Process Capability

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Process Capability

• Ross L. Fink

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Process capability is the ability of the process
to meet the desired quality (as measured by the
specifications)
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Cp-- Process Capability Ratio
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Cpk Process Capability Ratio
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Cut-Offs

• Typical
• Cp and Cpk gt 1.33
• Might be raised
• Cost of failure
• Non-Normality of quality characteristic
• Process consistently goes out of control
• Motorolas Six Sigma Quality

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Motorolas Six Sigma Quality

• Cp 2.00, and Cpk 1.50
• PPM 3.4

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Normal v. Six Sigma Quality

• Normal Six Sigma
• Cp 1.33, Cpk 1.33 Cp 2.00, Cpk 1.50
• No. of Prob. Within Spec. PPM
  Prob. Within Spec. PPM
• Characteristics
• 1 0.999936628
  63.37 0.999996599 3.40
• 2 0.999873260 126.74 0.999993198
  6.80
• 3 0.999809896 190.10 0.999989798
  10.20
• 4 0.999746536 253.46 0.999986397
  13.60
• 5 0.999683180 316.82 0.999982996
  17.00
• 10 0.999366460 633.54 0.999965992
  34.01
• 20 0.998733321 1266.68 0.999931986
  68.01
• 50 0.996836311 3163.69 0.999829974
  170.03
• 100 0.993682631 6317.37 0.999659977
  340.02
• 500 0.968809735 31190.27 0.998301040 16
  98.96
• 1000 0.938592302 61407.70 0.996604967
  3395.03

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Six Sigma Quality Programs

• Six Sigma Quality--Technical quality--3.4 PPM
• Breakthrough Strategy
• Training--Master Black Belts, Black Belts, and
  Green Belts

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Breakthrough Strategy

• Recognize
• Define
• Measure
• Analyze
• Improve
• Control
• Standardize
• Integrate

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Cost of Quality

• Appraisal
• Prevention
• Internal Failure
• External Failure