Chapter 14 SixSigma Management and Tools

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Chapter 14 - Six-Sigma Management and Tools

• 6S Organization, DMAIC, Taguchi Method, Robust
  Design, Design of Experiments, Design for Six
  Sigma, Reasons for 6S Failure

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Topics
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Six Sigma Evolution

• Started as a simple quality metric at Motorola in
  1986 (Bill Smith)
• Migrated to Allied Signal
• (acquired Honeywell and took its name)
• Picked up by General Electric
• Commitment by CEO Jack Welch in 1995
• Grown to be an integrated strategy for attaining
  extremely high levels of quality

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What is Six-Sigma?

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Percent Not Meeting Specifications

• 1S 32
• 2S 4.5
• 3S 0.3
• 6S 0.00034

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Six-Sigma Levels

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Statistics - DPU

• Defect
• Six Sigma any mistake or error passed on to the
  customer ???
• General view any variation from specifications
• DPU (defects per unit)
• Number of defects per unit of work
• Ex 3 lost bags 8,000 customers
• .00375

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Statistics dpmo (defects per million
opportunities)

• Process may have more than one opportunity for
  error (e.g., airline baggage)
• dpmo (DPU 1,000,000)
• opportunities for error
• Ex (3 lost bags 1,000,000) (8,000 customers
  1.6 average bags)
• 234.375

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Statistics dpmo (contd)

• May extend the concept to include higher level
  processes
• E.g., may consider all opportunities for errors
  for a flight (from ticketing to baggage claim)

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Statistics - Off-Centering

• Represents a shift in the process mean
• Impossible to always keep the process mean the
  same (this WOULD be perfection)
• Does NOT represent a change in specifications
• Control of shift within 1.5 s of the target
  mean keeps defects to a maximum of 3.4 per
  million

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Statistics - Off-Centering (contd)Source Evans
Lindsay, The Management and Control of Quality,
Southwestern, 2005
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k-Sigma Quality Levels

• Number of defects per million
• For a specified off-centering and
• a desired quality level

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k-Sigma Quality Levels Source Evans
Lindsay, The Management and Control of Quality,
Southwestern, 2005
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Six Sigma and Other Techniques

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Organizing Six Sigma

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Key Players

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Distribution of Six Sigma Trained Employees

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Six Sigma Tools

• DMAIC, Taguchi Method, Design for Six Sigma

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DMAIC

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DMAIC Overview

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Define (1)

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Define (2)

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Define (3)

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Measure (1)

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Measure (2)

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Measure (3)

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Measure (4)

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Repeatability Reproducibility

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Measurement System Evaluation

• Variation can be due to
• Process variation
• Measurement system error
• Random
• Systematic (bias)
• A combination of the two

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Metrology - 1

• Definition The Science of Measurement
• Accuracy
• How close an observation is to a standard
• Precision
• How close random individual measurements are to
  each other

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Metrology - 2

• Repeatability
• Instrument variation
• Variation in measurements using same instrument
  and same individual
• Reproducibility
• Operator variation
• Variation in measurements using same instrument
  and different individual

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RR Studies

• Select m operators and n parts
• Calibrate the measuring instrument
• Randomly measure each part by each operator for r
  trials
• Compute key statistics to quantify repeatability
  and reproducibility

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RR Spreadsheet Template
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RR Evaluation

• Repeatability and/or reproducibility error as a
  percent of the tolerance
• Acceptable lt 10
• Unacceptable gt 30
• Questionable 10-30
• Decision based on criticality of the quality
  characteristic being measured and cost factors

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Calibration

• Compare 2 instruments or systems
• 1 with known relationship to national standards
• 1 with unknown relationship to national standards

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Analyze (1)

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Analyze (2)

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Analyze (3)

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Analyze (4)

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Improve

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Control Phase

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The Taguchi Method

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The Taguchi Method provides

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Design of Experiments (DOE)

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Robust Design

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The Taguchi Process

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Design for Six Sigma

• DFSS

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Design for Six-Sigma (DFSS)

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DMADV

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IDOV

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Reasons for Six Sigma Failure

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Reasons for Six-Sigma Failure - (1)

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Reasons for Six-Sigma Failure - (2)

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Summary