MSA测量系统分析报告课件

TrainingMaterialfor

MEASUREMENT

SYSTEM

ANALYSIS

TrainingMaterialfor

MEASU1Contents:INTRODUCTIONFORMEASUREMENTSYSTEMANALYSISGENERALMETHODSILLUSTRATIONFORMEASUREMENTSYSTEMANALYSISVARIABLEGAGEANALYSISMETHOD1)THEAVERAGE-RANGEMETHOD2)THEANOVAMETHODATTRIBUTEGAGEANALYSISMETHOD1)SHORTMETHOD2)HYPOTHESISTESTANALYSIS3)SIGNALDETECTIONTHEORY4)LONGMETHODACCEPTABILITYCRITERIACONCLUSIONFOURMETHODSCOMPARISONContents:INTRODUCTIONFORMEA2Introduction:BasicrequirementsbyQS-9000&TS16949BaseonQS9000&TS16949requirements,allmeasurementsystemwhichwerementionedinQualityPlanshouldbeconductedMeasurementSystemAnalysis.MSARequirementIntroduction:Basicrequiremen3Introduction:ThecategoryofMeasurementSystemMostindustrialmeasurementsystemcanbedividedtwocategories,oneisvariablemeasurementsystem,anotherisattributemeasurementsystem.Anattributegagecannotindicatehowgoodorhowbadapartis,butonlyindicatesthatthepartisacceptedorrejected.ThemostcommonoftheseisaGo/No-gogage.VariableGageAttributeGage(Go/No-goGage)Introduction:Thecategoryof4Introduction:WhatisameasurementprocessOperationOutputInputGeneralProcessMeasurementAnalysisValueDecisionProcesstobeManagedMeasurementProcessMeasurement:Theassignmentofanumericalvaluetomaterialthingstorepresenttherelationsamongthemwithrespecttoaparticularprocess.MeasurementProcess:Theprocessofassigningthenumericalvaluetomaterialthings.Introduction:Whatisameasur5Introduction:WhatarethevariationsofmeasurementprocessIntroduction:Whatarethevar6Introduction:WhatarethevariationsofmeasurementprocessMeasurement(Observed)Value=ActualValue+VarianceofTheMeasurementSystem2σobs=

2σactual+

σvarianceofthemeasurementsystem2Introduction:Whatarethevar7Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?TheFiveCharacterizationsofMeasurementSystem:

1.LocationVariation:Bias;Stability;Linearity

Bias

isthedifferencebetweentheobservedaverageofmeasurementsandareferencevalue.Biasisoftenreferredtoasaccuracy.ItisasystematicerrorcomponentofthemeasurementsystemIntroduction:Wheredoesthev8Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?TheFiveCharacterizationsofMeasurementSystem:

1.LocationVariation:Bias;Stability;Linearity

Stability(Alias:Drift):Stabilityisthetotalvariationinthemeasurementsobtainedwithameasurementsystemonthesamemasterorpartswhenmeasuringasinglecharacteristicoveranextendedtimeperiod.Astablemeasurementprocessisinstatisticalcontrolwithrespecttolocation.StabilityIntroduction:Wheredoesthev9Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?TheFiveCharacterizationsofMeasurementSystem:

1.LocationVariation:Bias;Stability;Linearity

Linearityisthedifferenceinthebiasvaluesthroughtheexpectedoperatingrangeofthemeasurementinstrument.Itisasystematicerrorcomponentofthemeasurementsystem.LinearityIntroduction:Wheredoesthev10Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?TheFiveCharacterizationsofMeasurementSystem:

2.WidthVariation:Repeatability;Reproducibility;GageR&R

Repeatabilityisthevariationinmeasurementsobtainedwithonemeasurementinstrumentwhenusedseveraltimeswhilemeasuringtheidenticalcharacteristiconthesamepartbyanappraiser.ItisaWithin-systemvariation,commonlyreferredtoasE.V.---EquipmentVariation.RepeatabilityIntroduction:Wheredoesthev11Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?TheFiveCharacterizationsofMeasurementSystem:

2.WidthVariation:Repeatability;Reproducibility;GageR&R

Reproducibilityisthevariationintheaverageofthemeasurementsmadebydifferentappraisersusingthesamegagewhenmeasuringtheidenticalcharacteristicsofthesamepart.Itisbetween-systemvariation,commonlyreferredtoasA.V.---AppraiserVariation.ReproducibilityIntroduction:Wheredoesthev12Introduction:Wheredoesthevariationofmeasurementsystemcomefrom?TheFiveCharacterizationsofMeasurementSystem:

