To help
avoid such unpleasant surprises, it would be nice to know
from one hour to the next just how the line is doing, whether
it is too slow (and why), and what countermeasures to take
under various circumstances.
Production management boards serve exactly this purpose.
Production management boards should be simple in design
and should emphasize providing information that answers
the following key questions:
◾◾ How do current results compare to estimated results?
◾◾ Why was the line stopped the last time?
◾◾ What kind of improvement is needed?
◾◾ Will there be any spillover into overtime or tomorrow’s
schedule?
The factories that already have production management
boards tend to post them only in factory managers’ offices.
However, they do very little good when only the managers
can keep an eye on them.
The people on the factory floor—the workshop leaders
and equipment operators—have the greatest need to have
Visual Control ◾
Production Management Board for
December 1
Figure 9.14
Line A
Cycle time: 60"
Hour
Est.
Act.
Diff.
8:30–9:30
60
58
–2
9:30–10:30
60
10:40–12:00
80
12:45–2:00
75
2:00–3:00
60
3:30–4:00
60
4:00–5:00
60
60
120
60
58
118
0
Cycle time
Est.
Act.
Comments
Diff.
–2
Defect at
Process No. 1
–2
200
275
335
395
455
Production Management Board.
production management boards to keep them informed. It is
a good idea to have a production management board posted
as “the final process” in the line, so that everyone checks it
at least once per production cycle. Nothing works better to
keep workshop leaders and operators aware of current conditions in their workshops and conscious of problems and
their solutions.
Most production management boards look something like
the example shown in Figure 9.14.
Relationship between Visual
Control and Kaizen
This topic reminds me of a visit I once paid to a European
automobile assembly plant. While touring the plant, I noticed
a large and fancy andon hanging from the ceiling at the
final process in the assembly line. They must have spent a
lot of money to buy and install that andon, much more than
any Japanese manufacturer would have spent. I also noticed,
however, that it never seemed to light up at all.
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Curious, I asked the factory’s chief production engineer
why the andon was not lit.
He said that when the company managers went to visit
some factories in Japan, they were very impressed with the
andon there and decided to adopt the tool in their own
­factory. Once the andon was installed, the line workers soon
found that no one ever came to the rescue when they pressed
the “call” buttons, and so the problems that prompted them
to call for help did not get resolved. In fact, the only change
the andon made was to create the wasted motion involved in
pressing the call buttons!
Within a month of the andon’s arrival, the workers stopped
pressing the call buttons, and eventually it was decided just
to unplug the andon to save electricity costs.
Nonsensical as it sounds, this case was not an isolated
oddity. Similar episodes have occurred in America and even
in Japan.
All too often, people have casually adopted the external
trappings of JIT production, such as the various JIT tools
and techniques, without committing themselves to learning
the concepts and spirit of JIT. The results of such misguided
approaches include wastebaskets full of kanban, completely
baffling standard operations that lack any trace of rationale, and decorative andon that hang from the ceiling like
ill-conceived chandeliers.
No matter how many visual control tools we bring into
the factory, if we do not use them correctly to discover and
promptly correct abnormalities, the tools are no more valuable than money that is always kept under a mattress.
If we can make abnormalities obvious and perform prompt
analyses of their causes, we can expect to make improvements based on such discoveries and analyses at least half
of the time.
Figure 9.15 shows the roles that various visual control tools
can play in the improvement cycle. Let us remember that just
introducing visual control tools will not automatically result
Visual Control ◾
Improvement Cycle = Visual Control
Abnormality
occurs
Standardize
improvement
Visual control
tool(s)
Discover
abnormality
Make
improvement
Look for cause
right away
Figure 9.15
The Roles of Visual Control Tools in the Improvement
Cycle.
in improvements. Visual control tools only do one-third of
the job—they help make abnormalities obvious and therefore easier to discover. The other two-thirds—analyzing the
abnormality and taking corrective action—still must be done
by the factory people themselves.
Visual control is meaningless unless we look at it from the
larger perspective of the improvement cycle.
473
About the Author
Hiroyuki Hirano believes Just-In-Time (JIT) is a theory and technique to
thoroughly eliminate waste. He also calls the manufacturing process the
equivalent of making music. In Japan, South Korea, and Europe, Mr. Hirano
has led the on-site rationalization improvement movement using JIT production methods. The companies Mr. Hirano has worked with include:
Polar Synthetic Chemical Kogyo Corporation
Matsushita Denko Corporation
Sunwave Kogyo Corporation
Olympic Corporation
Ube Kyosan Corporation
Fujitsu Corporation
Yasuda Kogyo Corporation
Sharp Corporation and associated industries
Nihon Denki Corporation and associated industries
Kimura Denki Manufacturing Corporation and associated industries
Fukuda ME Kogyo Corporation
Akazashina Manufacturing Corporation
Runeau Public Corporation (France)
Kumho (South Korea)
Samsung Electronics (South Korea)
Samsung Watch (South Korea)
Sani Electric (South Korea)
Mr. Hirano was born in Tokyo, Japan, in 1946. After graduating from
Senshu University’s School of Economics, Mr. Hirano worked with Japan’s
largest computer manufacturer in laying the conceptual groundwork for the
country’s first full-fledged production management system. Using his own
I-475
I-476
◾ About the Author
interpretation of the JIT philosophy, which emphasizes “ideas and techniques for the complete elimination of waste,” Mr. Hirano went on to
help bring the JIT Production Revolution to dozens of companies, including Japanese companies as well as major firms abroad, such as a French
automobile manufacturer and a Korean consumer electronics company.
The author’s many publications in Japanese include: Seeing Is Understanding: Just-In-Time Production (Me de mite wakaru jasuto in taimu
seisanh hoshiki), Encyclopedia of Factory Rationalization (Kojo o gorika
suru jiten), 5S Comics (Manga 5S), Graffiti Guide to the JIT Factory Revolution (Gurafiti JIT kojo kakumei), and a six-part video tape series entitled
JIT Production Revolution, Stages I and II. All of these titles are available
in Japanese from the publisher, Nikkan Kogyo Shimbun, Ltd. (Tokyo).
In 1989, Productivity Press made Mr. Hirano’s JIT Factory Revolution:
A Pictorial Guide to Factory Design of the Future available in English.
Business Improvement
JIT Implementation Manual
The Complete Guide to Just-in-Time Manufacturing • Second Edition
Volume 3
Flow Manufacturing – Multi-Process Operations and Kanban
HIROYUKI HIRANO
“It is a book for manufacturing companies that are fighting desperately for survival and that will go
to any length to improve their factories and overcome the obstacles to success. One could even call
this book a ‘bible’ for corporate survival.”
—Hiroyuki Hirano
Known as the JIT bible in Japan, JIT Implementation Manual — The Complete Guide to Just-inTime Manufacturing presents the genius of Hiroyuki Hirano, a top international consultant with vast
experience throughout Asia and the West. Encyclopedic in scope, this six-volume practical reference
provides unparalleled information on every aspect of JIT— the waste-eliminating, market-oriented
production system. This historic, yet timeless classic is just as crucial in today’s fast-changing global
marketplace as when it was first published in Japan 20 years ago.
Covering all the techniques essential to setting up a flow production system in manufacturing, Volume
3: Flow Manufacturing — Multi-Process Operations and Kanban includes a basic introduction
to the relationship between inventory and flow production and their roles in manufacturing. It also
provides discussion of multi-process operations and precautions and procedures for developing them.
Outlining the key topic of labor cost reduction and steps to achieving it, this definitive volume also
covers the essentials of kanban and visual control systems in a flow manufacturing environment.
PP9026
ISBN: 978-1-4200-9026-0
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w w w. p r o d u c t i v i t y p r e s s . c o m
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 4
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 4
Leveling –
Changeover and Quality Assurance
HIROYUKI HIRANO
Originally published as Jyasuto in taimu seisan kakumei shido manyuaru copyright © 1989 by JIT Management Laboratory Company, Ltd., Tokyo, Japan.
English translation copyright © 1990, 2009 Productivity Press.
CRC Press
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Contents
Volume 1
1
Production Management and JIT Production Management....... 1
Approach to Production Management................................................... 3
Overview of the JIT Production System................................................ 7
Introduction of the JIT Production System...........................................12
2
Destroying Factory Myths: A Revolutionary Approach............ 35
Relations among Sales Price, Cost, and Profit......................................35
Ten Arguments against the JIT Production Revolution.........................40
Approach to Production as a Whole....................................................44
Volume 2
3
“Wastology”: The Total Elimination of Waste..........................145
Why Does Waste Occur?....................................................................146
Types of Waste.................................................................................. 151
How to Discover Waste..................................................................... 179
How to Remove Waste......................................................................198
Secrets for Not Creating Waste...........................................................226
4
The “5S” Approach..................................................................237
What Are the 5S’s?.............................................................................237
Red Tags and Signboards: Proper Arrangement and
Orderliness Made Visible...................................................................265
The Red Tag Strategy for Visual Control............................................268
The Signboard Strategy: Visual Orderliness.......................................293
Orderliness Applied to Jigs and Tools................................................307
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Volume 3
5
Flow Production......................................................................321
Why Inventory Is Bad........................................................................321
What Is Flow Production?..................................................................328
Flow Production within and between Factories.................................332
6
Multi-Process Operations....................................................... 387
Multi-Process Operations: A Wellspring for Humanity on the Job......387
The Difference between Horizontal Multi-Unit Operations and
Vertical Multi-Process Operations......................................................388
Questions and Key Points about Multi-Process Operations................393
Precautions and Procedures for Developing Multi-Process
Operations.........................................................................................404
7
Labor Cost Reduction..............................................................415
What Is Labor Cost Reduction?.......................................................... 415
Labor Cost Reduction Steps............................................................... 419
Points for Achieving Labor Cost Reduction........................................422
Visible Labor Cost Reduction.............................................................432
8
Kanban.................................................................................. 435
Differences between the Kanban System and Conventional Systems....435
Functions and Rules of Kanban........................................................440
How to Determine the Variety and Quantity of Kanban...................442
Administration of Kanban.................................................................447
9
Visual Control......................................................................... 453
What Is Visual Control?......................................................................453
Case Study: Visual Orderliness (Seiton)..............................................459
Standing Signboards..........................................................................462
Andon: Illuminating Problems in the Factory....................................464
Production Management Boards: At-a-Glance Supervision................. 470
Relationship between Visual Control and Kaizen.............................. 471
Volume 4
10 Leveling...................................................................................475
What Is Level Production?................................................................. 475
Various Ways to Create Production Schedules...................................477
Contents
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Differences between Shish-Kabob Production and Level Production.....482
Leveling Techniques..........................................................................485
Realizing Production Leveling............................................................492
11 Changeover............................................................................. 497
Why Is Changeover Improvement (Kaizen) Necessary?.....................497
What Is Changeover?.........................................................................498
Procedure for Changeover Improvement...........................................500
Seven Rules for Improving Changeover.............................................532
12 Quality Assurance.................................................................. 541
Quality Assurance: The Starting Point in Building Products..............541
Structures that Help Identify Defects.................................................546
Overall Plan for Achieving Zero Defects............................................561
The Poka-Yoke System.......................................................................566
Poka-Yoke Case Studies for Various Defects.......................................586
How to Use Poka-Yoke and Zero Defects Checklists.......................... 616
Index.............................................................................................. I-1
About the Author.......................................................................... I-31
Volume 5
13 Standard Operations.............................................................. 623
Overview of Standard Operations.....................................................623
How to Establish Standard Operations..............................................628
How to Make Combination Charts and Standard Operations Charts.....630
Standard Operations and Operation Improvements...........................638
How to Preserve Standard Operations...............................................650
14 Jidoka: Human Automation.................................................... 655
Steps toward Jidoka...........................................................................655
The Difference between Automation and Jidoka...............................657
The Three Functions of Jidoka..........................................................658
Separating Workers: Separating Human Work from Machine Work.....660
Ways to Prevent Defects.................................................................... 672
Extension of Jidoka to the Assembly Line.......................................... 676
15 Maintenance and Safety......................................................... 683
Existing Maintenance Conditions on the Factory Floor......................683
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What Is Maintenance?........................................................................684
CCO: Three Lessons in Maintenance.................................................689
Preventing Breakdowns.....................................................................683
Why Do Injuries Occur?....................................................................685
What Is Safety?.................................................................................. 688
Strategies for Zero Injuries and Zero Accidents..................................689
Volume 6
16 JIT Forms................................................................................711
Overall Management......................................................................... 715
Waste-Related Forms.........................................................................730
5S-Related Forms............................................................................... 747
Engineering-Related Forms................................................................777
JIT Introduction-Related Forms..........................................................834
Chapter 10
Leveling
What Is Level Production?
Differences in Reducing Patterns of
Product and Parts Inventories
Usually, factories can effectively use a statistical inventory
control method, such as the reorder point method, for handling products and replacement parts. Such methods are not
suitable for inventories of assembly parts and other parts and
materials being used in the factory. One reason for this is the
different kinds of demand for these two kinds of inventory.
As shown in Figure 10.1, demand for products is more or less
constant, which means that product inventory levels can be
Product inventory
Reorder point
Parts inventory
Reorder point
Figure 10.1
Demand Trends for Product and Parts Inventories.
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expected to decline smoothly. By contrast, demand for parts is
subject to sudden large orders that immediately deplete parts
inventory, which is therefore more difficult to manage.
The kind of statistical inventory control that works well for
“steady-demand” inventories, such as product and replacement parts inventories, does not work as well for “suddendemand” inventories, such as assembly parts and materials.
Approach to Leveling
Customers buy just what they want, just when they want it,
and in just the amount they want. Overall, this tends to result
in a steady demand for products, as reflected in steady shipments from product warehouses.
If the factory can restock the warehouse just as steadily
by manufacturing only what the warehouse needs, when
it needs it, and in just the amount needed, we would see
the same smooth trend reflected in the factory’s demand for
parts and materials. However, most production schedules are
drafted on the premise of lot production or, as we in JIT
­disparagingly call it, “shish-kabob production.”
Shish-kabob production may help raise production efficiency in assembly lines, but there is more to a company than
assembly lines. We also have to consider shish-kabob production’s impact on other corporate activities, such as sales, distribution, and purchasing. Most factories also include various
preassembly processes and parts processing lines. Therefore,
just because shish-kabob production may suit assembly line
operations does not mean it is a good approach from the
perspective of the entire factory or company.
Let us suppose, for example, that the managers of a factory’s
final assembly line decide to boost the line’s output performance by assembling only product X this week and only
product Z next week. This means that all preassembly processes that specialize in product X will be too busy this week
Leveling
and will sit idle all next week. Conversely, the processes dedicated to product Z will be idle this week and overworked
next week.
Obviously, these preassembly processes need to be
scheduled more evenly to enable them to keep up with the
assembly line’s demand, even though this means that many
of the pre­assembly products will have to sit as inventory
until the assembly line is ready to use them. Naturally, such
scheduling creates various kinds of waste, such as surplus
production waste, idle time waste, conveyance waste, and
inventory waste.
It should be obvious enough by now that it does no
good to seek improved efficiency and productivity for
one section of the factory at the expense of other sections. Instead, we must center our operations on customer
needs and try to achieve an even level of high productivity­
throughout the factory, with low costs and Just-In-Time
scheduling. The JIT technique for doing precisely that is
called production leveling.
Various Ways to Create
Production Schedules
How do factories go about creating production schedules?
Actually, each factory’s method seems to be different, and
one can gain a sense of the factory’s history by examining
the particular method it uses. Broadly speaking, there are four
main production scheduling methods, each based primarily
on the number of production opportunities per month:
◾◾ Once-a-month production
◾◾ Once-a-week production
◾◾ Once-a-day production
◾◾ Level production
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Once-a-Month Production
Once-a-month production scheduling often happens when
low demand for certain products results in only one production opportunity per month.
Generally, this method starts with a figure for how many
products need to be made in a month, and from this figure
we calculate the standard daily output that will add up to the
desired monthly totals.
Figure 10.2 shows an example of once-a-month production.
In this example, it has been decided that products X, Y,
and Z would be manufactured in that order. Because the
demand for these products varies, the factory is prepared to
adjust the number of production days for each model to produce the correct totals to meet current demand.
Standard Production Schedule
Model
1
One month
2
3
Estimated
production output
Month
4
X 1,000 units
X
Y
600 units
Z
400 units
Y
Z
Monthly Production Schedule
Figure 10.2
Model
Quantity
X
1,000
Y
600
Z
400
1
One month
2
3
4
1,000
Once-a-Month Production.
600
400
Leveling
I have not included twice-a-month production scheduling
as a type by itself because the twice-a-month approach is
almost exactly like the once-a-month approach, except that
everything works within a two-week time frame instead of
a month.
In the past, once-a-month production scheduling did a
pretty good job of serving factory needs. Back then, markets were more stable, product variety was much smaller,
and factories could generally sell whatever they made. If we
change our perspective from the producer’s standpoint to the
­consumer’s standpoint, however, we can see that traditional
once-a-month production scheduling is a rather stubborn
and selfish method (that is, a “product-out” method in which
factories push their products onto the market). It is as if the
factory people were saying: “Look, this is all we make, and
we only make them once a month. So take it or leave it.”
Those days are long gone. Today, it is not easy to find factories that stick to the old once-a-month program. Most have
switched to once-a-week production scheduling. But even
that has not changed things that much.
Once-a-Week Production
Whether it be once-a-month or once-a-week production,
the basic philosophy is the same. The big difference is that
product warehouses and production opportunities are only
one-fourth as big as they used to be.
Figure 10.3 illustrates once-a-week production.
As seen in the figure, the month’s estimated output is
unconditionally divided into four equal weekly totals, with
a separate production schedule created for each week.
Sometimes the output for the current week must be raised or
lowered depending upon how product inventory levels stood
at the end of the previous week.
In today’s fast-paced manufacturing world characterized by
increasing product diversity, manufacturers find themselves
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Estimated production output
(monthly)
Month
Week
X
1,000
250 units
Y
600
150 units
Z
400
100 units
Previous
week’s
spillover
Weekly Production Schedule
Model Quantity
Month
3
2
1
4
250
X
1,000
Y
600
Z
400
150
Figure 10.3
100
Once-a-Week Production.
compelled to break down monthly production schedules into
at least four (weekly) parts.
Once-a-Day Production
Many factories are taking up the challenge of maintaining
daily production schedules. The idea is to divide up the estimated monthly output into the number of working days in
the month so that production of the entire assortment of
models gets repeated once a day. This puts a focus on manufacturing using an integrated production line.
Figure 10.4 shows an example of once-a-day production
scheduling.
As seen in Figure 10.4’s example, once-a-day production
is a much more sophisticated and detailed way of scheduling production because it provides 20 times the production
Leveling
Estimated production output
(monthly)
Number of working days: 20
Month
Day
X
1,000 units
50
Y
600 units
30
Z
400 units
20
Daily Production Schedule
Model Quantity
One Month
2
3
1
X
1,000
50 units per day
Y
600
30 units per day
Z
400
20 units per day
4
Assembly schedule for one day
Model Quantity
This is still
“shish-kabob”
production
Figure 10.4
X
50
Y
30
Z
20
8am
One Day
12 noon
5pm
50 units
30 units
20
units
Once-a-Day Production.
opportunities of once-a-month production and produces 20
times less inventory.
Detailed as it is, however, once-a-day production does not
necessarily mean level production. If we look at the production schedule for any particular day (see the example in
Figure 10.4), we find that the factory spends all morning turning out product X, part of the afternoon producing product Y,
and the rest of the afternoon with product Z. In other words,
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the factory is still carrying out the same old “shish-kabob”
production routine, but with more model changeovers.
Leveling Production
The fundamental concept underlying level production is that
production of different product models—whether it be lot
production or one-piece flow production—can be evenly
spread out to match the current sales trends, which also
require adjusting the production pitch accordingly and maintaining an integrated production line. As such, level production is a thoroughly “market-in” approach.
We might define production leveling as “making production
of various product models and volumes completely even.”
Figure 10.5 shows an example of level production. Comparing this to the previous example of once-a-day production,
we can see that they both add up to the same daily output
totals. Level production, however, divides the daily output
total by the amount of working time in the day (expressed
in minutes) to obtain an hourly pitch time. This pitch time is
called the cycle time.
In Figure 10.5’s example, the tact time is 9.6 minutes for
product X, 16 minutes for product Y, and 24 minutes for
product Z. The factory needs to organize its production line
to maintain these tact times while using a mixed-flow production method.
Differences between Shish-Kabob
Production and Level Production
One chief characteristic of level production is that, within a
certain month, the same products are produced in the same
quantities each day and within each time band in the day.
Let us examine the ways in which level production differs
from “shish-kabob” production.
Leveling
Monthly output
X
1,000
Y
600
Z
400
Working days in month: 20
Daily output
X
1,000 ÷ 20 = 50
Y
600 ÷ 20 = 30
Z
400 ÷ 20 = 20
Working minutes in day: 480
Level production
Model Quantity
One day
12 noon
8am
5pm
X
50
1 unit every 9.6 minutes
Y
30
1 unit every 16 minutes
Z
20
1 unit every 24 minutes
Tact time: 4.8 minutes
(X: 9.6 minutes, Y: 16 minutes, Z: 24 minutes))
X
Y
X
Z
X
Y
X
Z
X
Y
Line flow
Repeat this production sequence 10 times
Figure 10.5
Production Leveling.
Difference 1: Production Philosophy
Production philosophy regarding the making of products
constitutes a major point of difference between level production and “shish-kabob” production. Shish-kabob production
goes hand in hand with the “product-out” production philosophy. The main points of the “product-out” philosophy are to
develop products that are easy to manufacture and to set-up
the production line to facilitate large-lot production of such
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products. Level production instead emphasizes serving market
needs, which means it follows the “market-in” philosophy.
Difference 2: Production Method
Shish-kabob production is made up of lots (the chunks on the
“shish-kabob” skewer). Changeovers must be made after each lot
is completed. In level production, all of the various models are
mixed into each cycle time within the overall production line.
Difference 3: Approach to Efficiency
In shish-kabob production, we generally try to maximize efficiency at specific processes, such as the pressing or cutting
processes. In level production, we try instead to maximize
overall efficiency within the framework of the cycle time.
Difference 4: Approach to Machines
In shish-kabob production, we spend at least a few hours
turning out the same product model, then we retool and
begin manufacturing a different model for a while. To keep
the line moving quickly, we need fast (the faster the ­better)
and, preferably, general purpose machines that require l­ittle
retooling to changeover to a different product model. Usually,
such equipment is expensive and bulky.
By contrast, for level production we need equipment that is
just fast enough to keep within the cycle time and that is small
enough to be placed directly into the production line. This
usually calls for small, inexpensive, and specialized machines.
Difference 5: Inventory and Lead-Time
Shish-kabob production inevitably includes production flow
cut-off points between certain processes. Wherever such a
cut-off point exists, there will necessarily be an accumulation
of in-process inventory. In-process inventory means retention,
and retention means a longer lead-time and a greater need
for conveyance. In level production, we try to synchronize
all processes within the cycle time. This effectively eliminates
Leveling
in-process inventory and minimizes both lead-time and conveyance needs.
These are just the major points of difference between conventional shish-kabob production and level production. It is
not hard to see which production method is better suited to
today’s demands for fast turnaround and dynamism in production. Figure 10.6 summarizes the above differences in a
tabular format.
