I.3 Philosophy and History

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I.3 Philosophy and History

• Some Goals of Manufacturing
• Various Paradigms
• Some Aspects of Taguchis Philosophy
• On-Line and Off-Line Quality Control
• Design Aspects

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Some GoalsThe Quality Timeline
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ParadigmsThe Inspection Paradigm

• Inspect Output To RemoveUnsatisfactory Product

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ParadigmsShewharts Paradigm

• Cant Inspect Quality Into A Product
• Detect And Correct Quality Problems By Monitoring
  The Manufacturing Process
• Two Types Of Variation In A Manufacturing Process

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ParadigmsShewharts Paradigm - Terminology

• Shewhart Assignable Cause Variation (ACV) and
  Chance Causes Of Variation (CCV)
• Deming ACVLocal Faults, Special Causes,
  CCVCommon Cause Variation
• Juran ACVSporadic Problems CCVChronic
  Problems

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ParadigmsShewharts ParadigmObjective

• Monitor The Process To Detect When ACV Is
  Present.
• How Do You Detect ACV? Control Charts

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ParadigmsShewharts ParadigmTwo Ways To Improve
Quality

• Eliminate Assignable Causes To Bring Process Into
  Statistical Control
• Improve The System By Reducing Common Cause
  Variation

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ParadigmsTweaking The Variation ParadigmThe
Variation/Complexity Paradigm
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ParadigmsThe Variation/Complexity Paradigm

• Paraphrase Deming - Reduce Variation And
  Complexity And You Improve Quality

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ParadigmsDeming and Juran

• Originally Found That 80 to 85 Of The Quality
  Problems Required Managements Input In Order To
  Correct.
• Over The Years This Percentage Increased To Where
  They Found That 94 to 96 Of Quality Problems
  Were Systemic!

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ParadigmsDeming And Jurans Extension

• Need Managements Involvement

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ParadigmsDeming and Taguchi

• Customer Satisfaction is the Determining Factor
  in Product Design
• Taguchi - Quality is measured in terms of loss to
  society
• -Wring Out the Variation
• Deming and Juran - Controlling the Process
  (On-Line QC)
• Taguchi - Design Robust (Rugged) Processes and
  Products (Off-Line QC)

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ParadigmsTaguchi - Another Way To Improve Quality

• Build Rugged/Robust Products And Processes By
  Making Things Insensitive To Unknown Or
  Uncontrollable Sources Of Variation

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Some Aspects of Taguchis PhilosophyPrevention
Rather Than Detection

• Rather Than Detecting Defects, Lets Design
  Quality Into The Product Right From The
  Beginning. An Ounce of Prevention...

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Some AspectsTaguchis Approach

• During the 50s and 60s Developed A Philosophy
  and Methodology Concerning Product Design and
  Production

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Some AspectsDesign Aspects of Taguchis
Philosophy

• Robust Products And Processes Through
  Engineering Design (Statistical Design Of
  Experiments, DOE, Plays A Role Here)
• Parameter Design
• Choose Parameter (Factor) Levels To
• Optimize Process or Product Performance
• Mitigate Uncontrollable Factors

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Some AspectsDesign Aspects of Taguchis
PhilosophyFactors

• Control Factors
• Easily controlled sources of variation
• Noise
• Uncontrollable
• External - Environmental
• Goal - Design Product to Be Insensitive to Noise
  Factors