2.WidthVariation:Repeatability;Reproducibility;GageR&R

GageR&RmeansGagerepeatabilityandreproducibility,whichcombinedestimateofmeasurementsystemrepeatabilityandreproducibility.Thiscombinedmeasurementerrortheniscomparedwiththeprocessoutputvariabilitytocomputethegagepercentage

R&R(%R&R).The%R&Risthebasisformakingajudgmentofwhetherthemeasurementsystemisgoodenoughtomeasuretheprocess.Introduction:Wheredoesthev13AnalysisTechniques:

CurrentlytherearethreetechniquesforvariablemeasurementsystemandfourtechniquesforattributemeasurementsystemanalysiswererecommendedbyAIAGMSAReferenceManual.RangeMethodAverage-RangeMethodANOVAShortMethodLongMethodHypothesisTestAnalysesSignalDetectionTheoryFollowingsaresomepracticalexamplestoillustratehowtoperformfourmethodsrespectively.VariableGageAttributeGageAnalysisTechniques:Currentl14AnalysisTechniques:PreparationbeforeMSATheapproachtobeusedshouldbeplanned.Thenumberofappraisers,numberofsampleparts,andnumberofrepeatreadingsshouldbedeterminedinadvance.Theappraisersshouldbeselectedformthosewhonormallyoperatetheinstrument.Thesamplepartsmustbeselectedfromtheprocessandrepresentitsentireoperatingrange.Theinstrumentmusthaveadiscriminationthatallowsatleastone-tenthoftheexpectedprocessvariationofthecharacteristictobereaddirectly.Themeasurementprocedureshouldbedefinedinadvancetoensuretheconsistentmeasuringmethod.AnalysisTechniques:Preparati15AnalysisTechniques:VariableGageAnalysisGeneralGageR&RStudy:

TheAverageandRangeMethodTheANOVAMethodThecommonstepforconductingGageR&Rstudy:1.Verifycalibrationofmeasurementequipmenttobestudied.2.Obtainasampleofpartsthatrepresenttheactualorexpectedrangeofprocessvariation.3.Addaconcealedmarktoeachidentifyingtheunitsasnumbers1through10.Itiscriticalthatyoucanidentifywhichunitiswhich.Atthesametimeitisdetrimentaliftheparticipantsinthestudycantelloneunitfromtheother(maybiastheirmeasurementshouldtheyrecallhowitmeasuredpreviously).4.Request3appraisers.RefertotheseappraisersasaA,B,andCappraisers.Ifthemeasurementwillbedonerepetitivelysuchasinaproductionenvironment,itispreferabletousetheactualappraiserthatwillbeperformingthemeasurement.AnalysisTechniques:Variable16Forextremecases,aminimumoftwoappraiserscanbeused,butthisisstronglydiscouragedasalessaccurateestimateofmeasurementvariationwillresult.5.LetappraiserAmeasure10partsinarandomorderwhileyourecordthedatanotingtheconcealedmarking.LetappraisersBandCmeasurethesame10partsNote:Donotallowtheappraiserstowitnesseachotherperformingthemeasurement.The

reasonisthesameaswhytheunitmarkingsareconcealed,TOPREVENTBIAS.6.Repeatthemeasurementsforallthreeappraisers,butthistimepresentthesamplestoeachinarandomorderdifferentfromtheoriginalmeasurements.Thisistoagainhelpreducebiasinthemeasurements.AnalysisTechniques:VariableGageAnalysis……10Parts3Appraisers3TrialsForextremecases,aminimumo17TheAverageandRangeMethod:

Arangecontrolchartiscreatedtodetermineifthemeasurementprocessisstable

andconsistent.Foreachappraisercalculatetherangeoftherepeatedmeasurementsforthesamepart.AnalysisTechniques:VariableGageAnalysisTheAverageandRangeMethod:18AnalysisTechniques:VariableGageAnalysisTheaveragerangeforeachoperatoristhencomputed.Theaverageofthemeasurementstakenbyanoperatoriscalculated.Acontrolchartofrangesiscreated.Thecenterlinerepresentstheaveragerangeforalloperatorsinthestudy,whiletheupperandlowercontrollimitconstantsarebasedonthenumberoftimeseachoperatormeasuredeachpart(trials).AnalysisTechniques:Variable19AnalysisTechniques:VariableGageAnalysisThecenterlineandcontrollimitsaregraphedontoacontrolchartandthecalculatedrangesarethenplottedonthecontrolchart.Therangecontrolchartisexaminedtodeterminemeasurementprocessstability.Ifanyoftheplottedrangesfalloutsidethecontrollimitsthemeasurementprocessisnotstable,andfurtheranalysisshouldnottakeplace.However,itiscommontohavetheparticularoperatorre-measuretheparticularprocessoutputagainandusethatdataifitisin-control.AnalysisTechniques:Variable20AnalysisTechniques:VariableGageAnalysisRepeatability-EquipmentVariation(E.V.)Theconstantd2*isbasedonthenumberofmeasurementsusedtocomputetheindividual