Leveling Techniques
Cycle Time and Cycle Tables
“How long does it take to make one product unit?” This is
a very important question both for the equipment operators
and the factory managers, and it is something we must know
before we can draft a production schedule. If the factory is
carrying out shish-kabob production, the general per-item
manufacturing pitch can be decided based on the equipment capacity and available manpower. But this is not the
best way to figure the production pitch. Calculating a pitch
based on machinery and manpower is a production-centered
approach. It may enable the factory to achieve a fast pitch,
but even a lightning-speed pitch does no good unless the
products can be readily sold. Otherwise, the factory is just
stocking product warehouses and raising costs. We should
look instead to current market needs as a basis for determining the manufacturing pitch.
Cycle Time
The cycle time is the amount of time (expressed in minutes
and seconds) within which one item must be manufactured.
In JIT, we obtain the cycle time by dividing the total production output required to match current market needs by the
amount of work time (expressed in minutes) in the day.
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Inventory and
Lead-time
Approach to
Machines
Approach to
Efficiency
Production
Method
Production
Philosophy
Differences between Shish-Kabob Production and Level Production
Shish-Kabob Production
Level Production
Product-out (production-centered)
philosophy
“Produce just what is easy to make, just
when it is easy to make it, and in just the
amounts that are easy to make.”
Market-in (market-centered)
philosophy
“Produce just what is needed, just when it
is needed, and in just the amounts
needed.”
Lot (shish-kabob) arrangement
Arrange products into large
model-specific lots to minimize
changeovers.
Cycle time arrangement
Arrange products into assortments that
match market needs and can be manufactured within the cycle time in an in-line
production configuration.
Emphasis on individual process
efficiency
The production pitch is based on the
rhythm of individual processes with
maximum efficiency sought at each
process.
Emphasis on overall line efficiency
We try to improve the efficiency of the
entire line within the framework of the
cycle time.
High-speed, general purpose, large, and
expensive machines
We need faster machines to handle large
lot volumes, which usually means we
need a large, expensive, general purpose
machine.
Moderate-speed, specialized, small,
and inexpensive machines
Our machines need only be fast enough
to keep up the cycle time. The important
thing is that the machines be small and
specialized enough to fit right into the
production line to handle one-piece flow
operations. Such machines are usually
much less expensive than large, general
purpose machines.
Large inventories and long lead-times
When workpieces are worked on in lots,
retention is inescapable. Retention
accumulates in-process inventory and
results in longer lead-times and a
greater need for conveyance.
Small inventories and short lead-times
When workpieces flow along one piece
at a time within the cycle time, there is
very little in-process inventory, which
means shorter lead-times and almost
no need for conveyance.
Figure 10.6 Differences between Shish-Kabob Production and Level Production.
Leveling
PER-DAY
PER-MONTH PRODUCTION TOTAL
PRODUCTION =
WORKING DAYS IN MONTH
TOTAL
CYCLE = AMOUNT OF WORK TIME (MINUTES) IN DAY
TIME
PER-DAY PROD
DUCTION VOLUME
Specifically, we begin by dividing the month’s production
output by the number of working days in the month. Then
we divide each working day’s working time (minutes) by the
required output for the day (see the equations on previous
page). The result is the cycle time.
“Cycle List” and “Nonreserved Seat” Methods
We can use the particular cycle time for each item and the
various product models in the mixed-flow operation to establish a single constant pattern of production flow.
Cycle lists are wheel-like illustrations that show the constant production pattern that gets repeated throughout the
day to turn out the required variety and volume of products.
If the proportionate shares of product models are 50 percent
for product X, 30 percent for product Y, and 20 percent for
product Z, we could express that pattern in a cycle list like
the one shown in Figure 10.7.
It is best to follow the cycle list as closely as possible. However, an array of problems sometimes arises to cause variation
in cycle times. When such variation is common, I always suggest adopting the “nonreserved seat” version of the cycle list.
Each cycle scheduled in a nonreserved seat cycle list includes
one or two steps that are kept available (“nonreserved­”) to
compensate for variations. (See Figure 10.8.)
The point of the nonreserved seat cycle list is to have the
“nonreserved seat” section of the list compensate for variations caused by small accumulations of in-process inventory,
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480-minute work day
END
START
X
Y
X
Y
Required quantity:
100 units
One day:
10 repetitions of cycle
Pitch:
4.8 minutes
Z
X
X
Figure 10.7
Z
Y
X
END
START
Nonreserved
seat
X
Cycle List.
Y
Y
X
X
Z
Z
X
X
Y
Figure 10.8
“Nonreserved Seat” Cycle List.
Leveling
which is evident from corresponding detached kanban. If
the timing of the kanban is part of the problem, the cycle list
itself needs to be revised.
The “Reserved Seat” Method for
Practical Use of Cycle Lists
A workshop can more easily get used to working with a cycle
list if it is already offset by a “reserved seat” system.
The “reserved seat” has proven most effective in workshops that have processes such as plating or painting—that
is, any process that uses hangers for batch processing of
workpieces. Due to certain quality issues, people in plating
and painting workshops have a hard time getting away from
the idea of shish-kabob production. Generally, if the factory
is manufacturing three product models (X, Y, and Z), these
processes would handle workpieces for each model in separate batches, as shown in Figure 10.9.
Processing model-specific batches of workpieces as shown
in Figure 10.9 leads to the following problems:
Problem 1
In JIT’s pull production system, the lots are always pulled
from downstream processes. At the painting process
shown in the figure, this would require a large amount
of in-process inventory between the painting process
and the previous (upstream) process.
X
X
X
X
X
X
Y
Y
Y
Y
Y
X
X
Workpiece for Product X
(8 units × 3 hangers)
Figure 10.9
Y
Workpiece for Product Y
(6 units × 2 hangers)
Z
Z
Z
Z
Z
Z
Z
Z
Z
Workpiece for Product Z
(9 units × 2 hangers)
Shish-Kabob Production in a Painting Process.
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Problem 2
The processes downstream from the painting process
handle mixed-model flow production. This would necessitate a large amount of in-process inventory between the
painting process and the next (downstream) process.
Problem 3
Defects can easily arise from damage that occurs to
workpieces when they are removed in batches from the
hangers after being painted.
Problem 4
Since hangers always carry the same types of workpieces,
a change in the proportions of product models in the
production schedule causes variation-related problems in
paint operations.
Problem 5
The painting process interrupts the overall production
flow and makes it difficult to raise overall efficiency.
Figure 10.10 shows how all of these problems can be
solved by leveling production at the painting process via the
“reserved seat” method.
The “reserved seat” configuration of workpieces on hangers eliminates the need for in-process inventory while opening up space and providing adaptability toward model mix
changes. Even the work of setting workpieces on hangers
and removing them has been leveled to enhance operational
smoothness and stability.
X
X
Y
X
X
Y
Z
Z
Z
Product X workpieces (4) + Product Y workpieces (2) +
Product Z workpieces (3) × 6 hangers
Figure 10.10 Application of Reserved Seat Method at a Painting Process.
Leveling
The “Baton Touch Zone” Method and
Bypass Method
Line balancing is vital for successful assembly line operations.
It is especially important to maintain a constant amount of
work for each line worker when the line handles a mixed
flow of various product models in small lots. In mixed-model
assembly lines, the key is to keep the assembly workers performing the same tasks so that their efficiency will be roughly
equal to single-model (mass production) assembly lines. If the
workers have to change their tasks with each model, they are
much more likely to make defects, such as assembly errors or
omitted parts. In addition, their efficiency will suffer.
This is why production leveling and group technology
(GT) are so important at the design stage. At the delivery
stage, sequential delivery is also necessary. Another way to
help level out manual labor on the line is by using a cooperative operation technique, such as the “baton touch zone”
method or the “bypass” method.
The Baton Touch Zone Method
This method takes its name from the way relay runners
pass batons within a zone to avoid the difficulty of passing
the “work” of carrying the baton at any specific completion
point. In the factory, the baton touch zone is a certain range
of operations within which an operator may pass on his or
her work to the next operator. The flexibility afforded by
such a baton touch zone helps maintain line balancing when
product models are changed. (See Figure 10.11.)
The Bypass Method
When the amount of manual work differs so much from
product model to product model that the baton touch zone
method will not work, we can use the bypass method to
establish a separate “bypass” line that can accommodate the
model change. (See Figure 10.12.)
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Tasks at process 1
Assembly line
492
1) Worker A
2) Worker B
3) Worker C
Baton touch zone
4) Worker D
5) Worker E
Tasks can be passed
within the baton touch
zone at any point that
helps balance the line.
6) Worker F
Tasks at process 2
Figure 10.11
The “Baton Touch Zone” Method.
Mixed-model flow line
X
Y
X
X
X
Y
X
X
X
X
Pitch = 1 minute
Y
Bypass line
Figure 10.12
Y
Y
Y
Pitch = 3 minutes
The Bypass Method.
However, we cannot make bypass lines from just any line.
We must first establish mixed-model flow production and
­balance the line based on that type of production. Please
remember that the bypass method should only be used as a
last resort when the baton touch zone method is not feasible.
Realizing Production Leveling
Developing Flow Production
If production is leveled for only one group of the factory’s
production processes, such as only the assembly line, it may
not work to raise the factory’s overall efficiency. To do that,
the entire production system must be developed as a flow
production system.
Leveling
Door preparation process
1
4
1
worker workers worker
Second floor
Assembly plant
Hanger conveyor
Assembly line
Before improvement
Preparation process
Attach
knobs
Install
packaging
Attach
bottom
hinge
Door
storage
area
Door
supply
Attach
top
hinge
Intermediate
storage area
Install
Second floor
Ping-pong area
U-shaped area for
door preparation
Assembly plant
Assembly line
U-shaped cell for
door preparation
Inventory reduction
Manpower reduction
Set up ping-pong area
l
tal g
Ins agin
ck
pa
Install
Attach
hinges
At
kn tach
ob
s
After improvement
Door fastening
process
Storage area for two sets
Assembly line
Figure 10.13 Flow Production Improvement at a Sink Cabinet Factory.
Figure 10.13 shows a sink cabinet manufacturer’s door
preparation process before improvement. Before the
improvement, the door preparation process was located on
the s­econd floor of the factory. The workers at that process would select doors from the assortment of doors in
stock and hook them onto a hanger conveyor that would
carry them down to the assembly line on the first floor.
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Once production was ­leveled at the assembly line, the door
preparation process was no longer able to keep up with
the assembly line’s needs, and people began wondering if
the door preparation process could establish mixed-model
preparation operations to match the mixed-model assembly
operations at the assembly line.
To make this improvement, the factory managers moved
the door preparation process down to the first floor so that
all workers and equipment could be on the same floor. They
set-up this process as a U-shaped manufacturing cell right
next to the door fastening process in the main assembly line.
They then synchronized production in this cell to match
that of the leveled mixed-model flow line. As a result, they
reduced inventory to almost zero, achieved a major reduction
in manpower, and took advantage of the open space on the
second floor to set-up a long-wanted ping-pong table.
Improved (Kaizen) Retooling
Factories generally include both processing lines and assembly lines. The key point for production leveling of processing
lines is to improve retooling. Being able to switch among
product models and to improve the balance of assembly line
operations are the main concerns of production leveling in
assembly lines.
Figure 10.14 shows how one factory improved its shipment
pickup operations so that goods completed by the assembly line are picked up eight times a day (once every hour),
instead of just once a day. To make hourly pickup possible,
the assembly line mainly had to improve its product model
changeover procedures to shorten the changeover time.
Once they did this, the post-assembly inventory dropped to
one-eighth of its former level and accumulation of in-process
inventory after the preparation and processing steps was
eliminated, thus establishing smooth flow production.
Leveling
1 pickup per day
◾
1 pickup per hour (8 per day)
Pickup times
80 units
Shipping
center
40 units
8:00 9:00 10:00 11:00 13:00 14:00 15:00 16:00
Product X: 80 units
10
10
10
10
10
10
10
10
Product Y: 40 units
5
5
5
5
5
5
5
5
Product Z: 20 units
2
3
2
3
2
3
2
3
20 units
X
Y
Z
Pickup once a day
X
Y
Z
X
X
Y
Z
Transportation
kanban
Pickup 8 times per day
X
Assembly
line
Y
Z
X
Assembly
line
X
Y
Preparation
process
Preparation
process
X
Processing
line
Figure 10.14
495
Processing
line
Improving Changeover at an Assembly Line.
Y
Z
Z
Production
kanban
Chapter 11
Changeover
Why Is Changeover Improvement
(Kaizen) Necessary?
One obsolete notion that still finds firm believers in many
factories is that of “economic lot size.” Economic lot sizes are
thought to be whatever lot size helps to minimize the sum
of changeover costs and inventory costs. Factories traditionally have tried to keep their lot sizes as close to the ideal
“economic­lot size” as possible.
Factories have often economized not so much by approximating the ideal economic lot size, but by making lots a little
larger and minimizing die changes by using more parts from
fewer dies. These money-saving efforts probably had some
value during the bygone days of limited product variety and
large-scale mass production. However, today the trend is for
diverse product models and small-lot production with short
delivery deadlines. These radically different circumstances
require a new approach to economic lot sizes.
The conventional idea of economic lot size assumes
that inventory costs and changeover costs are constant; but
changeover costs can vary significantly. Moreover, changeover
improvements can drastically reduce the changeover costs.
Often, when factory managers look at costs within processes,
they do not include costs related to in-process inventory in
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overall inventory costs and they only recognize changeover
costs. In terms of the entire factory’s efficiency, however,
large-scale lot production incurs a wide array of waste-related
costs, such as surplus production cost, idle time costs, conveyance costs, inventory costs, set-up and removal costs, and
defect-related costs. And that is not all: Larger lot sizes also
mean more in-process inventory, and the more in-process
inventory a factory has, the longer the lead-time for its
­products. Aside from costs, the factory must deal with the
accumulation of goods at certain points and a disruption in
the overall flow of goods.
Many factories find themselves in dire straits trying to keep
up with current market demands for wide variety and small
lots, short delivery, and high quality. The kinds of improvements JIT brings to changeovers can shorten changeover time
and enable various product models to be made more quickly
and efficiently.
What Is Changeover?
Types of Changeover Operations
Changeover means a certain kind of set-up that we must
make before beginning a different set of operations. Often,
a changeover’s set-up procedure involves rearranging things.
The following are the main types of changeover procedures
performed in factories.
Type 1: Exchanging Dies and Blades
This kind of changeover is very common in machining shops
and is usually a prime candidate for JIT improvement. Often
the machine tool operators must retool their machines by
exchanging metal dies, casts for injection molding, drill bits,
saw blades, and the like.
Changeover
Type 2: Changing Standard Parameters
Computer-programmed high precision cutters and chemical processing equipment often require operators who can
change the standard parameters used for different processing tasks. Unfortunately, the more of this kind of changeover
a machine needs, the more smooth operations depend on
highly trained operators.
Type 3: Exchanging Assembly Parts or Other Materials
Whenever an assembly line switches to assembling a different product model, it needs to receive supplies of the parts
and other materials that go into the new model. The related
changeover procedures for this can include exchanging dies
(die changing is not unique to processing lines!). In assembly lines, exchanging equipment components is sometimes
referred to as “switchover” or “retooling.”
Type 4: General Set-up Prior to Manufacturing
This type of changeover includes all the miscellaneous set-up
tasks that must be done before we can begin manufacturing products. These tasks can include arranging the equipment and assigning jobs to workers, checking drawings, and
sweeping up.
Approach to Changeover Times
Many factory people think of changeover time as the period
that begins when the operator starts performing changeover
procedures and ends when he or she completes those procedures. This, however, is not really the case. Instead, we should
remember the following definition of changeover time:
Changeover time begins when the current processing task
is finished and ends when the next processing task produces
a defect-free product.
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More specifically, the part of this time period during which
the machine does not add any value to the workpiece is called
the “internal changeover time.” Many people tend to confuse
the internal changeover time with the entire changeover time.
The entire changeover time is the sum of the internal and
external changeover times. This may be easier to remember
in terms of an equation:
Changeover time = internal changeover time
+ external changeover time
◾◾ Internal changeover time: Internal changeover time
begins when the current processing task is finished and
ends when the next processing task produces a defectfree product. Throughout this time, the machine does
not add any value to the workpiece.
◾◾ External changeover time: External changeover time is
the time spent by the operator carrying out set-up procedures independent of the machine while the machine
is operating.
Therefore, when seeking to improve changeover operations,
we need to address possible changes in both the internal and
external changeover procedures in order to make a comprehensive changeover improvement.
Procedure for Changeover Improvement
Depending upon the type of work involved, changeover procedures fall into three categories: internal changeover, external
changeover, and waste.
◾◾ Internal changeover procedures: These procedures cannot be implemented unless the machine is stopped (not
operating).
Changeover
Flush out wasteful
operations and
apply the 5S’s to
eliminate waste
Form a
changeover
kaizen team
Analyze
changeover
operations
Transform internal
changeover into
external
changeover
Improve external
changeover
Improve remaining
internal
changeover
Figure 11.1
Changeover Improvement Steps.
◾◾ External changeover procedures: These procedures can
be implemented whether or not the machine is stopped
(not operating).
◾◾ Waste: This includes searching for jigs and tools, waiting
for the crane, and other nonproductive activities that are
not directly related to changeover procedures. If there
is too much of this, the factory itself may get stopped in
its tracks.
Figure 11.1 shows how we can divide up various changeover improvement steps according to these three categories.
Step 1: Form a changeover kaizen team
Once people recognize a growing need for changeover
improvement, they need to analyze the situation and form
a changeover kaizen (improvement) team. At this point,
it is vital that the newly formed team receive strong support from the company’s upper management.
Step 2: Analyze changeover operations
If we find that a certain changeover operation is taking
an extra long time, we need to analyze it to find the reason. Using JIT changeover improvement tools, such as
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changeover result tables and changeover analysis charts,
we can make the problems more obvious and explicit.
Step 3: Flush out wasteful operations and apply the 5S’s to
eliminate waste
We can start by categorizing all current changeover
operations into internal changeover operations, external
changeover operations, and wasteful changeover operations. Then we can eliminate the waste, preferably by
applying the 5S’s (the 5S’s are described in Chapter 4).
Step 4: Transform internal changeover into external changeover
People have often found clever ways to turn internal
changeover tasks that had previously required an idle
machine into external changeover tasks that can be performed while the machine is running. Whenever this has
been done, it has resulted in considerable shortening of
the overall changeover time.
Step 5: Improve remaining internal changeover
Once we have transformed at least some of the internal
changeover work into external changeover work, we will
have a clearer understanding of the remaining i­nternal
changeover procedures. At this point, we are ready to
review these remaining procedures and see if there are
ways to make them take less time. Sometimes we can
do this by reducing or eliminating bolts, developing cassette units of replacement parts, or establishing parallel
changeover procedures.
Step 6: Improve external changeover
Since the overall changeover time is the sum of the internal changeover time and the external changeover time,
we should make time-saving improvements in both internal and external changeover. Ways of improving external
changeover include establishing proper arrangement and
orderliness (the first and foremost of the 5S’s), developing
more specialized machines, and offering additional training in changeover-related skills.
Changeover
Launching Changeover Kaizen Teams
Often, an acute need for changeover improvement is disguised
in seemingly unrelated complaints, such as: “Lately, our capacity utilization rates have been dropping for some reason,” or,
“We’re having trouble keeping up with the product­diversification trend.” Even when the need for changeover improvement is obvious, individuals rarely get inspired enough to
make the improvement by themselves.
Figure 11.2 shows one way to make the need for changeover improvement obvious to everyone, namely by plotting
on a graph the relationship between the number of product
models handled and the equipment capacity utilization rate.
The following are a few pointers for changeover improvement teams.
1. Learn the changeover improvement rules
All changeover kaizen team members should meet at
least once for a study session so that everyone can gain
a firm understanding of the rules and “tricks” for changeover improvements.
2. Set-up and carry out a schedule of “public changeover
demonstrations”
Schedule a series of weekly changeover demonstrations
that are open to everyone in the factory to watch. Try
to include as many different types of equipment and
production lines as possible in the series. The schedule
of demonstrations should be drawn up in an attractive
format and posted throughout the factory.
Everyone who attends a changeover demonstration
should be acknowledged as an observer and a possible
source of improvement ideas. It might help to divide the
improvement team members to review the demonstration
together and brainstorm further improvement ideas.
The public changeover timetable shown in Figure 11.3
may come in handy when reviewing public changeover
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Model and Operating Rate
Trend Chart
Model
Process
Boring (No. 2 Mfg.)
Process manager
Yamagawa
Machine code
M11
Operator
Fujiyoshi
Types
20
Capacity utilization rate
Jan 88
Jan 88
Date
1/10/89
Types
52
Dec 88
%
Dec 88
2.6
Times
2.6
%
100%
70
87%
90
60
80
Capacity utilization
52
(2.6)
50
70
60
Model
40
49%
(56.3%)
30
50
40
20
30
10
20
Capacity
Year/
utilization Model month
10
1
2
3
4
5
6
7
8
9
10
11
12
20
23
23
26
27
30
31
35
45
44
50
52
87
86
85
80
80
75
72
68
57
57
72
49
Figure 11.2
Graph Showing the Relationship between the Variety
of Product Models and Equipment Capacity Utilization Rates.
demonstrations. Be very careful to avoid negative talk
about individual improvement ideas, such as: “That will
never work,” or, “Even if we try that, it’s impossible.”
People should feel free to put forth any idea without fear
of it being shot down on the spot. Finally, use a changeover improvement list (shown in Figure 11.4) to write
Changeover
Public Changeover
Timetable (1)
Process (code)
Description of changeover
No. 2 Mfg, No. 2 Print
Change colors on two rolls
Model
AV1N400 Entered by
Date
(600”)>MAGDP (400”)
Sandler
11/3/88
Operator Operator
(timer)
Lennon (David)
Time
Figure 11.3
Rosen (Cheryl)
Public Changeover Timetable.
Changeover
Improvement List ( )
No.
McTlghe (Naill)
Items in need
of improvement
Process (code)
No. 2 Mfg, No. 2 Print
Model
AV1N400
(600”)>MAGDP (400”)
Description of changeover
Change colors on two rolls
Entered by
Date
Sandler
11/3/88
Proposed improvement
Person
in
charge
Target Confirmation
date
1
Line up plate cylinder carts Make carts easier to move
in U-shaped formation,
around
and make this a rule
Jones
1/10
2
Make wrapping paper
tube placement a onetouch operation
Jones
1/10
3
Make plate cylinder
Develop specialized carts, use
replacement a one-worker stoppers and other jigs or tools
job (currently two workers) to change internal changeover
into external changeover
Jones
1/10
4
Disable backward motion
of plate cylinder carts
Jones
1/10
Figure 11.4
Use velcro tape to enable
one-touch operation
Place carts below pull-out rolls
Changeover Improvement List.
down all of the proposed improvement ideas in detail,
including a description of the proposed improvement,
the parties involved, and other details. Make sure everyone in the changeover improvement team reads the list.
3. Be sure to carry out lateral development of improvements
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The prime opportunity for changeover improvement is
when we have succeeded in making an improvement
on one machine or set of equipment, since we would
then have the know-how to “laterally develop” the same
improvement on other similar machines. For instance,
if we have succeeded in reducing changeover time for
a certain pressing unit to under ten minutes, we can go
ahead and make the same improvement on the factory’s
nine other presses, which gives us ten times the “bang”
for the same initial “buck” of improvement effort.
No matter what kind of JIT improvement we have made,
we should always be mindful of the great impact our improvement can have when developed laterally (or “horizontally”)
to other machines, processes, or people.
Analyzing Changeover Operations
Before making an improvement in changeover operations,
we need to compile some results to check out the following
possible problems:
1. Variation in the frequency of changeover operations.
2. Variation in the changeover sequence or method depending upon the workers involved or on the general “mood”
of the day.
3. Major variation in changeover times depending upon the
product models.
