FAILUREMODEANDEFFECTSANALYSIS(FMEA)
FailureModeEffectAnalysisisasystematicapproachofidentifyingandinvestigatingpotentialDesignorProcessweakness.
Thismeansthatit’saprocessthattriestounderstandallthefuturepotentialproblems(FailureModes)ofadesignorprocess.Onceallthepotentialfailuremodes,includingtheextremeandunlikelyones,havebeendetailed,thenextstepistothenunderstandtheEffect.TheEffectiswhatwillhappeniftheFailureModeoccurs,willthepartjuststopworkingorcoulditkillsomebody.
“Somuchforthesafetymatch!”
OncealltheFailureModesandtheirEffectsareunderstood,theinformationisthenAnalyzedandaRiskPriorityNumber(RPN)isgenerated.TheRiskPriorityNumberisanumberwhichrateseachFailureModeforitsSeverity(whateffectwillithaveonthecustomer),itsOccurrence(whatarethechancesofthecustomerfindingtheproblem),anditsDetection(whatarethechancesoffindingtheproblemin-house,beforethecustomer).
TheRPNfiguresarethenputintonumericalorder,andtheoneswiththelargestRPNfiguresshouldbepriorities.Workingonthesemayinvolvere-designofapartoraprocess,orjustaminortweak,theaimistoreduceitsRPNfiguretoaverylownumber.
Thestepstotheprocessareasfollows:-
Understandthepartorprocess
DefineitsFunction
IdentifypotentialFailureModes
DescribetheEffectofFailure
DeterminetheCauses
Understandthecurrentcontrols
CalculatetheRPNrisknumber
TakeactiontolowertheRPNnumber
Understandtheresults
Gobacktostep1,oruntiltheRPNriskisbelowacceptablestandards
ABlackandDeckerexampleisshownbelowandwecanseethatthetwohighestissueshaveaRiskprioritynumberof245.Aftertherecommendedactionstookplacethisisreducedto98whichisfarmoreacceptable.
ForaverydetailedanalysisofFMEAconsulttheChrysler,Ford,GeneralmotorsAIAG"FMEAGuide."(See"Bibliography"sectionofthiswebsite.)
Whichmeanswhat?
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