ranges(n)

ortrials,thenumberofpartsinthestudy,andthenumberofdifferentconditionsunderstudy.TheconstantK1isbasedonthenumberoftimesapartwasrepeatedlymeasured(trials).Theequipmentvariationisoftencomparedtotheprocessoutput

toleranceorprocessoutputvariationtodetermineapercentequipmentvariation(%EV).AnalysisTechniques:Variable21AnalysisTechniques:VariableGageAnalysisReproducibility-AppraiserVariation(A.V.)Xdiffisthedifferencebetweenthelargestaveragereadingbyanoperatorandthesmallestaverage

readingbyanoperator.TheconstantK2isbasedonthenumberofdifferentconditionsanalyzed.Theappraiservariationisoftencomparedtotheprocessoutputtoleranceorprocessoutputvariationtodeterminea

percentappraiservariation(%AV).

AnalysisTechniques:Variable22AnalysisTechniques:VariableGageAnalysisRepeatabilityandReproducibility(GageR&R)Thegageerror(R&R)iscomparedtotheprocessoutputtolerancetoestimatetheprecisiontotoleranceratio(P/Tratio).Thisisimportanttodetermineifthemeasurementsystemcandiscriminatebetweengoodandbadoutput.Thebasicinterestofstudyingthemeasurementprocessistodetermineifthemeasurementsystemiscapableofmeasuringaprocessoutputcharacteristicwithitsownuniquevariability.ThisisknowasthePercentR&R(P/Pratio,%R&R),andcalculatedasfollows:AnalysisTechniques:Variable23AnalysisTechniques:VariableGageAnalysisProcessorTotalVariation:Iftheprocessoutputvariation(m)isnotknown,thetotalvariationcanbeestimatedusingthedatainthestudy.Firstthepartvariationisdetermined:Rpistherangeofthepartaverages,whileK3isaconstantbasedonthenumberofpartsinthestudy.Thetotalvariation(TV)isjustthesquarerootofthesumofthesquaresofR&RandthepartvariationAnalysisTechniques:Variable24AnalysisTechniques:VariableGageAnalysisTheANOVAMethod:

A

weaknesswiththeAverage-RangemethodofusingtherangetodeterminegageR&Risthatitdoesnotconsiderthevariationintroducedintoameasurementthroughtheinteractionbetweendifferentconditions(appraiser)andthegage.Consequently,toaccountforthisvariationananalysisofvariancemethod(ANOVA)isutilized.Inaddition,whenthesamplesizeincreases,useoftherangetoestimatethevariationinnotveryprecise.Furthermore,withsoftwarepackagesreadilyavailable,theANOVAmethodisaviablechoice.Thetotalvariationinanindividualmeasurementequals:Theparttopartvariationisestimatedbyp2;theoperatorvariationisestimatedbyo2;theinteractioneffectisestimatedbyop2;whilerepeatabilityisestimatedbyr2

AnalysisTechniques:Variable25AnalysisTechniques:VariableGageAnalysisPart:Operator:Interaction:Repeatability:AnalysisTechniques:Variable26AnalysisTechniques:VariableGageAnalysisTotal:ThegageR&Rstatisticsarethencalculatedasfollows:MeasurementError:Part:Operator:Interaction:Reproducibility:Repeatability:MeasurementError:Total:AnalysisTechniques:Variable27AnalysisTechniques:VariableGageAnalysisAcceptabilityCriteria:Thegagerepeatabilityandreproducibility:%R&R(P/Pratio:%totaloftotalvariance;P/Tration:%totaloftolerance):Lessthan10% Outstanding 10%to20% Capable 20%to30% MarginallyCapable Greaterthan30% NOTCAPABLE