4. Dies, jigs, and tools are not being put back properly and
workers must waste time looking for them.
5. There seems to be an unnecessary number of bolt loosening and tightening operations involved in the changeover.
6. Only one worker knows how to perform the fine-tuning
operations following changeover.
7. The workshop always needs to turn out about 10 test
runs following changeover.
Changeover
Changeover
Results Table ( )
Item
Before
After
CV311
–05
CA231
–06
CA231
–06
VA921
–04
VAR21
–04
Date
Process name
No. 3 Mfg, Press
Machine code
M13-123
ChangeOperator over
time
10/1
Jones
15’ 30”
10/1
,,
20’ 10”
MC379
–01
10/1
,,
14’ 13”
MC377
–01
CB211
–02
10/1
,,
25’ 54”
CB211
–02
NA366
–03
10/2
,,
14’ 01”
M366
–03
2N11
–01
10/3
,,
18’ 24”
Figure 11.5
Measurements by Jones
Period 10/1/88 to 12/1/88
Time (minutes)
10
20
30
40
Changeover Results Table.
These kinds of problems tend to crop up in workshops
that have not learned to perform changeover operations
skillfully. To make such problems obvious enough to clearly
recognize and resolve, we need to compile results data concerning changeover operations.
Figure 11.5 shows a “changeover results table.” By entering
data describing current changeover operations, we can more
easily discover which changeover operations are giving the
workshop operators the most trouble and which are taking
up too much time. Once we know such facts, we are in a
better position to begin making improvements.
Once we recognize from the data entered on the changeover results table that a certain changeover operation is particularly difficult, we can target that changeover operation for
improvement and perform a public changeover demonstration
to analyze it. We need to enter the data from the demonstration on either a public changeover timetable (Figure 11.3) or
a changeover operations analysis chart (Figure 11.6). Public
changeover timetables are the more useful of the two when
several operators are performing the changeover and are
observing each others’ work. Changeover operations analysis­
charts are r­ecommended when there is only one operator
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Changeover
Operations
Analysis Chart
Minutes
39.7
Process (code)
No. 3 Mfg, Press M13
Model
MC377-01>CB211.02
Description of changeover
Mold change and width adjustment
Operator (timer)
Yamashima
Date
12/15/88
Changeover categories
Read Operation
time
time
Internal External Waste
Improvement
plan
No.
Changeover
operation
1
Go to pick up tools
1‘ 05”
1‘ 05”
Make specialized cart
for picking up tools
2
Go to pick up lift set
3‘ 15”
2‘ 15”
Make specialized cart
for picking up lift sets
3
Remove cover bolts (4)
5‘ 55”
2‘ 40”
Remodel for boltless
design
4
Remove side bolts (6)
8‘ 59”
3‘ 04”
Figure 11.6
Changeover Operations Analysis Chart.
performing the changeover and when that operator needs
detailed changeover-related data from which to plan improvements. If you do use a changeover operations analysis chart for
changeovers done by several workers, a separate chart form
should be filled out for each worker. These forms can then be
used as a basis for filling out a public changeover timetable that
will show how the workers’ operations relate to each other.
The thing to remember when filling out changeover operation analysis charts is to get into detail while observing and
describing each changeover operation. When the observer has
too many operations to observe, the improvement plans will
be too numerous and the improvements too vague. The most
important part of this chart is the categorization of changeovers.
The observer must carefully distinguish among internal changeover operations, external changeover operations, and wasteful
operations. The type of improvement to be made may depend
very much on how the changeover operation is categorized.
Identify Wasteful Operations and
Apply the 5S’s to Eliminate Waste
Waste is everywhere—in every workshop and in every operation. Naturally, there are bound to be various types of waste
Changeover
Waste in
changeover
operations
Figure 11.7
Waste in
internal
changeover
Waste in
external
changeover
Replacement waste
Adjustment waste
Preparation waste
Cleanup waste
Waste in Changeover Operation.
lurking within changeover operations. If, after standing back
and watching a changeover operation, we have found nothing in the operation that adds any value to the workpiece,
we can put that operation in the “waste” category. This is
not to say that it is simply a matter of removing the entire
changeover operation as superfluous. Removing wasteful
changeover operations always requires some consolidation
and standardization of dies, jigs, and/or tools, the establishment of specialized lines, or other measures to incorporate
the changeover’s functions into other operations.
The next step is to distinguish between the essential and
nonessential ingredients in each changeover operation and
thoroughly remove the nonessential elements.
As shown in Figure 11.7, we need to distinguish waste
in internal changeover operations from waste in external
changeover operations.
Waste in Internal Changeover Operations
Waste in internal changeover operations includes “replacement waste,” such as when exchanging dies or blades, and
“­adjustment waste,” such as when making the necessary adjustment to achieve output of nondefective products following­
the changeover.
◾◾ Replacement waste
Most of the waste created during replacement of dies
or blades is related to removing and fastening bolts. We
should regard bolts as our enemies. When necessary,
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they are necessary evils; when unnecessary, we should
find some way to eliminate them. When bolts are necessary evils, we can at least use small nets, C washers, or
other devices that enable us to loosen or tighten the bolt
with just one turn of the wrench.
All such improvements fall under the category of internal changeover improvement.
◾◾ Adjustment waste
I have often heard factory workers explain, “That guy
over there is the only one who can fine-tune that machine
correctly.” Why in the world would a factory want to
have a machine whose correct operation depended on
one individual? Why hasn’t that individual taught others
how to do the tricky adjustment correctly?
We must go even more deeply into this issue to ask, “Why
does the fine-tuning have to be done to begin with?” Fine-tuning
is only needed when machines have been allowed to stray
from their standard settings. In JIT, we have a saying: “If you
move your hands, make sure your feet and the standards stay
put.” Factory managers and workers must find a way to operate
the equipment without straying from the standard parameters.
If that is impossible, they must improve the changeover operation to eliminate the need for additional adjustments.
Waste in External Changeover Operations
Almost all of the waste found in external changeover operations is in some way related to the 5S’s. This kind of waste is
basically either “preparation waste” or “cleanup waste.”
◾◾ Preparation waste
When it comes to preparation waste, the chief culprit is usually “searching waste.” Workers waste time searching for
carts, jigs and tools, dies, blades, cleaning equipment, and
various other misplaced items. None of that searching waste
would exist if only the factory enforced the two most basic
of the 5S’s—proper arrangement and orderliness.
Changeover
◾◾ Cleanup waste
Not surprisingly, the main cleanup-waste villain is
“returning waste.” Workers waste time walking around
to put back the same assortment of items—cleaning
equipment carts, jigs and tools, dies, blades, and so
on. Rarely do they stop to wonder if all that walking
around is really necessary. A thorough implementation
of the 5S’s—or even just 2S’s (proper arrangement and
orderliness)—would teach them that in practically all
cases, things can be quickly replaced locally, without
any walking required.
Even after a workshop has eliminated all preparation
waste and cleanup waste in its changeover operations, its
total changeover time will still depend very much on how
well the 5S’s (especially proper arrangement and orderliness)
are enforced. Figure 11.8 shows the JIT form called “changeover 5S checklist.” In the figure, this checklist has been filled
with data taken from a machining (boring line) workshop.
The checklist helps us evaluate 5S enforcement in changeovers at each process.
The following symbols were used on the checklist to indicate how well specific operations were performed (parenthetical comments indicate how symbols are used to answer
yes/no questions):
○ Can be done well (or “Yes”)
Can be done, but not well (or “Mostly yes”)
× Cannot be done (or “No”)
Turning Internal Changeover
into External Changeover
Figure 11.9 shows a time graph analysis of improvements in
changeover procedures. The graph indicates that the 5S’s were
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Changeover
5S Checklist
No.
Process
No. 2 Mfg, boring line
Workshop leader
Rivera
5S checklist item
1
Are different sets of jigs and tools used
for changeover kept by each machine?
2
Are the jigs and tools within easy reach
during changeovers?
3
Are the jigs and tolls laid out according
to the order of use during changeover?
4
Are the jigs and tools laid out in an
orderly manner?
5
Are there some carts reserved expressly
for use in changeover and do they have
a prescribed storage site?
6
Are the items in the carts arranged in
an orderly manner?
7
Does each machine carry instructions
from the changeover operations manual?
8
Are the operators performing the
changeover as instructed in the manual?
9
Have quality standards been set for
each model?
10
Are the standards posted on each
machine?
11
Are defect-free samples of each model
on display for reference?
12
Are the samples displayed next to the
appropriate machines?
13
Are the required measuring instruments
kept next to each machine that needs
them?
14
Are the measuring instruments all kept
within easy reach?
15
Are the measuring instruments kept in
an orderly manner?
16
Is it clear where blades and other replaced
itetms should go after changeover?
17
Is it clear where blades and other
replaced items should be before
changeover?
18
Is the next workpiece kept next to the
machine?
Figure 11.8
Date and
Operator
512 ◾
Changeover 5S Checklist.
Machine code
Checked by
Rivera
MD001
Date
1/15/89
1/9 1/10 1/11 1/12 1/13 1/14 1/15 Improvement
plan
Changeover
Step
Improvement Step
1
(Before improvement)
Launch changeover kaizen team
(all machines stopped)
2
Analyze current changeover
operations
3
Identify wasteful operations
and apply the 5S’s
4
Change internal changeover
into external changeover
5
Improve internal changeover
6
Improve external changeover
Figure 11.9
Internal Changeover
External Changeover
Total changeover time
Machine stop time
Internal
changeover
Preparation &
cleanup time
Waste
External
changeover
Time Graph Analysis of Changeover Improvements.
applied to remove a lot of waste at Step 3 in the improvement. The most important part of the improvement was turning internal changeover to external changeover.
The following is a case study of the transformation of
internal changeover into external changeover at a printed
circuit board (PCB) assembly plant.
From Internal Changeover to External
Changeover at a PCB Assembly Plant
Like most PCB lines, this one was staffed by many workers
and involved the assembly of many components. The gist
of this improvement was to question the need for a single
PCB assembly line and to discover the advantages of splitting
up the equipment and workforce into several model-specific
assembly lines.
For some factories, such a major reorganization of assembly operations is just too ambitious an undertaking. Naturally,
keeping one assembly line means that changeover operations
will be needed whenever the line changes product models.
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The following three points are musts for assembly lines that
include dozens of workers and that must carry out changeover operations when switching models:
1. All product-model changeover must take place within
the cycle time.
2. The PCB substrate board sizes must not vary from model
to model.
3. The line must use assembly work methods that prevent
the need for operational balancing after changeover.
Before launching into the first and foremost of these three
musts, a little more needs to be said about the second and
third ones. If the same assembly line must handle substrate
boards in various sizes, the boards should be carried in containers of equal size in order to avoid having to adjust the
width of the conveyor belt during each model change.
The third must concerns the balance of assembly operations on the line. The options are either to reorganize and
rebalance the assembly operations after each model change,
or to use a flexible-operations method—such as cooperative operations or the baton touch zone—to avoid having to
rebalance after model changes.
Figure 11.10 illustrates an example of the first and most
important must, changeover within cycle time.
Before the improvement, whenever a model change
occurred, all of the previous model’s workpieces had to be
completed and removed from the conveyor so that the conveyor width could be changed. While this was going on,
the assembly workers were busy changing parts sets. They
had managed to reduce their overall changeover time to
15 minutes. Since there were 10 people on the assembly line,
we can figure the total labor “down time” as (15 minutes ×
10 persons =) 150 minutes. Changing product models four
times a day would incur a daily total labor down time of
600 minutes or 1.5 worker-days.
Changeover
Before improvement
After improvement
Changeover
within one cycle
PCB assembly line
PCB assembly line
B
Manpower: 10 assembly workers
When line is empty, switch product
models
Each assembly worker must change
parts sets during changeover for
new models.
Total changeover time: 15 minutes
Parts boxes (before improvement):
separate small boxes
Empty
A
A
Cart reserved for
changeover
during cycle time
Moves in pace
with conveyor
pitch
Switching of parts sets done (by foreman)
as external changeover
Reserved cart used only for changeover
within cycle time
Changeover time within cycle: 20 seconds
Parts boxes (after improvement):
set of boxes with handles for
easy management
Figure 11.10 Changing Internal Changeover into External Changeover at a PCB Assembly Line.
Changing Internal Changeover to External
Changeover in an Injection Molding Process
The following is a case study of how internal changeover
was changed to external changeover in an injection molding process. Two workers handled the changeover operations
before the improvement, but their respective responsibilities
were not made very clear, resulting in a total changeover time
of about 40 minutes. An analysis of their changeover operations revealed that all of their changeover operations were
internal, meaning that they were being performed while the
machines were stopped. (See Figure 11.11.)
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Before improvement
After improvement
Total changeover time: 40 minutes
Total changeover time: 5 minutes
Crane
Unloading stage for
previous mold
1) Find tools
2) Prepare and arrange tools
3) Remove hot runner (for coolant)
4) Wait for crane, then operate crane
5) Attach hook, hand hook from crane
6) Remove bolts
7) Open injection molding machine
8) Attach previous mold to crane hook,
use crane to move it to storage area
9) Detach hook and set it up on new mold
10) Move new mold to injection molding
machine, set in position
11) Finish setting new mold in injection
molding machine, then close the machine
12) Insert and tighten bolts
13) Detach hook and remove crane
14) Switch chucks in auto-extraction device
15) Set parameters and preheat
molding machine
16) Switch injection parts supply boxes
17) Put away tools
18) Start molding machine
19) Stop machine to check quality of
first product
Figure 11.11
Description of operation
Worker A
Worker B
1) Preheat mold
2) Move new mold onto loading stage
3) Prepare and arrange tools
4) Prepare injection parts supply boxes
5) Lower positioning notch
Remove bolts
1) Close injection modling machine
2) Remove bolts from right side
3) Open injection molding machine
4) Set previous mold onto
unloading stage
5) Load new mold from loading stage
6) Close the injection molding
machine
7) Insert and tighten bolts on tight
side
8) Set parameters
9) Start injection molding machine
Post- changeover
cleanup
Internal changeover
Description of operation
Positioning
notch
External
changeover
Loading
stage
for next
mold
Internal
changeover
Injection
molding
machine
1) Switch chucks in auto-extraction
device
2) Check quality of first product
3) Store away previous mold
4) Clean up tools
Remove bolts
from left side
Raise positioning
notch
Insert and tighten
bolts on lift side
Connect hot runner
Switch injection
parts supply boxes
Changing Internal Changeover to External Changeover in an Injection
Molding Process.
Changeover
The improvement included reassigning the two workers’
tasks according to the sequence of the changeover operation
and changing as much of the internal changeover procedures
as possible into external changeover procedures. As a result,
they were able to greatly reduce the overall changeover time
to about five minutes.
Changing Internal Changeover to External
Changeover in a Wire Harness Molding Process
Figure 11.12 shows an example of how internal changeover
was changed to external changeover in a wire harness molding process.
In this process, some rubber is molded onto part of the
wire harness. Before the improvement, the harness was set
directly into the metal mold. This took a lot of time to do, and
the workers had nothing to do during the actual molding process. An analysis came up with the following measurements:
◾◾ Harness setting time: 10 seconds (internal changeover)
◾◾ Idle time during molding process: 10 seconds
Molding jig
Setting jig
Figure 11.12
Changing Internal Changeover to External Changeover
in a Wire Harness Molding Process.
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As part of the improvement, two sets of molding jigs were
created so that four harnesses could be set as external changeover operations. This greatly shortened each harness’s metal
mold setting time and dramatically improved productivity in
the molding process. It also completely eliminated the idle
time during the molding process. As a result:
◾◾ Harness setting time: 10 seconds (external changeover)
◾◾ Mold jig replacement time: two seconds
◾◾ Idle time during molding process: none
Improving Internal Changeover
Two types of waste can be found in internal changeover
operations: replacement waste, as when replacing dies or
blades, and fine-tuning waste, as when adjusting the equipment to produce a defect-free product.
The following describes three methods for dealing with
and eliminating these three types of waste:
◾◾ Replacement waste
◾◾ Fine-tuning waste
◾◾ Serial waste
Eliminating Replacement Waste
If we take a close look at changeover operations, we usually
find that a lot of the work involves fastening and unfastening
objects such as:
◾◾ Loosening and tightening bolts
◾◾ Setting up or removing supports or blocks
◾◾ Setting up or removing dies and blades
◾◾ Attaching or removing air hoses
◾◾ Attaching or removing chutes
None of the above fastening and unfastening procedures
adds any value to the workpiece or product. Therefore, it is
best if we can somehow eliminate them.
Changeover
I suggest taking the following approach in improving
changeover operations.
Step 1: Can we do without this part of the changeover
procedure?
Our first question should be as simple as, “Why do we
have to replace this die (or blade)?” This line of questioning
may well lead to a standardizing or function-combining
improvement that will eliminate this particular replacement operation.
Similarly, we may find a way to avoid having to use
bolts altogether if we ask, “Why do we have to tighten
and loosen bolts?”
Step 2: Can we reduce the number of times this operation
must be done?
For example, we might ask, “Why does this die have to
use eight bolts?” If we can reduce the number of bolts,
we reduce the number of bolt tightening operations.
When numerous bolts are being used, we should always
ask whether all of them are really necessary.
Step 3: Can we reduce the time spent on this operation?
The most passive kind of improvement we can make
is to keep operations the way they are and just reduce
the amount of time spent on them. For instance, we can
reduce the amount of time spent screwing in bolts and
machine screws.
Other examples of alternatives for removing waste are:
◾◾ Improving an operation by removing the need for
certain tools.
Wrenches, screwdrivers, and hammers are just some of
the tools commonly used in changeover operations. We
can reduce the number of tools that must be picked up,
handled, and put back by finding ways around them or by
combining their functions into single tools. Figure 11.13
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Before improvement
After improvement
Allen wrench was glued
onto the bolt as a permanent
handle for turning
Allen wrench
Allen wrench
Glue
Bolt
Hexagonal
hole in bolt
Figure 11.13
Allen wrench was inserted
into the bolt and kept there
Eliminating the Need for Tools.
shows how the need for tools can be eliminated for certain bolt-tightening operations.
◾◾ Reduction of bolt tightening
Bolts are our enemies. The fewer, the better. If we cannot
reduce their number, we may at least be able to reduce
the number of turns needed to tighten or loosen them.
Turning bolts is a big waste of time. Only the final turn
really performs the function of tightening or loosen­ing
the bolt; all the other turns are pure waste, just turning
the screw threads through the nut. Figure 11.14 shows
an example of a bolt that protrudes well past the nut. In
general, a bolt is secure after about three turns, so there
is no need for such a long bolt.
Before improvement
Figure 11.14
After improvement
Reduction of Bolt Tightening.
Changeover
Before improvement
After improvement
Workers had to remove the
nuts and washers to change
the die.
Time required for operation:
200 seconds
Figure 11.15
Workers only had to loosen
the nuts slightly to change
the die.
Time required for operation:
300 seconds
Eliminating the Need to Remove Nuts and Washers.
◾◾ Improvement that eliminates the need to remove
nuts and washers.
Figure 11.15 shows an improvement that enables dies to
be changed without having to completely remove nuts
and washer from bolts. Before this improvement, it took
200 seconds to remove the nuts and washers from the
bolts each time the die was changed. After the improvement, the slip-off bolt allowed workers to change dies
by just slightly loosening the nuts. This reduced the die
replacement time to just 30 seconds.
◾◾Improvement that eliminates the need to remove
bolts.
Figure 11.16 shows before and after illustrations of a
bolted-in drill bit. Before the improvement, workers had
to completely remove six bolts from the drill in order
Before improvement
After improvement
Hole for
tightening bolts
Hole for
loosened bolts
Bolts must be removed completely
to exchange drill bit.
Total drill bit replacement time:
240 seconds
Figure 11.16
Bolts need only be loosened slightly and
slid through slots into side holes to exchange
drill bit.
Total drill bit replacement time: 40 seconds
Eliminating the Need to Remove Bolts.
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Before improvement
Removed bolts to
exchange tool bit
and holder
Figure 11.17
After improvement
Holder
Tool bit
Boltless one-touch
tool bit exchange
One-Touch Tool Bit Replacement.
to exchange the drill bit. Exchanging the bit took about
240 seconds, including the time spent in removing the
bolts and old bit and fastening the bolts and new bit.
After the improvement, the bolts had larger holes
drilled next to them, connected by narrow slots. When
the bolts are loosened just a couple of turns, they can be
moved into the slot, where they remain loose while the
bit is being exchanged. This improvement reduced the
total bit replacement time to just 40 seconds.
One touch tool bit exchange. Figure 11.17 illustrates an
improvement that made tool bit exchange on an NC lathe a
one-touch operation. Before the improvement, the workers
had to remove all of the bolts, then remove the tool bit and
its holder and replace it with another tool bit and holder.
After the improvement, the tool bits were made
detachable from their holders and all the holders were
redesigned in a standard size. This enabled the w
­ orkers
to change only the tool bits while leaving the standard
holder bolted to the base. The complete elimination
of bolt loosening and tightening reduced the tool bit
replacement time from 50 minutes to 3 minutes.
Changeover
Upper die
Die exchange
Manual vice lever
Stopper
Direction
of vice
tightening
Die
holder
Vice arm
Figure 11.18
Lower die
Bolster
Standard
position
Improvement for Boltless Die Exchange.
◾◾ Improvement for boltless die exchange
Figure 11.18 illustrates an improvement that enables die
exchanges to be made without using any bolts. In this
case, the boltless fastener is a common hand-tightened
vice. The operator just releases the vice lever to loosen
the die for replacement. Once the operator has the new
die in place, he or she just pulls the vice lever back to
clamp the die into the standard position.
Removing Fine-Tuning Waste
How often I have heard factory workers mutter something
along the lines of, “Hey, nobody can get that machine to
work right except that guy over there.” What happens to
flexibility and reliable productivity in a workshop when only
one person is capable of performing certain changeovers and
adjustments? Does the procedure really have to be so difficult or the machine so quirky that it takes an “old hand” to
handle it? Does it have to depend on a special, experienced
worker and is it really so difficult to standardize?
The most important question of all is whether the need
for fine-tuning is preventable. In most cases, fine-tuning is
needed simply because the standards are not being strictly
adhered to. Workers often set machines up according to what
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“looks” or “feels” right, then they make a trial run and adjust
the machine until it works correctly and turns out a product
that matches the defect-free sample.
Fine-tuning can include the following types of operations:
◾◾ Adjusting die positions
◾◾ Adjusting the die-shut height
◾◾ Adjusting the fastened height
◾◾ Adjusting feed roller width and height
◾◾ Adjusting conveyor width
While all appear to be necessary operations, none of them
in fact add any value to the product. Adjustments do not
always have to exist, no matter how necessary they may
seem. Let us turn to a few examples of improvements that
eliminated such fine-tuning operations.
◾◾ Protruding jigs eliminate the need for setting positions manually.
Figure 11.19 illustrates an improvement that did away
with the need for manual adjustment of dies following
changeover at a pressing machine. Before the improvement, the press operator had to use his eyes and ­intuition
to center the die within a bolster crossed by vertical and
horizontal lines. This was not always easy to do on the
first attempt, and subsequent manual adjustments were
often needed.
After the improvement, the bolster contains two protruding jigs (stopper pegs) that fit into notches on the die
to ensure proper positioning.
◾◾ Spacer blocks eliminate the need for manual positioning.
Figure 11.20 shows how spacer blocks were used to
eliminate workpiece length positioning prior to cutting. Before the improvement, the operator would visually adjust a movable limit switch block to the particular
Changeover
Before improvement
After improvement
Positioning
stopper
Bolster
Cross lines Center
die
Positioning
stopper
Die
Die
Positioning
notch
Operator uses vision and
intuition to center die on
cross lines.
