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OnlineStudentGuide

OpusWorks2016,AllRightsReserved

FailureMode&EffectsAnalysis(FMEA)

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TableofContentsLEARNINGOBJECTIVES......................................................................................................................................2INTRODUCTION....................................................................................................................................................3FMEADEFINED.........................................................................................................................................................................3FMEAISABOUTRISKASSESSMENT.....................................................................................................................................3FAILUREMODEANDEFFECTSANALYSIS(FMEA).............................................................................................................3TWOUSESOFFMEA................................................................................................................................................................4WHENISTHEFMEASTARTED?.............................................................................ERROR!BOOKMARKNOTDEFINED.CAUSEANDEFFECTMODELFORFMEA...............................................................................................................................5PROCESSFMEAFORM.............................................................................................................................................................5DEVELOPASTRATEGY..............................................................................................................................................................5

FMEASTEPS...........................................................................................................................................................6PROCESSFMEASTEPS.............................................................................................................................................................6STEP1.FLOWCHARTTHECURRENTPROCESS....................................................................................................................6PROCESSFLOW..........................................................................................................................................................................7STEP2.DETERMINETHEFUNCTIONSANDREQUIREMENTS.............................................................................................7STEP3.BRAINSTORMPOTENTIALFAILUREMODES..........................................................................................................8POTENTIALFAILUREMODES..................................................................................................................................................9STEP4.LISTPOTENTIALEFFECTANDSEVERITY...............................................................................................................9STEP5.DETERMINEPOTENTIALCAUSESANDOCCURRENCE.......................................................................................106.DETERMINECURRENTCONTROLSANDDETECTION...................................................................................................11TESTINGTHELOGIC...............................................................................................................................................................12STEP7.DETERMINERISKANDACTIONPRIORITIES.......................................................................................................12SHORTCOMINGSOFRPN.......................................................................................................................................................13STEP8.TAKEACTIONTOREDUCERISK............................................................................................................................13STEP9.CALCULATERESULTINGRPNS..............................................................................................................................14STEP10.FOLLOWUP............................................................................................................................................................14FMEAHELPFULHINTS:........................................................................................................................................................14

©2016byOpusWorks.Allrightsreserved.Version5.5November,2016TermsofUseThisguidecanonlybeusedbythosewithapaidlicensetothecorrespondingcourseinthee-LearningcurriculumproducedanddistributedbyOpusWorks.NopartofthisStudentGuidemaybealtered,reproduced,stored,ortransmittedinanyformbyanymeanswithoutthepriorwrittenpermissionofOpusWorks.TrademarksAlltermsmentionedinthisguidethatareknowntobetrademarksorservicemarkshavebeenappropriatelycapitalized.CommentsPleaseaddressanyquestionsorcommentstoyourdistributorortoOpusWorksatinfo@OpusWorks.com.

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LearningObjectives

Uponcompletionofthiscourse,studentwillbeableto:• DefineFMEAanddiscussitsuseasaprojectriskassessmenttool• Describethe10stepsforconstructingaprocessFMEA• ExplaintheFMEAscoringcriteria• DiscusshowtotranslateFMEAresultsintoaction

Introduction

FMEADefined

FMEA(FailureModeandEffectsAnalysis)isamethodtoidentifyandmanagerisks.Itisasystematicapproachusedtoexaminepotentialfailuresandprevent,orminimize,theimpactonproductsandprocesses.Itenhancesanorganization’sabilitytopredictproblems,itprovidesasystemorrankingandprioritizationtodeterminewhichproblemshavethehighestrisk,andtakestepstoeliminateorreducetheimpactoflikelyfailuremodes.FMEAIsAboutRiskAssessment

FMEAisatoolusedforriskassessment.Riskrelatestoprojectsinanumberofways,andchangesoverthecourseofaproject.Forexample,earlyoninaproject,teamsusestatisticaltoolstoquantify

uncertaintyandhelpthemunderstandtheprobabilitiesofmakingwrongdecisions.Later,theteamsshifttheirfocustosolutionsandwhatcouldgowrong.Insomecases,teamsmaynotbeabletodropalloftheriskstoacceptable,manageablelevelsbytheendoftheirprojects.Insuchcases,itisimportantforteamstouseFMEA,asafull-disclosuremedium,tofacilitatethetransitionbacktotheprocessowners.

