FMEA在生产管理质量中的作用英文版)pp.ppt

FMEASteps 1DefinethescopefortheFMEA2Identifyteammembers customer andknowledgeexperts3Developrolesandresponsibilitiesforteammembers4Studytheproduct process service5DevelopratingscalesforSeverity Occurrence andDetection6Brainstormfailuremodes knownandpotential7Listtheeffects causes andcurrentcontrolsforeachfailuremode8AssignratingsforSeverity Occurrence andDetection9CalculateRPN10DecideonathresholdRPN11PrioritizebasedonRPNandseverity orasrequiredbythecustomer12Identifycorrectiveactions13Implementandverifyeffectivenessofcorrectiveaction14Completethedocumentation 1DefinethescopefortheFMEADefinetheboundarieswithinwhichtheproduct process orservicewillbestudied identifyingtheoperatingassumptions currentconditions andconstraintsifany Example1 ConductaProcessFMEAonPCBmanufacturingline1 startingwithoperation10andendingwithoperation250 Theassumptionisthatdesignofpartsiscorrect andnoshortagesThelineissetupasshowninprocessflowdrawing 809901Example2 ConductDesignFMEAonthepressurereliefvalve Part JJJKKK forpotentialfailuresunderextremeoperatingconditionsAssumenopreventivemaintenancewillbeconductedonceinstalledDocumentontheFMEAstartupform FMEA StepbyStep ScopeoftheFMEA Pointstoconsider WhoarethecustomersfortheFMEA andwhataretheirrequirements expectationsExample Conduct Process FMEAontheassemblylineforProductA coveringoperations110through230WhenwillthisFMEAbeconsideredcompleteunderthegivenconditions Remember FMEAsareconsideredlivingdocuments assuchtheyneedtobeupdated revisedasthingschange Example FMEAwillbeconsideredcompletewhentheteamhasimplementedallcorrectiveactionsasagreeduponbasedontheRPNthreshold ThiswillformthebasisfordecidingthelevelatwhichyoushouldconducttheFMEA andthescopeofworkinvolved LevelFocusFailureCauseEffectModeSystemCarOverheatingCoolingsyst StrandedonfailuretheroadSubSystemCoolingSystemInadequateThermostatCarOverheatingcoolantflowstuckclosedSubAssemblyThermostatStuckclosedBiMetalSpringInadequatebrokencoolantflowComponentBiMetalSpringBrokenFatigueThermostatstuckclosed Important Youmustbeabletoseeacascadingoffailuremodes causes andeffectssimilartoabove TheInfluenceofLevel CompanyPlant1Plant2Plant3Plant4 PCBLinePowerSuppliesFHPMotors Op10Op20 Op250 FMEAcanbeconductedatanyoftheselevels italldependsonyourobjective TheInfluenceofLevel LevelFocusFailureCauseEffectModeSystemFactory Plant2 LatedeliveriesLowFPYLosttocustomeronLine2businessSubSystemLine2 PowerSupplies LowFPYHighReworkLatedeliveriesat aftertestingOperationTestingHighreworkTestingresultsLowFPYOp210inconsistent ExampleofaProcess Op120 OpA20 OpA10 Op10 Op210 Op240 Op250 Important Youmustbeabletoseeacascadingoffailuremodes causes andeffectssimilartoabove TheInfluenceofLevel 2Identifyteammembers customer andknowledgeexpert sGettheteamtogether identifythecustomerandinvolvethemintheprocess Somepreliminaryworkmustbedonetounderstandtheproduct process service sotherightteamcanbeassembled Example TeammembersincludeJohnPatton KiritChawla Customerrep KimHeaston andBettyChung TeamLead Nooneknowsenoughabouttheprocessatthistime DocumentontheFMEAstartupform FMEA StepbyStep 3DeveloprolesandresponsibilitiesforteammembersWhodoeswhatintheteam Clearlydefinetherolesandresponsibilitiesforeachoftheteammembers Atthistime itisimportanttoconsiderthestrengthsofeachindividualandleveragethesame Example TeamLead Coordinatetheactivitiesoftheteam andkeepontrackActascheerleader andinterfacewithmanagementEnsurethedecisionsaremadewithconsensusCustomer DefinerequirementsParticipateindevelopingratingscales especiallyforSeverityKnowledgeExpert Asconsultantprovideinfoondetailsofproduct processorservice FMEA StepbyStep 4StudytheProduct Process ServiceTheobjectiveofthisstepistoacquireasmuchknowledgeaspossible Itishighlyrecommendedthatallteammembersdelveintothis sincethereisnootherwaytofamiliarizeyourselfwiththeproduct process service Example1 TheteamresponsibleforconductingProcessFMEAongaspanelsproductionlinespends2weeksonthelinebuildinggaspanels andtestingthesame Example2 TheFMEAteamresponsibleforDesignFMEAonamedicalimplantstudiesthewaytheproductisgoingtobehandledintheoperatingroom andusedbythesurgeon Example3 FouroutoffivemembersoftheFMEAteamspend3dayswiththephoneoperators andorderprocessinggrouptogetfirsthandunderstandingofallthestepsinvolvedinbookinghotelrooms