FMEA在生产管理质量中的作用英文

FMEASteps

1 DefinethescopefortheFMEA2 Identifyteammembers,customer,andknowledgeexperts3 Developrolesandresponsibilitiesforteammembers4 Studytheproduct/process/service5 DevelopratingscalesforSeverity,Occurrence,andDetection6 Brainstormfailuremodes,knownandpotential7 Listtheeffects,causes,andcurrentcontrolsforeachfailuremode8 AssignratingsforSeverity,Occurrence,andDetection9 CalculateRPN10 DecideonathresholdRPN11 PrioritizebasedonRPNandseverity,orasrequiredbythecustomer12 Identifycorrectiveactions13 Implementandverifyeffectivenessofcorrectiveaction14 Completethedocumentation1 DefinethescopefortheFMEA

Definetheboundarieswithinwhichtheproduct,process,orservicewillbe studied,identifyingtheoperatingassumptions,currentconditions,and constraintsifany.

Example1: ConductaProcessFMEAonPCBmanufacturingline1,startingwith operation10andendingwithoperation250. Theassumptionisthatdesignofpartsiscorrect,andnoshortages Thelineissetupasshowninprocessflowdrawing#809901 Example2: ConductDesignFMEAonthepressurereliefvalve(Part#JJJKKK) forpotentialfailuresunderextremeoperatingconditions Assumenopreventivemaintenancewillbeconductedonceinstalled

DocumentontheFMEAstartupform

FMEA;StepbyStep

ScopeoftheFMEAPointstoconsider:WhoarethecustomersfortheFMEA,andwhataretheirrequirements/expectationsExample:Conduct(Process)FMEAontheassemblylineforProductA,coveringoperations110through230 WhenwillthisFMEAbeconsideredcompleteunderthegivenconditions(Remember,FMEAsareconsideredlivingdocuments,assuchtheyneedtobeupdated/revisedasthingschange.)Example:FMEAwillbeconsideredcompletewhentheteamhasimplementedallcorrectiveactionsasagreeduponbasedontheRPNthreshold

Thiswillformthebasisfordecidingthelevelatwhichyoushouldconduct theFMEA,andthescopeofworkinvolved..SystemSubsystemComponentProcessServiceLevel Focus Failure Cause Effect ModeSystem Car Overheating Coolingsyst. Strandedon failure theroad SubSystem CoolingSystem Inadequate Thermostat CarOverheating coolantflow stuckclosedSubAssembly Thermostat Stuckclosed BiMetalSpring Inadequate broken coolantflowComponent BiMetalSpring Broken Fatigue Thermostat stuckclosed Important:Youmustbeabletoseeacascadingoffailuremodes,causes,andeffectssimilartoaboveExampleofaProduct

Safety,LubricationEngine,Braking,ExhaustTrans.,Cooling

Thermostat

Diaphragm,BiMetalSpringRadiatorPumpVBeltTheInfluenceofLevel

CompanyPlant1 Plant2 Plant3 Plant4PCBLine PowerSupplies FHPMotorsOp10 Op20 …. …. Op250FMEAcanbeconductedatanyoftheselevels;italldependsonyourobjectiveTheInfluenceofLevelLevel Focus Failure Cause Effect ModeSystem Factory(Plant2) LatedeliveriesLowFPY Lost tocustomer onLine2 business

SubSystem Line2(PowerSupplies) LowFPY HighRework Latedeliveries at/aftertesting Operation Testing Highrework Testingresults LowFPY Op210 inconsistent

ExampleofaProcessOp120OpA20OpA10Op10Op210Op240Op250Important:Youmustbeabletoseeacascadingoffailuremodes,causes,andeffectssimilartoaboveTheInfluenceofLevel2 Identifyteammembers,customer,andknowledgeexpert/sGettheteamtogether,identifythecustomerandinvolvethemintheprocess.Somepreliminaryworkmustbedonetounderstandtheproduct/process/service,sotherightteamcanbeassembled.