FailureModeandEffectsAnalysis(FMEA)

TheFMEAlinksinformationfromseveralsourcesincludingProcessMaps,QualityFunctionDeployment(QFD)AnalysisandCauseandEffectDiagrams.Avaluableriskassessmenttool,itallowstheteamtoexamineallpotentialfailures,causes,andeffectsonthecustomer;ithelpstheteamprioritizethefailures;itdocumentstheteam’swork,conclusions,andresults;itdocumentsproposedcorrectiveactionstopreventfailures;andithelpsdirecttheteamtoimplementcorrectiveactions.FMEAhelpsteamsnarrowdownmultiplecauses.Insomecriticalsituations,however,thisnarrowingdownmaynotbepossible.Insuchcases,theteammustimplementcorrectiveactionsformultiplecauses.

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TwoUsesofFMEA

TherearetwousesofFMEA,processFMEAanddesignFMEA.Let’stakealookateach.

AprocessFMEAisusedtoassessthepotentialweaknessofamanufacturing,administrativeorserviceprocess.Itconcentratesontherisksoftheprocessnotperformingtothedesignintentortocustomer

requirements.TheProcessFMEAfocusesonfactorsrelatedtopeople,machinesorequipment,methodsorprocedures,measurements,andenvironment.AdesignFMEAfocusesonwhatmightgowrongwithaproduct,service,orprocessdesign.Ithelpstheteamcreatedesignsinwaysthatwillavoidanticipatedfailuresfromoccurring.Byenablingtheteamtoidentifypotentialproduct,service,process,orsafetyissues,thedesignFMEAattemptstopreventfailuresfromhappeninginthefirstplace.StartingFMEA

ThemainpurposeofFMEAmethodologyistomaximizecustomersatisfactionbyeliminatingorreducing

knownorpotentialproblems.Todothis,theteammustbeginFMEAasearlyaspossible.Earlyonintheprocess,theteamwillnothaveallthefactsandinformationitneeds,butitshouldbeginFMEAanyway.Ahelpfulguidelineforteamstorememberis,“Dothebestyoucanwithwhatyouhave.”IfateamwaitstobeginFMEAuntilithaseverythingitneeds,includingdrawings,specifications,andaclearconcept,itwillnevergetstarted;oritwillbeginsolatethatthedesignwillalreadybeestablished,andtheFMEAwillbeineffective.OnceaFMEAisinitiated,itbecomesalivingdocument,whichisupdated,asneeded,throughoutthecourseoftheproject.Inreality,anFMEAisneverreallycompleted.Toensureitalwaysreflectsthecurrent

process,theinformationontheFMEAshouldbeupdatedaschangestotheprocessoccur.

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CauseandEffectModelforFMEA

ThisistheCauseandEffectmodelforFMEA.NoticethatthetimesequenceforCauseandEffectforFMEAbeginswiththecausecreatingthepotentialfailuremode,whichisobservedbytheeffect.Theeffectwillhaveatriggermechanism,whichgeneratesanaction.Apreventiveactionaddressesthecause,whilecontingentactionsaddressonlytheeffects.ProcessFMEAForm

NowthatyouunderstandthedefinitionandpurposeofanFMEA,wewillwalkthroughthestepsforcreatingit.TheprocessFMEAformisshownhere.ItfollowsthegeneralmodeldefinedbytheAutomotiveIndustryActionGroup(AIAG)andisrecognizedasanindustrystandard.AcopyofthisforminExcelformatcanbeobtainedhere.

DevelopaStrategy

BeforebeginningtheFMEA,theteammustdevelopastrategytodeterminehowrisksmightimpactaproject.Todothis,itshouldconsiderthefollowingissues:Whatcontrollableactions,conditions,oreventsisthesolutiondependenton?Whatuncontrollableactions,conditions,oreventsisthissolutiondependenton?Inwhatwaysisthisprocessnewordifferentfromthewayitwasdoneorexistedbefore?Whatassumptionsarebasedoninference,supposition,orspeculation?Whatfactorsareinflexible,unchangeable,orlockedin?Whereistherelittleornomarginforerror?

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FMEASteps

ProcessFMEASteps

ThetenstepsforcreatingaprocessFMEAareasfollows:1.Flowchartthecurrentprocess2.Determinethefunctionandrequirementsofeachprocessstep3.Brainstormpotentialfailuremodes4.Listthepotentialeffectsandseverity5.Determinepotentialcausesandoccurrence6.Determinecurrentcontrolsanddetection7.Establishriskandactionpriorities8.Takeactiontoreducerisks9.Calculateresultingriskprioritynumbers(RPNs)10.FollowupStep1.FlowcharttheCurrentProcess

ThefirststepforcreatingaprocessFMEAistoflowchartthecurrentprocess.