Figure 11.19
Positioning
notch
Bolster
Operator slides die notches
against stoppers to center
die on bolster.
Protruding Jigs Eliminates the Need for Manual
Adjustment.
Before improvement
Movable limit
switch block
After improvement
Model-specific
spacer block
Fixed block
Clamp lever
Operator shifts movable limit
switch block laterally to set
feed length on workpieces.
Total workpiece changeover
time: 6 minutes
Use of model-specific spacer
block facilitates feed length
adjustment
Total workpiece changeover
time: 12 seconds
Figure 11.20 Spacer Blocks Eliminate the Need for Manual Positioning.
length setting for each model. After the improvement,
the movable block now has a simple hand-turned clamp
lever that eliminates the need for wrenches or other tools.
Furthermore, model-specific spacing blocks are used to
eliminate the need for workpiece length positioning. As
a result, the changeover time was reduced from 6 minutes to just 12 seconds.
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Before improvement
After improvement
Inspectors had to
adjust the dial
position for each
different product
model.
Workpiece
Length of workpieces
vary among different
product models.
Figure 11.21
Model-specific spacer block
(color-coded)
Spacer Blocks Eliminate the Need for Manual Dial
Positioning.
◾◾ Spacer blocks eliminate the need for manual dial
positioning.
Figure 11.21 shows how spacer blocks can be used to
eliminate the need for manual dial positioning. Before the
improvement, inspectors used dial gauges to check product quality. Since different product models had ­different
lengths, the inspectors had to adjust the dial position
whenever a model change occurred.
After the improvement, model-specific spacer blocks
were made for the inspectors to insert, when necessary, under shorter product models. This eliminated the
need to adjust the dial position, which takes a lot longer
than switching spacer blocks. To prevent errors due to
selecting the wrong spacer block, the blocks were color
coded—a technique promoted by JIT’s 5S campaign.
◾◾ Standardization of die height
There are three types of standards used for changing die
sets:
1. Matching bolster center with die center (X and Y axes).
We call this the “centering position standard.”
2. Matching die with the die-shut height (Z axis). This is
the “die height standard.”
Changeover
Before improvement
After improvement
Die set B
Die set A
Die set A
Die set B
Upper base
a
m
n
ℓ
ℓ
a
Lower base
Different die sets had different heights,
so operators had to adjust the press’s
die-shut height during each die-set
changeover.
Figure 11.22
Spacer block
Upper and lower bases were fastened
to each die set to standardize the
positions of fastening hardware. In
addition, spacer blocks were fastened
onto the shorter die sets to equalize
their heights and thereby eliminate the
need for any die-shut height adjustments.
Standardization of Die Set Height.
3. Setting the height (Z axis) of the laterally (X and Y axes)
positioned and fastened workpiece. This is called the
“fastened height standard.”
Figure 11.22 shows how by standardizing the height of the
dies, one workshop was able to eliminate the need for shut
height adjustment.
Before the improvement, each die had a different height,
which meant that the operator had to adjust the die-shut
height. Since the die-shut had to be exact for each die, it
often took over 20 minutes of adjustments to get it right.
The improvement was simply to make all die sets the same
height. Specifically, bases with the same fastening hardware
were added onto all of the shorter die sets. To equalize the
die set heights, spacer blocks were added to all the shorter
die sets to bring them up to the tallest set’s height. This effectively eliminated all that trial-and-error adjustment of the dieshut height, reduced changeover time to just two minutes­,
and ensured defect-free products the first time.
Eliminating Serial Operations
From the perspective of operational methods, changeover
operations can be broken down into serial operations and
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Before improvement
Blade replacement changeover as
serial operation
7
5
6
2
3
4
1
Blades changed in order
Transfer machine blade replacement
includes 7 steps.
Blades are replaced serially by one
worker.
Step 1 (3 minutes) + Step 2 (6 minutes)
Step 3 (6 minutes) + Step 4 (6 minutes)
Step 5 (3 minutes) + Step 6 (3 minutes)
Step 7 (5 minutes) = 32 minutes
After improvement
Worker C
Worker B
4
Figure 11.23
3
Worker A
2
Blade replacement changeover as
parallel operation
1
Blades changed in parallel
Three workers work simultaneously
instead of one worker working alone.
Worker A does Step 1 (6 minutes) and
Step 2 (6 minutes), for a total of 12
minutes.
Worker B does Step 3 (6 minutes) and
Step 4 (6 minutes), for a total oif 12
minutes.
Worker C does Step 5 (6 minutes) and
Step 6 (6 minutes), for a total of 12
minutes.
Establishing Parallel Operations in Transfer Machine
Blade Replacement.
parallel operations. Serial operations are operations done
in order from start to finish by one worker, and the total
changeover time is simply the sum of the time spent by that
worker on the series of operations.
Parallel operations involve splitting up the changeover
operation into two or more segments, which are performed
simultaneously by several workers. In this case, the changeover time is the amount of time required for the longest
­segment of the changeover operation.
Figure 11.23 shows an example of parallel operations in
the replacement of a transfer machine’s blades. Before the
improvement, one person performed the entire seven-step
blade replacement operation as a serial operation. The total
time required for this serial operation was calculated: Step 1
(3 minutes) + Step 2 (6 minutes) + Step 3 (6 minutes) + Step 4
Changeover
(6 minutes) + Step 5 (3 minutes) + Step 6 (3 minutes) + Step 7
(5 minutes) = 32 minutes.
After the improvement, the blade replacement changeover
was reorganized into 5 steps and was worked into the overall
workshop schedule so that instead of one worker performing
it as a serial operation, three workers each performed about
a third of it.
In other words:
◾◾ Worker A did step 1 (6 minutes) and step 2 (6 minutes),
for a total of 12 minutes.
◾◾ Worker B did step 3 (6 minutes) and step 4 (6 minutes),
for a total of 12 minutes.
◾◾ Worker C did step 1 (6 minutes) and step 2 (6 minutes),
for a total of 12 minutes.
The total changeover time was therefore 12 minutes.
Improving External Changeover
So far, we have improved changeover by turning as much
internal changeover into external changeover as possible
and by improving the remaining internal changeover. These
improvements should have resulted in a significant reduction
in changeover time due to less stopped time for the machines,
correspondingly higher capacity utilization rates, and more
frequent changeovers (due to faster production turnaround).
However, we should not stop with improving the remaining internal changeover. That would leave a storehouse of
external changeover waste safely hidden away. The key to
maximizing the efficiency of changeover operations is to
bring all possible improvements to both the internal and
external changeover parts.
The key to improving external changeover operations is
the 5S strategy, and particularly the two most basic of the
5S’s, proper arrangement (seiri) and orderliness (seiton).
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Proper Arrangement and Orderliness
Applied to Die Storage Sites
Even modest-scale factories usually keep a stock of 10 or
20 dies on hand. As the product diversification trend continues, factories are likely to need increasingly large assortments
of dies. Usually, the dies have sharply different frequencies
of utilization. If there are 10 dies, two or three will be used
70 or 80 percent of the time, while the remaining seven or
eight dies will be used only for special-order products.
Under such conditions, we might best begin making
improvements by finding out just which dies are used how
often, then storing the dies so that the more they get used,
the closer they are kept to the people who use them. This
alone will eliminate the need for a conveyor, and conveyor
waste is a major form of waste.
Once we have figured out where the dies should be kept,
we need to implement the “signboard strategy.” We can post
signboards that indicate exactly where the dies go, such as
by outlining the die shapes in their storage sites to make it
obvious where all the dies should be placed.
Figure 11.24 shows an example of a properly arranged
and orderly die storage site and signboard. The signboard’s
location and item indicators are the same as for in-process
inventory signboards and serve the same function of making
Before improvement
Place
indicator Address indicator
A
1
2
After improvement
Address indication
Machine no.
M1
A11
1
456
456
Shelf
indicator
Figure 11.24
Color coding
123
Color coded
according to
model and machine
C131
Block gauge
indication
Die Storage Site Using Signboard Strategy.
Changeover
“what goes where” obvious to everyone. To enhance orderliness, the dies are also grouped and color-coded according to
which models and machines they are used for.
Carts Reserved for Changeover
Factories that make large equipment items, such as NC
machines and printing presses, tend to use a lot of cranes,
hoists, and other kinds of large conveyance equipment.
These cranes, hoists, and the like are used to move everything along, including tiny items, such as small jigs or workpieces. In such cases, workers end up spending a lot of time
just waiting to use the busy conveyance equipment. To avoid
such problems, the factory should be able to switch from
cranes and hoists to more agile and economical conveyance
devices, such as carts and conveyor belts.
Similarly, in press factories, we can find people using forklifts to move boxes full of small dies. As with cranes and hoists,
people waste time looking or waiting for an available forklift.
Big, expensive conveyance devices like forklifts, cranes,
and hoists must be shared among the various stations on
the production line. Naturally, there will be plenty of times
where the demand for such devices exceeds the current
supply. It may help to think of the conveyance devices as
another process on the line. When the flow of goods goes
from several processes to just one process (a shared conveyance device), the flow turns to a flood. The result is idle time
waste and retention waste.
So, what can be done? There is really only one answer:
Conveyance must become part of flow production or, to put
it more succinctly, we need to establish “flow conveyance.”
One of the best ways to integrate conveyance into a flow
production system is by establishing specialized carts and
conveyor belts that are reserved for certain uses.
Figure 11.25 shows a specialized cart that is reserved solely
for changeover operations. As can be seen in the figure, this
cart is equipped with two roller boards for sliding old and
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Rotation direction
for roller boards
Old die
New die
Bolster
Roller
board
Jig and
tool shelf
After sliding the old die onto the empty roller board,
the roller boards are rotated 180 degrees and the new
die is slid onto the bolster.
Figure 11.25
Specialized Cart for Changeover Operations.
new dies off and onto bolsters during die changeover operations. All of the jigs, measuring instruments, vices, and other
tools needed for changeover operations are kept right on the
cart’s shelves.
External Changeover: Drill Bit Replacement
Figure 11.26 shows an external changeover operation for
changing drill bits in a machining center. Before the improvement, the worker stopped the machining center to set-up the
drill bit. After the improvement, workers used a specially
built cart for drill bit replacement, which they preset with
various drill bits as an external changeover operation so that
when it is time to change drill bits, they can wheel the cart
right over to the machining center.
Seven Rules for Improving Changeover
In the heyday of large-scale mass production, production engineers used to agree that “the fewer changeovers, the better.”
Changeover
Preset drill bit
Jig shelf
Caster
Figure 11.26
External Changeover of Drill Bits.
However, in today’s market—where large product variety, small
output volumes, and short delivery are all in demand—many
factories are having to make frequent product model changeovers to match production to current market needs.
When market needs change, the factory must have the
courage to improve its long-cherished changeover system. In
years of improving changeovers, I have discovered certain
“correct ways to do things” that appear valid in most every
case. In this manual, I have presented these as the “Seven
Rules for Improving Changeover.” We will look at them one
by one.
Rule 1: Changeover Begins and
Ends with the 5S’s
Changeover improvement begins with the 5S’s because all
improvement begins with the 5S’s. In fact, thorough implementation of the 5S’s is especially essential for successful
improvement of changeovers. Factories that do a very poor
job in changeover operations can find their changeover time
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cut in half very easily once they have established the 5S’s.
The half that they lose is all the waste that arises from searching for things, distinguishing things, using things inefficiently,
and moving things around.
The 5S’s are the very foundation for changeover improvement, and the most important of the 5S’s are proper arrangement (seiri) and orderliness (seiton).
Salient Points
◾◾ Discard. Get rid of everything that is not needed. If in
doubt, throw it out. That goes for any kind of item or
equipment. Use the red tag strategy to identify unneeded
items. (For a description of the red tag strategy, see
Chapter 4.)
◾◾ Indicators. Put up signs showing exactly where jigs, tools,
in-process inventory, and other things belong. Use the
signboard strategy to do this thoroughly. (For a description of the signboard strategy, see Chapter 4.)
◾◾ Color-coding for orderliness. Sort out items into modelspecific or machine-specific groups and color code the
items by group.
◾◾ Tool consolidation/elimination for orderliness. Ask why
each tool is necessary and see if tool functions can be
consolidated or certain tools eliminated while still getting
the job done.
◾◾ Specialization. Develop specialized carts, tools, and other
equipment that will improve changeover efficiency.
Rule 2: Change Internal Changeover into
External Changeover, Then Improve the
Remaining Internal Changeover
Many of us tend to count changeover time by including only
internal changeover time. Instead, we should distinguish
between internal and external changeover, and try to shift
as much internal changeover as possible into the realm of
Changeover
external changeover. After that, we are ready to start improving the remaining internal changeover. Any improvements
made in internal changeover at this point will bring valuable
results indeed.
Salient Points
◾◾ Analyze current changeover operations. Use a changeover
operations analysis chart to flush out and elucidate all of
the things that go into current changeover operations.
◾◾ Ask “Why?” again and again. Ask why each segment of
the internal changeover operations must remain a part of
internal changeover operations. See if it can be changed
to an external changeover operation.
Rule 3: Bolts Are Our Enemies
When it comes to changeover improvements, bolts are Public
Enemy No. 1. Whenever we see them, we should start thinking of ways to do without them. If we cannot get rid of them,
we may a least be able to reduce their numbers or redesign
them so that they can be sufficiently tightened or loosened
with just one turn. This will help us eliminate waste caused
by needlessly long bolts.
Salient Points
◾◾ Take the “boltless” approach. Bolts are rarely necessary.
More desirable substitutes include autoclamps (QDC),
fasteners with levers on top, cassette style snap-in components, knock pins, and the like.
◾◾ Use fewer bolts. If the equipment is bolted together by
12 bolts, see if it can be reduced to 10 bolts. Always ask
how many bolts are really needed.
◾◾ Make bolts shorter. Do not use bolts that are any longer
than needed. Only the last turn of the bolt or machine
screw does the actual fastening and only the first turn
does the loosening.
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◾◾ Eliminate the need to completely remove bolts. There are
plenty of ways—such as using sliding bolts, bolts with
side-slots, or bolts with C washers—in which bolts can be
loosened sufficiently without being completely removed.
This saves time wasted in putting removed bolts away,
finding them again, and inserting them.
Rule 4: If You Have to Use Your Hands,
Make Sure Your Feet Stay Put
A sure sign of a poorly planned changeover operation is when
workers must walk here and there to perform it. Walking
around in search of a wrench or a die or a cart is all a big
waste of time. Remember, each second of walking is a ­second
of wasted time. If a worker must take 20 steps to pickup a tool,
that is 20 seconds of waste. Or rather, 40 seconds of waste:
20 seconds of waste to get the tool and another 20 seconds
of waste to put it back. The changeover time gets longer with
each step the changeover operators take.
Salient Points
◾◾ Specialize. Develop specialized carts and tools that will
be used exclusively for changeover. Keep all tools laid out
in an orderly manner and within arm’s reach throughout
the changeover operation.
◾◾ Keep all switches close at hand. The rule against walking
during changeover operations applies also to all switches
and control panels used during such operations. Move
them closer, even if that means modifying the equipment.
◾◾ Establish parallel operations. Leaving a changeover operation to just one worker not only takes longer (since
the changeover steps must be done sequentially), but
often requires the worker to walk around the equipment
to make the necessary changes. We can save a lot of
changeover time by using several workers and assigning
Changeover
standardized segments of the changeover operation for
them to do at the same time in parallel.
Rule 5: Don’t Rely on Special Fine-Tuning Skills
One of the strongest-held obsolete notions about changeover operations is that the equipment always requires some
fine-tuning after changeover. Not only that, but often the
fine-tuning is so difficult that it takes “an old hand” to do it.
Factory people accept this situation as natural and inevitable.
There is no sense in paying the price of relying on certain
individuals when adjustments can be standardized so that
anyone can do them or, better yet, can often be eliminated
altogether by strictly adhering to changeover standards.
Salient Point
◾◾ Abolish fine-tuning. We must give up the notion that
fine-tuning is necessary. It never has been necessary and
never will be if we take measures to abolish it.
Rule 6: Standards Are Standard;
They Are Not Flexible
One thing that often leads to fine-tuning after changeover
is the attitude that changeover standards can be “fudged” a
­little. Standards usually prescribe specific X, Y, and sometimes Z positions for dies, blades, fasteners, and other new
parts set-up during changeover operations. If the changeover work is off-standard, the whole factory is off-standard.
Standards are no longer standards if they can be interpreted a
little differently during each changeover operation. Standards
are meant to be kept, not fudged.
Salient Points
◾◾ Avoid having to make position adjustments. Use stoppers, notches, centering cross lines, spacer blocks, or
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other devices that enable components to fit snugly into
their correct positions to avoid having to “fiddle” around
with them.
◾◾ Avoid having to make height adjustments. Different dies
or other components often have different heights, which
means the press or other equipment must be adjusted
for each changeover. Again, we can use height adjusters,
such as spacer blocks, uniform bases, and stand-alone
fasteners, to make component heights uniform to eliminate the need for height adjustments as part of internal
changeover operations.
Rule 7: Standardize All Changeover Operations
A common myth among factory workers is that changeover
is an independent kind of work in which each individual
worker displays his or her “know-how” and familiarity with
the equipment. This belief is hardly conducive to standardization, so we need to recognize it for what it is and discard it.
If standardization is impossible, improvement is impossible. Keeping that simple phrase in mind will help us make
progress as we work to improve changeover operations.
Salient Points
◾◾ Do not spend money on improvements. Do not leap
toward expensive solutions to improve problems. The
more money we spend, the less we will use our ingenuity to solve these problems.
◾◾ Make improvements right away. Once someone has
come up with an improvement idea, the time to act on
it is now. Why now? Mainly because immediate action is
most likely to inspire ingenious ideas and is least likely to
involve expensive solutions. Right away does not mean
“later today” or “later this week.” It means as soon as the
improvement idea arises.
Changeover
I have made a separate listing of the “Seven Rules for
Improving Changeover.” Please feel free to photocopy this list
and post it wherever it may serve as a reminder.
Seven Rules for Improving Changeover
◾◾ Rule 1
Changeover Begins and Ends with the 5S’s.
◾◾ Rule 2
Change Internal Changeover into External Changeover,
then Improve the Remaining Internal Changeover.
◾◾ Rule 3
Bolts Are Our Enemies.
◾◾ Rule 4
If You Have to Use Your Hands, Make Sure Your Feet
Stay Put.
◾◾ Rule 5
Don’t Rely on Special Fine-Tuning Skills.
◾◾ Rule 6
Standards Are Standard; They Are Not Flexible.
◾◾ Rule 7
Standardize All Changeover Operations.
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Chapter 12
Quality Assurance
Quality Assurance: The Starting
Point in Building Products
As discussed in earlier chapters, the essential meaning and
purpose of JIT production is to serve customer needs by
making “only what is needed, only when it is needed, and
only in the required amount.” Why, then, do we also speak
of JIT as “ideas and techniques for the total elimination of
waste”? Eliminating waste cuts costs and lower costs help
serve customer needs for lower prices.
JIT puts so much emphasis on cost-cutting through waste
elimination that JIT leaders can easily find themselves putting quality assurance considerations on the back burner. But
they should never make quality assurance anything less than
a top priority.
Quality assurance is essential to both JIT production and
large-scale mass production. Quality is the most fundamental characteristic of production, no matter what production
system we use.
In JIT, we are not so much concerned with low-defect
­targets, such as a certain number or percentage of defects per
month. Instead, we look at each defect as it occurs and ask,
“Why did that happen?” until we find the defect’s root cause.
Then we go after that cause with an improvement that will
prevent the same defect from happening again.
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Let us always keep the following points in mind:
1. Always follow standard operations.
2. Establish “one-piece flow” whenever possible to minimize manufacturing lead-time.
3. Stop the line whenever a defective item is produced.
4. Act immediately to make an improvement that goes right
to the source of the problem.
5. Remember: “Quality is built into products at each process.”
Figure 12.1 illustrates JIT’s five levels of quality assurance
achievement. Where does your factory rank among these
five levels?
JIT’s Five Levels of Quality
Assurance Achievement
Level 1: Factory Ships Defective Products
At this level, the factory either does not use inspectors or uses
them only superficially, so that there is little or nothing to stop
defects from being produced and shipped to customers.
At this level, the physical presence of inspectors means
nothing.
Factories that maintain a daily flow of defects going to
customers have no choice but to deal with defectives as they
are exposed by customer complaints. This is a very laborious
way of dealing with defectives and is bound to put the f­actory
into the red.
This may sound facetious, but the only way to totally eliminate defects at a Level-1 factory is to totally shut it down.
Level 2: Factory Does Not Ship Defective Products
When factories are having a hard time preventing customer
complaints, management may decide to boost the number of
inspectors if the company can afford the extra costs.
Quality Assurance
LEVEL
Factory ships
defective
products
Factory does
not ship
defective
products
Factory is
reducing
defects
FACTORY
O
P
E
R
A
T
I
O
N
S
MOTTO
“Lots of defectives
and lots of customer
complaints”
E
R
R
O
R
S
O
P Improvement
E
R
E
A
R
T
R
I
O O
N R
S
S
O
P Improvement
E
R
E
A
R
T
R
I
O O
N R
S
S
I
N
S
P
E
C
T
I
O
N
I
N
S
P
E
C
T
I
O
N
Factory
processes
do not send
defectives
downstream
O
P Improvement
E
R
E
A R
T
R
I
O O
N R
S
S
I
N
S
P
E
C
T
I
O
N
Factory
processes
do not create
defectives
O
P Improvement
E
R
E
A
R
T
R
I
O
O
R
N
S
S
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S
P
E
C
T
I
O
N
Figure 12.1
“Lots of defectives
but no customer
complaints”
ZERODEFECT
MEASURES
INSPECTION
Shut down
the factory.
No inspectors
Use more
inspectors.
Sorting
inspectors
Boost IE-type
improvements.
Inspectors
who use
feedback
data
Train operators
to identify and
remove defects.
Independent
inspection by
operators
Throughly
implement
the “3 Zeros”
in production.
Inspection
at the
source
Defect-free
products
“Defectives producted
in one production
run are not repeated
in subsequent
production runs.”
Defect-free
products
“When defectives are
produced at one
process, they do not
get passed on to the
next process.”
Defect-free
products
“When an error
occurs, the process
does not produce
defectives.”
Defect-free
products
The Relationship among Errors, Defects, and Inspection:
A Method for Corporate Survival.
At this level, the inspectors’ job is to sort the defective
products from the good ones. More money for inspection
therefore simply means more thorough sorting. Completely
thorough sorting will effectively prevent customer complaints,
but it does nothing at all to reduce the factory’s production of
defective goods.
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The best we can say about a factory that has crawled out
of the depths of the first quality assurance level to reach this
level is that it saves itself the trouble, expense, and bad publicity of dealing with customer complaints. Not really worth
a round of applause, is it?
The motto at this level might be “Lots of defectives but no
customer complaints.”
Naturally, all those defectives and inspectors are costing
the factory a fortune. The factory’s long-term survival is still
in doubt.
Level 3: Factory Is Reducing Defects
When I enter a factory that has achieved Level 3 in quality
assurance, I usually find some telltale signs of it, such as big
banners proclaiming “Support the Zero Defects Campaign,”
or something else to that effect. Right away, one gets the
impression that the factory managers are trying to heighten
awareness throughout the company that a zero-defect campaign is in force.
The kind of inspection carried out at this level is called
“information-based inspection.” When a defective unit is
found at the inspection process, the inspectors inform the
process that produced the item, and thus the inspection process helps encourage workers to make improvements that
will prevent the defect’s recurrence.