FMEA StepbyStep 5DevelopratingscalesforSeverity Occurrence andDetectionOnceyouhavegainedenoughknowledgeabouttheproduct process serviceandaboutthewayitmaybeusedbythecustomer enduser youareinapositiontodevelopmeaningfulratingscales Mostratingscalesareonascalefrom1to10 howeversomemayusea1to5scale Whichofthetwo islessimportantthanensuringthatthesamescaleisusedthroughoutthecompany Youmayhavetodevelop adaptthescalestosuityourneedsForexamples seenextpage FMEA StepbyStep CausesFailureModes EffectsOccurrenceDetectionSeverity Howfrequent Whohasthemostinfo Ifeliminated willfailurebeavoided Howeasytodetectwithcurrentcontrols Whohasthemostinfo Ifpreventedwilleffectsbeeliminated Howsevere Whohasthemostinfo QuantifyingFailureModes EffectsandCauses CausesmaybeusedinplaceofFailureModesinsomecases 5DevelopratingscalesforSeverity Occurrence andDetectionExamplefromDesignFMEA SeverityOccurrenceDetectionEffectCauseFailureModeorCause 1Remotechance 1ppm2Verylow1to53Verylow5to104Moderate10to1005Moderate100to1K6High1Kto10K7High10Kto100K8VeryHigh100Kto1M9VeryHigh1Mto10M10Almostcertain 1Certaintobedetected2Veryhighchanceofdetection3Highchanceofdetection4Moderatelyhighchanceof 5Moderatechanceofdetection6Lowchanceofdetection7Verylowchanceof 8Remotechanceof 9Veryremotechanceof 10Slipsbyundetected 1Noeffect2Minoreffect fit cosmetics3Majoreffect fit cosmetics4MinorreductioninFunction5Customerdissatisfied6Majorreductioninfunction7Totallydysfunctional8Presentsminorhazard9Presentsinjuryhazard10Fatalifused NOTE TheabovewereusedbytheauthorwithamanufacturerofhomeelectricalappliancesforaDesignFMEA FMEA StepbyStep 5DevelopratingscalesforSeverity 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 willslipbyunnoticed NOTE TheabovewereadaptedfromoneoftheProcessFMEAapplicationsledbytheauthor 5DevelopratingscalesforSeverity Occurrence andDetection SeverityOccurrenceDetectionEffectCauseFailureModeorCause NOTE Thisblankisforusebyparticipantsinclass FMEA StepbyStep 6Brainstormfailuremodes knownandpotentialFailuremodesshouldbedescribedin physical ortechnicalterms notasasymptomnoticeablebythecustomer Theideaistoidentifyasmanyfailuremodesaspossible Thiswillinvolvegettingallteammembersandstakeholdersinvolved however theproperapproachtobrainstormingmustbeused Deferalljudgment maybeeventoasubsequentmeeting Thebiggestriskinthisstepisthatparticipantswillstartmixingupfailuremodeswithcauses andeffects Topreventthis itishighlyrecommendedthatthemeetingleaderdoadryruntofamiliarizethegroupwiththedifferencesbetweenfailuremodes effects andcauses Alistingoftheproduct process services specifications oroutputsandrequirementswillbenefithere Postitpadsareaconvenientwayofcollectingthisinformation andgroupingitintologicalgroups Ifyouwritetheseonaworksheet makesureyouleaveenoughspaceforeffectsandcauses FMEA StepbyStep 6Brainstormfailuremodes knownandpotentialfortheProduct DesignExample OverheatingSlowaccelerationSkidsCatchesfireExcessivestoppingdistancePoorgasmileageWobbles50mphPoorcorneringOilleakRattlingofreardoorLatchdoesnotholdWipersineffectiveHorndoesn tworkStiffsteeringandsoon Question Arealltheabovefailuremodesforthecar FMEA StepbyStep Keepingadistinctionbetweenthethreewillpreventyoufromgettingintocircularloops Whenyousensegettingintosuchaloop askWhatproduct designistheFMEAbeingconductedon focus Whataretheperformancerequirements specificationsofthe focus SeparatingFailureModes EffectsandCauses 6Brainstormfailuremodes knownandpotentialfortheProcess Example ExcessivebacklashNoiseexceedsspecificationsDefectsperunit25 inexcessofstandardTestfixtureoperationunsafeOilleaksQuestion Arealltheabovefailuremodesfortheprocess FMEA StepbyStep Keepingadistinctionbetweenthethreewillpreventyoufromgettingintocircularloops EffectsofFailurearedefinedastheeffectsofthefailuremodeonthefunction asperceivedbythecustomer Whenyousensegettingintosuchaloop askWhatpartoftheprocessistheFMEAbeingconductedon focus Whataretheperformancerequirements specificationsofthe focus SeparatingFailureModes EffectsandCauses Multiplicitywillexistforcauses failuremodes andeffects CauseofFailureisdefinedasanindicationofadesignweakness theconsequenceofwhichisthefailuremode FailureModes Willsharecauses andeffectsCauses Thereasonsforfailure canbeoneormanyforagivenfailuremodeEffects Theresultsofthefailure