Lean Manufacturing & Just-in-Time
"The most dangerous kind of waste is
the waste we do not recognize." Shigeo Shingo
Reducing Waste: Push versus Pull System
Raw
Material
Supplier
Final
Assembly
Customer
FGI
PUSH
Raw
Material
Supplier
Final
Assembly
Customer
FGI
PULL
Information Flow
Material Flow
Push System
 Every worker maximizes own output, making
as many products as possible
 Pros and cons:
 Focuses on keeping individual operators and
workstations busy rather than efficient use of
materials
 Volumes of defective work may be produced
 Throughput time will increase as work-in-process
increases (Little’s Law)
 Line bottlenecks and inventories of unfinished
products will occur
 Hard to respond to special orders and order
changes due to long throughput time
Pull System
 Production line is controlled by the last
operation, Kanban cards control WIP
 Pros and cons
 Controls maximum WIP and eliminates WIP
accumulating at bottlenecks
 Keeps materials busy, not operators. Operators
work only when there is a signal to produce.
 If a problem arises, there is no slack in the system
 Throughput time and WIP are decreased, faster
reaction to defects and less opportunity to create
defects
Features of Lean Production
WHAT IT IS
WHAT IT DOES
• Attacks waste
• Management philosophy
• “Pull” system though the plant
• Exposes problems and bottlenecks
• Achieves streamlined production
WHAT IT ASSUMES
WHAT IT REQUIRES
• Employee participation
•
•
•
•
• Stable environment
Industrial engineering/basics
Continuing improvement
Total quality control
Small lot sizes
Kaizen
5
A Little History!
 Ford: Design for manufacturing
 Start with an article that suits and then study to find
some way of eliminating the entirely useless parts.
This applies to everything— a shoe, a dress, a
house, a piece of machinery, a railroad, a
steamship, an airplane. As we cut out useless parts
and simplify necessary ones, we also cut down the
cost of making. ...But also it is to be remembered
that all the parts are designed so that they can be
most easily made."
A Little History!
 Ohno – put ideas into practice systematically
 “When bombarded with questions from our group on
what inspired his thinking, Ohno just laughed and said
he learned it all from Henry Ford's book."
TPS: Toyota Production System
 A system that continually searches for and
eliminates waste throughout the value chain.
 Views every enterprise activity as an operation and
applies its waste reduction concepts to each activity from Customers to the Board of Directors to Support
Staff to Production Plants to Suppliers.
Elimination of Waste
Muda
Acronym – CLOSED MITT
 Complexity
 Labor
 Overproduction
 Space
 Energy
 Defects
 Materials
 Inventory
 Time
 Transportation
Elimination of Waste
1. 5S
2. Group technology
3. Quality at the source
4. JIT production
5. Kanban production control system
6. Minimized setup times
7. Uniform plant loading
8. Focused factory networks
10
Minimizing Waste – 5S
“Good factories develop beginning with the 5S’s.
Bad factories fall apart beginning with the 5 S’s.”
- Hirouki Hirano
Japanese
Seiri
Seiton
Seiso
Seiketsu
Shitsuke
Translation
Proper arrangement
Orderliness
Cleanliness
Cleanup
Discipline
English
Sort
Simplify
Sweep
Standardize
Sustain
Minimizing Waste – 5S
 A place for everything and everything in its place
 Not just a housekeeping issue
 Critical foundation for




Setup reduction
Pull systems
Maintenance
Inventory management
Minimizing Waste: Group Technology
Using Departmental Specialization (Job Shop) for plant layout
can cause a lot of unnecessary material movement
Note how the flow lines are going back and forth
Saw
Saw
Saw
Grinder
Grinder
Heat Treat
Lathe
Lathe
Lathe
Press
Press
Press
Minimizing Waste: Group Technology
Revising by using Group Technology Cells can reduce
movement and improve product flow
Grinder
Saw
1
2
Lathe
Lathe
Press
Lathe
Press
Heat Treat
Grinder
Saw
Lathe
A
B
Minimizing Waste: JIT





Only produce what’s needed
The opposite of “Just In Case” philosophy
Ideal lot size is one
Minimize transit time
Frequent small deliveries
Pro’s
Con’s
•Minimal inventory
•Requires discipline
•Less space
•Requires good problem solving
•More visual
•Suppliers or warehouses must be close
•Easier to spot quality issues
•Requires high quality
???
Minimizing Waste: JIT
Inventory
Hides Problems
Machine
downtime
Scrap
Work in
process
queues
(banks)
Paperwork
backlog
Vendor
delinquencies Change
orders
Engineering design
redundancies
Inspection
backlogs
16
Design
backlogs
Decision
backlogs
Minimizing Waste – Quality at the
Source
 “Do it right the first time”
 Call for help
Andon
 Immediately stop the process and correct it vs.
passing it on to inspection or repair
Jidoka
Minimizing Waste – Kanban
Signaling device to control flow of material
•Cards
•Empty containers
•Lights
•Colored golf balls
•Etc
Minimizing Waste – Setup Times
 Long setup times drive:
 Long production runs
 Large lots
 Long lead times
 JIT requires small lots and minimum kanbans
 Setup reduction
 Focused efforts
 Problem solving
 Flexible equipment
Minimizing Waste – Plant LoadingHeijunka
Suppose we operate a production plant that produces a single
product. The schedule of production for this product could be
accomplished using either of the two plant loading schedules below.
Not uniform
Uniform
Jan. Units
Feb. Units
Mar. Units
Total
1,200
4,300
9,000
Jan. Units
3,500
or
Feb. Units
Mar. Units
Total
3,000
3,000
3,000
9,000
How does the uniform loading help save labor costs?
21
Minimizing Waste –
Focused Factory
Networks
Coordination
System Integration
These are small specialized
plants that limit the range of
products produced
(sometimes only one type of
product for an entire facility)
TPS – Respect for People
 Level payrolls
 Cooperative employee unions
 Subcontractor networks
Keiretsu
 Bottom-up management style
 Quality circles (Small Group Problem Solving)
TPS – 4 Rules
1.
All work shall be highly specified as to content, sequence,
timing, and outcome
2.
Every customer-supplier connection must be direct, and
there must be an unambiguous yes-or-no way to send
requests and receive responses
3.
The pathway for every product and service must be simple
and direct
4.
Any improvement must be made in accordance with the
scientific method, under the guidance of a teacher, at the
lowest possible level in the organization
Lean Implementation
Total Quality
Management
Product
Design
Flow
Process
Continual Inventory
Reduction
Empowered Workforce
Problem Solving
Performance Measurement
Involved
Suppliers
Stable
Schedule
Kanban
Pull
Summary and Conclusions…
 Lean Production is the set of activities that achieves
quality production at minimum cost and inventory
 The flow of material is pulled through the process by
downstream operations
 Lean originated with the Toyota Production System
and its two philosophies – elimination of waste, and
respect for people
 CLOSED MITT forms of waste