The motto at this level is, “Defectives produced in one production run are not repeated in subsequent production runs.”
The main ammunition in reducing defects is not so much
extra inspectors as it is the application of IE improvement methods and the training of line workers in some of those methods.
Level 4: Factory Processes Do Not
Send Defectives Downstream
The factory has not yet gotten past creating defective products. Still, whenever a defective is produced, the workers do
their best to nip the problem in the bud and prevent further
Quality Assurance
defects. Accordingly, the motto at this level is, “When defectives are produced at one process, they do not get passed to
the next process.
At this level, the process operators themselves become
inspectors, checking the quality of every item they produce.
W call this kind of arrangement “independent inspection.”
If the inspection work is centered on machines and tools,
the processes need to have automatic inspection devices or
poka-yoke devices. If the inspection work is mainly work
done by the operators, their inspection operations need to be
included in the set of strictly enforced standard operations.
Level 5: Factory Processes Do Not
Create Defectives to Begin With
Some people pass off the idea of zero defects as being unrealistic. Parroting an old phrase, they say, “To err is human, so
there will always be at least a few defects.” Such people do
not understand the Zero Defects philosophy.
To understand what “zero defects” is all about, we need to
distinguish between errors and defects. They are not the same
thing. Defects are results and errors are the causes of those
results. We can say that the Zero Defects philosophy begins
with this crucial distinction between errors and defects.
No one will argue with the truism that “to err is human.”
But neither should anyone oppose the idea that while to
err is human, the ability to prevent errors from leading to
defects is also human. This is the idea that serves to inspire
zero-defect campaigners.
Feet firmly planted in this optimistic concept, we can work
confidently to minimize human errors and, better yet, come
up with ways to prevent people from making errors in the
first place. This latter strategy is like killing two birds with
one stone.
At the fifth level, inspection goes all the way back to the
source of defects. Factories at this level are ready to accept
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the challenge of the “three zeros”: zero defects, zero waste,
and zero delays.
Structures That Help Identify Defects
Defects as People-Made Catastrophes
In any factory, the essential ingredient is people. And whenever we have people, we will have mistakes. Mistakes can
lead to defects and defeat. No matter how much we wish to
avoid making mistakes, sooner or later we will make one.
There are basically two ways we can look at human errors.
The first approach looks at mistakes as natural and inevitable. The idea is that “to err is human” and it’s only natural
that people will make mistakes now and then. The second
approach looks at mistakes as evil and declares, “People
make mistakes, but they are also able to reduce their mistakes to almost zero.”
The measures we take to deal with the possibility of mistakes differ greatly depending upon which of the above two
approaches we identify with. The first approach affirms the
human tendency to err. Naturally, if errors are accepted as
natural and allowed to occur freely, the factory must take
after-the-fact measures in dealing with defects arising from
errors. People end up pouring effort into keeping defective
goods from being passed downstream to subsequent processes or, at least, to the customer. This approach requires
a large number of inspection personnel and an extensive
“defect filter” just before the shipment stage to sort out defective products.
The second approach challenges the inevitability of errors
and takes a positive attitude toward focusing attention and
efforts in trying to prevent them. This approach goes directly to
the source of errors with improvements wrought via education,
cultivation of greater discipline, and the establishment of flow
Quality Assurance
production, standard operations, and other error-preventing
measures. The idea is to immediately alert supervisors to
errors and to conditions that facilitate errors.
So, which approach is better? Obviously, the second one.
In taking this approach, we must remember to aim our criticisms at the errors themselves and not at the people who
make them. Another important thing is to build a strong
commitment among the factory employees to prevent errors
and achieve the zero-defect goal.
The springboard for taking anti-error measures all the way
back to the source of errors is the realization that no matter­
how much effort and how many resources we invest in
product­inspection, mistakes will occur and lead to defects.
Defects are man-made catastrophes. If we can remember
that, along with the motto “Quality is built into products at each
process,” we can work in earnest to truly eliminate defects.
Misunderstanding Found in Inspection
The following happened at a certain factory’s quality assurance meeting.
The factory’s managers found themselves unable to slow the
flow of product quality complaints from customers. They had
hung banners proclaiming “Quality First,” “Quality Assurance
Month,” and other messages intended to raise everyone’s
quality-consciousness. But it ended in failure. Customer complaints remained as numerous as ever.
The factory superintendent was not happy. He bellowed at
the others attending the quality assurance meeting, “Double
the inspection staff!” Apparently, the superintendent had
decided it was time to pull out all the stops and spare no
expense in weeding out defective products before they are
shipped to customers. Noble as it sounds, this approach is a
big mistake.
If we look carefully, we can find a major misperception
at work here. The superintendent has failed to make a clear
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distinction between defects and customer complaints. The
two are indeed very different matters.
Factories build things at processes in workshops. Obviously,
the workshop has no intention of making defective items.
Nevertheless, when the products are finished, some containing defects built in at earlier processes are shipped off to
customers. The defects go unnoticed until the unlucky customers who receive these products try to use them.
Any defect in a product exists in the product from the
moment it is built in. Usually, the defect is not recognized right
away as such. Often, it is only the person using the product
(the customer) who notices the defect. When that happens, the
customer gets confused, disappointed, and perhaps even angry,
and sends in a complaint to the manufacturer or distributor.
To put it another way, defects in products are latent when
produced and are made apparent when the products are used.
Beefing up the inspection process is one way to reduce
the number of customer complaints. But often, the latent
defects are not apparent enough when the products are
merely inspected. They may become apparent only after the
product is put to regular use. (See Figure 12.2.)
In such cases, we cannot prevent customer complaints
unless we undertake defect correction and prevention measures closer to the source of the defects.
End user
(customer)
No inspection process
Processing
Latent
defect
Apparent
defect
With inspection process
Processing
Latent
defect
Inspection
End user
(customer)
Apparent
defect
Defect-free
product
Figure 12.2 The Relationship between Defects and Inspection.
Quality Assurance
The following are three principles that should guide our
efforts at nipping defects in the bud.
Principle 1: Don’t Make Surplus Products
At the most basic level, we can say that simply making products creates opportunities for creating defects. Therefore, we
can say that making extra products leads to extra defects.
In other words, factories should manufacture only the
amounts needed by the customers. Making more than that
leads to defects, and for several reasons. First of all, having
surplus goods causes some goods to be retained as warehouse
inventory. Having warehouse inventory requires stockpiling
and conveying the warehoused goods. Finally, stockpiling
and conveying inevitably leads to more dents and damage in
the products during handling. This alone is reason enough to
support the Just-In-Time philosophy.
Principle 2: Simplify and Facilitate
Production Operations
While in theory the best way to prevent defects is to refrain from
building any products at all, this is obviously not the answer.
While making the minimum number of required products,
we should not only find ways to simplify the production process itself, but also, within that context, find ways to simplify
and facilitate the handling of the process.
Two key techniques for doing this are poka-yoke (or mistake-proofing, described later in this chapter) and standard
operations (described in Chapter 13).
Principle 3: Once You Make a Product, Use It
The person best able to discover defects in a product is the
product’s user. Every manufacturer of products should be
well aware of this fact.
Obviously, no factory worker thinks, “Let’s make some
defective products.” Defects are always made by mistake and
thus often go unnoticed.
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Quite often, the defect is not noticeable to anyone except
the user.
The user can be the end user (customer) or someone
downstream in the factory, such as the assembly line worker
who finds that defective semifinished product A will not fit
together with defect-free semifinished product B to make
product C.
Still, the best discover of defects—even minuscule defects—
is the end user. This is because the end user puts the product
to use more frequently and in more ways.
It follows that the most effective way to minimize defects
is to make some use of the workpiece or product as soon as
it is processed or assembled. The two best methods for this
are flow production and multi-process operations (described
in Chapters 5 and 6 respectively).
When we make mistakes during the manufacturing of
products, those mistakes will remain hidden if we process
and pass along the products in lots (as in “shish-kabob” production). By the time the defect is discovered, who knows
how many defective units have been made?
So, let every production line worker remember this pair of
truisms: “The best discoverer of defects is the user” and, “The
best expert in creating defects is the operator.”
Factors behind Defects
All kinds of defects get produced in factories. Holes get drilled
or punched in the wrong places, workpieces get incorrectly
processed by damaged drills or saws, assembly workers overlook a component or two—the list is endless.
Even if everyone in the factory hates defects like the devil,
they will still keep making defective goods.
When defects occur, it is only natural that factory managers
and workers start asking simple questions, such as, “Why did
that defect occur?”
Quality Assurance
To better understand how defects get made, let us first
break the typical manufacturing company down into nine
basic elements. It so happens that seven of these elements
start with the letter M. It may be helpful to remember them as
the “7M’s plus E&I.” Figure 12.3 lists these nine elements.
For factories, the most important functional elements
are Man/Woman, Material, Machine, Money, Method, and
Information. On a day-to-day basis, the essential elements
for factories are Man/Woman, Material, Machine, Method,
and Information.
Specifically, the factory first receives operation instructions
(Information), then procures supplies of parts and m
­ aterials
(Material), sets up the machinery and other equipment
(Machine), and employs operators (Man/Woman) to manufacture products using standard procedures (Method).
These five elements (4M’s plus I) are where defects most
often occur in the factory. Let us look at these elements one
by one.
Element 1: Man/Woman
People make mistakes for all sorts of reasons, including
fatigue, negligence, getting the sequence of operations wrong,
attaching the wrong component, and so on.
Now, I would be the first to admit that, as the saying goes,
“to err is human.” If, however, we do nothing to reduce our
mistakes, we will keep making them forever. The important
thing is to remember not only that people are able to make
mistakes, but also that people are able to reduce the number
of mistakes they make.
Factories could not exist without people. The element
Man/Woman is thus the central element. The other key elements—Material, Machine, and Information—are relatively
peripheral. Figure 12.4 illustrates this concept.
After all, it is people that create and process information
and that move materials around. It is also people that build,
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7M’s
plus E&I
Description
Man
Directors, managers, sales people,
operators, etc.
Material
Products, assembled parts, parts,
materials, raw materials, etc.
Machine
Buildings, warehouses, machines,
conveyance equipment, etc.
Importance
to factory
Money
Method
Management techniques, sales
methods, production methods, etc.
Marketing
Market surveys, product planning,
price strategies, sales promotion, etc.
Management
Efficient management of the other
six “M”s
Engineering
Basic technologies, applied technologies, production technologies, etc.
Information
Customer information, order data,
production data, distribution data, etc.
The double circles indicate highest degree of importance and the
triangle the lowest degree
Figure 12.3
Nine Basic Elements in Manufacturing Companies (7M’s plus E&I).
Quality Assurance
Machine
Information
Man/Woman
Method
Material
Figure 12.4 The Five Essential Elements for Everyday Manufacturing Activities.
install, and operate machines. In the manufacturing world,
people are the foundation for just about everything.
Accordingly, any error reduction must rely heavily on
­factory-wide participation in programs that continually foster
education, training, and management by objectives.
Element 2: Material
Imagine a newlywed couple who has been enjoying their most
important wedding gift, a set of furniture with a fancy brand
name, only to discover during the hot, humid s­ ummer that bugs
are infesting the dresser drawers. They and other c­ustomers
complain loudly to the furniture store, who in turn bombards
the manufacturer with complaints and w
­ arranty claims.
To avoid this problem in the future, the manufacturer is
searching for a more insect-resistant material for its furniture.
The manufacturer receives all of its materials and assembly
parts from an independent supplier. They find it hard to get
the supplier to understand their need for stricter specifications concerning resistance to insect infestation and cannot
reach an agreement to purchase materials that meet those
stricter specifications. The supplier seems intent on doing
things its “own way.”
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Obviously the furniture manufacturer must find a way
to gain understanding and achieve improvements from the
­supplier. The key to success in doing this is to think of the
supplier as just another process in the furniture production
line, and to work just as hard to integrate that process as all
the other processes that happen inside the furniture factory.
Element 3: Machine
Factory managers must never allow themselves or their
subordinates to become complacent in the belief that “the
machines will do a great job if we just let them do the work.”
Like people, machines can make mistakes. Reliability is a
temporary feature in any machine.
Sometimes one of the machine’s functions starts deteriorating and produces defective goods. Older machines tend to
lose their precision very quickly. Other machines are difficult
to retool and require special attention for correct maintenance and replacement of jigs, drill bits, or blades.
The factory workers who still believe that manufacturing
machines should just be expected to turn out products in
rapid succession are dangerously deluded. They need to rid
themselves of that delusion. And while they are at it, they
should also relieve themselves of the burden of pouring fruitless hours of labor into maximizing equipment capacity utilization rates. The question of how much equipment capacity
to utilize should be answered by customer orders, not by the
machine’s potential capacity.
So much for wrong approaches: What is the right one?
The best approach is to develop devices that can be built
onto or in the machine to automatically stop the machine’s
operation upon detecting defects (or even potential defects).
In JIT vocabulary, we call this approach “Human Automation”
or “Automation with a Human Touch.”
The old-fashioned types among us need to do a complete about-face and replace old ideas. “Our widgets sell like
pancakes, so let’s turn out as many as possible,” should be
Quality Assurance
replaced with a more realistic concept, such as, “We cannot
afford defects, nor can we afford to make more than the
­market will support.”
Lastly, we also need to turn away from an emphasis on
the equipment’s capacity utilization and instead focus on the
degree of possible utilization. That means asking how consistently can we keep the equipment in working order.
Element 4: Method
The equipment layout, flow of goods, and operational methods differ so much between Toyota and Nissan factories, it is
hard to believe they are both producing automobiles.
The way a manufacturer makes its products says a lot
about the manufacturer’s history and philosophy. Once a
manufacturer gets set in its way of making things, its employees begin to loathe any suggestion of radically changing the
­factory’s production methods to suit a big change in the business environment.
When manufacturers design their production systems with
an emphasis on large lots and maximum output, we call it
“product-out production.” Their main concern is to get the
product out. By contrast, when manufacturers focus on a
level production flow and output based on market needs, we
call it “market-in production.” They bring the needs of the
market into the factory.
It should be obvious by now which type of production is
better for today’s market environment. Along with establishing “market-in production” throughout the factory, we need
to implement and enforce standard operations among all factory workers.
We cannot do any of this, however, until we succeed in
changing the way people think about manufacturing.
Element 5: Information
The spoken word is like software in a computer; we can
never see it, but it makes everything happen—including
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mistakes. Likewise, instructions given orally can be misunderstood, sometimes with disastrous consequences. There is
an expression in Japanese to the effect that “the spoken word
is a weapon that leaves no trace of itself.” If what you have to
communicate is important, be sure to put it in writing.
Of course, that can create other problems. When everything
gets put in writing, we soon have a factory full of memos,
vouchers, notices—a paper trail too voluminous to read.
Another problem is that writing things down does not guarantee error-free communication. Poorly explained or poorly
understood information becomes poorly written or poorly
read information. Naturally, the more mistakes in communication we have, the more product defects we can expect
to encounter.
Nonetheless, the first thing to do is to avoid oral instructions. Factories instead need written instructions that are
brief and to the point. This is where computers make an
excellent tool for the systematic processing and management
of information.
Another way to prevent communication errors is JIT’s
“visual control” approach, which uses signboards, kanban,
and other tools to make operation instructions and other
information obvious to everyone.
Figure 12.5 groups together the five elements of daily manufacturing activity just mentioned, the two main approaches
people take to these elements, the kind of action that follows­
each approach, and the JIT improvement measures that
correspond­to JIT-oriented approaches.
The ideas presented in the figure include two main points:
◾◾ Point 1: Don’t Give Up before You Start!
Taking a fatalistic attitude and saying, “Well, nothing can
be done about errors since people naturally make mistakes,” or, “Everybody’s different, so different workers will
inevitably do the same tasks differently,” is tantamount to
giving up on improvement before we even start.
Quality Assurance
ELEMENT
APPROACH
Human errors must
MATERIAL
ERRORS AND DEFECTS
Not all materials
are defect-free
MACHINE
Machines
sometimes
produce defects
No JIT measure
We can reduce
human errors
Get everyone
involved in errorprevention activities
Education, discipline,
management by
objective
Not much can be
done about
defective materials
Concentrate on
keeping a steady
supply of materials
to avoid shortages
Make sure material
supplies are not only
steady but also up
to our standards
inevitable
We can substantially
reduce the amount of
defective materials
Not much can be
done about the
defects machines
sometimes produce
We can take steps
to prevent machinecaused defects
Workers naturally develop their own style
making each process
Operation and
a little different
manufacturing
methods are often We can eliminate
left up to the
idiosyncrasies in
individual workers operation and manuto develop
facturing methods
METHOD
People cannot avoid
INFORMATION explaining things or
Oral instructions
are often
misunderstood
JIT MEASURE
Focus management
efforts on production
output and operating
time
MAN/WOMAN be accepted as
People make
mistakes
ACTION
◾
hearing incorrectly
We can minimize
mistakes due to poorly
explained or misunderstood oral instructions
Make up for defects
by emphasizing a
high capacity
utilization rate
Develop and install
devices that stop
machine-caused
defects
No JIT measure
Give guidance to
suppliers, inspect
all supplied materials
No JIT measure
Human automation,
poka-yoke,
total preventive
maintenance
Leave the “how” up to
the individual workers,
as long as their output No JIT measure
is high enough
Establish one-piece
Standard operations,
flow production
flow production
based on standard
operations
Keep giving oral
instructions
Put communications in
writing as concise match
up information with
the subjects discussed
Figure 12.5 The Five Main Elements behind Errors and Defects.
No JIT measure
Computer-based
information systems,
visual control
(kanban, etc.)
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As long as we accept the status quo as inevitable, we
stand absolutely no chance of improving it.
◾◾ Point 2: Every Defect Has Its Source in People
How easy it is to blame defects on inanimate objects: “We
got some bad materials,” or, “The machine broke down.”
If we stop to ask why, such as, “Why did defective
materials get delivered here?” or, “Why did the machine
break down?,” and if we keep asking why until we reach
the ultimate culprit, we will invariably find that culprit to
be a person or group of people.
As mentioned earlier, in the manufacturing world, people
are the foundation for just about everything. Behind every
defect lies at least one instance of human error.
Causes of Defects
To repeat something that bears repeating, all defects can be
traced back to some kind of human error.
Cutting machines start turning out defective workpieces
when the operator forgets to change the blade at the scheduled time. Another machine starts producing defects because
it was overlooked during the last routine maintenance check.
Assembly lines start spurting out defective products because
an assembly worker got the models mixed up and started
attaching the wrong parts.
No matter what the example, we can surely find a human
goof at its source.
Figure 12.6 shows how some common kinds of defects are
causally linked to typical human errors.
As can be seen in the figure, defects are broken down
into two basic types. The first kind of error occurs during
any operation that adds value to the product. We call this
“processing defect.”
Processing defects come in two types—processing omissions and processing errors. Processing omissions are when
Quality Assurance
DEFECTIVE PRODUCT
Processing
omission
Material defect
Processing
error
Second-level
cause of defect
First-level
cause of defect
Processing defect
Error in
adjustment
Figure 12.6
Causes of Defects.
Missing
part
Error in
operation
Wrong
workpiece
Wrong
part
Error in
setting up
workpiece
Error in
equipment
maintenance
Other type
of error
someone has overlooked any part of the processing that is
required to make the finished product. Processing omissions
can be further broken down into cases where an entire process has been overlooked, which we call “process omissions,”
and cases where only some operations in a process were
missed, which are called “operation omissions.”
Processing errors occur when processing that is expected
in the final product has been performed incorrectly. This can
include cases where the wrong kind of processing was performed, or the processing precision was not high enough, so
that the final product is substandard in terms of processing.
In contrast to processing defects, factories also experience
“material defects,” which means that the material itself is of
inferior quality.
The first-level causes of material defects are “missing part”
and “wrong part.” Missing part simply means that someone
failed to attach a required part to the product during assembly­
as specified in the assembly instructions.
Wrong part means that the correct number of parts have
been assembled, but that at least one of the parts is the
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wrong one for that particular product model. The shape of
the wrong part may be identical to the correct part, but the
precision of processing in some other aspect of the part may
be different enough to result in a defective finished product.
The second-level causes that lead to either processing
defects or material defects are “error in adjustment,” “error
in operation,” “error in setting up the workpiece,” “wrong
workpiece,” “error in equipment maintenance,” and “error in
preparation of blades, jigs, or tools.”
◾◾ Error in adjustment. This refers to errors made when
adjusting equipment or jigs during equipment retooling operations.
◾◾ Error in operation. This occurs when the operator operates the equipment incorrectly.
◾◾ Error in setting up the workpiece. In this instance, the
operator processes a workpiece that has been incorrectly
positioned during set-up.
◾◾ Wrong workpiece. This is when workpieces for different
models look alike, and the operator sets up and processes the wrong kind of workpiece.
◾◾ Error in equipment maintenance. This is when the equipment is in poor condition due to inadequate maintenance
work or an oversight during maintenance checks.
◾◾ Error in preparation of blades, jigs, or tools. Here, a defect
occurs due to an error or omission made during the preparation of blades, jigs, or tools required for processing.
Second-level causes lead to first-level causes. For example, an
error in setting up the workpiece (second-level cause) can very
easily result in a wrong part (first-level cause). Other secondlevel causes can lead to almost any of the first-level causes.
Which of these causes tend to happen most often? After analyzing a number of case studies, I have come up with “The Ten
Worst Causes of Defects,” which are shown in Figure 12.7.
Quality Assurance
The Ten Worst Causes of Defects
No.
1
Processing omissions
No.
2
Processing errors
No.
3
Error in setting up the workpiece
No.
4
Missing part
No.
5
Wrong part
No.
6
Wrong workpiece
No.
7
Error in operation
No.
8
Error in adjustment
No.
9
Error in equipment maintenance
No. 10
Figure 12.7
Error in preparation of blades, jigs, or tools
The Ten Worst Causes of Defects.
As you can see, processing omissions and errors are the
two worst causes of defects. This is because the analysis of
case studies showed these processing-related causes to be
the most frequent phenomena.
By contrast, the case studies included relatively few
instances of defects arising from improperly prepared equipment, blades, and jigs, or other equipment-related problems.
The results of this analysis support my earlier contention
that people are at the bottom of nearly every defect in the
factory. Therefore, we should regard the prevention of human
errors as our primary objective. We should also implement
poka-yoke (or mistake-proofing) devices and standard operations as effective means of addressing problems in the element “Man/Woman’s” relationship with other elements, such
as “Method” and “Information.”
Overall Plan for Achieving Zero Defects
Why Must Defects Occur?
To answer that simple question, we need to take a deeper
look into human errors and the other elements that cause the
creation of defects.
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We have already seen how the element “Man/Woman”
stands as the primary cause behind almost all defects. This
does not mean, however, that the “Man/Woman” element is
the only element we need to address when making efforts to
prevent defects.
We must begin by thinking of the factory itself as a living­
being. We should also remember that production is a ­system.
Therefore, while viewing “Man/Woman” as the core element,
we must develop devices to prevent the occurrence and
­creation of defects.
Figure 12.8 illustrates the overall plan for achieving zero
defects in factories.
Man/Woman
◾◾ Device 1: Basic training
People are the root cause of errors and defects. We
must make sure a good foundation of basic training has
been laid. This training should include topics such as
Overall plan for achieving zero defects
Poka-yoke
(mistake-proofing)
Visual control
Machine
Information
Company-wide
preventive maintenance
Basic training
Multiple skills
training
Man/Woman
Flow production
Standard
operations
Method
Material
Preventive
(independent)
inspection
Basic strategy for zero defects
The 5S’s (proper arrangement, orderliness, cleanliness, cleaned up,
and discipline)
Figure 12.8 Overall Plan for Achieving Zero Defects.