Example: TeammembersincludeJohnPatton,KiritChawla(Customerrep)KimHeaston,andBettyChung(TeamLead)Nooneknowsenoughabouttheprocessatthistime.DocumentontheFMEAstartupform

FMEA-StepbyStep3

Developrolesandresponsibilitiesforteammembers

Whodoeswhatintheteam.Clearlydefinetherolesandresponsibilities foreachoftheteammembers.Atthistime,itisimportanttoconsiderthe strengthsofeachindividualandleveragethesame.

Example: TeamLead: Coordinatetheactivitiesoftheteam,andkeepontrack Actascheerleader,andinterfacewithmanagement Ensurethedecisionsaremadewithconsensus

Customer: Definerequirements Participateindevelopingratingscales,especiallyfor SeverityKnowledge Expert: Asconsultantprovideinfoondetailsofproduct/ processorservice

FMEA-StepbyStep4 StudytheProduct/Process/Service

Theobjectiveofthisstepistoacquireasmuchknowledgeaspossible. Itishighlyrecommendedthatallteammembersdelveintothis,since thereisnootherwaytofamiliarizeyourselfwiththeproduct/process/service.

Example1: TheteamresponsibleforconductingProcessFMEAongaspanels productionlinespends2weeksonthelinebuildinggaspanels, andtestingthesame.

Example2: TheFMEAteamresponsibleforDesignFMEAonamedicalimplant studiesthewaytheproductisgoingtobehandledinthe operatingroom,andusedbythesurgeon.

Example3: FouroutoffivemembersoftheFMEAteamspend3dayswiththe phoneoperators,andorderprocessinggrouptogetfirsthand understandingofallthestepsinvolvedinbookinghotelrooms.FMEA-StepbyStep

