MSA测量系统分析(英文版).ppt

SPCforTestSystem GaugeR R 1 2 有多少個黑點 3 這些橫線是不是平行的 4 是靜的還是動的 5 三個正方形 6 幾何謎題 7 沒有適當的量測工具就無法管理品質 8 比較式絕對式 待測量 轉換訊息 標準值 顯示 量測儀 量測之種類 待測量 標準量 轉換訊息 轉換訊息 比測儀 顯示 轉換放大 9 BasicConcepts EveryProcessproducea Product EveryproductpossessesQualities Features EveryQualityFeatureCanbemeasuredTotalVariation ProductVariation MeasurementVariationSomeVariationInherentinSystemDesign SomeVariationisduetoaFaultyperformanceoftheSystem s 10 ComponentsofMeasurementSystem EquipmentorGageTypeofGage Attribute go nogo visionsystemsVariable calipers probe coordinatemeasurementmachinesUnitofMeasurement discriminationAtleast1 10of6 processstandarddeviation 6s Otherrules atleast1 10oftoleranceOperator OperatingInstructionsPartlocatingororientationschemeagagemustbeabletoconsistentlylocatethepartbeingmeasured 11 TermsYouShouldKnow Measurementsystem Thecollectionofoperations procedures gagesandpersonnelusetoobtainmeasurementsofworkpiececharacteristics Gage Adeviceusedtoobtainmeasurements Repeatability Repeatability Precision Thevariationinmeasurementobtainedwithonemeasurementinstrumentwhenusedbyoneoperatortomeasure anidenticalcharacteristiconthesamepart EV EquipmentVariation Reproducibility Thevariationintheaverageofthemeasurementsmadebydifferentoperatorsusingthesamemeasurementinstrumentwhenmeasuringidenticalcharacteristicsonthesamepart AV AppraiserVariation 12 TermsYouShouldKnow Bias Thedifferencebetweentheobservedaverageofmeasurementsandthereferencevalue PercentR R Thepercentageofprocessvariationrelatedtothemeasurementsystemforrepeatabilityandreproducibility Stability Thetotalvariationinthemeasurementsobtainedwithameasurementsystemonthesamemasterorpartswhenmeasuringsinglecharacteristicsoveranextendedtimeperiod Linearity Thedifferenceinthebiasvaluesthroughtheexpectedoperatingrangeofthegage 13 1 Accuracy Differencebetweenthetrueaverageandtheobservedaverage trueaveragemaybeobtainedusingamoreprecisemeasuringtool 14 2 Reproducibility Variationinaverageofmeasurementsmadebydifferentoperatorsusingthesamegagemeasuringthesamepart AppraiserVariation AV 15 3 Repeatability Precision Randomvariationinmeasurementswhenoneoperatorusesthesamegagetomeasurethesamepartseveraltimes EquipmentVariation EV 16 4 Stability Differenceintheaverageofatleast2setsofmeasurementsobtainedwithagageasaresultoftime 17 PrecisionandAccuracy 18 AccuracyandStability Measuresamepartsusingamorepreciseinstrument Accuracy Measuresamepartsusingthesamegageatalaterdate StabilityorDrift 19 MeasurementSystemVariables 20 PossibleSourcesofProcessVariation 21 SourcesofMeasurementError SystematicVariations1 accuracy impropercalibrationofequipment2 reproducibility differentoperatorsusingsameequipmentwithdifferenttechniquesRandomVariations3 repeatability forexample inconsistentpartlocating PeriodicVariations4 stability wear deterioration environmentalconditions 22 TheGR RDesignModel Supposemultipleoperators measuremultiplepartsseveraltimeseach Then Intermsofthegageperformance between operatorreproducibilityisduetotheoperatoreffectandtheoperator partinteraction Within operatorrepeatabilityisfromthepureerrorterm 23 TheComponentsofVariance 24 MeasurementError GageR R 25 Averages ANOVAanalysisbeginswiththecalculationofallrelevantaverages Here sanexample 26 TypesofGageErrorandAnalysisMethods Accuracy GageAccuracy Bias