Quality Assurance
the overall role of people in factories, management by
objective, and making a habit of following the regulations and standards.
◾◾ Device 2: Multiple skills training
Many defects are the result of human ignorance. Factory
workers are sincerely trying to make defect-free products,
but their lack of certain knowledge and skills can make
it hard for them to discover defects.
As mentioned earlier, the people best able to discover defects
are the users. They alone put the product to practical use and
can therefore best judge whether the product is defective.
It follows that products and workpieces should be used as
soon as they are made. It is also more effective to have the
person who made the product do the practical testing, rather
than someone else. In one-piece flow production using multiprocess operations, the operator accompanies each workpiece
to the various processes in the workshop, and can therefore
make a thorough inspection while “using” (processing) the
workpiece at subsequent processes.
Information
◾◾ Device 3: Visual control
At a typical factory, a quality control inspector comes by
each workshop once a month to check on defects. He
or she conducts analyses, writes up quantitative results,
and then puts the data away in a desk. That is usually
the end of it.
It does little good to collect data on the occurrence of
defects and improvements if they are not going to be shared
and discussed with the shop-floor workers. The analytical
data should not only be explained to the workers, but should
also be translated into graphical representations that help the
workers see what the data means. This is part of visual control,
and it is vital that visual control be rooted in the workshops.
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Material
◾◾ Device 4: Preventive (independent) inspection
Downstream inspection is powerless to prevent the production of defective goods. The best defect prevention
is the kind that detects and corrects errors before they
lead to defects. That kind of defect prevention can only
be obtained by combining processing or assembly with
inspection, all in the same place.
Machine
◾◾ Device 5: Poka-yoke
One of the tools used by the JIT production system is
“human automation.” Human automation means customizing factory machines so that they not only manufacture
products, but also detect defects and automatically stop the
machine whenever a defect occurs or is about to occur.
Human automation also includes the development and
use of poka-yoke (mistake-proofing) devices that help
keep machines from producing defective goods.
◾◾ Device 6: Company-wide preventive maintenance
One important way to prevent defects and ensure high
productivity is to make sure the factory equipment is
operating in top condition, both in terms of its functions
and its capacity.
Upkeep of equipment should not be left to the maintenance staff alone. After all, it is the equipment operators and
not the maintenance technicians who spend all day working
with the equipment and who best understand its operating
“health.” Operators need to learn what they can do on a daily
basis to keep the equipment in top shape.
Method
◾◾ Device 7: Flow production
As mentioned above, the best way to discover defects is
to use the product just as soon as it is made. One-piece
Quality Assurance
flow production enables factory floor workers to do
just that.
◾◾ Device 8: Standard operations
Wherever we find operators who think, “I don’t really
know the best way to do this,” or, “It’s up to me to
decide how this should be done,” we can be sure to find
lots of defective products.
By drawing up a chart that describes the correct
equipment layout and operational procedures, we can
establish a clearly defined set of standard operations that
everyone in the factory can understand and follow.
Basic Strategy for Zero Defects
◾◾ Device 9: The 5S’s (proper arrangement, orderliness,
cleanliness, cleaned up, and discipline)
We have just described the various defect-prevention
devices that fall under the categories of the factory’s
five main functional elements (Man/Woman, Material,
Machine, Method, and Information). However, none of
these devices stand much of a chance of working well
unless we have first laid a strong foundation. The strongest and most appropriate foundation for preventing
defects is the one we create by implementing the 5S’s
(proper arrangement, orderliness, cleanliness, cleaned
up, and discipline).
The Poka-Yoke System
The Poka-Yoke Concept and Methodology
In Japan, quality control experts coined the term “poka-yoke,”
which translates to “mistake-proofing.” Poka-yoke refers to
where the mistake is made—poka refers to the operation and
yoke to the prevention of mistakes.
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Condition of defect
Defect is about
to occur
(warning)
D
e
f
e
c
t
s
Stop for abnormalities
Immediately stops the
current operation or
function whenever
an abnormality is
detected
Device
Stop devices
Error control
Prevents defects from
being produced whenever it appears they are
about to be produced
Warning signal
Signal (lamp, alarm, etc.)
warns people of abnormalities or errors
Control devices
Stopped for defect
P
o
k
a
y
o
k
e
Immediately stops the
current operation whenever a defect is
detected
Defect has
occurred
(detection)
Flow control
Prevents defective product from being passed
to next process
Warning devices
Defect signal
Signal (lamp, alarm, etc.)
warns people that a
defect has occurred
Figure 12.9 The Relationship between Poka-Yoke Devices and Defects.
Poka-yoke devices are already in use throughout Japan.
You will find them in most factories that employ at least 10
or 20 workers. Very few factories, however, have homegrown
poka-yoke devices that cleverly solve factory-specific problems.
Figure 12.9 shows how poka-yoke devices can be divided into
three main types.
The three types of poka-yoke devices shown in Figure 12.9
are described below.
Stop Devices
◾◾ Stop for abnormalities. This kind of device can detect certain abnormalities that can lead to defects. When it detects
Quality Assurance
such an abnormality, the device stops the machine’s current operation or function. This is analogous to staying
home from work when you have a bad cold.
◾◾ Stop for defects. This kind of device can detect when the
machine has produced a defective product and immediately stops the machine’s current operation or function
so that it does not turn out more defective products. This
is analogous to leaving work to go home to bed when a
cold is compounded by a bad fever.
Control Devices
◾◾ Error control. This kind of device prevents operators from
straying from standard operations and making errors. An
analogy for this would be closing your eyes when you
see a dust cloud coming your way.
◾◾ Flow control. This kind of device keeps defective goods
from being passed to the next process. An analogy for
this would be the way an eye that has a speck of dust on
it begins watering to remove the dust.
Warning Devices
◾◾ Warning signal. This kind of device uses lamps and/or
buzzers to warn people when an abnormality that may
lead to a defect has occurred. This is analogous to a
wind chime that sounds only when the wind is strong
enough to constitute a certain degree of a fire hazard.
◾◾ Defect signal. This kind of device uses lamps and/or
buzzers to warn people when a defect has occurred. The
analogy in this case is a fire alarm that alerts people that
a fire has started.
As you can see, poka-yoke devices operate in one of two
ways: as a device that informs us when a defect may be
about to occur, or as a device that informs us when a defect
has actually occurred. It should be obvious which kind of
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operation is more valuable. As the saying goes, an ounce of
prevention is worth a pound of cure. That is why JIT leaders
stress the need to develop devices that detect abnormalities
and give advance warning about the potential for defects.
It is not always easy, however, to predict when a defect
is likely to occur. In such cases, we have to respond to the
defect as it arises. When a defect occurs in the factory, we
should treat it as a true emergency. The alarm lights and
buzzer should grab our attention and bring immediate action
to resolve the problem that created the defect.
Poka-Yoke Approaches
Imagine a kaizen team member standing in a workshop that
has been producing defective goods and asking himself,
“What kind of poka-yoke device shall I use?
Basically, he can take one of three approaches:
1. He can look at the shape of the part being processed
and check whether it is usable or unusable.
2. He can study the sequence of processing steps carried
out by the operator.
3. He can check the quantitative parameters of the operations.
If he takes the first approach, he needs to check the standards regarding the shape, dimensions, and weight of the
part of other material involved and see if any of those standards are not being met. He can use this method to sort
defective good from nondefective ones. We call this method
the “item characteristics method.”
If he takes the second approach, which we call the “operation step method,” he may discover that at least one of the
steps is sometimes not being done correctly, and can then
develop a poka-yoke device to prevent operator negligence
at that step.
Quality Assurance
If he takes the third approach, he needs to study numerical data describing the various quantifiable parameters of
the operation, such as the number of times an operation is
repeated, the number of parts involved, the time required,
and so on. Variations or gaps in these numerical data can
help him sort out defective and defect-free products. We call
this the “statistical method.”
Let us look a little more closely at each of these approaches
and their corresponding methods.
Item Characteristics Method
◾◾ Shape method. For this method, we need to have standards set for various shape characteristics, such as holes,
angles, dents or creases, protrusions, curves, and so on.
Then we can compare each item’s shape characteristics
against these standards to see if the item is defective.
◾◾ Dimension method. In this case, we need to have standards set for various dimensions, such as height, length,
width, thickness, diameter, and the like. We then ­compare
each item’s dimensional characteristics against these standards to see if the item is defective.
◾◾ Weight method. Armed with weight standards, we can
simply weigh each item to check for extra mass that
indicates a defect. We can also check the weight balance
between the right and left halves of certain items.
Operation Step Method
◾◾ In-process sequence method. The purpose of poka-yoke
here is to find out when operators stray from standard
operations, either in their own work or in the way they
work with the equipment, and to keep them from continuing the sequence of operations in that process.
◾◾ Between-process sequence method. In this case, pokayoke devices work to stop operations whenever a process
within a series of processes is performed incorrectly or
is overlooked.
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Statistical Method
◾◾ Counter method. Here, we check the workshop against
the current standards for the number of times an operation should be repeated or the number of parts involved.
Poka-yoke devices can detect when the numbers are
wrong and can issue a warning.
◾◾ Remainder method. Sometimes, parts are grouped into
sets before being processed or assembled. A poka-yoke
device can detect when any part remains in used sets
and can sound an alarm to notify everyone that a part
has been omitted.
◾◾ Other statistical methods. Other numerical values that
can be monitored by poka-yoke devices include pressure, electrical current, temperature, and time. Poka-yoke
devices can notify us whenever any of these values are
off standard.
Poka-Yoke Detection Devices
There are all kinds of devices that can be used to detect
abnormalities. Generally, such detection devices can be categorized into contact devices and noncontact devices.
Let us look at a few typical examples in each of these
two categories.
Contact Devices
◾◾ Microswitches and limit switches. These types of detectors
are the ones most commonly used as poka-yoke devices.
They work best in detecting the presence and position of
workpieces, dies, and bits or blades. Microswitches offer
a variety of actuators to choose from, according to the
specific application. Figure 12.10 lists the main types of
actuators and their respective features.
◾◾ Other contact devices. Although microswitches and
limit switches are the most often used types of contact
Figure 12.10
Vibrating/
shock
resistance
Very good
OK
Roller attached to the panel
assembly is suitable for use
with rapidly moving cams or
docks.
OK
Medium
Operated by a short straight
stroke, this switch features a
snap-action mechanism that
responds to direct contact
with the pin. It therefore
offers the highest precision for
position detection. However,
it also has the least amount of
overtravel among all the
actuators, and therefore
requires a reliable stopper.
Operable under a small
operating force, suited for use
with rapidly moving cams or
docks. Also features large
stroke. Levers are available in
various shapes and configurations to suit different types
of operation.
OK
Medium
Medium
Features
This is a hinged lever with a
roller attached. Also suitable
for rapidly moving cams or
docks. Requires less operating
force on the pin than does the
hinged lever and uses a larger
stroke.
OK
Medium
Roller/leaf
spring type
◾
This is a hinged roller lever
that can also be operated
using a unidirectional operating device. If the operating
device presses from the opposite direction, the roller section
bends and prevents the
actuator from operating. As
such, this device is especially
suited for applications where
reverse-direction operation is
to be avoided.
Good
Operating
force
Large
Large
Small
Medium
Small
Overtravel
Small
Large
Small
Unidirectional
hinged roller
lever
Medium
Hinged roller
lever
Medium
Hinged lever
Medium
Roller push
button type,
attached to
panel
Small
Pin push
button type
Large
Name
Large
Shape
Pretravel
Quality Assurance
This is leaf spring with a roller
attached. Can be used with
high-speed cams.
Microswitch Actuators: Types and Features.
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switches, there are some other kinds of “touch switches”
that feature highly sensitive detection of workpiece positions. In addition, differential transformers can be used
to detect changes in electromagnetic force as a type of
contact pressure and trimetron switches can be used for
dial gauge applications.
Noncontact Switches
◾◾ Photoelectric switches. Photoelectric switches can be used
with devices that transmit and reflect light. As detectors,
photoelectric switches come in two types: unidirectional
switches that detect the interruption of light transmission between two photoelectric switches, and reflector
switches that use reflected light beams. Reflector switches
are further broken down into dispersion reflectors and
feedback reflectors. (See Figure 12.11.)
Photoelectric switches are also sometimes ­
classified
according to function. Some have external amplifiers, others­
have built-in amplifiers, and still others include built-in
power supplies. Figure 12.12 shows how photo­
electric
switches are classified according to detection method and
function. Figure 12.13 shows how photoelectric switches
Use of photoelectricity
as a detection method
Unidirectional
method
Figure 12.11
Dispersed reflection
method
Photoelectric Switch Detector.
Feedback reflection
method
Quality Assurance
Detection
method
Figure 12.12
Reflection
method
Switches with separate amplifiers
Switches with built-in amplifiers
Switches with built-in power supplies
Light-transmitting
objects
Light-blocking
objects
Object
Unidirectional
method
Switches with separate
amplifiers
Switches with built-in
amplifiers
Switches with built-in
power supplies
The Relationship between Object, Detection Method,
and Function of Photoelectric Switches.
Photoelectric switch with built-in amplifier
(Uses)
For confirming passage of solid
(light-reflecting) objects
For detecting translucent objects
For confirming supply of parts
For confirming passage of
wafers
Figure 12.13
The Use of Photoelectric Switches.
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with built-in amplifiers are used. Figure 12.14 shows how
fiber optic switches are used.
◾◾ Proximity switches. Proximity switches are activated when
they come close to an object. Some proximity switches
use electromagnetism to detect proximity. Figure 12.15
shows various ways of using proximity switches.
◾◾ Positioning sensors. Noncontact switches also include
sensors that help position objects correctly. Figure 12.16
shows some ways these can be used.
◾◾ Outer diameter and width sensors. These sensors use
groups of parallel light beams to obtain a precisely measured image of the object being detected. These ­sensors
can continually measure object dimensions, such as outer
diameter and width. Figure 12.17 shows some ways of
using outer diameter and width sensors.
◾◾ Displacement sensors. Displacement sensors, which usually
use lasers or other optical media, can measure an object’s
directional dimensions without touching the object. They
can also measure various colors and m
­ aterials characteristics. Figures 12.18A and 12.18B show several uses for displacement sensors.
◾◾ Metal passage sensors. These noncontact sensors can
detect the passage of metal objects. Their uses include
detection of fast-moving metal objects and counting very
small metal objects. Figure 12.19 shows how metal p
­ assage
sensors can be used.
◾◾ Color mark sensors. Color mark sensors can be used to
sense the difference between two slightly different colors
and to detect very small marks. Figure 12.20 shows how
color mark sensors can be used.
◾◾ Vibration switch. These sensors can detect vibration
in almost any kind of material. They can also be used
to detect the passage, width, and missing drill bits in
­various objects. Figure 12.21 shows some ways of using
vibration switches.
Quality Assurance
Fiber optic switch
Positioning of lead
frame
Detection of
resistor leads (wires)
For confirming passage
of parts on parts feeder
For confirming supply
of parts
For detecting presence
of pins or leads on
electronic components
For detecting presence
of small holes
Bidirectional detection
Mark detection
IC missing pin
detection
Detection of fronts
and backs of chip
components
Wire break detection
Confirmation of
product unit passage
on conveyor
Figure 12.14
The Use of Fiber Optic Switches.
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Proximity switches
(Uses)
Grip confirmation
For confirming presence/
absence of small screws
For counting teeth in a
gear
For detecting broken drill
bits
For confirming presence/
absence of metal caps
For confirming presence/
absence of small holes
For counting continuous
movement of objects
For controlling drills
Figure 12.15
Uses of Proximity Switches.
◾◾ Double-feed sensor. Double-feed sensors generally work
in one of two ways: as top-and-bottom sensors or as edge
sensors. Figure 12.22 shows how double-feed sensors can
be used.
This concludes our brief description of contact and
noncontact detectors, switches, and sensors that are used
daily in factories. There are many types of detectors that
Quality Assurance
Positioning sensors
(Uses)
Hoop material positioning
Slide table positioning
For confirming front/back
of nuts
For confirming cylinder
strokes
For confirming presence/
absence of contact point
For determining height
of screws
For confirming adhesion
For confirming passage
of lead frames
Figure 12.16
The Use of Positioning Sensors.
have not been described here, and new, more sophisticated kinds are being developed all the time. This is an
area where a constant need for data gathering and practical research exists. Figure 12.23 lists the various kinds of
switches and sensor described in previous pages.
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Uses of outer diameter and width sensors
Projector
Measured
object
Receiver
Image
sensors
(Uses)
For measuring outer diameter
of tubes and poles
For measuring width of sheet
materials
For inspecting height of products
For measuring outer diameter of
tubes and poles in X & Y directions
Figure 12.17
Uses of Outer Diameter and Width Sensors.
For further reference, please check the follow product
catalogs listed under the manufacturer.
−− Electronics Co., Ltd.
−− Sensor Catalog, 1985
−− Optical Displacement Sensors
−− Amplifier-Equipped Proximity Switches
Quality Assurance
Displacement sensor
Rubber roller balance sensor
Ceramic plate warp sensor
Watch face height gauge
Wound tape volume gauge
Figures 12.18A
Uses of Displacement.
−− Fiber Optic Switches
−− Ultra-Compact Photoelectric Switches
−− Matsushita Electric Industrial Co., Ltd.
−− Control Devices, 1984–85
−− MP Photoelectric Switches
−− Microswitches
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Sheet thickness gauge
Ceramic capacitator detector
Relay contact displacement gauge
Motor oscillation and shaft
balance gauge
Coating vat fluid surface level
detector
Bottle cap height detector
Front/back and height detector
for parts feeder
Laser torch height control
Figures 12.18B (continued)
−− Triode MQ Photoelectric Switches
−− Limit Switches
−− Color Mark Sensors
−− Hitachi Electric Co., Ltd.
−− Best Control Devices from Omron, 7th Ed.
Quality Assurance
Metal passage sensor
(Uses)
For confirming
passage of screws
Detection of metal
fragments in capsules
Noncontact
confirmation of
expulsion from press
For counting parts
Detection of metal
fragments in plastic
parts
Confirmation of
expulsion from
forming machine
Figure 12.19
Uses of Metal Passage Sensors.
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Color mark sensor
Sensor
Controller
(Uses)
Color mark detector
Disk mark detector
Figure 12.20 How to Use Color Mark Sensors.
Resist mark detector
Quality Assurance
Vibration switches
Controllers
Sensors
(Uses)
Package edge sensor
Expulsion error detector
Width defect detector
Burr detector
Clock/calendar variation
recorder
Broken or missing bit
detector
Processing start detector
Fo confirming passage
of workpieces
Figure 12.21
Uses of Vibration Switches.
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Double-feed sensor
Top-and-bottom detector
Controller
Sensor
Standard type
Compact type
Sensor
Standard type
Compact type
Edge detector
Controller
(Uses)
Detection from
above and below
Tube lip detector
Confirming pieces in
aluminum boxes
Metal fragment
detector for metal
containers
Edge detector (A)
Edge detector (B)
Double lead frame
detector
Figure 12.22 Uses of Double-Feed Sensors.
Quality Assurance
Contact type
Limit switches
Temperature gauges
Voltage gauges
Timers
Alarm devices
Assembly equipment,
control devices
Cutting machines and
inspection devices
Touch switches
Fiber optic switches
Proximity switches
Non-contact type
Current gauges
Repetition detectors
Foreign matter detectors
Color detectors
Dent detectors
Weight detectors
Surface defectors
Microswitches
Photoelectric switches
Positioning sensors
Outer diameter and
width sensors
Displacement sensors
Metal object passage
sensors
Color mark sensors
Vibration sensors
Double-feed sensors
Conveyors and
elevators
Wood processing and
food processing equipment
Valves and robots
Assembly equipment
and gauges
Cutting machines and
inspection devices
Assembly machines
and gauges
Bolt tapper, presses,
and counters
Assembly equipment
Drilling and shearing
machines
Assembly equipment
and presses
Gauges
Pressure gauges
Alarms
585
Detection devices
Line and position detectors
Other statistical methods
Remainder method
Statistical
methods
Counter method
Between-process sequence
In-process sequence method
Weight method
Dimension method
Detector devices
Shape method
Uses
Item charac- Operatteristics
ion step
method
method
◾
Temperature gauges
and thermostats
Current gauges
Refrigeration
equipment
Counters
Drilling machines
Timers
Body press
Buzzers
Alarm devices
Lamps and blinking
lights
Andon
Figure 12.23 Poka-Yoke Detection Devices and Their Uses.
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Poka-Yoke Case Studies
for Various Defects
The following pages describe 28 examples of poka-yoke
devices, beginning with a table that categorizes these examples
according to the type of defect causes they work to prevent.
Cause of Defect
Processing
omissions (6)
Theme
1. Preventing hole count errors during hole punching
2. Preventing deburring omissions
3. Preventing omission of spindle hole punch
process
4. Preventing omission of grinding process
5. Preventing omission of assembly step
6. Prevent omission of hole drilling
Processing
errors (7)
7. Preventing board insertion errors
8. Preventing pin dimension errors
9. Preventing errors in aligning press dies
10. Preventing variation in hose cut lengths
11. Preventing bridge defects
12. Preventing insufficient torque when tightening
bolts
13. Preventing drilling defects
Error in setting
up workpiece (6)
14. Preventing incorrect drill position during drilling
process
15. Preventing defects due to error in setting up
product
16. Preventing incorrect attachment of bracket
17. Preventing processing errors due to workpiece
set in wrong direction
18. Preventing incorrect positioning of workpiece
prior to drilling
19. Preventing tap processing errors
Quality Assurance
Cause of Defect
Missing item (5)
Theme
20. Preventing omission of inserted part
21. Preventing omission of name
22. Preventing omission of brush
23. Preventing omission of items during packing
24. Preventing omission of E rings
Wrong part
25. Prevention of wrong part assembly
26. Preventing mixing of nondefective and defective
items
Wrong
workpiece
27. Preventing errors in gear assembly
Error in
preparation of
blades, jigs, or
tools
28. Preventing errors in attachment of left and right
drawer rails
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Theme 1
Defect cause category
Preventing hole count errors during
hole punching
Processing omission
Problems
Sometimes, the operator at the hole punching process fails to check the
number of punched holes and punches fewer than the specified number.
Before improvement
After improvement
The operator counted the holes as
he or she was punching them. This
left room for counting errors and
led to problems arising from having
too few holes.
Installed a limit switch to confirm
the punching of holes and to count
the number of punched holes.
Nondefective item
Limit switch for counting holes
Nondefective item
Buzzer
Jig
Limit switch for checking workpiece position
Defective item
Defective item
Quality Assurance
Theme 2
Defect cause category
Preventing deburring omissions
Processing omission
Problems
Sometimes, after the diecasting process, the operator forgets to deburr
the workpiece and instead sends it directly downstream. This has led to
complaints from customers
Before improvement
After improvement
Pre-shipment inspectors visually
checked products to confirm
deburring. However, some products
that lacked deburring still were sent
to customers, leading to customer
complaints.
A poko-yoke pin was attached to
the base to detect when the
deburring process is omitted. This
device effectively eliminated all
deburring omissions.
Nondefective item
Nondefective (processed) item
Nondefective item
Nondefective (processed) item
Poka-yoke pin for detecting processing
omission
Sectional
view of
product
Sectional
view of
product
Product set guide
Defective item
Defective item
Location of defect
Base
Defective (unprocessed) item
Defective (unprocessed) item
Pin prevents unprocessed item from being
set onto base
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Theme 3
Defect cause category
Preventing omission of spindle hole
punch process
Processing omission
Problems
Normally, spindle holes are punched in the workpiece, and then the
workpiece is bent. However, sometimes the workpiece is bent before its
spindle holes are punched.