canbeoneormanyforagivenfailuremode SeparatingFailureModes EffectsandCauses ProductFMEA CauseFailureModeEffect SeparatingFailureModes EffectsandCauses ProcessFMEA ImproperSeating MissingInstructions Cause2 LooseNuts Cause4 Failstorquetest UnsafeatTesting Effect3 Assembledbackwards FailureMode3 CauseFailureModeEffect SeparatingFailureModes EffectsandCauses 7Listtheeffects causes andcurrentcontrolsforeachfailuremodeTocapturetheeffects causes andexistingcontrolsifanyforthefailuremodeinquestion Inputfromcustomer knowledgeexpertswillbeespeciallyhelpfulatthisstep Caution Manyteamscommiterrorsofwishfulthinkinghere especiallywithregardtocurrentcontrols Youshouldfocusonthecurrentstate andnotonwhatcouldbedone orwhatoughttobedone Nowstartdocumentingontheworksheet knowingthateachfailuremodecanhavemultipleeffects andmultiplecauses FMEA StepbyStep 7Listtheeffects causes andcurrentcontrolsforeachfailuremodeExample FMEA StepbyStep 8AssignratingsforSeverity Occurrence andDetectionHereweaccomplishtheconversionofeachofthesefactorsintoanumericalvalue Dependingonthequalityoftheratingscalesthisstepcanbeveryeasyorsomewhatfrustrating Therewillbetimeswhentheteamwilldisagreeonthevaluesassignedtoaparticularcause effect orfailuremode Ratherthanvoting itisrecommendedthattheteamtrytoreachconsensus Incaseofdisagreements knowledgeexpert sopinioncanbeusedtoincreaseunderstanding ormoredatacanbesought Inanycasetheteam sdecisionshouldprevail Documentontheworksheet FMEA StepbyStep 8AssignratingsforSeverity Occurrence andDetectionExample FMEA StepbyStep 9CalculateRPNSimplyassigningratingsforSeverity Occurrence andDetectiondoesn thelpquantifytheriskintoasinglemeasurablevalue Multiplyingtheratingscoresthusfillsthisgap NotethatinthisapproachwehavemaintainedequalweightforeachofthethreeS O andD Example FMEA StepbyStep 10DecideonathresholdRPN withoutignoringhighseverityfailuremodesIdentifythefailuremodesyouwillchoosetoworkon Itmaynotbepracticaltoaddressallofthem Thiscriticalstepmustbeconductedwithcustomerinvolvement andconsensusbuilding Manyteamsrunintodifficultieshere especiallywhenthecustomerinsistsallitemsneedtobeaddressed Itneedstobeunderstoodthatsomeelementofriskwillalwaysbepresent Thequestionthereforeis Whatlevelofriskisacceptable Someofthedifferentapproachesthathavebeenusedtodefinethethresholdare ParetoAnalysis Topcauseforeachfailuremode etc DocumentonFMEAstartupformtoindicatethiswasdiscussed andagreementreachedonthethresholdvalue FMEA StepbyStep 10DecideonathresholdRPN withoutignoringhighseverityfailuremodesExampleusingParetoChart FMEA StepbyStep 10DecideonathresholdRPN withoutignoringhighseverityfailuremodesExampleusingRPN 200foreachfailuremode FMEA StepbyStep 11PrioritizebasedonRPNandseverity orasrequiredbycustomerArriveattheorderinwhichyouwillstartaddressingthefailuremodesandcausesforcorrectiveaction AlthoughRPNandseveritybasedprioritizationseemsthemostlogical yourdecisiontoproceedmustbemadewithcustomerinput Thisstepiseasilyaccomplishedbysortingthedata indescendingorder Youcandothiswithineachfailuremodetomaintaindataintegrity Documentationonworksheetisimportanttoensurethewholeteamisinsync FMEA StepbyStep 11PrioritizebasedonRPNandseverity orasrequiredbycustomerExampleofsortedworksheetbyRPNwithineachfailuremode FMEA StepbyStep 12IdentifycorrectiveactionInthisstepyouidentifythecorrectiveactionsneededtoeliminate controlthecauses andreducetheriskleveltoorbelowtheagreeduponthreshold Therewillbetimeswhenyoucannotworkontherootcause insuchcasesthebestcourseofactionwillbeviaadditionofcontrols adequatewarningdevices mechanismsofimpendingfailure Re evaluatetheratingsforS O andD followedbyRPNcalculation Discussionwiththecustomerisimportantagainsincethecorrectiveactionswillimpactthem Knowledgeexpertsmayalsoprovidevaluableinputastowhatkindsofcorrectiveactionwillbebestsuitedforthegivencause failuremode Finally fromallpossiblecorrectiveactions theteammaychooseonebasedoncost benefitanalysis speedofimplementation andthenewlevelofrisk FMEA StepbyStep 12IdentifycorrectiveactionExample allcauseswithRPN 200areaddressed FMEA StepbyStep 12IdentifycorrectiveactionQuestions 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 andvoiceofcustomerDetailsofprojectscreatedandimplementedaspartofactionitems PortablesCosmeticProcessFMEAResults Area Portab