FortheP/PratioandtheP/Tratio,eitherorbothapproachescanbetakendependingontheintendeduseofthemeasurementsystemandthedesiresofthecustomer.Generally,Ifthemeasurementsystemisonlygoingtobeusetoinspectiftheproductmeetsthespecs,thenweshouldusethe%R&Rbaseonthetolerance(P/Tratio).Ifthemeasurementsystemisgoingtobeuseforprocessoptimization/characterizationanalysis,thenweshouldusethe%R&Rbaseontotalvariation(P/Pratio).AnalysisTechniques:Variable28AnalysisTechniques:VariableGageAnalysisAcceptabilityCriteria:ForaGagedeemedtobeINCAPABLEforit’sapplication.Theteammustreviewthedesignofthegagetoimproveit’sintendedapplicationandit’sabilitytomeasurecriticalmeasurementscorrectly.Also,ifare-calibrationisrequired,pleasefollowcaliberationsteps.Ifrepeatabilityislargecomparedtoreproducibility,thereasonsmightbe:1)theinstrumentneedsmaintenance,thegageshouldberedesigned2)thelocationforgagingneedstobeimproved3)thereisexcessivewithin-partvariation.Ifreproducibilityislargecomparedtorepeatability,thenthepossiblecausescouldbe:1)inadequatetrainingonthegage,2)calibrationsarenoteffective,3)afixturemaybeneededtohelpusethegagemoreconsistently.AnalysisTechniques:Variable29AnalysisTechniques:VariableGageAnalysisTheMeasurementBias:

Usingacertifiedsample,andacontrolchartofrepeatedmeasurements,thebiasofameasurementprocesscanbedetermined.Biasisthedifferencebetweentheknownvalueandtheaverageofrepeatedmeasurementoftheknownsample.Biasissometimescalledaccuracy.ProcessVariation=6SigmaRangePercentBias=BIASProcessVariationAnalysisTechniques:Variable30AnalysisTechniques:VariableGageAnalysisLinearity:Linearityofameasurementprocessisthedifferenceinthebiasorprecisionvaluesthroughtheexpectedoperatingrangeofthegauge.Toevaluatelinearity,agraphcomparingthebiasorprecisiontotheexpectedoperatingrangeiscreated.Aproblemwithlinearityexistsifthegraphexhibitsdifferentbiasorprecisionfordifferentexpectedoperatingranges.Byusingthefollowingprocedure,linearitycanbedetermined.1)Selectfivepartswhosemeasurementscovertheoperatingrangeofthegage.2)Verifythetruemeasurementsofeachpart.3)Haveeachpartberandomlymeasured12timesonthegagebyoneoperator.4)Calculatethepartaverageandthebiasforeachpart.5)Plotthebiasandthereferencevalues.6)Calculatethelinearregressionlinethatbestfitsthesepoints.AnalysisTechniques:Variable31AnalysisTechniques:VariableGageAnalysis7)Calculatethegoodnessoffitstatistic:

AnalysisTechniques:Variable32AnalysisTechniques:VariableGageAnalysis8)Determinelinearityandpercentlinearity:Linearity=SlopexProcessvariation(m)%Linearity=100[linearity/ProcessVariation]TheacceptabilitycriteriaofBias,LinearitydependonQualityControlPlan,characteristicbeingmeasuredandgagespeciality,suggestedcriteriaofESGisasfollowing:Under5%-acceptable5%to15%-maybeacceptablebaseduponimportanceofapplication,costofmeasurementdevice,costofrepairs,etc.,Over15%-Considerednotacceptable-everyeffortshouldbemadetoimprovethesystemThestabilityisdeterminedthroughtheuseofacontrolchart.Itisimportanttonotethat,whenusingcontrolcharts,onemustnotonlywatchforpointsthatfalloutsideofthecontrollimits,butalsocareotherspecialcausesignalssuchastrendsandcenterlinehugging.GuidelineforthedetectionofsuchsignalscanbefoundinmanypublicationsonSPC.AnalysisTechniques:Variable33AnalysisTechniques:AttributeGageStudy

ShortMethod:

AShortMethodexampleforbatterylengthgo/no-gogagestudy:TheShortmethodneedtobeconductbyselecting20partswhichhavebeenmeasuredbyavariablegageinadvance,someofthepartsareslightlybelowandabovebothspecificationlimits.Twoappraisersthenmeasureallpartstwicerandomly.MeasurementResulttable1AnalysisTechniques:Attribute34AnalysisTechniques:AttributeGageStudyAcceptabilitycriteria:Ifallmeasurementresults(fourperpart)agree,thegageisacceptable.Ifthemeasurementresultsdonotagree,thegagecannotbeaccepted,itmustbeimprovedandre-evaluated.Conclusion:Becausetable1listedmeasurementresultsarenotwholeagreement,atpart15#and17#,appraiser’sdecisionsarenotagree.sothebatterylengthgagecannotbeusedandmustbeimprovedandre-evaluated.AnalysisTechniques:Attribute35AnalysisTechniques:AttributeGageStudy

