DFMEA培训资料.ppt

潜在的失效模式及其效应分析（FMEA）,培训员:王运良,内容,课程目的什么是FMEAFMEA的起源为什么要用FMEAFMEA的分类什么时候用FMEA特殊特性在FMEA怎样做FMEA怎样降低过程的风险（RPN）FMEA中常见的问题缺陷树分析和FMEA,课程目的,明白FMEA的角色和作用明白过程FMEA（DFMEA）的概念和技术以及怎样应用明白设计FMEA（DFMEA）的概念了解缺陷树分析（FTA）了解零缺陷质量控制和防错法的概念以及他们对FMEA的含意,什么是FMEA?,潜在的失效模式及其效应分析潜在的而不只是现有的失效模式研究的对象效应（后果）失效模式的影响,是一个前期质量策划的工具用来评估潜在的失效模式和失效模式产生的原因,区分失效的优先次序。根据失效模式的风险和所采取的行动来消灭和减少发生的几率。提供一个方法用来分析制程并持续改进。FMEA必须与别的质量工具结合才能更好的解决问题，如DOE，SPC，因果分析图等FMEA的焦点是通过问题的前摄来达到预防的目的而不是解决现有的问题。,什么是FMEA?,FMEA的分类,三种类型的FMEA系统FMEA(SFMEA)设计FMEA(DFMEA)过程FMEA(PFMEA),FMEA的起源,FMECA（FailureModeEffectsandCriticalityAnalysis）失效模式的后果及其危险程度分析起源于20世纪50年代航空航天业以及美国军工业分类和等级目标是预防致命的问题的发生特别强调安全问题FMEA失效模式及其效应分析-1960s和70s首先使用FMEA的是可靠性工程师,为什么要用FMEA?,汽车行业QS9000和TS16949APQP手册过程安全管理行动(PSM)（美国职业安全健康局）CFR1910.119999999列出PFMEA是六种方法中的一种用来评估危险性FDA（美国药品管理局）-GMPs设计FMEA是其中一个工具用来评估一个新的设计。ISO9001预防行动的要求.FMEA是一个很好的持续改进的工具来符合这个条款的要求。ISO14000可以用来评估有害物质的风险。,为什么用FMEA？,一个早期的FMEA,SFMEA从概念开发的开始阶段到正式的设计方案开始前。用于评估系统的失效风险DFMEA从概念开发的后期阶段开始到设计方案完成。用于评估设计的失效风险PFMEA从设计开发完成开始到产品的试产前。用于评估制造过程的失效风险。,什么时候做FMEA？,FMEA的时间表,DFMEA:从过程的早期开始.设计的草图完成后，在任何的工具设计开始前。PFMEA:从过程开发的早期阶段开始，已经大致确定了过程的初步方案。应在量产的方案确定之前或量产批准前。,概念设计设计设计完成试生产产品和过程批准量产开始,PFMEA,DFMEA,SFMEA,三种FMEA之间的关系,SFMEA,PFMEA,DFMEA,三种FMEA之间的关系,典型的汽车产品发展的三步曲,典型的汽车产品发展的三步曲,典型的汽车产品发展的三步曲,SomeKeyFMEATerms,CustomerInputTeam-TeamSelection(Cross-Functional)Ranking-RankingofDecisionsRiskPriorityAssessmentDesignProcessProductionProcess,AutomotiveAcronyms:,AIAG:AutomotiveIndustryActionGroupAPQP:AdvancedProductQualityPlanningDFMEA:DesignFailureModeandEffectsAnalysisDOE:DesignofExperimentsFMA:FailureModesAnalysisFMEA:FailureModeandEffectsAnalysisKCC:KeyControlCharacteristicKPC:KeyProductCharacteristicPFMEA:ProcessFailureModeandEffectsAnalysisPPAP:ProductionPartApprovalProcessPSW:ProductSubmissionWarrantQFD:QualityFunctionDeployment,AutomotiveMadness,特殊特性,产品的特殊特性尺寸，性能参数。影响产品的功能，可靠性，寿命，耐用性，安全性可能影响法律法规的符合性一般由客户指定，图纸上用特殊的符号标出。如“”，“”等。,特殊特性,过程的特殊特性可能产品的影响产品的功能，可靠性，寿命，耐用性，安全性，或可能影响法律法规的符合性或产品后续生产过程的制造过程参数。一般通过FMEA评估产生，由制造商自己指定。产品和过程的特殊特性都应当包含在控制计划中。,CharacteristicsI,CharacteristicsII,CharacteristicsIII,CharacteristicsIV,CharacteristicsV,怎样用FMEA评估过程的风险？,什么是失效模式一般指的产品的失效（缺陷）。这些缺陷可能是功能，装配，外形方面的问题，对客户满意度有不同程度的影响。注意：不一定是外部客户，有可能指的是内部客户。,怎样用FMEA评估过程的风险？,失效模式的风险度一般用RPN（风险度序数）来表示过程的风险度，RPN最小为1，最大是1000。RPN越大，被评估过程的风险越大。,怎样用FMEA评估过程的风险？,失效模式的严重度（S）一般用S（严重度）来表示产品的缺陷对最终使用，或下道工序，以及客户满意度的影响程度。D最小为1，最大是10。D越大，产品的缺陷越严重，缺陷造成的后果越严重。,怎样用FMEA评估过程的风险？,失效模式的发生频率（O）用O（发生频率）来表示产品的缺陷的可能性。O最小为1，最大是10。O越大，产品的缺陷发生的可能性越大。,怎样用FMEA评估过程的风险？,失效模式的不可探测度（D）用D（不可探测度）来表示产品的缺陷的被发现的可能性。D最小为1，最大是10。D越大，产品的缺陷越难以被探测到的可能性越小。,怎样做PFMEA？,成立一个跨部门的小组制造（工艺）工程师设备工程师设计工程师品质工程师生产工程师/主管可靠性工程师工业工程师等。在开始FMEA前，把小组的人员先写在FMEA表格的上边。,一般是组长,怎样做PFMEA？,2.定义所涉及的产品的特殊特性：客户图纸规格书等。必要时应与客户沟通，以确保领会客户的要求。,练习1,指定一个产品，并定义产品的特殊特性。,怎样做PFMEA？,3.