TheflowchartmustdescribetheflowoftheproductorserviceinenoughdetailtoshowalloperationswithinthescopeoftheFMEA.Withtheprocessflowchartinhand,theteamshouldfamiliarizeitselfwiththeprocessbyphysicallywalkingit.Thiswillalloweveryoneontheteamtounderstandthebasicflowandworkingsoftheprocesscomponents.Thereareseveralreasonsforreviewingtheprocess.First,thereviewhelpsensurethatallteammembersunderstandtheprocessandthescopeoftheFMEA.Italsohelpstheteamidentifythemaincomponentsoftheprocessand

determinethefunctionsandrequirementsofeach.Finally,ithelpsensurethatnostepshavebeenoverlookedandthattheteamisstudyingtheentireprocess.

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ProcessFlow

ToillustrateaflowchartforFMEA,wewillusetheexampleofacookiebakingprocess.Tokeeptheteamfocused,itisimportanttoscopethestartandendpointsoftheFMEAprocess.Inourexample,theprocessbeginswithcookiedoughalreadypreparedandendswithfinishedcookiesonaservingplate.Atthispoint,theteammayfindithelpfultolisttheinputsandoutputsofeachprocessstep.Step2.DeterminetheFunctionsandRequirements

StepTwoforcreatingaprocessFMEAistodeterminethefunctionsandrequirementsofeachprocessstep.Todothis,theteamliststheprocessfunctionthatcorrespondstoeachprocesssteporoperationbeinganalyzed.Theprocessfunctiondescribesthepurposeorintentoftheoperation.Next,theteamliststherequirementsforeachprocessfunction.Requirementsarethedesignandcustomerspecificationsthatmustbemet.Toillustrate,let’scontinuewithourcookiebakingprocessexample.Asyouseehere,thefirstprocesssteporfunctionistoformthedoughintoballsandplacethemonthebakingsheet.Therequirementsforthissteparethatdoughballsareofuniformsizeandchocolatechipsareuniformlydistributed.Thesecondprocessstepistobakethecookies.Therequirementsarethatcookiesarelightbrownincolorandcookedthrough,notraw.Thenextstepistoremovethecookiesfromtheoven.Therequirementforthisstepisthatcookiesarecooledtoroomtemperature.Thefinalprocessstepistoplacethecookiesontheservingplate,andtherequirementisthatnocookiesarebroken.

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Step3.BrainstormPotentialFailureModes

StepThreeistobrainstormpotentialfailuremodes.Thepotentialfailuremodeisdefinedasthemannerinwhichtheprocesscouldpotentiallyfailtomeetcustomerrequirements.Thecustomerisdefinedaseithertheend-userorthesubsequentdownstreamoperation.

Thethirdstepisbestaccomplishedinateamenvironment,togetasmanydifferentviewsofthefunctionaspossible.Thebrainstormingteamshouldincludedesigners,processexperts,buyers,customers,suppliers,processoperators,andanysupportpeoplewhohaveexperiencewiththeprocessbeinganalyzed.Inadditiontotheideasgeneratedbythemembers,otherpotentialfailuremodeswillbegeneratedasaresultofthesynergyofthegroupprocess.OneofthekeystosuccessofprocessFMEAistodefineasmanypotentialfailuremodesaspossible,fromasmanypointsofviewaspossible.

Becauseofthecomplexityofmostproductionandbusinessprocesses,thelistofpotentialfailuremodescanbecomequitelarge.Itissometimesbestfortheteamtoholdaseparatesessionthatfocusesonconsolidatingthelistofpotentialfailuremodes.Varioustoolsareavailableforrefiningthelistofpotentialfailuremodes,includingAffinityDiagramsandMindMaps.Theteamshoulddeterminefailuremodesforeachstepintheprocess.Itcanthengroupthembythetypeoffailure,(suchaselectrical,mechanical,clerical,dataentry,handling,orcontamination),orbywherethefailureoccurred.Withoutthegroupingstep,theteammaywastealotoftimeandenergyjumpingfromoneaspectoftheprocesstoanother,andbackagain.

