09capability(制程能力)-資料下載頁
2025-02-18 07:26本頁面
【正文】 k?? ?, )st st Cpk = Cp(1k) where T X 3? K = st 24 Six Sigma Training Long Term Process Capability Ratios Process Width +3? 3? T LSL USL USL LSL 6? Pp = lt Pp assumes the Process is Centered P p ( Maximum Allowable Range of Characteristic ) ? lt Z = 3Pp ( Normal Variation of the Process ) 25 Six Sigma Training Long Term Process Capability Ratios Ppk accounts for the Mean Shift in the Process Ppk = Pp(1k) where T X 3? K = lt lt lt P Min( X LSL 3 USL X 3 pk ? ? ? , ) Z = 3Pp lt 26 Six Sigma Training The Process Improvement Plan calls for performing a Shortterm Capability study during the Measurement Phase to establish the process baseline. Minitab’s process capability functions allow you options on what std. dev. to use in the capability ratio calculations: Short term Capability uses the within subgroup standard deviation calculated in Minitab. This measures the “instantaneous” capability and may be used to establish process entitlement. Long term capability uses the Overall Standard Deviation (Total): By using the overall standard deviation, you get the best estimate of your long term capability. Process Improvement Plan 27 Six Sigma Training Assessing Process Capability for Attribute Data ? Verify Attribute Measurement System ? Count process defects and total units processed ? Calculate PPM and DPU (Defects per unit) ? Calculate Zscore short term and long term (Sigma Level) Count Process Defects Calculate PPM DPU Calculate Zst Zlt 28 Six Sigma Training Assessing Process Capability for Attribute Data Calculate DPU, PPM and Zscore for the following process: D ef or ma ti onC ol orA ir Bu bb leWe ig ht De v.1 2 01 3 22 9 34 3 11 2 . 31 3 . 53 0 . 04 4 . 21 0 0 . 0 8 7 . 7 7 4 . 2 4 4 . 21 0 0 05 0 001 0 08 06 04 02 00D e f e c tC o u n tP e r c e n tC u m %PercentCountP a r e t o C h a r t f o r D e f e c t s? Total defects = 976 ? Total units produced = 9,000 ? DPU = ? PPM = 108,444 ? Zlt = ? Zst = + = 29 Six Sigma Training What Does All This Mean? ShortTerm C p to RTY C p (from Minitab for shortterm study) (assumes the process is centered) Z ST = 3 * C p ( Page Vision of 6 sigma, MH Book) Z LT = Z ST – P p = Z LT / 3 DPU (area from table using Z ST ) PPM = DPU * 1,000,000 RTY = e DPU RTY% = RTY * 100 PPM to C p PPM = [(Total Defects) / (Total Production)] * 1,000,000 DPU = PPM / 1,000,000 RTY = e DPU RTY% = RTY * 100 Z ST (get from table using shortterm DPU as area) C p = Z ST / 3 ( assumes the process is centered) Z LT = Z ST – P p = Z LT / 3 30 Six Sigma Training LongTerm P p to RTY P p (from Minitab for longterm study) Z LT = 3 * P p Z ST = Z LT + C p = Z ST / 3 DPU (area from table using Z LT ) PPM = DPU * 1,000,000 RTY = e DPU RTY% = RTY * 100 PPM to P p PPM = [(Total Defects) / (Total Production)] * 1,000,000 DPU = PPM / 1,000,000 RTY = e DPU RTY% = RTY * 100 Z LT (get from table using longterm DPU as area) P p = Z LT / 3 Z ST = Z LT + C p = Z ST / 3 31 Six Sigma Training 演講完畢，謝謝觀看！
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