StudyGageLinearityStudy Repeatability ReproducibilityGageR R Methods X bar RangeorANOVA RepeatedMeasurementStudyRepeatability Static DynamicStudyStability RepeatedMeasurements 27 VariancePartitioning ThetotalvarianceoftheGR Rdataispartitionedintocomponentsaccordingtothemodel Variancesadd soallpartitionedpiecessumtothetotaldatavariance 28 TwoWayAnovaTable 29 GageR RAcceptance Todetermineacceptability aratioistypicallyformedcomparinggagevariationtoeither GageR R ofToleranceWidthGageR R ofTotalVariation6s represents99 73 ofvaluesifnormaldistribution5 15s represents99 ofvaluesifnormaldistribution 30 CriteriaforEvaluatingGageR R GageR R TVorR R ToleranceifR R is 30 measurementsystemneedsimprovement 31 ConductingaGageR RStudy 1 Plantheapproach Whatisnatureofoperatorandmeasurementinteraction Reproducibilitycanbenegligiblesometimes 2 Select3welltrainedoperators3 Select10partsfortest Selectsamplepartsshouldrepresententirenormalproductionrange Prefercoverthedistributionof 4sigma 4 Repeatmeasureeachparts3times 5 Takemeasurementsinrandomorder 6 Takeblindmeasurement Personmeasuringdoesn tknowwhichpieceisbeingmeasured whatpreviousmeasurementswere orwhatotherappraisersfound 32 ConductingaGageR RStudy 7 Recordallmeasurementsonworksheet 8 Calculatetrialrangeforeachpieceforeachoperatorandrecordvalues calculateR R squarerootofthesumofthesquaresoftherepeatabilityandreproducibility 9 Keepthestandardparts itsreadingfor EquipmentCorrelation purpose 33 GuidelinesForGaugeR RAcceptance Under10 Error Acceptable10 30 Error MaybeAcceptabledependingontheimportanceoftheapplication Over30 error Improvementisneeded 34 GaugeR RStudy 35 GaugeR RStudy 36 GaugeR RStudy 37 GaugeR RStudy 38 GaugeR RStudy 39 AnovaMethodExample EquipmentCalibrationBySimpleLinearityModel Y mX b 40 41 SelectionofStandardUnits Setupabout10pcsstandardunitswhichcancovertheoverallspreadofnormalproduction Prefer2rejectunitbeyondupper lowerspec AgingallunitsFindstandardreading 42 RegressionAnalysis EquipmentvsStandard MeasureStandardunitoneachindividualtestequipmentseveraltimes TaketheaverageofmeasurementdataforeachunitRegressionAnalysis EquipmentReadingvsStandardReading Ifcorrelationcoefficient 90 thencalculatetheslopeandoff setpertestm c Ifcorrelationcoefficient 90 findthereason TestResult ActualReadingXSlope Offset 43 MeasurementDataofStandardSets eachTestMachine 44 RegressionAnalysis 45 AddTranslationKey AfterCorrection ReadingXSlope OffsetTestresultbecomecloseramongtestmachines Slope OffsetperTestEquipment 46 EquipmentLongTermStabilityTest Equipmentlongtermstabilitycanbecheckedbytesting1 3workingstandardunitspereachtimebeforeoperatorusethattestmachineandplotthetestresultsonaSPCchart 47 ComputingKappa GR RTestForvisualinspector 48 KappaCoefficient Cohen 1960 Rater2 Rater1 pi xp i 39 075 01 Highreliabilityrequiresthatthefrequenciesalongthediagonalshouldbe chanceandoffdiagonalfrequenciesshouldbe chance Usemarginalfrequencies probabilitiestoestimatechanceagreement Proportionagreementobserved po ipii 1 n inii Proportionagreementexpectedbychance pc ipi xp i 49 KappaCoefficient Cohen 1960 Proportionagreementobserved po ipii 1 n inii Proportionagreementexpectedbychance pc ipi xp i 50 Select20goodand20badpartsHaveeachinspectorinspecteachofthepartsandrecordwhetherit Passed or Failed capturedataina KappaStudyDataTable Perform