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PotentialFailureModes

Recallthat,whenpreparinganFMEA,theteammakesthefollowingtwoimportantassumptions:first,thatincomingmaterialsarecorrect,andsecond,thatthebasicdesignoftheproductiscorrect.DuringtheFMEAprocess,theteammaydiscoverpotentialproblemsrelatedtoincomingmaterialsandproductdesign.Itshouldrecordanysuchpotentialproblemsforfutureanalysis,butshouldnotincludethemwithinthescopeoftheprocessFMEA.Totheextentpossible,theteamshoulddescribepotentialfailuremodesintechnicalterms,ratherthanassymptomsnoticedbythecustomer.Iftherequirementshavebeenproperlydefined,thepotentialfailuremodeswouldbethefailuretomeetspecifiedrequirements.Itisimportanttonotethateachrequirementmayhavemultiplefailuremodes.Step4.ListPotentialEffectandSeverity

StepFouristolistthepotentialeffectsandseverity.Thepotentialeffectofthefailureshouldbedescribedintermsofwhatthecustomermightnoticeorexperience.Remember,thecustomermaybeaninternalcustomeroranenduser.Let’sgobacktoourcookiebakingprocessexample.Here,theeffectofburntcookiesisbadtaste.Noticethattherearetwoeffectsforrawcookies,includingcookiesfallingapartandahealthriskduetoundercookedfood.Theseverityisthevalueassociatedwiththemostseriouseffectforagivenfailuremode.Itisscoredfromonetoten,withtenbeingthemostsevereandonebeingtheleast.Asyoucanseeinourexample,thehealthriskhasthehighestseverityscore.Thisscorewillbeusedfortheanalysis.

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Step5.DeterminePotentialCausesandOccurrence

StepFiveistodeterminepotentialcausesandoccurrenceoffailure.Thepotentialcauseofthefailureisdefinedasanindicationofhowthefailurecouldoccur,andassomethingthatcanbecorrectedorcontrolled.Inthisstep,theteamidentifiesanddocumentseverypotentialcauseforeachfailuremode.Let’stakealook,onceagain,atourcookiebakingprocessexample.Asyouseehere,thepotentialfailuremode,burntcookies,iscausedbyeitheradefectiveovengauge,whichcausesovercooking,oradefectivetimer,whichrunsslow.Therawcookiescouldalsobecausedbyadefectiveovengauge,orbytheovendoorbeingopened,resultinginlossofheat.OntheFMEA,theteamrankstheoccurrencesaccordingtothelikelihoodthataspecificcausewilloccur.Occurrencesarerankedonascaleofonetoten,withonebeingaverylowprobabilityofoccurrenceandtenbeingveryhigh.Scoringcriteriaforoccurrencecanbebasedonprocessperformancemetrics,suchasprocesscapabilityordefectivepartspermillion.

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6.DetermineCurrentControlsandDetection

StepSixistodeterminecurrentcontrolsanddetection.Currentprocesscontrolsanddetectionmethodsarethoseactivitiesthatcanpreventthecauseofthefailurefromoccurringordetectthefailuremode,shoulditoccur.Todevelopcontrols,theteammustidentifywhatisgoingwrong,whyitisgoingwrong,andhowthefailurecanbepreventedordetected.Controlsthatfocusonpreventionprovidethegreatestreturns.Commonprocesscontrolsincludesuchthingsascontrolplans,designorprocessaudits,mistakeproofing,measurementcapabilitystudies,processordesigncapabilitystudies,standardoperatingproceduresandoperatortraining,andcontrolcharts.

Detectionisrankedonascalefromonetoten,withonemeaningdetectioniscertainandtenmeaningthedefectcannotbedetected.Inourexample,thecontrolusedtodetectadefectiveovengaugeisamonthlytemperaturecheck.Similarly,thetimerischeckedannually.Theoperatorinstructionsserveasthecontrolforpreventingtheovendoorfrombeingopenedduringthebakingcycle.

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TestingtheLogic

WhenconstructinganFMEA,teamssometimeshavetroublefiguringoutwheretoplacecertaininformation.Recallthatcause,failuremode,andeffectoccurinatimesequence.Therefore,oncetheteamhascompletedalineontheFMEA,itcantestitslogicbyinsertingthecause,failuremode,andeffectintothefollowingsentences:“Ifcause,thenfailuremode.HowdoIknow?Effect.”Inourcookiebakingprocess,forexample,wewouldcompletethesesentencesasfollows:“Ifovengaugeisdefective,thenburntcookies;HowdoIknow?Theytastebad”.Inthiscase,weconfirmthatthetimesequenceislogical,andwehaveplacedinformationinthecorrectcolumns.Step7.DetermineRiskandActionPriorities

StepSevenistodetermineriskandactionpriorities.Oneapproachteamscanusetohelpprioritizeactionsistouseariskprioritynumber(orRPN).TheRPNistheproductoftheseverity,timestheoccurrence,timesthedetection.WithinthescopeofanindividualFMEA,thisvaluecanrangebetweenoneand1,000.TheRPNscoringinanFMEArepresentsarelativerankingwithinthescopeoftheindividualFMEA.Thenumbersthemselveshavenomeaningotherthantohelpwithactionprioritization,i.e.,ahigherRPNusuallyindicatesanitemthathasamoresevererisk.