Before improvement
After improvement
The process sequence was:
Pins were attached to the die
used for bending so that workpieces
without spindle holes cannot be
set onto the die. This effectively
prevented any hole punch omissions.
1. Hole punching
2. Bending
If the order gets reversed and the
workpiece is bent before the holes
are punched, it is impossible to
punch the holes after bending.
The operators tried carefully to
avoid this mistake, but it still
happened occasionally.
Correct processing sequence
After cutting
After hole punching
Correct processing sequence
Cutting
Hole punching
Bending
Cannot be
set onto die
Can be
set onto die
Poka-yoke
pin
Die
Incorrect processing sequence
Incorrect processing sequence
Cutting
Bending
Hole punching
Cannot
punch
holes
Quality Assurance
Theme 4
Defect cause category
Preventing omission of
grinding process
Processing omission
Problems
Pre-shipment inspectors often found defective products in which the
grinding process was omitted, due to operators’ misplacement of
workpieces or their skipping of workpieces when stopping processing to
take a break.
Before improvement
After improvement
The operator worked with the
grinding machine in front, the
unprocessed workpieces at the left,
and the processed ones at the right.
Sometimes, the operator would
mistakenly place an unprocessed
workpiece in the processed pile at
the right.
A chute with adjustable
dimensions was attached between
the grinding machine and the box
for processed workpieces. The
sides of the chute were tapered to
allow only ground (processed)
workpieces to pass through.
Nondefective (processed) item
Nondefective (processed) item
Insert
Grinding machine
Poka-yoke
chute
ф 60
Unprocessed
workpieces
Processed
workpieces
Defective (unprocessed)
item
Defective
(unprocessed)
item
ф 66
Workpiece
Chute
ф 60
(Unprocessed workpieces cannot pass through chute.)
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Theme 5
Defect cause category
Preventing omission of
assembly step
Processing omission
Problems
If the operator is absent or for some other reason fails to insert a
right-angle piece onto the workpiece, the defect is not noticed until the
inspection at the end of the assembly line.
Before improvement
After improvement
Operator inserted right-angle
pieces into workpieces as they
were conveyed to downstream
processes.
Two limit switches were installed.
If the limit switches do not detect
the right-angle piece on the
workpiece, the conveyor is
automatically stopped. This
reduced assembly omissions
for this process to zero.
Limit switches
Take piece from box
Attach piece to
workpiece
Conveyor
(When right-angle
piece is inserted)
(When right-angle
piece is not inserted)
Limit switches
Workpiece
Conveyor
Quality Assurance
Theme 6
Defect cause category
Preventing omission of hole drilling
Processing omission
Problems
Operators sometimes mistake one model for another and do not drill
holes in models where holes are required.
Before improvement
After improvement
The processing sequence for one
model was cutting → hole drilling
→ pressing and for another model
it was simply cutting → pressing.
Sometimes, operators mistake one
model for another and do not drill
required holes.
Since the press jig must be
changed when changing models,
two poko-yoke pins were attached
to the jig for the model requiring
holes so that the model cannot be
pressed unless its holes have been
drilled. This prevented omission of
hole drilling in the model that
required it.
Nondefective item
Nondefective item
Workpiece
Workpiece
Hole
Hole
Defective item
Defective item
Poka-yoke pins
to prevent
omission of hole
drilling
Holes omitted
Press jig
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Theme 7
Defect cause category
Preventing board insertion errors
Processing errors
Problems
Whenever a wrong board gets inserted into a slot, it does not get noticed
until the final inspection process.
Before improvement
After improvement
Two adjacent boards—the detection
circuit board and the control circuit
board—have the same connection
pin configurations and appear
similar in general. This makes it
easy to insert them into the
wrong slots.
Guide pins were attached to
different positions on the two slots
and notches were made in
corresponding positions on the
boards to prevent incorrect
insertion of boards.
Detection
circuit board
Control
circuit board
Detection circuit
and control
circuit boards
Detection
circuit board
Control
circuit board
Quality Assurance
Theme 8
Defect cause category
Preventing pin dimension errors
Processing errors
Problems
When a pin is attached during the board assembly process, it must not
protrude more than 10 mm. Some that measured more than 10 mm
slipped through the inspection process and were passed downstream.
Before improvement
After improvement
After attaching the pin to a board,
the operator checked the board
to make sure the pin did not
protrude more than 10 mm, and
then passed the board to the
next process.
To make it easier for operators to
check pin lengths, they developed
a jig that included a guide pin set
into the jig so that the board and
pin would not fit if the board’s pin
was longer than 10 mm.
10 mm
10 mm
Board
Pin
Gauge
Pin
Board
Jig
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Theme 9
Defect cause category
Preventing errors in aligning
press dies
Processing error/error in jig
preparation
Problems
Sometimes the operator inserted the top die upside-down onto the
bottom die, which caused defective castings and/or damaged dies.
Before improvement
After improvement
The two guide pins for the two
halves of the die were of equal
size, which enabled the top half
of the die to be placed correctly or
upside-down onto the bottom half.
When placed upside-down,
it resulted in defective castings
and/or damaged dies.
The die was redesigned to have
guide pins in different sizes making
it impossible to place the top half of
the die upside-down onto the
bottom half.
Top half of die
Top half of die
фa
фA
Guide pin
Guide pin
Bottom
half of die
Bottom
half of die
Quality Assurance
Theme 10
Defect cause category
Preventing variations in hose
cut lengths
Processing error
Problems
Under current conditions, operator was unable to stretch hose out straight
to measure length prior to cutting. This resulted in some variation in hose
cut lengths.
Before improvement
After improvement
The operator clamped down one
end of the hose and wound the
hose around three guide pegs
before cutting it using the
fixed-position cutter. However,
the hose could rest at various
points along the guide pegs,
which caused some variation in
the hose cut length.
The guide pegs were tapered so
that, when pulled tight, the hose
would always slip down to the
bottom of the pegs. This ensured
uniform hose cut lengths.
Guide pegs
Improved guide peg
Hose clamp
Cutter
Hose
Hose
Pulling hose tight
causes hose to
slip to bottom of
guide peg
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Theme 11
Defect cause category
Preventing bridge defects
Processing error
Problems
The soldering process on a motor safety mechanism involved many
soldering points and little space between the points. It was difficult for
newer operators to avoid making bridge defects.
Before improvement
After improvement
As can be seen in the drawing
below, the motor safety mechanism
has five soldering points, which are
all close together. Newer operators
and operators who made careless
mistakes produced solder bridges
between some points, resulting in
defective products.
The insulator was improved by
adding dividers between each
pair of soldering points to prevent
solder bridges from forming.
This reduced solder bridge
defects to zero.
To motor
and power
supply
Example of bridge defect
Dividers between
soldering points on insulator
Insulator
Solder
Quality Assurance
Theme 12
Defect cause category
Preventing insufficient torque when
tightening bolts
Processing error
Problems
Sometimes, operators do not notice when the pneumatic drill’s gauge
shows abnormally low air pressure, which results in insufficient torque on
the bolts.
Before improvement
After improvement
The conveyor kept operating even
when the pneumatic drill’s air
pressure was low, which resulted in
insufficient torque on the bolts.
When the pneumatic drill’s air
pressure drops to 5 kg/cm2 or less,
an alarm lamp starts blinking,
a bell rings, and the conveyor
automatically stops.
Bolt tightening process
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Theme 13
Defect cause category
Preventing drilling defects
Processing error
Problems
Drill is sometimes withdrawn from workpiece before completely
drilling a hole, causing a defective hole that creates problems in the
assembly process.
Before improvement
After improvement
The drill is able to drill holes
completely, but sometimes it is
withdrawn too soon, leaving an
incomplete (defective) hole. It was
left up to the operator to determine
by “instinct” whether or not the hole
was drilled completely. This led to
oversights and problems at the
assembly line.
Two limit switches were installed on
the drilling machine. Limit Switch 1
is activated whenver the drill is
lowered and is deactivated when
the drill is fully raised. Limit
Switch 2 is activated when the drill
is lowered completely. If Limit
Switch 1 gets deactivated before
Limit Switch 2 is activated, a
buzzer sounds to alert the
operator that the hole was not
drilled completely.
Buzzer
L/S1
L/S2
Limit Switch 1:
Detects start of
drilling operation
Limit Switch 2:
Detects completely
lowered drill
Quality Assurance
Theme 14
Defect cause category
Preventing incorrect drill
position during drilling process
Error in setting up workpiece
Problems
During the drilling process, the operator occasionally sets up the
workpiece in an upside-down position and then drills holes in it. The
holes end up in the wrong places, and this defect is generally not noticed
until the assembly line.
Before improvement
After improvement
When setting up the workpiece, the
operator is supposed to set the
grooved section of the workpiece
against the jig, then drill two holes
in the workpiece.
A limit switch was installed in the
jig to detect the presence of an
upside-down workpiece alongside
the jig. If the workpiece is set
correctly, the limit switch fits into
the workpiece groove and is not
activated. If set upside-down, the
limit switch is activated and the
machine is unable to operate.
This effectively reduced drilling
position defects at this process
to zero.
Newer operators sometimes insert
the workpiece upside-down, which
causes the holes to be drilled in
the wrong places. Even veteran
operators make this mistake
occasionally out of carelessness.
Correct workpiece position
Correct workpiece position
Jig
Jig
Groove
Groove
Limit
switch
Incorrect workpiece position
Incorrect workpiece position
Correct workpiece position
Jig
L/S
Incorrect
hole positions
Groove
Workpiece
Incorrect workpiece position
L/S
Workpiece
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Theme 15
Defect cause category
Preventing defects due to error in
setting up product
Error in setting up workpiece
Problems
When pressing the product, if the die is not set just right, the press turns
out a defective product.
Before improvement
After improvement
The operator set the product in
the die, checked its position, then
pressed it. Sometimes, however,
the position was not exactly right
and the resulting product
was defective.
A limit switch was installed that
does not allow the press to
operate unless the product is set
exactly right. This improvement
reduced press defects at this
process to zero.
Press
Product set-up limit switch
Product
To
ON/OFF
circuit
Quality Assurance
Theme 16
Defect cause category
Preventing incorrect attachment
of bracket
Error in setting up workpiece
Problems
When attaching a bracket to a case, it is easy to get the case reversed
since the case is symmetrical on the right and left sides.
Before improvement
After improvement
The correct way to set-up the case
is to have the front groove at the
bottom. However, operators
sometimes set the case
upside-down, which causes the
bracket to get attached at the
wrong place.
A poka-yoke lip was glued onto the
jig so that the case cannot sit flat
on the jig unless its front groove is
on the bottom. This reduced
bracket attachment defects to zero.
Nondefective item
Nondefective item
Nondefective item
Nondefective item
Side view
Poka-yoke lip
Defective
item
Defective item
Defective case set-up
Defective case setup
Case cannot be set flat if upside-down
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Theme 17
Defect cause category
Preventing processing errors due
to workpiece set in wrong direction
Error in setting up workpiece
Problems
Workpiece is sometimes set in reverse and then is bent, which causes
problems in the assembly line and has led to delayed shipments.
Before improvement
After improvement
The operator was supposed to
check the direction of the
workpiece before setting it in
the jig. Occasionally, the operator
mistakenly inserted the workpiece
in reverse.
Two poko-yoke guide pins were set
in the jig to match the holes in the
workpiece. This prevents the
workpiece from being set in the jig
in reverse and consequently
reduced the corresponding defect
to zero.
Nondefective item
Nondefective item
Defective item
Defective
item
Poka-yoke guide pins
prevent reverse placement
of workpiece
Quality Assurance
Theme 18
Defect cause category
Preventing incorrect positioning of
workpiece prior to drilling
Error in setting up workpiece
Problems
Since the workpiece does not have a distinctive shape, it is easy to
set it on the drill jig upside-down or in reverse. Either of these errors
causes drilling defects that are generally not discovered until the
assembly process.
Before improvement
After improvement
When the workpiece is set in
reverse, the drill holes go in the
wrong places and result in a
defective product. Usually, this is
not noticed until the assembly
process, which causes problems
for delivery and upsets customers.
Instead of relying on the operators
to carefully check the workpiece
position, a poka-yoke jig was
created. This jig does not allow the
workpiece to be set in any position
except the correct one.
Drill
Drill
Jig
Workpiece
Jig arm
to prevent
reverse set-up
Workpiece
Nondefective
item
Nondefective item
Drill hole
Defective
item
Defective item
Upside-down
Reverse
Jig arm to
prevent
upside-down
set-up
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Theme 19
Defect cause category
Preventing tap processing errors
Error in setting up workpiece
Problems
If the workpiece is not set just right in the jig at the tapping process,
the tap will process the wrong part of the workpiece, resulting in a
defective product.
Before improvement
After improvement
Sometimes the workpiece was not
set flat on the jig (as shown in the
drawing below). If the operator
makes this mistake and taps the
workpiece, the product will
be defective.
A new jig with a poka-yoke side
plate was developed to prevent the
operator from inadvertently setting
the back edge of the workpiece on
the back of the jig. This new jig
achieved two improvement points:
1. It raised the back guide edge
for the workpiece.
2. It also provides a guide edge in
the middle for the workpiece.
Normal
set-up
Normal setup
Higher back
guide edge
Tap
Tap
Workpiece
Jig
Middle guide edge
Abnormal setup
Abnormal
set-up
Tap
Workpiece
Jig
Side plate
Quality Assurance
Theme 20
Defect cause category
Preventing omission of
inserted part
Missing item
Problems
An insert part must be attached to the workpiece prior to diecasting.
However, this part is often omitted. To prevent this, a special inspection
process was added so that each workpiece can be inspected.
Even so, complaints regarding missing insert parts have been
received from customers.
Before improvement
After improvement
A special inspection process was
added so that each workpiece can
be inspected to confirm placement
of the insert part. Check marks
were made on workpieces with
insert parts, but sometimes the
marks were made on workpieces
that actually did not have an
insert part.
A sensor was installed at the
deburring process that follows the
diecasting process. This sensor
detects the presence or absence
of the insert part. If the part is not
there, the sensor prevents the
press from operating.
Insert part
Press
Cutaway view
of workpiece
Insert part
Die
ON/OFF
circuit
Exterior view of workpiece
Sensor
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Theme 21
Defect cause category
Preventing omission of nameplate
Missing item
Problems
When operators are distracted or stop for breaks, they tend to forget to
glue on the nameplate.
Before improvement
After improvement
When the problem of missing
nameplates was discovered,
operators were admonished to be
more careful about remembering to
glue them on. However, the
problem persisted.
A photoelectric switch was installed
to detect whether or not the
nameplate has been attached.
If not attached, the switch activates
a lamp and buzzer to alert the
operator. This device effectively
prevented the operators from
forgetting to attach nameplates.
Product
Product
Name plate
Lamp
Name plate
Photoelectric
switch
Quality Assurance
Theme 22
Defect cause category
Preventing omission of brush
Missing item
Problems
Two brushes are supposed to be attached to a mouthpiece unit, but
sometimes operators fail to attach one of them.
Before improvement
After improvement
A separate inspector was assigned
to this process to ensure that both
brushes are attached to each
mouthpiece unit. In addition, the
piles of mouthpieces with and
without brushes were moved
farther apart to avoid mix-ups.
Two improvements were made to
prevent omission of either of the
brushes.
1) An automatic brush assembling
machine was developed.
Pneumatic
cylinder
Appearance of mouthpiece unit
with both brushes attached.
Brush
Switch
Mouthpiece unit
Switch
Both brushes
attached
The machine will not operate if a
brush is omitted. A sensor detects
when a brush is missing and
automatically informs the
operators.
2) Poka-yoke device
Chute
Poka-yoke
device
When the mouthpiece/brush
units are sent via the chute to the
box for finished products, the chute
has a poka-yoke notch in it that will
catch mouthpieces that are not
raised in the middle by brushes on
both sides, as shown in the
drawing below.
Nondefective
product
Poka-yoke notch
Defective
product
◾
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Theme 23
Defect cause category
Preventing omission of items
during packing
Missing item
Problems
There are six items to be included in each box at the packing process.
Sometimes the packers forget to include all of the items.
Before improvement
After improvement
The two packers divide up three
tasks:
Photoelectric switches were
installed at the top and bottom front
edges of the supply boxes
containing items to be packed.
These switches are activated
whenever a packer reaches into a
box to pickup an item. If a switch
on any of the supply boxes is not
activated, the box being packed is
blocked by a stopper. If all of the
photoelectric switches have been
activated, the stopper allows the
box to proceed and the box then
passes a limit switch which
deactivates all the photoelectric
switches in preparation for the next
round of packing.
1. Assembling boxes
2. Cleaning off items to be packed
3. Packing items
When the inspectors have an extra
heavy workload or when the
packers are especially busy, boxes
with missing items are sometimes
shipped to customers.
Items to
be packed
Plastic sheet
Coat
Handle
Owner’s manual
Maintenanceservice item
Photoelectric
switches
Stopper
Limit switch
Quality Assurance
Theme 24
Defect cause category
Preventing omission of E rings
Missing item
Problems
Sometimes workers forget to attach E rings and ship the product
without them.
Before improvement
After improvement
Workers are supposed to visually
confirm that E rings are attached.
However, sometimes workers
forget both to attach them and to
confirm attachment, so products
occasionally are shipped without
E rings.
Instead of visually checking for the
presence of E rings, a pneumatic
device was developed that
automatically attaches the E rings
and uses a microswitch to confirm
their attachment.
Nondefective item
Nondefective item
Nondefective item
Pneumatic cylinder
Nondefective item
Workpiece
E ring
E ring
Microswitch
Defective item
Defective item
Defective item
Defective item
Pneumatic
cylinder
Microswitch
◾
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JIT Implementation Manual: Volume 4
Theme 25
Defect cause category
Prevention of wrong part assembly
Wrong part
Problems
Several model changes are made each day at this factory’s assembly
line, and sometimes the assembly workers mix up the various models’
parts and end up assembling the wrong parts.
Before improvement
After improvement
To keep the changeover times
between models short, the
assembly line workers simply put
some of the smaller parts from
other models into a parts storage
stand. This made it easy for
them to pickup the wrong part
by mistake.
A revolving rack was installed in
place of the previous parts storage
stand. The model-specific parts
revolve within the rack, as shown
below. On one side of the rack, an
indicator panel shows which
model’s parts can be set for the
drawer. The workers push a button
to select which model they want
and to open the drawer. This
device effectively prevented
workers from mixing up the parts.
Model indicator panel
Parts storage
stand
Drawer
Revolving rack
C
D
B
Drawer
A B CD
E F GH
I J K L
Model indicator
panel
E
A
F
L
K
G
J
I
H
Quality Assurance
Theme 26
Defect cause category
Preventing mixing of nondefective
and defective items
Wrong part
Problems
The people who inspect integrated circuits (ICs) for specified
characteristics sort out the ones that meet the specifications from those
that do not. The two boxes that the ICs are sorted into are right next to
each other, and the inspectors sometimes put defective ICs into the
nondefective IC box and vice-versa. This has resulted in complaints from
customers who received defective ICs.
Before improvement
After improvement
The inspectors used an IC tester to
check the ICs’ characteristics and
placed the IC into the defective box
or the nondefective box depending
upon the test results.
As shown in the drawing below, the
IC tester was connected to a
divider switch mechanism that
automatically diverts ICs to the
proper box according to the test
results. The inspectors need only
place the ICs onto the chute. This
eliminated errors in sorting ICs.
IC test
Chute entry point
Nondefective
item
Defective
item
Box for
nondefective items
Box for
defective items
Divider
switch
mechanism
Box for
nondefective items
IC tester
Box for
defective items
◾
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Theme 27
Defect cause category
Preventing errors in gear assembly
Wrong workpiece
Problems
The product’s time switch includes a switch for selecting between two
cycle settings, 50 Hz and 60 Hz, each of which connects to one of two
adjacent gears. There is a three-teeth difference between these two
gears, which is not enough of a difference to make them easily
distinguishable by sight. Consequently, sometimes the gears get
assembled in the wrong places.
Before improvement
After improvement
The assembly workers had to
assemble the two slightly different
gears right next to each other, and
it was easy to get them mixed up
and put them in the wrong place.
The gear posts were improved as
shown below. In addition, since the
gears are made of plastic, it was
decided that the 50 Hz gear would
be made of white plastic and the
60 Hz of blue plastic to make it
easy to tell them apart.
These two improvements
succeeded in reducing gear
assembly errors to zero.
50 Hz gear
aф
bф
The 50 Hz gear
will not fit onto
the 60 Hz gear’s
post.
60 Hz gear
Bф
Aф
The 60 Hz gear
will not fit onto
the 50 Hz gear’s
post.
Quality Assurance
Theme 28
Defect cause category
Preventing errors in attachment of
left and right
Error in preparation of blades, jigs,
or tools drawer rails
Problems
At the process where workers attach drawer rails, the rail jig
sometimes slips between attaching one rail and the next, resulting in a
mismatch of rails on the right and left sideboards. Other problems result
when a worker forgets to turn the jig over backwards to do the other
sideboard’s rails.
Before improvement
After improvement
Workers used the same jig to
attach drawer rails on both the left
and right sideboards.
The jig for attaching rails was set
in a frame so that it could not slip
between rail settings and had to
be turned over backwards to
attach the other sideboard’s rails.
(See drawing below.)
If the jig is shifted at all between
rail settings or if the worker forgets
to turn the jig over for the other
sideboard’s rails, the rails do not
match on the right and left
sideboards and the drawer cabinet
cannot be assembled.
This new jig eliminated all rail
attachment errors.
Nondefective and defective items
Nondefective and defective items
Left
sideboard
Left and right rail
positions must match
Right
sideboard
Jig flips over like a page in a book
Jig for
attaching rails
Drawer rails
If the rail positions
do not match, the drawer
cabinet cannot be
assembled.
Left sideboard
Jig for
attaching rails
Work table
Right sideboard
◾
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JIT Implementation Manual: Volume 4
How to Use Poka-Yoke and
Zero Defects Checklists
We have seen many ways in which poka-yoke and zero defects
devices can be developed to solve particular problems.
In terms of human resources, we need to maintain a program of continual education and training. As for equipment
and operations, we need to review the various jigs, tools,
equipment layout, and operation methods to see how the
poka-yoke concept can be applied to eliminate defects caused
by human error.
The poka-yoke approach to zero defects leads to profound
improvements. If someone is a knowledgeable and experienced industrial engineer or quality control engineer, we
would expect him or her to devise various ways to make
defect-reducing improvements. However, we can also seek
and expect fresh ideas from kaizen team members and newer
factory floor workers, as well as the “old hands.”
In a company-wide quality assurance program, the central
wellspring for improvement ideas should be the rank-and-file
workers. Factories cannot always count on the “professionals­”
to produce strokes of genius. Instead, everyone must pull
together, and when they can do that, they will need powerful
tools for improvement that everyone can use.
One such tool is the JIT checklist for poka-yoke and zero
defects. In Japan, we use the nickname “poka-zero” for this
sheet. (See Figure 12.24.)
Workers will need a little instruction in order to use the
poka-yoke/zero-detect checklists correctly. Below is a step-bystep description of the checklist.
Division, Department, Process, Model
First, enter the company division, department, and the name
of the process where the item in question is being checked.
