CSUN
Engineering
Management
Six Sigma Quality
Engineering
Week 4
Measure Phase
Chapter 5 Outline
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Process Map/Spaghetti Diagram
Cause & Effect Fishbone Diagram
Cause & Effect Matrix
Reproducibility & Repeatability (Gage R&R)
Capability Analysis
Components of Variation Studies
FMEA
Process Map/Spaghetti Diagram
What is a Process Map?

A process map is a graphical representation of the flow of a
process

A detailed process map includes information that can be used to
improve the process, such as:
•
•
•
•
•
Process Times
Quality
Costs
Inputs
Outputs
Types of Process Map







Basic process map
Detailed process map
Work-flow (spaghetti diagrams)
Top-down flowchart
Deployment flowchart
Opportunity flowchart
Current State / Future state maps
Uses of a Process Map








Identify areas for focus of improvement efforts
Identify and eliminate non-value added steps
Combine operations
Assist root cause analysis
Baseline for failure mode and effect analysis (FMEA)
Identify potential controllable parameters for designed
experiments
Determine needed data collection points
Eliminate unnecessary data collection steps
Detailed Process Map Example
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( Y's)
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hi
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(
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( Y'
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U
ni
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U
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r ym
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ot
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ar
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em
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oughn
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of
( x
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at
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em
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em
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ual
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at
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C
M
ak
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up
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N
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eom
et
r
y
C
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em
per
C
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S
Cl
eanl
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s
N
H
um
i
di
t
y
S
Lev
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of
N
M
as
s
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G
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y
of
S
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r
v
el
oc
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S
Lev
el
of
(
R
at
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S
Pendant
st
y
N
G
eom
et
S
Am
ount
per
N
O
per
at
o
( pr
Y
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W
ei ght
of
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ual
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y
Ap
( H
eat
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em
ov
N
Spec
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S
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i m
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f r om
s
S
R
at
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of
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H
um
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Fl
ui di t
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Pow
er
o
RUMB
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C
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Process Maps

Should include
•
•
•
•
•
Major activities and tasks
Sub-processes
Process boundaries
Inputs
Outputs

Documents reality, not how you think the process is supposed
to be completed

Should identify opportunities for improvement
Steps for Process Mapping

Scope the process
• Identify the start and end points of the process of interest

Document the top level process steps
• Create a flow chart

Identify the inputs and outputs
• What are the results of doing each process step? (Y’s)
• What impacts the quality of each Y? (x’s)

Characterise the inputs
Characterising Inputs

Inputs can be classified as one of three types
 Controllable (C)
• Things you can adjust or control during the process
• Speeds, feeds, temperatures, pressures….

Standard Operating Procedures (S)
• Things you always do (in procedures or common sense things)
• Cleaning, safety….

Noise (N)
• Things you cannot control or don not want to control
(too expensive or difficult)
• Ambient temperature, humidity, operator...
Example
Machining a shaft
on a lathe
C
C
C
C
C
C
C
S
C
N
N
N
S
Inputs (x’s)
Rotation speed
Traverse speed
Tool type
Tool sharpness
Shaft material
Shaft length
Material removal per cut
Part cleanliness
Coolant flow
Operator
Material variation
Ambient temperature
Coolant age
Outputs (Y’s)
Diameter
Taper
Surface finish
Order Entry Process Map
As-Is
BEFORE
40 NVA STEPS
NOTE: FROM THE CUSTOMER’S
VIEWPOINT ALL OF ORDER ENTRY
IS NON-VALUE ADDED
Order Entry Process Map
New
REMEMBER: FROM THE CUSTOMER’S VIEWPOINT
ALL OF ORDER ENTRY IS NON-VALUE ADDED
BEFORE
40 NVA STEPS
We eliminated the steps that
were NVA and
UNNECESSARY (WASTE)
AFTER
11 NVA STEPS
Work-flow or Spaghetti Diagram

A work flow diagram is a picture of the movements of people,
materials, documents, or information in a process.

Start by tracing these movements onto a floor plan or map of
the work space.

The purpose of the work-flow diagram is to illustrate the
inefficiency in a clear picture.