5 DevelopratingscalesforSeverity,Occurrence,andDetection Onceyouhavegainedenoughknowledgeabouttheproduct/process/service andaboutthewayitmaybeusedbythecustomer/enduser,youarein apositiontodevelopmeaningfulratingscales. Mostratingscalesareonascalefrom1to10,howeversomemayusea1to5 scale.Whichofthetwo,islessimportantthanensuringthatthesamescale isusedthroughoutthecompany. Youmayhavetodevelop/adaptthescalestosuityourneeds Forexamples,seenextpageFMEA-StepbyStepCausesFailureModes*EffectsOccurrenceDetectionSeverityHowfrequent?Whohasthemostinfo?Ifeliminated,willfailurebeavoided?Howeasytodetectwithcurrentcontrols?Whohasthemostinfo?Ifpreventedwilleffectsbeeliminated?Howsevere?Whohasthemostinfo?QuantifyingFailureModes,EffectsandCauses*CausesmaybeusedinplaceofFailureModesinsomecases5DevelopratingscalesforSeverity,Occurrence,andDetectionExamplefromDesignFMEA:SeverityOccurrenceDetectionEffectCauseFailureModeorCause1Remotechance,<1ppm2Verylow1to53Verylow5to104Moderate10to1005Moderate100to1K6High1Kto10K7High10Kto100K8VeryHigh100Kto1M9VeryHigh1Mto10M10Almostcertain…………..1Certaintobedetected2Veryhighchanceofdetection3Highchanceofdetection4Moderatelyhighchanceof..5Moderatechanceofdetection6Lowchanceofdetection7Verylowchanceof...8Remotechanceof…….9Veryremotechanceof...10Slipsbyundetected1Noeffect2Minoreffect-fit/cosmetics3Majoreffect-fit/cosmetics4MinorreductioninFunction5Customerdissatisfied6Majorreductioninfunction7Totallydysfunctional8Presentsminorhazard9Presentsinjuryhazard10FatalifusedNOTE:TheabovewereusedbytheauthorwithamanufacturerofhomeelectricalappliancesforaDesignFMEAFMEA-StepbyStep5DevelopratingscalesforSeverity,Occurrence,andDetectionExamplefromProcessFMEA:Severity-effect1Noeffectonoperators,users,orcurrentanddownstreamprocesses2Minorreworkatcurrentstep/nodysfunctionintroducedinproduct3Reworkatcurrent/subsequentstepscausingsomedelayedschedules,orproductisrenderedpartiallydysfunctional4Heavyreworkatsubsequentoperation,majordelaysinschedules,orproductfunctionisseverelyimpacted5RiskofinjuryorfatalOccurrence-cause1Veryrareoccurrence,X00ppboroncein3to5years2Rareoccurrence,XtoX000ppm,2to5occurrencesin3years3Frequentoccurrence,X000toX0,000ppm,1to3occurrencesin1year4Highfrequencyofoccurrence,X0,000toXMppm,over4occurrencesperyear5AlmostcertainDetection-failuremode(orcauseinsomecases)1Certaintobedetected,beforeanymeasurabledamageisdone2Automatedinspection/detectionorstrongprocesscontrolsexistatcurrentsteporwithinthesystemboundaries3Samplingplansusedforinspectionpurposes4100%manualinspectionmethodsusedwithinsystemboundaries5Defectunlikelytobedetected,willslipbyunnoticedNOTE:TheabovewereadaptedfromoneoftheProcessFMEAapplicationsledbytheauthor5DevelopratingscalesforSeverity,Occurrence,andDetectionSeverityOccurrenceDetectionEffectCauseFailureModeorCauseNOTE:ThisblankisforusebyparticipantsinclassFMEA-StepbyStep6Brainstormfailuremodes,knownandpotentialFailuremodesshouldbedescribedin““physical”ortechnicalterms,notasasymptomnoticeablebythecustomer.Theideaistoidentifyasmanyfailuremodesaspossible.Thiswillinvolvegettingallteammembersandstakeholdersinvolved,however,theproperapproachtobrainstormingmustbeused.Deferalljudgment,maybeeventoasubsequentmeeting.Thebiggestriskinthisstepisthatparticipantswillstartmixingupfailuremodeswithcauses,andeffects.Topreventthis,itishighlyrecommendedthatthemeetingleaderdoadryruntofamiliarizethegroupwiththedifferencesbetweenfailuremodes,effects,andcauses.Alistingoftheproduct/process/services’specifications,oroutputsandrequirementswillbenefithere..Postitpadsareaconvenientwayofcollectingthisinformation,andgroupingitintologicalgroups.Ifyouwritetheseonaworksheet,makesureyouleaveenoughspaceforeffectsandcausesFMEA-StepbyStep6Brainstormfailuremodes,knownandpotentialfortheProduct/DesignExample:OverheatingSlowaccelerationSkidsCatchesfireExcessivestoppingdistancePoorgasmileageWobbles50mphPoorcorneringOilleakRattlingofreardoorLatchdoesnotholdWipersineffectiveHorndoesn’tworkStiffsteeringandsoon…..Question:Arealltheabovefailuremodesforthecar?FMEA-StepbyStep

CausesFailureModesEffectsCarandit’sperformancerequirementsUsers/Customers

Componentparts,&sub-systems

Leadto LeadtoKeepingadistinctionbetweenthethreewillpreventyoufromgettingintocircularloops.Whenyousensegettingintosuchaloop,askWhatproduct/designistheFMEAbeingconductedon(focus)?Whataretheperformancerequirements/specificationsofthe(focus)?SeparatingFailureModes,EffectsandCauses6Brainstormfailuremodes,knownandpotentialfortheProcess:Example:ExcessivebacklashNoiseexceedsspecificationsDefectsperunit25%inexcessofstandardTestfixtureoperationunsafeOilleaksQuestion:Arealltheabovefailuremodesfortheprocess?Op120OpA20OpA10Op10Op210Op240Op250MachineWeldbracketsIntegrationTestingCrate&ShipAssembleAxleMountWheelsSystemBoundariesFMEA-StepbyStep

CausesFailureModesEffectsOperation240Users/Customers/OperatorsDownstreamoperationsPlantdeliverables

