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Neil W. Polhemus, CTO, StatPoint Technologies, Inc.
Implementing Lean Six Sigma
Using Statgraphics
Copyright 2011 by StatPoint Technologies, Inc.
Web site: www.statgraphics.com
Lean Six Sigma
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Lean Six Sigma
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Lean manufacturing – focuses on reducing cost through
process optimization.
Six Sigma – focuses on meeting customer requirements and
stakeholder expectations, and improving quality by
measuring and eliminating defects.
www-935.ibm.com/services/uk/bcs/pdf
/driving_operational_innovation_using_lean_six_sigma.pdf
Statgraphics Software
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Statgraphics Centurion XVI.I –Windows standalone application
with over 170 basic and advanced statistical methods.
Statgraphics Sigma Express 1.1 – Excel add-in with 70+
procedures covering the needs of Six Sigma green belts and
most black belts. Available for Excel 2003, 2007, 2010.*
*Pre-release evaluation version available by sending contact information to
Statgraphics Centurion XVI.I
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Statgraphics Sigma Express
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Example #1 (Define) –
Cause-and-Effect Diagram
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Cause-and-effect diagrams (also called fishbone or Ishikawa diagrams)
illustrate the causes of specific events.
Event: defects
Major causes: material, personnel, environment, machines, …
Input – Analysis Options dialog box
creates diagram
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Data structure for saving
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Sigma Express also provides Excel template
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Example #2 (Measure) – Gage Studies
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“Gage Studies” refers to the process of evaluating measurement
processes to verify that they are capable of measuring responses well
enough to permit the use of SPC and DOE techniques.
In Statgraphics, the main procedures all follow the AIAG guidelines:
• Gage Study Setup – to create a data template.
• Analysis of Variable Data
1. Average and Range Method and ANOVA Method evaluate R&R
based on full study.
2. Range Method evaluates R&R based on short study.
3. *Gage Linearity and Accuracy evaluates bias.
• Analysis of Attribute Data
1. *Risk Assessment Method – based on consistency of appraisals
2. *Analytic Method and *Signal Theory Method – other approaches
* Not in Sigma Express product.
Statistical Model
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2
.
2
processtmeasuremenproducttotal
22
. ilityreproducibityrepeatabilprocesstmeasuremen
Gage study setup
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Typical gage study data file
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Data input dialog box
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Analysis Options
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Tolerance = USL – LSL (distance between specification limits)
If operators measure the same parts, the structure is “crossed”.
Tables and Graphs
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R&R Plot
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R&R Plot for Anne_1-Carlos_3
Operators
-4
-2
0
2
4
Devia
tio
n f
rom
Avera
ge
Anne Bob Carlos
R&R Table
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Tolerance Analysis
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%ˆ6
100.
tolerance
processtmeasuremen
Precision-to-tolerance ratio:
Example #3 (Analyze) – Capability Analysis
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Determines whether a process is “capable” of meeting established
specification limits.
DPMO – Defects Per Million Opportunities.
“Defect” = nonconformance to a specification.
Typical Data
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Measured resistivity of n = 100 electronic components. USL = 500.
Capability Assessment SnapStat
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Analysis Options
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After Box-Cox Transformation
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Capability Analysis Statlet®
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Example #4 (Improve) – DOE
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Step 1: Define Responses
Step 2 – Define Experimental Factors
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Step 3 – Select Design
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Step 4 – Paste to Excel Worksheet
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Analyze Experiment
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Tables and Graphs
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Analysis Window
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Paste Back to Excel
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Example #5 (Control) – Individuals with
EWMA
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Suggested by Stu Hunter
Data Input Dialog Box
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X Chart – Pane Options
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X Chart with EWMA (l = 0.2)
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285.13
X Chart for strength
0:00 3:20 6:40 10:00 13:20 16:40
time
220
240
260
280
300
X
254.64
224.15
Note: inner zone provides 3-sigma limits for the EWMA.
Exponential Smoothing Statlet
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Example #6 - Monte Carlo Simulation
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Step 1
Normal (12.1, 1.9)
Step 2
Normal (7.3, 0.5)
Step 3
Exponential (0.2)
Step 4
Uniform (2.0, 6.0)
Cycle time = Step 1 + Step 2 + MAX(Step 3, Step 4)
Cycle
time
Data Input Dialog Box
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Analysis Options
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Results
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Histogram of cycle time
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Histogram
0 20 40 60 80
Cycle time
0
500
1000
1500
2000
2500
fre
qu
en
cy