HypothesisTestAnalysis:

Shortmethodshouldknowthevariablereferencevalueofsamplesinadvance.However,insomesituationsitishardtorealizetogetallsamplesvariablereferencevalue.Sointhiscase,Hypothesistestanalysisshallbeappliedforgagestudy.IIII

TargetIIIIIUSLLSLAnalysisTechniques:Attribute36AnalysisTechniques:AttributeGageStudyHypothesistestanalysisdependsoncrosstabulationmethodwhichneedstotakearandomsampleof50partsfromthepresentprocessanduse3appraiserswhomake3measurementsoneachpartanddecideifthepartisacceptableornot.Appraisersmeasurethepartsandifthepartiswithinlimitstheygive“1”andifnottheygive“0”andwritethoseresultsinatable.Inordertoeliminateanybiasproduced,thelabeledsamplesaremixedbeforegivingtoappraisersforidentificationineachtrails.

Followingtable2listedfillergagemeasuringresultsforthebattery\weldinggap:

……50Samples3Appraisers3TrialsAnalysisTechniques:Attribute37Table2FillergagemeasuringresultTable2Fillergagemeasurin38Table2FillergagemeasuringresultTable2Fillergagemeasurin39Table2FillergagemeasuringresultAnalysisTechniques:AttributeGageStudyInordertodeterminethelevelofagreementamongtheappraisers,weappliedCohen’sKappawhichisusedtoassessinter-raterreliabilitywhenobservingorotherwisecodingqualitative/categoricalvariables.Itcanmeasuretheagreementbetweentheevaluationsoftworaterswhenbothareratingthesameobject.Table2Fillergagemeasurin40Step1.Organizethescoreintoacontingencytable.Sincethevariablebeingratedhastwocategories,thecontingencytablewillbea2*2table:Table3AnalysisTechniques:AttributeGageStudyA*BCross-TabulationTable3Step1.Organizethescoreint41AnalysisTechniques:AttributeGageStudyStep2.Computetherowtotals(sumacrossthevaluesonthesamerow)andcolumntotalsoftheobservedfrequencies.Step3Computetheoveralltotal(showinthetable3).Asacomputationalcheck,besurethattherowtotalsandthecolumntotalssumtothesamevaluefortheoveralltotal,andtheoveralltotalmatchesthenumberofcasesintheoriginaldataset.Step4Computethetotalnumberofagreementsbysummingthevaluesinthediagonalcellsofthetable.Σa=53+89=142Step5Computetheexpectedfrequencyforthenumberofagreementsthatwouldhavebeenexpectedbychanceforeachcodingcategory.ef===21.6Repeattheformulaforothercell,wegototherexpectedcount(showinthetable3).rowtotal*coltotaloveralltotal59*55150AnalysisTechniques:Attribute42Step6Computethesumoftheexpectedfrequenciesofagreementbychance.Σef=21.6+57.6=79.2Step7ComputeKappa

K===0.89

Step8EvaluateKappa-Ageneralruleofthumbisthatvaluesofkappagreaterthan0.75indicategoodtoexcellentagreement;valueslessthan0.4indicatepooragreement.

Repeatabovestep,wecangotfollowingkappameasuresfortheappraisers:Table4AnalysisTechniques:AttributeGageStudyΣa-ΣefN-Σef142-79.2150-79.2Table4Step6Computethesumofthe43Usingthesamestepstocalculatedthekappameasuretodeterminetheagreementofeachappraisertothereferencedecision:Table5TotalsummaryonTable6:AnalysisTechniques:AttributeGageStudyTable5Usingthesamestepstocalcul44AnalysisTechniques:AttributeGageStudyAnalysisTechniques:Attribute45AnalysisTechniques:AttributeGageStudyTheAIAGMSAreferencemanualedition3providesacceptabilitycriteriaforeachappraisersresults:Definition:FalseAlarm–Thenumberoftimesofwhichtheoperator(s)identifyagoodsampleasabadone.Miss–Thenumberoftimesofwhichtheoperatorsidentifyabadsampleasagoodone.AnalysisTechniques:Attribute46NumberofcorrectdecisionsTotalopportunitiesforadecisionEffectiveness=AnalysisTechniques:AttributeGageStudyNumberofFalseAlarmTotalopportunitiesforadecisionFalseAlarmRate=NumberofFalseAlarmTotalopportunitiesforadecisionMissRate=Sosummarizingalltheinformationoftheexamplewiththistable:Table7NumberofcorrectdecisionsTot47AnalysisTechniques:AttributeGageStudyConclusion:ThemeasurementsystemwasacceptablewithappraiserB,marginalwithappraiserA,andunacceptableforC.SoweshalldetermineifthereisamisunderstandingwithappraiserCthatrequiresfurthertrainingandthenneedtore-doMSA.Thefinaldecisioncriteriashouldbebasedontheimpacttotheremainingprocessandfinalcustomer.Generally,themeasurementsystemisacceptableifall3factorsareacceptableormarginal.Minitabalsocanperformattributegageanalysis,butitdidn’tdeclaretheacceptabilitycriteria,soitisnotrecognizedbyQS9000standard.AnalysisTechniques:Attribute48AnalysisTechniques:AttributeGageStudy

