制程能力分析最经典教材.ppt

* * * * * * * * * * * * * * * Case 1 stable,centred, not capable Case 2 stable, not centred, not capable Case 3 stable, not centred, not capable, mean outside spec limits Case 4 not stable, centred, capable Case 5 not stable, not centred, not capable Case 6 not stable, not centred, not capable, mean outside spec limits Definitions if Cp = Pp then STABLE ( no shifts) if Cp=CPK then CENTRED if Cpk greater than 1.5 then world class * * * * * * * * * * Typos a) number of units inspected = 482 b) number of defects = 12 c) opportunities = 1 or 10 ( upto you) d) use Sigcalc get sigma equivalent = 3.46 or 4.31 e) but defects per unit is the same in each case, 0.0249 ie 2.49% Scratches a) add up total units inspected = 1415 b) total number defectives = 23 for defectives opportunity is 1, either it is good or it is bad c) use Sigcalc report capability as 1.625% defectives or as 3.64 sigma equivalents d) use Minitab Binomial, file: KG scratches.mpj * * 118-68 = 50 so spec covers 4 std deviations process is centered, so 1 std dev at bottom outside spec 1 std dev above spec so approx 100% - 95% = 5% ie 2.5% above, 2.5% below * * * * * * * * * * * * * * * * * * * * Process Mean Process SD, Method 1 Process SD, Method 2 Upper Spec Lower Spec Cp Cpk Pp Ppk 50 10 10 80 20 80 10 10 80 20 110 10 10 80 20 50 10 5 80 20 80 10 5 80 20 110 10 5 80 20 針對不同狀況，決定您將從何著手改善：流程穩定性、使平均值居中、減少標準差 在您的小組裏，計算下列的 Cp, Cpk, Pp 和 Ppk 使用 Minitab 計算流程能力 使用 Minitab 的兩個步驟:1. 六合一 (Six Pack) 分析工具來檢查穩定性、常態性和計算流程能力 2. 詳細的流程能力計算 首先執行 SIX PACK 檔案： Capable2.MPJ 選取：Process 1 選取： 子群組大小 = 1 規格下限 = 80規格上限 = 100 使用 Minitab StatQuality ToolsCapability Sixpack (Normal) 流程能力指標 使用 Minitab 穩定性 是否有不尋常的模式 常態性 使用 Minitab StatQuality ToolsProcess Capability (Normal) 檔案： Capable2.MPJ 選取： Process 1 選取： 子群組大小 = 1 規格下限 = 80規格上限 = 100 結果 指標 請準備報告 小組練習 分析 PROCESS 2, PROCESS 3, 和 PROCESS 4. 對每個流程決定其數據是否適合用來預測或僅能用來診斷分析 對每個流程，如果需要改善，請決定改善流程的攻擊策略 Process Mean Process SD, Method 1 Process SD, Method 2 Upper Spec