WorkinstructionsOperatorerrorsPrioroperations

Leadto LeadtoKeepingadistinctionbetweenthethreewillpreventyoufromgettingintocircularloops.(EffectsofFailurearedefinedastheeffectsofthefailuremodeonthefunction,asperceivedbythecustomer.)Whenyousensegettingintosuchaloop,askWhatpartoftheprocessistheFMEAbeingconductedon(focus)?Whataretheperformancerequirements/specificationsofthe(focus)?SeparatingFailureModes,EffectsandCausesFailureMode2Cause1Cause2Cause3Cause4Effect1Effect2Effect3FailureMode1FailureMode3Multiplicitywillexistforcauses,failuremodes,andeffects(CauseofFailureisdefinedasanindicationofadesignweakness,theconsequenceofwhichisthefailuremode.)FailureModes:Willsharecauses,andeffectsCauses:Thereasonsforfailure,canbeoneormanyforagivenfailuremodeEffects:Theresultsofthefailure,canbeoneormanyforagivenfailuremodeSeparatingFailureModes,EffectsandCausesProductFMEAOverheatingBrakesbindingCause2LowtirepressureCause4PoorGasMileageStalledonroadEffect3PooraccelerationFailureMode3CauseFailureModeEffectSeparatingFailureModes,EffectsandCausesProcessFMEAImproperSeatingMissingInstructionsCause2LooseNutsCause4FailstorquetestUnsafeatTestingEffect3AssembledbackwardsFailureMode3CauseFailureModeEffectSeparatingFailureModes,EffectsandCauses7Listtheeffects,causes,andcurrentcontrolsforeachfailuremodeTocapturetheeffects,causes,andexistingcontrolsifanyforthefailuremodeinquestion.Inputfromcustomer,knowledgeexpertswillbeespeciallyhelpfulatthisstep.Caution:Manyteamscommiterrorsofwishfulthinkinghere,especiallywithregardtocurrentcontrols.Youshouldfocusonthecurrentstate,andnotonwhatcouldbedone,orwhatoughttobedone.Nowstartdocumentingontheworksheet,knowingthateachfailuremodecanhavemultipleeffects,andmultiplecauses.FMEA-StepbyStep7Listtheeffects,causes,andcurrentcontrolsforeachfailuremodeExample:FMEA-StepbyStep8AssignratingsforSeverity,Occurrence,andDetectionHereweaccomplishtheconversionofeachofthesefactorsintoanumericalvalue.Dependingonthequalityoftheratingscalesthisstepcanbeveryeasyorsomewhatfrustrating.Therewillbetimeswhentheteamwilldisagreeonthevaluesassignedtoaparticularcause,effect,orfailuremode.Ratherthanvoting,itisrecommendedthattheteamtrytoreachconsensus.Incaseofdisagreements,knowledgeexpert’’sopinioncanbeusedtoincreaseunderstanding,ormoredatacanbesought.Inanycasetheteam’sdecisionshouldprevail.DocumentontheworksheetFMEA-StepbyStep8AssignratingsforSeverity,Occurrence,andDetectionExample:FMEA-StepbyStep9CalculateRPNSimplyassigningratingsforSeverity,Occurrence,andDetectiondoesn’thelpquantifytheriskintoasinglemeasurablevalue.Multiplyingtheratingscoresthusfillsthisgap.NotethatinthisapproachwehavemaintainedequalweightforeachofthethreeS,O,andD.Example:FMEA-StepbyStep10DecideonathresholdRPN,withoutignoringhighseverityfailuremodesIdentifythefailuremodesyouwillchoosetoworkon.Itmaynotbepracticaltoaddressallofthem.Thiscriticalstepmustbeconductedwithcustomerinvolvement,andconsensusbuilding.Manyteamsrunintodifficultieshere,especiallywhenthecustomerinsistsallitemsneedtobeaddressed.Itneedstobeunderstoodthatsomeelementofriskwillalwaysbepresent.Thequestionthereforeis“Whatlevelofriskisacceptable”?Someofthedifferentapproachesthathavebeenusedtodefinethethresholdare;ParetoAnalysis,Topcauseforeachfailuremode,etc.DocumentonFMEAstartupformtoindicatethiswasdiscussed,andagreementreachedonthethresholdvalue.FMEA-StepbyStep