画出产品的生产流程图.,PROCESSFLOWDOCUMENT,FlowCHART,PreliminaryProcessDescriptionofanticipatedmanufacturingprocessdevelopedfrompreliminarybillofmaterialandproduct/processassumptions.(P10#1.10APQP)however,itdoestaketechnicalandphysicallimitationsofaprocessintoconsideration(DesignRules),TheProcessPotentialFMEAIdentifiespotentialproduct-relatedfailuremodesAssessesthepotentialcustomereffectsofthefailuresIdentifiesthepotentialinternalandexternalmanufacturingorassemblyprocesscausesandidentifiesprocessvariablesonwhichtofocuscontrolsforoccurrencereductionand/ordetectionofthefailurecondition(s)Developsrankedlistofpotentialfailuremodes,thusestablishingaprioritysystemforcorrectiveactionconsiderationsDocumentstheresultsofthemanufacturingorassemblyprocess,ProcessPotentialFMEAAProcessPotentialFMEAisananalyticaltoolutilizedbyaProcessFMEAteamasameanstoensurepotentialfailuremodesandtheirassociatedcausesareidentified,consideredandaddressed.Teamsshouldberunbytheowneroftheprocessorsomeonewhounderstandstheprocesswell.Definesreasonsforrejectionatspecificoperations.InpreparationfortheFMEA,theassumptionshouldbemadethattheincomingpartsandmaterialsarecorrect.Acomparisonofsimilarprocessesandareviewofcustomerclaimsrelatingtosimilarcomponentsisarecommendedstartingpoint.Aknowledgeofthepurposeofthedesignisnecessary.Itcanbecause-associatedwithapotentialfailuremodeinasubsequentoperationoraneffectassociatedwithapotentialfailureinapreviousoperation.Eachpotentialfailuremodefortheparticularoperationshouldbelistedintermsofapartorprocesscharacteristic.,ProcessFMEAFociCustomersinclude:EndUserNextManufacturingorProcessStepProcessEngineersAssemblyEngineersRepairFunctionsTestEngineersProductAnalysisDealershiporotherSalesOutlet,ProcessFMEABenefitsAsasystematicapproach,theProcessPotentialFMEAparallelsandformalizesthementaldisciplinethatanengineergoesthroughinanymanufacturingplanningprocess.TheProcessPotentialFMEAidentifiespotentialproductrelatedprocessfailuremodes.TheProcessPotentialFMEAassessesthepotentialcustomereffectsofthefailures.TheProcessPotentialFMEAidentifiespotentialmanufacturingand/orassemblyprocesscauses.TheProcessPotentialFMEAidentifiessignificantprocessvariablestofocuscontrolsforoccurrencereductionanddetectionoffailureconditions.TheProcessPotentialFMEAdevelopsalistofpotentialfailuremodesrankedaccordingtotheiraffectonthecustomer,thusestablishingaprioritysystemforcorrectiveandpreventiveactionconsiderations.,MoreProcessFMEAConsiderationsTheProcessFMEAisalivingdocument.TheProcessFMEAshouldbecontinuallyupdatedaschangesoccurthroughoutallphasesofproductdevelopmentandonintoandthroughtotheendofproduction.TheProcessFMEAshouldbeginwithaflowchartoftheprocesses-fromreceivingthroughshippingandwarehousing.ThePotentialFailureModes/CauseswhichcanoccurduringmanufacturingorassemblyprocessarecoveredbytheProcessFMEAbutsomeinformation(severityrankings,identificationofsomeeffects