【质量管理精品文档】spc-advanced80-92.ppt

X R控制图 過程控制 a 計算及繪畫控制限 樣本容量低於7時 極差並沒有LCL 解释控制图 Changeinlevel Changeinvariability 解釋控制圖 確定是否有不受控的情況 檢查過程記錄 找出並列明任何特殊原因 再計算控制限 控制上限 UCL 控制下限 LCL 控制上限 UCL 控制下限 LCL 受控過程 不受擯過程 Test1 OnePointBeyondZoneA Test2 NinePointsinaRowonOneSideoftheCenterLine Test3 SixPointsinaRowSteadilyIncreasingorDecreasing Test4 FourteenPointsinaRowAlternatingUpandDown x x x x x x 控制图失控检验 Test5 TwoOutofThreePointsinaRowinZoneAorBeyond Test6 FourOutofFivePointsinaRowinZoneBandBeyond Test7 FifteenPointsinaRowinZoneC AboveandBelowCenterline Test8 EightPointsinaRowonBothSidesofCenterlinewithNoneinZoneC x x x x x x x 控制图的失控检验 控制图失控检验 OnepointaboveUCL Twooutofthreesuccessivepointhereorabove Fouroutoffivesuccessivepointhereorabove Sevenoutofeightsuccessivepointhereorabove OnepointaboveLCL Twooutofthreesuccessivepointhereorbellow Fouroutoffivesuccessivepointhereorbellow Sevenoutofeightsuccessivepointhereorbellow 3s 2s 1s 3s 2s 1s 0 34 1 13 6 34 1 13 6 2 2 2 2 0 1 0 1 SeasonalTrends Thesecouldbecausedbysystematicchangeslike temperature operatorfatigue voltageorpressurefluctuations etc Mixtures Aclearindicationiswhenmostofthepointsareclosetothecontrollimits andalmostnopointsnearthecenterline Theseareusuallyduetounderestimatingtheprocessvariabilityor over control whereoperatorsintervenewiththeprocessfrequentlytryingtorespondtoinherentvariabilityinsteadofassignablecauses Thisalsooccurswhencontrollingtwoprocessesonthesamechart 控制图的趋势判断规则 Changesinprocessmeans Theseareusuallyduetotheintroductionofnewoperators machines procedures etc Canalsohappenbecauseofprocessimprovements Upward DownwardTrends Continuoustrendingonthesamedirection Theseareusuallycausedbycomponentwearamongothers 控制图的趋势判断规则 WhiteSpace Pointstendtoclusteraroundthemean Usuallycausedby 1 incorrectcontrollimits overestimatingprocessvariability 2 continuousimprovementspaying off Limitsshouldberecalculatedwhenthissituationisfound 控制图的趋势判断规则 製程控制 對特殊原因採取的措施1 即時分析失控情況是非常