10DecideonathresholdRPN,withoutignoringhighseverityfailuremodesExampleusingParetoChart:CausesCumulativeRPNCumulativeRPNCurve80%ofCumulativeRPNFMEA-StepbyStep10DecideonathresholdRPN,withoutignoringhighseverityfailuremodesExampleusingRPN>=200foreachfailuremode:FMEA-StepbyStep11PrioritizebasedonRPNandseverity,orasrequiredbycustomerArriveattheorderinwhichyouwillstartaddressingthefailuremodesandcausesforcorrectiveaction.AlthoughRPNandseveritybasedprioritizationseemsthemostlogical,yourdecisiontoproceedmustbemadewithcustomerinput.Thisstepiseasilyaccomplishedbysortingthedata,indescendingorder.Youcandothiswithineachfailuremodetomaintaindataintegrity.Documentationonworksheetisimportanttoensurethewholeteamisinsync.FMEA-StepbyStep11PrioritizebasedonRPNandseverity,orasrequiredbycustomerExampleofsortedworksheetbyRPNwithineachfailuremodeFMEA-StepbyStep12IdentifycorrectiveactionInthisstepyouidentifythecorrectiveactionsneededtoeliminate/controlthecauses,andreducetheriskleveltoorbelowtheagreeduponthreshold.Therewillbetimeswhenyoucannotworkontherootcause;insuchcasesthebestcourseofactionwillbeviaadditionofcontrols/adequatewarningdevices/mechanismsofimpendingfailure.Re-evaluatetheratingsforS,O,andD,followedbyRPNcalculation.Discussionwiththecustomerisimportantagainsincethecorrectiveactionswillimpactthem.Knowledgeexpertsmayalsoprovidevaluableinputastowhatkindsofcorrectiveactionwillbebestsuitedforthegivencause/failuremode.Finally,fromallpossiblecorrectiveactions,theteammaychooseonebasedoncost/benefitanalysis,speedofimplementation,andthenewlevelofrisk.FMEA-StepbyStep12IdentifycorrectiveactionExample-allcauseswithRPN>=200areaddressed:FMEA-StepbyStep12IdentifycorrectiveactionQuestions:Whydidthecauseofworntireshaveanactionitem,althoughtheRPNwas160?TraininginadvanceddrivingtechniquesreducestheRPNfrom350to200,shouldheteamstophere?Whyisitthattheseverityratingdoesnotreducealthoughtraininginadvanceddrivingtechniquesisprovided?Doyouthinktheteam’sworkisdone?13ImplementandverifytheeffectivenessofcorrectiveactionCorrectiveactionsidentifiedoughttobeimplementedlikeprojects-withadefinitestartandend.Inmanycasesaprojectteamsmaybeformedtocarryouttheimplementation.TheseprojectteamsmayhavemembersfromoutsidetheFMEAteam,howeveratleastonemembershouldbedrawnfromtheFMEAteam.Acheckontheeffectivenessofthecorrectiveactionisimportant,intheabsenceofwhichyouwillnothaveaclosedloopfeedbackonwhatreallytranspired.ThischeckshouldbeconductedbytheFMEAteamafterthecorrectiveactionshavebeeninplaceforsometime.Thisissobecausethecorrectiveaction,likeachange,maynotlast.Ittakesdiligentefforttoensurethechangewillhavepermanence.Ifthecorrectiveactionisnoteffectiveenough,youmayneedtoimplementsomemorecontrols/takemoreactions.13ImplementandverifytheeffectivenessofcorrectiveactionExampleofadditionalactiontakentoreduceriskfromdrivinghabits:14Completethedocumentationandsaveinarchives/databasesThislaststepisoverlookedbymanyoftheFMEAteams.Whileitisunderstandablethatthenextprojectneedstobeworkedon,itisalsoimportantnottolosetheknowledgegainedbytheteam.Thebestwaytodocumentistousearchivingsystemsinthecompanyiftheyexist,electronicstorageisnowacceptedbymostregulatoryagenciesnow.Itemsthatshouldbesavedinclude:FMEAstartupformFMEAworksheetsMeetingminutesProcessflowDesignspecs,andvoiceofcustomerDetailsofprojectscreatedandimplementedaspartofactionitemsPortab