)maycomefromtheDesignFMEA.Areductioninoccurrencerankingcanonlybeachievedbyimplementingaprocesschangethatcontrolsoreliminatesoneormorecausesofthefailuremode.,GeneralRatingofS,O,D,1.Omittedprocessing2.Processingerrors3.Errorssettingupworkpieces4.Missingparts5.Wrongparts6.Processingwrongworkpiece7.Mis-operation8.Adjustmenterror9.Equipmentnotsetupproperly10.Toolsand/orfixturesimproperlyprepared,11.Poorcontrolprocedures12.Improperequipmentmaintenance13.Badrecipe14.Fatigue15.LackofSafety16.Hardwarefailure17.Failuretoenforcecontrols18.Environment19.Stressconnections20.PoorFMEA(s).,ProcessFailureCauses,1.Standardizedworkinstructions/procedures2.Fixturesandjigs3.Mechanicalinterferenceinterfaces4.Mechanicalcounters5.Mechanicalsensors6.Electrical/Electronicsensors7.JobsheetsorProcesspackages8.Barcodingwithsoftwareintegrationandcontrol9.Marking10.Trainingandrelatededucationalsafeguards11.VisualChecks12.Gagestudies13.Preventivemaintenance14.Automation(RealTimeControl),ControlscanbeprocesscontrolssuchasfixturefoolproofingorSPC,orcanbepost-processinspection/testing.,Inspection/testingmayoccuratthesubjectoperationoratsubsequentoperation(s)thatcandetectthesubjectfailuremode.,ProcessControlExamples,TypicalProcessDocumentsSPCrecordsVisualaidesWorkinstructionsInspectioninstructions/recordsEquipmentoperatinginstructionsTrainingrecordsTraceabilityrecords,RecommendedActionsCorrectiveActionshouldbefirstdirectedatthehighestconcernsasrankorderedbyRPN.Theintentofanyrecommendedactionistoreducetheoccurrence,severityand/ordetectionrankings.Ifnoactionsarerecommendedforaspecificcause,thenthisshouldbeindicated.Onlyadesignrevisioncanbringaboutareductionintheseverityranking.Toreducetheprobabilityofoccurrence,processand/orspecificationrevisionsarerequired.Toincreasetheprobabilityofdetection,processcontroland/orinspectionchangesarerequired.Improvingdetectioncontrolsistypicallycostly.Theemphasisshouldbeplacedonpreventing,ratherthandetecting,defects.,Fault-treeanalysisisadeductiveprocessEspeciallyusefulforAnalyzingfailures,whenthecausesoffailureshavenotbeenidentifiedReliabilityengineeringToolMotorFailure,TheRoleandFunctionofFTA,MotorFailure,FaultTreeSymbolsTheEllipseThetopevent,theellipse,containsthedescriptionofthesystem-levelfaultorundesiredevent.Thissymbolappearsattheheadortopofthetreeandisincludedonlyonceinanytree.Theinputtotheellipseisfromalogicgate.TheRectangleThefaultevent,therectangle,containsabriefdescriptionofalower-levelfault.Thisdescriptionshouldbeshortwithoutbeingvague.Faulteventsappearthroughoutthetreeandhaveboththeirinputandoutputfromalogicgate.LogicGatesLogicGateinputsandoutputs,exceptfortheInhibitGate,whichisaddressedbelow,havesimilarconnections.TheoutputfromalogicgateistoanyfaulteventblockortoaTransferOutfunction.TheinputisfromanyfaulteventblockorfromaTransferInfunction.TheANDGateisthelogicgateinwhichtheoutputoccursonlyifallinputsexist.TheORGateisthelogicgateinwhichtheoutputoccursonlyifoneormoreoftheinputeventsoccur.,FaultTreeFundamentals1.DefiningtheUndesiredEvent(s)(MajorFault(s)a.Theundesiredeventismostoftenthefaultwhich,uponoccurrence,resultsincompletefailureofthesystem,thefailureofaback-upsystem,degradation,oranundetectedfailure.Thisisconsideredcatastrophicfailure.Themajorfaultisafailurewhichcauseslossofavailabilitythroughthedegradationorsystemshut-downand/orposesasafetyhazardtooperatorsand/ormaintenancepersonnel.Theundesiredevent,however,maybeanunusualfailureatasubsystemlevel,therootcauseofwhichisunknown.Anyobservableeventmaybechosenasthe“undesiredevent”.TheanalystmustrecognizethattheFTAwillnotidentifyfailuresunrelatedtothechosenevent.b.Todefinetheundesiredevent,thenormalsystemoperationandenvironmentmustbeknowninordertoallowtheanalysistoshowtheundesiredeventasafailure.Whendefiningtheundesiredevent,caremustbetakentopreventtherangeofthefaultsfrombecomingtoobroad.Forexample,“Failuretocompletetrip”,foranautomobile,isnotspecificenoughtoallowforeaseofanalysis.Thisisbecausefailurecouldvaryfromanairconditioningfault,whichcauseddiscomfort,tolossofenginepower,whichcausedlossofmobility.Bothfaultscouldbeconsideredfailure;however,lossofmobilityisobviouslyamuchmoreseverefaultthanlosingairconditioning.,FaultTreeFundamentals(Continued1)2.DefiningTypesofFaultsFaultsfallintotwobasiccategories:operationalandcomponent.OperationFaultTheoperationalfaultisonewhichoccurswhenacomponentisoperatingasitwasdesignedto,butataninappropriatetimeorplace.Anexampleisafailureofacontrolvalvetocloseortointerrupttheintroductionofareactantintoachemicalprocessduetoaninappropriatesignalfromanotherdevice.ComponentFaultThecomponentfaultcanbefurtherdividedintotwosub-categories:primaryandsecondary.APrimarycomponentfaultoccurswhenacomponentfailstofunctioninitsintendedenvironment.Example:Aradarunitdesignedforuseinaircraftwhichfailsduetovibration.ASecondarycomponentfailureoccurswhenacomponentfailstofunctioninanenvironmentotherthantheenvironmentforwhichitisintended.Example:Aradarunitdesignedforacargoaircraftfailsinafighteraircraftduetovibration.,FaultTreeFundamentals(Continued2)3.ComparisonofFaultOccurrenceandFaultExistenceThetermFaultOccurrencereferstothefactthatanundesiredeventhastakenplaceandmayormaynotstillexist.FaultExistence,however,impliesthatthefaulthasoccurredandcontinuestoexist.Therefore,thefaultcanbedescribedasbeingeithertransientorpermanent.Duringtheconstructionofthefaulttree,allsystemsanalystsshoulduseFaultOccurrence,ratherthanFaultExistence,asthefocusofinterest.4.ComparisonofFailureCausesandFaultEffectsAfailureisconsideredtobeaninabilitytoperformanormalfunction.Example:Valvedoesnotopen.AfaultisahigherlevelOccurrencewhichisusuallyprecededbyalower-levelfailure,suchasacasingcrackingduetooverheatingbecauseofalackofcoolantinductionduetoaninoperablevalve(lowerleveloffailure).However,afaultmayalsooccurwhennofailureispresent.Example:Coolantvalveoperatesproperly,butthesignaltooperateitencountersadelay.Afaulthasoccurred,butthereisnovalvefailure.Becauseofthis,itcanbestatedthatanyfailurecausesafault,butnoteveryfaultiscausedbyafailure.FailureCategories:a.Component,b.Environment,c.Human,d.Software.,FaultTreeConstructionStepsSummaryDeterminetheleveltowhichtheexaminationshouldbeconstructedBeginwiththesystem-levelfaultFullydescribealleventswhichimmediatelycausethiseventWitheachlower-levelfault,continuedescribingitsimmediatecausesuntilacomponentlevelfailureorhumanerrorcanbeattributedtothefault,FaultTreeConstructionStepsSummary(continued)FullydefineeachbranchofthetreebeforebeginninganotherbranchDuringtheconstructionofthetree,itisadvisabletouseablockdiagramofthesystemtosimplifydeterminingthemainbranchesIftheresultsoftheFMECAonthesystemareavailableatthetimeoftheFTAitisadvisabletousetheresultsindefiningthetopevent(s),AnalyzingtheFaultTree1.Determinetheminimalcut-setstosimplifythetree(qualitativeanalysis).2.Determinetheprobabilityofeachinputevent3.Combinetheprobabilityinputstologicgatesasfollows:a.ANDGate-Theprobabilityofoutputistheproductoftheprobabilitiesoftheinputs(P0=Pi1Pi2.Pin)b.ORGate-Theprobabilityofoutputisthesumoftheprobabilitiesoftheinputs(P0=Pi1+Pi2.Pin)4.Combinethegateinputprobabilitiesuntiltheprobabilityofthetopeventisdetermined.,Identifythesystemorequipmentlevelfaultstate(s)undesiredevent(s)ConstructthefaulttreePerformtheanalysistothecomponentlevel,Fault-TreeAnalysisProcedures,CriteriaforIdentifyingtheUndesiredEventThetopeventmustbemeasurableanddefinableThetopeventmustbeinclusiveofthelowereventsThetopeventistheresultofthelowerevents,CluesaboutCausesCananyequipmentfailurescontributetothiseffect?Materialfaults?Humanerrors?MethodsandProcedures?Softwareperformance?Maintenanceerrorsortheabsenceofmaintenance?Inaccuraciesormalfunctionofmeasurementdevice(s)?Environmentssuchaschemicals,dust,vibration,shockand/ortemperature?,Errors1Almostallerrorsarecausedbyhumanerror.Forgetfulness-Sometimesweforgetthingswhenwearenotconcentrating.Example:Apersonforgetstosethis/heralarmclockatnight.Safeguard:Establisharoutinewhichincludescheckingbeforegoingtobed.Errorsduetomisunderstanding-Sometimeswemakemistakeswhenwejumptothewrongconclusionbeforewerefamiliarwiththesituation.Example:Apersonusedtoastickshiftpushesthebrakepetalinanautomaticthinkingitistheclutch.Safeguards:Training,checkinginadvance,standardizingworkprocedures.Errorsinidentification-Sometimeswemisjudgeasituationbecauseweviewittooquicklyoraretoofarawaytoseitclearly.Forexample,a$1billismistakenfora$10bill.Safeguards:Training,attentiveness,vigilance.,Errors2Errorsmadebyamateurs-Sometimeswemakemistakesth