Quality Assurance
Process
Door process
Machine model
1 Remove
workpiece
Manual
operation
workpiece
Workpieces
1
collided
2 2 4 1 2 2 4
None
Error in
Defective
groove width cutting
Total points
Dented
Countermeasure
2 2 8 1 2 2 4 so they don’t rub
Difficulty
Workpieces
2
rubbed
Total points
Damaged
Description of
response
(evaluation)
Store workpieces
Person
in charge
Impact on company
Defect
cause
None
3 Store
2×600
Manual
groove process operation
Impact on processes
Defect
description
S101 lifter
2 S101 small
Occurrence frequency
Operation
(machine)
No.
3-point
response
Inspection
Operation
617
Entered by
Hirada
None
#
Standard
3-point
evaluation
Date
4/7/89
Deadline
Division
Manufacturing
Department
Prep.
Urgency
Poka-Yoke/Zero Defects
Checklist
◾
5/20 Ozaki
1 2 2 4 1 2 2 4
Use limit switch
2 2 2 8 2 2 2 8 to check length
Bent groove
Wrong jig
Damaged
Workpieces
2
rubbed
2 2 8 1 2 2 4 so they don’t rub
Dented
Workpieces
1
collided
2 2 4 1 2 2 4
Store workpieces
Figure 12.24 Poka-Yoke/Zero Defects Checklist.
Under the “model” column, put the machine model, product
model, or product name of the item for which the “poka-zero”
evaluation is being done.
Date, Entered by, No.
The person filling out the check sheet should enter the current
date and his or her name. In the “No.” column, put a checklist number or some other number that will help identify and
manage the checklists.
5/20 Ozaki
5/20 Ozaki
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◾ JIT Implementation Manual: Volume 4
#
If the operation pertains to the same process and the same
model, put a serial number for the operation here.
Operation
As the evaluator watches the actions of each operator, he or
she should vertically fill in the name of the operations in the
order in which they are performed. In the next four columns
to the right, fill in the operation method, description of defects,
and cause of defects for each operation listed vertically.
Operation Method
This is where to fill in the basic method of operation. Generally,
we divide the operation into human work and machine work
by using one of the following two descriptions:
◾◾ Manual operation
◾◾ Mechanical operation
If the operation is mechanical, write down the specific
name of the machine, such as “lathe” or “drilling machine.”
Standards
Write down any standard values given in the specifications,
drawings, or quality control manual. If there are no clearly
specified standards, enter “None.”
Inspection
Note whether an inspection was conducted following the
operation in question. If one was conducted, describe the
inspection method.
◾◾ None: No inspection.
Quality Assurance
◾◾ All: The inspector inspected every workpiece from the
operation.
◾◾ All/auto: A machine automatically inspected every workpiece from the operation.
◾◾ Sample: Indicates sampling inspection.
Description of Defect
Give a short description of the type of defect, such as “wrong
part” or “wrong hole position.”
Cause of Defect
Write down the main cause of the defect just described. For
example, if the defect was described as “wrong part,” you
might write “error in use of similar parts.” If it was “wrong
hole position,” you might put “workpiece set-up backwards.”
Three-Point Evaluation
The checklist includes a three-point evaluation for “scoring”
how often the defect in question occurs and how big an
impact it has on other processes and on the company.
◾◾ Frequency of occurrence: Score from one to three points
as shown below.
one point
Does not occur at all
two points
Sometimes
three points Often
◾◾ Impact on processes: Score the degree of impact the
defect has on other processes.
one point
No impact
two points
Some impact, but can be reversed by
making repairs
three points Wreaks havoc on other processes,
especially downstream ones
◾
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◾◾ Impact on company: Indicate what impact the defect
might have on the company if shipped to customers.
one point
No impact
two points
Might draw customer complaints, but
can be quickly taken care of through
after-sales service
three points Can cause major problems for the company. It might take a lot of time and
money to restore the company’s image
to its former level.
◾◾ Total points: Multiply the points scored in each of the
previous three categories
Total points = Frequency × impact on processes
× impact on company
If the total points range between four and nine, the
defect should be treated with poka-yoke/zero defects counter­
measures. If the total points range between 12 and 27, the
defect should be treated immediately and urgently with
poka-yoke/zero defects countermeasures.
Three-Point Response
Here, we score the estimated degree of urgency and difficulty involved in responding to the defect.
◾◾ Urgency: Analyze the response measures and estimate
how urgently they are needed.
one point:
Not urgent at all
two points: Need to minimize the defect’s impact,
but it is not urgent
three points: Must act immediately to prevent this
defect from recurring
◾◾ Difficulty: Analyze the response measures and estimate
their degree of difficulty.
Quality Assurance
one point:
Can easily prevent defect’s recurrence
by modifying jig or stand.
two points: Can prevent defect’s recurrence by
developing and installing a poka-yoke
device or zero-defects device within
the process.
three points: It will either be difficult to respond
within the process to prevent the defect’s
recurrence, or it will require a lot of
equipment investment.
◾◾ Countermeasure: Describe which level the poka-yoke or
zero-defects countermeasure will address.
three points: If countermeasure requires setting up a
separate inspection process to sort out
defective goods.
The more fundamental the level the poka-yoke or
zero-defects countermeasure will address, the higher the
score should be among points one, two, and three.
◾◾ Total points: Use the following formula to compute the
total for the three previous items.
Total points = Urgency × difficulty
× countermeasure method
If the total points range between four and nine, the countermeasure will be relatively easy to carry out. If the total points
range between 12 and 27, the defect-eliminating counter­
measure will be quite difficult. It will require the cooperation
of everyone in devising specific countermeasures.
Description of Response (Evaluation)
Write a detailed description of the countermeasure proposal
and include whatever poka-yoke devices it includes. Add any
evaluation remarks you might have.
◾
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JIT Implementation Manual: Volume 4
Deadline and Person in Charge
Be sure to set a deadline for the countermeasure’s implementation and enter the name of the person in charge of
the countermeasure. This will help keep track of progress in
poka-yoke/zero-detects projects.
After completing this checklist, send reports to all departments concerned regarding items deemed especially urgent
or important. Enlist their cooperation and investigative expertise in devising successful poka-yoke/zero defects measures.
Begin using the poka-zero checklist at major processes in
the factory, then broaden its application to all processes. Ultimately, each factory should encourage its affiliated factories­,
such as its suppliers and subcontractors, to do the same.
This section has described just one example of how pokayoke/zero defects checklists are used. Do not hesitate to revise
this checklist to suit the needs of your own factory and its
various processes.
About the Author
Hiroyuki Hirano believes Just-In-Time (JIT) is a theory and technique to
thoroughly eliminate waste. He also calls the manufacturing process the
equivalent of making music. In Japan, South Korea, and Europe, Mr. Hirano
has led the on-site rationalization improvement movement using JIT production methods. The companies Mr. Hirano has worked with include:
Polar Synthetic Chemical Kogyo Corporation
Matsushita Denko Corporation
Sunwave Kogyo Corporation
Olympic Corporation
Ube Kyosan Corporation
Fujitsu Corporation
Yasuda Kogyo Corporation
Sharp Corporation and associated industries
Nihon Denki Corporation and associated industries
Kimura Denki Manufacturing Corporation and associated industries
Fukuda ME Kogyo Corporation
Akazashina Manufacturing Corporation
Runeau Public Corporation (France)
Kumho (South Korea)
Samsung Electronics (South Korea)
Samsung Watch (South Korea)
Sani Electric (South Korea)
Mr. Hirano was born in Tokyo, Japan, in 1946. After graduating from
Senshu University’s School of Economics, Mr. Hirano worked with Japan’s
largest computer manufacturer in laying the conceptual groundwork for the
country’s first full-fledged production management system. Using his own
I-623
I-624 ◾ About the Author
interpretation of the JIT philosophy, which emphasizes “ideas and techniques for the complete elimination of waste,” Mr. Hirano went on to
help bring the JIT Production Revolution to dozens of companies, including Japanese companies as well as major firms abroad, such as a French
automobile manufacturer and a Korean consumer electronics company.
The author’s many publications in Japanese include: Seeing Is Understanding: Just-In-Time Production (Me de mite wakaru jasuto in taimu
seisanh hoshiki), Encyclopedia of Factory Rationalization (Kojo o gorika
suru jiten), 5S Comics (Manga 5S), Graffiti Guide to the JIT Factory Revolution (Gurafiti JIT kojo kakumei), and a six-part video tape series entitled
JIT Production Revolution, Stages I and II. All of these titles are available
in Japanese from the publisher, Nikkan Kogyo Shimbun, Ltd. (Tokyo).
In 1989, Productivity Press made Mr. Hirano’s JIT Factory Revolution:
A Pictorial Guide to Factory Design of the Future available in English.
Business Improvement
JIT Implementation Manual
The Complete Guide to Just-in-Time Manufacturing • Second Edition
Volume 4
Leveling – Changeover and Quality Assurance
HIROYUKI HIRANO
“It is a book for manufacturing companies that are fighting desperately for survival and that will go
to any length to improve their factories and overcome the obstacles to success. One could even call
this book a ‘bible’ for corporate survival.”
—Hiroyuki Hirano
Known as the JIT bible in Japan, JIT Implementation Manual — The Complete Guide to Just-inTime Manufacturing presents the genius of Hiroyuki Hirano, a top international consultant with vast
experience throughout Asia and the West. Encyclopedic in scope, this six-volume practical reference
provides unparalleled information on every aspect of JIT— the waste-eliminating, market-oriented
production system. This historic, yet timeless classic is just as crucial in today’s fast-changing global
marketplace as when it was first published in Japan 20 years ago.
Volume 4: Leveling — Changeover and Quality Assurance provides essential background on the
core concept of level production in a JIT, or lean, manufacturing system and the implementation
techniques. It also discusses changeover and the rules and procedures for changeover improvement
and covers quality assurance in the context of level production, including how to recognize structures
that create defects, plan for achieving zero defects, and make use of mistake-proofing devices.
PP9028
ISBN: 978-1-4200-9028-4
90000
www.taylorandfrancisgroup.com
9 781420 090284
w w w. p r o d u c t i v i t y p r e s s . c o m
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 5
JIT Implementation Manual
The Complete Guide to
Just-in-Time Manufacturing
Second Edition
Volume 5
Standardized Operations –
Jidoka and Maintenance/Safety
HIROYUKI HIRANO
Originally published as Jyasuto in taimu seisan kakumei shido manyuaru copyright © 1989 by JIT Management Laboratory Company, Ltd., Tokyo, Japan.
English translation copyright © 1990, 2009 Productivity Press.
CRC Press
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© 2010 by Taylor & Francis Group, LLC
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Version Date: 20140813
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Contents
Volume 1
1
Production Management and JIT Production Management....... 1
Approach to Production Management................................................... 3
Overview of the JIT Production System................................................ 7
Introduction of the JIT Production System...........................................12
2
Destroying Factory Myths: A Revolutionary Approach............ 35
Relations among Sales Price, Cost, and Profit......................................35
Ten Arguments against the JIT Production Revolution.........................40
Approach to Production as a Whole....................................................44
Volume 2
3
“Wastology”: The Total Elimination of Waste..........................145
Why Does Waste Occur?....................................................................146
Types of Waste.................................................................................. 151
How to Discover Waste..................................................................... 179
How to Remove Waste......................................................................198
Secrets for Not Creating Waste...........................................................226
4
The “5S” Approach..................................................................237
What Are the 5S’s?.............................................................................237
Red Tags and Signboards: Proper Arrangement and
Orderliness Made Visible...................................................................265
The Red Tag Strategy for Visual Control............................................268
The Signboard Strategy: Visual Orderliness.......................................293
Orderliness Applied to Jigs and Tools................................................307
v
vi
◾
Contents
Volume 3
5
Flow Production......................................................................321
Why Inventory Is Bad........................................................................321
What Is Flow Production?..................................................................328
Flow Production within and between Factories.................................332
6
Multi-Process Operations....................................................... 387
Multi-Process Operations: A Wellspring for Humanity on the Job......387
The Difference between Horizontal Multi-Unit Operations and
Vertical Multi-Process Operations......................................................388
Questions and Key Points about Multi-Process Operations................393
Precautions and Procedures for Developing Multi-Process
Operations.........................................................................................404
7
Labor Cost Reduction..............................................................415
What Is Labor Cost Reduction?.......................................................... 415
Labor Cost Reduction Steps............................................................... 419
Points for Achieving Labor Cost Reduction........................................422
Visible Labor Cost Reduction.............................................................432
8
Kanban.................................................................................. 435
Differences between the Kanban System and Conventional Systems....435
Functions and Rules of Kanban........................................................440
How to Determine the Variety and Quantity of Kanban...................442
Administration of Kanban.................................................................447
9
Visual Control......................................................................... 453
What Is Visual Control?......................................................................453
Case Study: Visual Orderliness (Seiton)..............................................459
Standing Signboards..........................................................................462
Andon: Illuminating Problems in the Factory....................................464
Production Management Boards: At-a-Glance Supervision................. 470
Relationship between Visual Control and Kaizen.............................. 471
Volume 4
10 Leveling...................................................................................475
What Is Level Production?................................................................. 475
Various Ways to Create Production Schedules...................................477
Contents
◾ vii
Differences between Shish-Kabob Production and Level Production.....482
Leveling Techniques..........................................................................485
Realizing Production Leveling............................................................492
11 Changeover............................................................................. 497
Why Is Changeover Improvement (Kaizen) Necessary?.....................497
What Is Changeover?.........................................................................498
Procedure for Changeover Improvement...........................................500
Seven Rules for Improving Changeover.............................................532
12 Quality Assurance.................................................................. 541
Quality Assurance: The Starting Point in Building Products..............541
Structures that Help Identify Defects.................................................546
Overall Plan for Achieving Zero Defects............................................561
The Poka-Yoke System.......................................................................566
Poka-Yoke Case Studies for Various Defects.......................................586
How to Use Poka-Yoke and Zero Defects Checklists.......................... 616
Volume 5
13 Standard Operations.............................................................. 623
Overview of Standard Operations.....................................................623
How to Establish Standard Operations..............................................628
How to Make Combination Charts and Standard Operations Charts.....630
Standard Operations and Operation Improvements...........................638
How to Preserve Standard Operations...............................................650
14 Jidoka: Human Automation.................................................... 655
Steps toward Jidoka...........................................................................655
The Difference between Automation and Jidoka...............................657
The Three Functions of Jidoka..........................................................658
Separating Workers: Separating Human Work from Machine Work.....660
Ways to Prevent Defects.................................................................... 672
Extension of Jidoka to the Assembly Line.......................................... 676
15 Maintenance and Safety......................................................... 683
Existing Maintenance Conditions on the Factory Floor......................683
What Is Maintenance?........................................................................684
CCO: Three Lessons in Maintenance.................................................689
viii
◾
Contents
Preventing Breakdowns.....................................................................683
Why Do Injuries Occur?....................................................................685
What Is Safety?.................................................................................. 688
Strategies for Zero Injuries and Zero Accidents..................................689
Index.............................................................................................. I-1
About the Author.......................................................................... I-31
Volume 6
16 JIT Forms................................................................................711
Overall Management......................................................................... 715
Waste-Related Forms.........................................................................730
5S-Related Forms............................................................................... 747
Engineering-Related Forms................................................................777
JIT Introduction-Related Forms..........................................................834
Chapter 13
Standard Operations
Overview of Standard Operations
Why Do We Need Standard Operations?
It so happens that many of the most important elements in
the daily activity of manufacturing begin with the letter “M.”
In factories, we are trying to find the best possible combination of Men/Women, Materials, and Machines and we
develop the most efficient Methods for making things, so that
we can make better products while spending less Money.
Standard operations can be defined as an effective combination of workers, materials, and machines for the sake of making­
high-quality products cheaply, quickly, and safely. As such, standard operations comprise the backbone of JIT production.
Many people make the assumption that standard operations are nothing more than standard operating procedures.
But this is not at all the case.
Standard operating procedures have to do with specific
standards for individual operations and are just part of what
we mean by standard operations. By contrast, standard operations involve the stringing together of individual operations
in a specified order to achieve an effective combination for
manufacturing products. Another name for standard operations would be “production standards.” One might ask why
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such production standards are necessary in the daily business
of manufacturing?
While this may seem like a simple question, it is actually
rather difficult to answer. Please think about it for a moment.
Why are production standards necessary for daily production activities?
In considering this question, let us suppose that we have
asked some other manufacturer to do some manufacturing
for us.
The person would probably ask such questions as:
“How do you make these products?,” “How much time and
money does it take to make them?,” and “When do you
need them delivered?”
Why does the other manufacturer need to know all these
things? Basically, because they need to fit the work we have
asked them to do into their current production schedule. They
will not know whether they can actually make the requested
products on schedule unless they have established standard
operations. Factories, therefore, need standard operations
right from the start.
Standard operations serve the following goals:
1. Quality: “What quality standards must the product meet?”
2. Cost: “Approximately how much should it cost to make
the products?”
3. Delivery: “How many products do you need delivered
and by when?”
4. Safety: “Is the manufacturing work itself safe?”
At the very least, standard operations should be able to
answer those four questions.
It should be clear enough by now why we define standard operations as an effective combination of workers,
­materials, and machines. We also need to remember that, like
all improvement, improvement in standard operations is an
endless process.
Standard Operations
Element 1:
Cycle time
Element 3:
Standard
in-process
inventory
(within the cell)
4
3
6
5
2
1
Finished goods
Materials
Figure 13.1
Element 2:
Work sequence
The Three Basic Elements of Standard Operations.
The Three Basic Elements of
Standard Operations
While standard operations involve the effective combination of three “M” elements—men/women, materials, and
machines—these elements differ from the three basic elements that go into standard operations. Figure 13.1 illustrates
these elements as they are used to create standard operations
in a U-shaped manufacturing cell.
Element 1: Cycle time
Cycle time is the amount of time it takes a worker to turn
out one product (within a cell). We use the production
output and the operating time to determine the cycle
time.
Element 2: Work sequence
This refers to the order in which the worker carries out
tasks at various processes as he or she transforms the initial materials into finished goods. It is not the same as the
“flow of products” concept we use in flow production.
Element 3: Standard in-process inventory
This indicates the minimum amount of in-process inventory (including in-process inventory currently attached to
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machines) that is required within the manufacturing cell
or process station for work to progress.
The contents of these three elements will differ from cell
to cell, and it is the immediate supervisor’s job to analyze the
cell and determine exactly what each element will include.
Types of Standard Operation Forms
Although there are only three basic elements (cycle time, work
sequence, and standard in-process inventory) in standard
operations, there are five types of standard operation forms.
Form 1: Parts-production capacity work table
This work table examines the current parts-production
capacity of each process in the cell. (See Figure 13.2.)
Form 2: Standard operations combination chart
This chart helps us make “transparent” (or obvious) the
temporal process of the relationship between human
work and machine work. (See Figure 13.3.)
Form 3: Standard operations pointers chart
We use this chart to list important points about the operation of machines, exchanging jigs and tools, processing
methods, and so on. (See Figure 13.4.)
Approval stamps
Process
626 ◾
Parts-Production
Capacity Work Table
Process name
1 Pick up raw materials
2 Gear teeth cutting
Part No.
Type
Part name
6" pinion
Quantity
Entered by
RY
Sato
Creation date
1
1/17/89
Basic times
Blades and bits
Graph time
Serial Manual Auto feed Complet- Retooling Retooling Per unit Total Production
retooling
time
No. operation time (B) ion time amount
capacity Manual work
time
time per unit
time (A)
I/G
C = A+B
(D)
(E)
Auto feed
F = E+D G = C+F
Min. Sec. Min. Sec. Min. Sec.
1
1
1
A01
4
35
39
400
2'10"
0.3"
39.3
717
4"
35"
A02
3 Gear teeth surface fin.
4 Forward gear surface fin. A03
5 Reverse gear surface fin. A04
6
15
21
1,000
2'00"
0.1"
21.1
1,336
6"
15"
7
38
45
400
3'00"
0.5"
45.5
619
7"
38"
5
28
33
400
2'30"
0.4"
33.4
844
5"
28"
6 Pin width measurement B01
7 Store finished workpiece
8
1
5
13
13
1
259
8" 5"
Figure 13.2
1
Parts-Production Capacity Work Table.
Standard Operations
Standard Operations Combination Chart
Process No.: 391-3637
No. required: 303 (600)
Item name: Door jamb (lintel)
Cycle time: 89' (54' needed)
Manual operations Entered by: Kawano
Auto feed
Walking Date: 1/31/89
Manual
1 Pull out workpiece
3
Process S101 gain (small) 15 10
2 at circular saw bench
S102 gain (large) 23 18
3 Process
at circular saw bench
B101 hinge fasten 12
Description of operation
2
2
2
Process name
Department Date
Machine number
Critical factors
(correct/incorrect, safety, facilitation, etc.)
Diagram of operation
Standard Operations Pointers Chart.
Required output
Breakdown no.
Critical factors
(correct/incorrect, safety,
facilitation, etc.)
Name
Figure 13.5
Confirmation
Date
Net
time
(min.
and
sec.)
Cycle time
Measure.
Description of operation
Check
Quality
Dept.
Safety point
Part no.
Part name
Quality check point
Work Methods Table
No.
Confirmation
Processing sequence
Stand. in-process inv.
Figure 13.4
5 10 15 20 25 30 35 40 45 50 55 65 70 75 80 85 90
Standard Operations Combination Chart.
Summary Table of
Standard Operations
No.
Operation times (in seconds)
Stand. in-process inv.
Figure 13.3
Analysis No.: 1 of 1
Walking
Description
Auto feed
Sequence
Time
Work Methods Chart.
Form 4: Work methods chart
This chart gives explicit instructions on how to follow
standard operations at each process. (See Figure 13.5.)
Form 5: Standard operations chart
This chart illustrates and describes the machine layout,
cycle time, work sequence, standard in-process inventory,
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Standard
Operations Chart
Line name
PG U-shaped cell
Process name
B03
B02
3
2
Gear cutting process
Description of operation
Gear cutting of 6" pinion
B01
4
Previous
Figure 13.6
1
7
Standard Operations Chart.
and other factors in standard operations. Operators
should use this chart to check how well they are following standard operations. (See Figure 13.6.)
How to Establish Standard Operations
Transparent Operations and
Standard Operations
The first step toward establishing standard operations is to gain
a grasp of the way operations are already. To do this, we need
to make what is only dimly and vaguely understood as clear
and “transparent” (obvious) as possible. This means we have to
flush out all of the problems that are hidden within the current
situation, look for their causes, and make improvements that
will remove those causes and bring about standard operations.
Once we have established standard operations in this way,
we still cannot afford to sit back and call the job done. We
must repeat the process of flushing out problems and making
operations completely transparent. As mentioned earlier­
,
improvement is an endless process. Once we have made
improvements, we establish them as standard operations.
Then we are ready for another round of problem-hunting to
further improve operations and achieve a higher standard.
This spiral of improvement in standard operations is illustrated in Figure 13.7.
Standard Operations
Transparent
operations
(Understanding
current operations)
Standard
operations
(Setting higher
standards for operations)
JIT
Factory
Revolution
Flushing out
problems
(Setting a cycle
time standard)
Finding causes and
making improvements
(applying the 5S’s and
improving operations)
Figure 13.7
Spiral of Improvement in Standard Operations.
Steps in Establishing Standard Operations
Establishing standard operations is a four-step process, as
described below.
Step 1: Create a parts-production capacity work table
List the processing capacity of each cell or process ­station
as it currently stands.
Step 2: Create a standard operations combination chart
Time manual operations, auto feed operations, and walking to elucidate the relationship between human work
and machine work.
Step 3: Create a work methods chart
The workshop will need one of these for passing along
instructions to new workers.
Step 4: Create a standard operations chart
This schematic chart will provide a visual aid for quickly
learning the machine layout, work sequence, and other
important factors.
That is all there is to it. Usually, we can incorporate the standard operations combination chart with a standard opera