How can you make the map look simpler? What lines
you eliminate?
can
56 Frame (Small Motor) Assy & Fabrication Before
BEFORE KAIZEN:
Area: 4640 sq ft
Operator Travel: 3696 ft
Product Travel: 1115 ft
x
x xx
x
xxx
x
Cause & Effect
Fishbone Diagram
Cause & Effect Fishbone Diagram

Objectives
• To understand the benefits of Cause & Effect Analysis
• To understand how to construct a C & E Diagram

Analysis
• A method a work group can use to identify the possible causes of a
problem
• A tool to identify the factors that contribute to a quality characteristic
Uses of C & E Fishbone Diagram

Visual means for tracing a problem to its causes

Identifies all the possible causes of a problem and how
they relate before deciding which ones to investigate

C & E analysis is used as a starting point for investigating
a problem
Fishbone Diagram

Effect
• The problem or quality characteristic
• The effect is the outcome of the factors that affect it
Effect
Fishbone Diagram
Causes

All the factors that could affect the problem or the quality
characteristic

Five Major Categories
• Materials
• Methods
• People
• Machines
• Environment
Machine
Environment
Effect
Material
Methods
People
Cause & Effect
matrix
The Eight Steps in Cause and Effect
Analysis

Define the Effect

Identify the Major Categories

Generate Ideas

Evaluate Ideas

Vote for the Most Likely Causes

Rank the Causes

Verify the Results

Recommend Solutions
Rating of
Importance to
Customer
2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1
5
&
6
Total
Process Step Process Input
Lower Spec
Target
Upper Spec
0
0
0
0
0
0
0
0
0
0
0
0
0
Total
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
4
Reproducibility & Repeatability
(Gage R&R)
“Data is only as good as the system that measures it. If you
can’t measure it, you can’t manage it.”
The Science of Measurement
“I often say that when you measure what you are speaking
about and express it in numbers, you know something about it.”
LORD KELVIN,
1891
He clearly stressed that little progress is possible in any field of
investigation without the ability to measure. The progress of
measurement is, in fact, the progress of science.
Objectives

Measurement Systems Analysis
 Key Terminology
 Variable Gauge R&R
• A tool for estimating measurement system error
• How to conduct a gauge R&R
• Minitab Output

Gauge R & R Study Exercise
Definitions

Variable Data
• Continuous measurements such as length, voltage, viscosity

Repeatability
• Variation in measurements obtained with one gage when used
several times by one appraiser.

Reproducibility
• Variation in the average of the measurements made by different
appraisers using the same measurement system.
What is GR&R?
Measurement Systems Analysis
How good is our
measurement system?
 2T
=
 2p
+
 2m
2T = Total Variance
2p = Process Variance
2m = Measurement Variance
GRRRRRRR!!!
Gauge R&R Allows Control of the
Measurement System
Variable Gauge R&R - What’s Involved?
3 Appraisers
1 Gauge
10 Parts
How to set up a Variable GRR Study

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Preparation & Planning
1 Gauge
3 Operators (Appraisers)
10 Parts
3 Trials
Randomize the readings
Code the parts (blind study) if possible
3 Ops x 10 parts x 3 trails = 90 Data Points
4 Ops x 10 parts x 3 trails = 120 Data Points
Minitab Gage R&R Graphical Output
The number of distinct categories of
parts that the process is currently able
to distinguish (Must distinguish at
least 5 types of parts)
Acceptability Criteria
R&R Indices
•  10%
• 10% - 30%
•  30%

Acceptable Measurement System
May be acceptable based upon application,
cost of measurement device, cost of repair,
etc.
Not acceptable. Measurement system
needs improvement.
Number of Distinct Categories Index
• 1
• 2 -4
•  5
Unacceptable. One part cannot be
distinguished form another.
Generally unacceptable
Recommended
Module 0025

Minitab Gage R&R Graphical Output
Minitab Gage R&R Graphical Output
Minitab Gage R&R Graphical Output
Minitab Gage R&R Statistical Output
Minitab Gage R&R Statistical Output
Capability Analysis
Process Capability Study
Cpk & Cp
•Cpk incorporates information about both the process spread and the process mean, so
it is a measure of how the process is actually performing.
•Cp relates how the process is performing to how it should be performing. Cp does
not consider the location of the process mean, so it tells you what capability your
process could achieve if centered.
Process Capability Study
Non-normal distributions
•Use Capability Analysis (Nonnormal) to assess the capability of an in-control
process when the data are from the nonnormal distribution. A capable process is able
to produce products or services that meet specifications.
•The process must be in control and follows a nonnormal distribution before you
assess capability. If the process is not in control, then the capability estimates will be
incorrect.
•Nonnormal capability analysis consists of a capability histogram and a table of
process capability statistics
Questions? Comments?