X-R 统计控制图的使用方法.ppt

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1、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UCLLCLAvgUCLLCLAvgChangeinlevelChangeinvariability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)中線控制下限(LCL)控制上限(UCL)中線控制下限(LCL)受控過程不受擯過程UCLLCLAABCCBUCLLCLAABCCBUCLLCLAABCCBUCLLCLAABCCBTest1.OnePointBeyondZoneATest2.NinePoin

2、tsinaRowonOneSideoftheCenterLineTest3.SixPointsinaRowSteadilyIncreasingorDecreasingTest4.FourteenPointsinaRowAlternatingUpandDownxxxxxx控制图失控检验UCLLCLAABCCBUCLLCLAABCCBUCLLCLAABCCBUCLLCLAABCCBTest5.TwoOutofThreePointsinaRowinZoneAorBeyondTest6.FourOutofFivePointsinaRowinZoneB

3、andBeyondTest7.FifteenPointsinaRowinZoneC(AboveandBelowCenterline)Test8.EightPointsinaRowonBothSidesofCenterlinewithNoneinZoneCxxxxxxx控制图的失控检验UCLLCLAABCCB控制图失控检验OnepointaboveUCLTwooutofthreesuccessivepointhereoraboveFouroutoffivesuccessivepointhereoraboveSevenoutofeightsucc

4、essivepointhereoraboveOnepointaboveLCLTwooutofthreesuccessivepointhereorbellowFouroutoffivesuccessivepointhereorbellowSevenoutofeightsuccessivepointhereorbellow3s2s1s-3s-2s-1s034.1%13.6%34.1%13.6%2.2%2.2%0.1%0.1%20100ObservationNumberUCLLCL20100ObservationNumberUCLLCLSeason

5、alTrends:Thesecouldbecausedbysystematicchangeslike:temperature,operatorfatigue,voltageorpressurefluctuations,etc.Mixtures:Aclearindicationiswhenmostofthepointsareclosetothecontrollimits,andalmostnopointsnearthecenterline.Theseareusuallyduetounderestimatingtheprocessvariabil

6、ityor“over-control”,whereoperatorsintervenewiththeprocessfrequentlytryingtorespondtoinherentvariabilityinsteadofassignablecauses.Thisalsooccurswhencontrollingtwoprocessesonthesamechart.控制图的趋势判断规则20100ObservationNumberUCLLCL151050ObservationNumberUCLLCLChangesinprocessmeans:

7、Theseareusuallyduetotheintroductionofnewoperators,machines,procedures,etc.Canalsohappenbecauseofprocessimprovements.Upward/DownwardTrends:Continuoustrendingonthesamedirection.Theseareusuallycausedbycomponentwearamongothers.控制图的趋势判断规则20100ObservationNumberUCLLCL“WhiteSpace”:

8、Pointstendtoclusteraroundthemean.Usuallycausedby:(1)incorrectcontrollimits(overest