SignalDetectionTheoryistodetermineanapproximationofthewidthoftheregionIIareasoastocalculatethemeasurementsystemGR&R.AlsousedfillergageasexampletoperformSignalDetectionapproach.Thetoleranceis0.45~0.55mm.Theprocessneedstotakearandomsampleof50partsfromthepracticalprocessanduse3appraiserswhomake3measurementsoneachpart,andthengotfollowingtable:Table8IIIITargetIIIIIUSLLSLAnalysisTechniques:Attribute49Table8SignalDetectionTableforFillerGage

Table8SignalDetection50Table8SignalDetectionTableforFillerGage

Table8SignalDetection51AnalysisTechniques:AttributeGageStudyAbovetable8showsthe50partsmeasurementresult,“0”standardrejected,“1”standardacceptable,code“-”standardregionI,code“x”standardregionII,code“+”standardregionIII.AndthenbaseonthepartreferencevaluetoarrangeinorderfromMax.toMin.,meanwhiletoshowthecode:Table9RegionIIIRegionIRegionIRegionIIRegionIIAnalysisTechniques:Attribute52AnalysisTechniques:AttributeGageStudyNextstepweshouldfindXavaluewhichlocatedregionI,butisthenearesttoregionII.XbvaluewhichlocatedregionIII,butisthenearesttoregionII.AndthencalculatethedistanceofregionII.

dLSL=

Xa,LSL-Xb,LSL=0.446697–0.470832=0.024135

dUSL=

Xa,USL-Xb,USL=0.566152–0.542704=0.0234480.0237910.55–0.45GR&R===0.023791

dUSL+dLSL20.023448+0.0241352%GR&R===0.277=27.7%

GR&RUSL-LSLConclusion:The%GR&Rislargerthan10%,butlessthan30%,itmaybeacceptablebaseduponimportanceofapplication,costofmeasurementdevice,costofrepairs,etc.AnalysisTechniques:Attribute53AnalysisTechniques:AttributeGageStudy

LongMethodisusedtheconceptoftheGagePerformanceCurve(GPC)todevelopameasurementsystemstudy.Itfocusesonassessingtherepeatabilityandbiasofthemeasurementsystem.ThepurposeofdevelopingaGPCistodeterminetheprobabilityofeitheracceptingorrejectingapartofsomereferencevalue.AnalysisTechniques:Attribute54ThefirststepofLongMethodisthepartselection.Itisnecessarytoknowthepartreferencevaluewhichwasmeasuredwithvariablemeasurementsystem.Theapproachshouldselect8partsasnearlyequidistantintervalsaspractical.TheMaximumandminimumvaluesshouldrepresenttheprocessrange.The8partsmustbemeasured20timeswiththeattributegage.Weuse“m”torepresentthemeasuringtimes,use“a”torepresentthenumberofaccepts.Forthesmallest(orlargest)part,thevaluemustbea=0;Forthelargest(orsmallest)part,thevaluemustbea=20;Forthe6otherparts,thevalue1≤a≤19.AnalysisTechniques:AttributeGageStudy……8Samples1Appraiser20TrialsThefirststepofLongMethod55AnalysisTechniques:AttributeGageStudyExample:Weuseafillergagetomeasurethefittinggapbetweenbatteryandhandphonewhichspecificationis0~0.2mm.Thenumberofacceptsforeachpartare:Table10Table10AnalysisTechniques:Attribute56AnalysisTechniques:AttributeGageStudyThesecondstepistheaccept