training material for msa.ppt

TrainingMaterialforMEASUREMENTSYSTEMANALYSIS,Contents:,INTRODUCTIONFORMEASUREMENTSYSTEMANALYSISGENERALMETHODSILLUSTRATIONFORMEASUREMENTSYSTEMANALYSISVARIABLEGAGEANALYSISMETHOD1)THEAVERAGE-RANGEMETHOD2)THEANOVAMETHODATTRIBUTEGAGEANALYSISMETHOD1)SHORTMETHOD2)HYPOTHESISTESTANALYSIS3)SIGNALDETECTIONTHEORY4)LONGMETHODACCEPTABILITYCRITERIACONCLUSIONFOURMETHODSCOMPARISON,Introduction:BasicrequirementsbyQS-9000Stability;LinearityBiasisthedifferencebetweentheobservedaverageofmeasurementsandareferencevalue.Biasisoftenreferredtoasaccuracy.Itisasystematicerrorcomponentofthemeasurementsystem,Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?,TheFiveCharacterizationsofMeasurementSystem:1.LocationVariation:Bias;Stability;LinearityStability(Alias:Drift):Stabilityisthetotalvariationinthemeasurementsobtainedwithameasurementsystemonthesamemasterorpartswhenmeasuringasinglecharacteristicoveranextendedtimeperiod.Astablemeasurementprocessisinstatisticalcontrolwithrespecttolocation.,Stability,Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?,TheFiveCharacterizationsofMeasurementSystem:1.LocationVariation:Bias;Stability;LinearityLinearityisthedifferenceinthebiasvaluesthroughtheexpectedoperatingrangeofthemeasurementinstrument.Itisasystematicerrorcomponentofthemeasurementsystem.,Linearity,Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?,TheFiveCharacterizationsofMeasurementSystem:2.WidthVariation:Repeatability;Reproducibility;GageRReproducibility;GageRReproducibility;GageRvalueslessthan0.4indicatepooragreement.Repeatabovestep,wecangotfollowingkappameasuresfortheappraisers:Table4,AnalysisTechniques:AttributeGageStudy,a-ef,N-ef,142-79.2,150-79.2,Table4,Usingthesamestepstocalculatedthekappameasuretodeterminetheagreementofeachappraisertothereferencedecision:Table5TotalsummaryonTable6:,AnalysisTechniques:AttributeGageStudy,Table5,AnalysisTechniques:AttributeGageStudy,AnalysisTechniques:AttributeGageStudy,TheAIAGMSAreferencemanualedition3providesacceptabilitycriteriaforeachappraisersresults:Definition:FalseAlarmThenumberoftimesofwhichtheoperator(s)identifyagoodsampleasabadone.MissThenumberoftimesofwhichtheoperatorsidentifyabadsampleasagoodone.,AnalysisTechniques:AttributeGageStudy,Sosummarizingalltheinformationoftheexamplewiththistable:Table7,AnalysisTechniques:AttributeGageStudy,Conclusion:ThemeasurementsystemwasacceptablewithappraiserB,marginalwithappraiserA,andunacceptableforC.SoweshalldetermineifthereisamisunderstandingwithappraiserCthatrequiresfurthertrainingandthenneedtore-doMSA.Thefinaldecisioncriteriashouldbebasedontheimpacttotheremainingprocessandfinalcustomer.Generally,themeasurementsystemisacceptableifall3factorsareacceptableormarginal.Minitabalsocanperformattributegageanalysis,butitdidntdeclaretheacceptabilitycriteria,soitisnotrecognizedbyQS9000standard.,AnalysisTechniques:AttributeGageStudy,SignalDetectionTheoryistodetermineanapproximationofthewidthoftheregionIIareasoastocalculatethemeasurementsystemGRForthelargest(orsmallest)part,thevaluemustbea=20;Forthe6otherparts,thevalue1a19.,AnalysisTechniques:AttributeGageStudy,1Appraiser,20Trials,AnalysisTechniques:AttributeGageStudy,Example:Weuseafillergagetomeasurethefittinggapbetweenbatteryandhandphonewhichspecificationis00.2mm.Thenumberofacceptsforeachpartare:Table10,Table10,AnalysisTechniques:AttributeGageStudy,Thesecondstepistheacceptanceprobabilitiescalculationforeachpartusingthebinomialadjustments:,Table11,AnalysisTechniques:AttributeGageStudy,Thethirdstep:PlotGagePerformanceCurvewithpartreferencevalueXTasXaxis,andtheprobabilityofacceptancePaasYaxis,GagePerformanceCurve,AnalysisTechniques:AttributeGageStudy,Thefourthstep:BaseonGagePerformanceCurvetofindXTvalueatPa=0.5%andPa=99.5%(usingnormalprobabilitypapercangetmoreaccurateestimates).WealsocanuseStatisticalForecastcalculationtogettheXTvalue.XT=0.264atPa=0.5%XT=0.184atPa=99.5%Bias=XT(atPa=0.5%)-USL=0.2640.2=0.064TherepeatabilityisdeterminedbyfindingthedifferencesoftheXTvaluecorrespondingtoPa=99.5%andPa=0.05%anddividingbyanadjustmentfactorof1.08.,AnalysisTechniques:AttributeGageStudy,Conclusion:Becausethefillergagerepeatabilityis7.4%,Biasis6.4%.Bothofthemarelessthan10%,sothegagecanbeacceptedtouse.,FourMethodsComparison,Thefourmethodsforattributemeasurementstudyhaverespectivefeature.TheShortmethodlooklikesimple,butitneedtoselectenoughpartswhichareslightlybelowandabovebothspecificationlimits,andmustmeasurevariablereferencevalueinadvance.HypothesisTestdidntneedtomeasurethevariablereferencevalue,soitisfeasibleformanufacturing,butitneedlargesamplesize.SignalDetectionmethodcandetermineanapproximationofthewidthoftheregionIIareasoastocalculatethemeasurementsystemGR&R.LongmethodisusedtheconceptoftheGagePerformanceCurve(GPC)toassesstherepeatabilityandbiasofthemeasurementsystem.Whentheim