Six Sigma Measurement

Yield and Defects LSL Target Value USL Probability of Defects Probability of Yield

The Normal Curve  2  3  4 5  6  68,26 % 95,46 % 99,73 % 99,9937 % 99, % 99, %  2  3  4 5  6  -6  -5  -4  -3  -2  +1  +2   +3  +4  +5  +6 

Statistical Interpretation of Six Sigma Let “X” be the quality characteristic of interest and (Length/Thickness/Temperature/Pressure etc.) USL = Upper Specification Limit LSL = Lower Specification Limit T = Target Value  Process Average  Process Standard Deviation X = Estimate of  s = Estimate of 

Calculation of Sigma level - When Process is Centered SIGMA LEVEL (Z) = USL - T s SIGMA LEVEL (Z) = T - LSL s OR ULMean = T

Calculation of Sigma level SIGMA LEVEL (Z) = X - LSL s When Process is Centered Closer To LSL ULTMean

Calculation of Sigma level SIGMA LEVEL (Z) = USL - X s When Process is Centered Closer To USL ULTMean

Calculation of Sigma level SIGMA LEVEL (Z) = USL - X s There is only Upper Specification Limit (USL) UMean

Calculation of Sigma level SIGMA LEVEL (Z) = X - LSL s There is only Lower Specification Limit (LSL) LMean

The Normal Curve wit Different Sigma Levels 1298 = LSL USL = 1322 USL = 1310 S = 2 (SIX SIGMA Quality Level) S = 3 (FOUR SIGMA Quality Level) S = 4 (THREE SIGMA Quality Level)

SIGMA LEVELDPMO 1 6,97, ,08, , , SIGMA (  ) QUALITY LEVELS (DPMO)

Converting Yield to Sigma Level Without Shift

DPMODPMO  MEANS DEFECTS PER MILLION OPPORTUNITIES  IS TRANSLATED INTO A SIGMA NUMBER Opportunities for Defect

Formula = Number of Defects # of Units x # of opportunities Formula = 319 defects on joints 1150 Units x 15 opportunities/joist Example 319 Defects, 1150 Items, 15 defect opportunity = DPO = x 10 6 =18,000 DPMO Defects/Opportunity & Defect/Million Opportunity