𝑹𝑷𝑵 = 𝑺𝒆𝒗𝒆𝒓𝒊𝒕𝒚×𝑶𝒄𝒄𝒖𝒓𝒆𝒏𝒄𝒆×𝑫𝒆𝒕𝒆𝒄𝒕𝒊𝒐𝒏RPNscoringtechniquesrelyonjudgment,andtheapplicationofscoringcriteriacanvaryfromproducttoproduct,teamtoteam,andfacilitatortofacilitator.Forthisreason,RPNvaluesfromdifferentFMEAsmustnotbecomparedorrankedagainsteachother.ThepurposeofRPNscoringistoisolatehigh-riskitemswithintheanalysis.Actionableitemsmustbedefinedbytheteam.TypicalcriteriafordeterminingactionableitemsinanFMEAincludethetop25percentofRPNsthataregreaterthan30;allRPNswithhighseverity(betweensevenandnine),regardlessofthe25percentthreshold;andanylineitemdeemedbytheFMEAownerortheteamtobecritical,regardlessofthecalculatedRPN.

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ShortcomingsofRPN

AlthoughRPNishelpfulforprioritizingactions,itdoeshavesomeshortcomings.Multivariatemeasures,likeRPN,cansometimesmasktheimportanceofpotentiallycriticalindividualfactors.Forexample,twofailuremodesmaywindupwiththesameRPN,whichcouldleadtheteamtobelievetheycarrythesameweightasfarasestablishingpriorities.Intheexampleshownhere,FailureModeAishalfaslikelytooccurasB,butthismaynotmakeupforthefactthatitistwiceassevere.Iftheproductisgoingtofailatacustomersite,itmaynotmatterthatitwilloccuronlyasmallpercentageofthetime.IntuitionandlogicmusttakeprecedenceinestablishingactionprioritiesfromRPN.

Lookingatthisexample,whichfailuremodedoyoufeelshouldhavethehigherpriority? Step8.TakeActiontoReduceRisk

StepEightforcreatingaprocessFMEAistotakeactiontoreducerisks.OncecauseswithlargeRPNsareidentified,recommendedactionsareidentifiedandimplementedtoreduceoreliminatethepotentialcausesoffailures.TheintentofanyrecommendedactionistoreduceRPNbycontrollingseverity,occurrence,anddetection.Severitycanbeimprovedonlybyredesigningtheproductorprocess.Toreduceoccurrence,processanddesignrevisionsmaybenecessarytoenabletheprocesstomeetspecificationsandcustomerrequirements.Errorormistakeproofingisthepreferredmethodforimprovingdetectiontechniquesorequipment.

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Step9.CalculateResultingRPNs

StepNineistocalculateresultingRPNs.RecalculatingRPNshelpstheteamevaluatetheeffectivenessoftherecommendedactionsinreducingorremovingthecauseofthefailuremode.CalculatingtheresultingRPNsalsogivestheteamabetterunderstandingoftheoverallimprovementsthathavebeenmadethroughitsefforts. Step10.FollowUp

Thetenthandfinalstepisfollowup.RecallfromStepEightthattheintentofrecommendedactionsistoreduceoverallriskandlikelihoodthatthefailuremodewilloccur.Theresponsibilityandtimingtocompletetheactionsshouldberecorded.CorrectiveactionsmaybetrackedinasystemoutsidetheFMEA,suchasaCorrectiveActiondatabase.ItistheresponsibilityoftheFMEAowner

toensurethattheactionsareidentified,enteredintotheappropriatesystem,andtrackedtoclosure.FMEAHelpfulHints:

HerearesomehelpfulhintsforasuccessfulFMEA:Brainstormwiththeteamtodevelopalistofpotentialfailuremodesandproblemsthatcouldresultfromunmanagedrisk.Don’tPanic!Manyitemsonthelistlikelyhavealowprobabilityofhappeningorlittleimpactiftheydohappen.

AlwaysthinkintermsofFMEAmeasures,suchasthefollowing:

Whatistheprobabilityofitshappening?Whatwilltheseriousnessbeifitdoeshappen?Canwedetectthefailureiforwhenitactuallyhappens?

Toavoidacurethatismoreexpensivethantheillness,ratethelistofpotentialfailuremodesandproblems.