FMEA Failure Mode and Effects Analysis.ppt

FMEAFailureModeandEffectsAnalysis,AdaptedfrompresentationbyDr.Stamper,Outline,FailureModeandEffectsAnalysisWhatisit?MotivationFMEAMethodsExampleFMEAin-classexercise,WhatisanFMEA?,Description:Aprocedurethatexamineseachiteminasystem,considershowthatitemcanfailandthendetermineshowthatfailurewillaffect(orcascadethrough)thesystemAcronymsFMEA:FailureModesandEffectsAnalysisFMECA:FailureModesandEffectsandCriticalityAnalysis,MotivationforConductingaFMEA,ImprovesdesignbydiscoveringunanticipatedfailuresHighlightstheimpactofthefailuresPotentiallyhelpfulduringlegalactionsProvidesamethodtocharacterizeproductsafetyOftenrequired(e.g.FDAandDODprocurement),MethodtoConductanFMEA(takenfromASMHandbookVol.11),Identifyallcomponentsorsystemsatgivenlevelofthedesignhierarchy.Listthefunctionofeachidentifiedcomponentorsystem.Identifyfailuremodesforeachcomponent/system.Typicallytherewillbeseveralwaysinwhichacomponentcanfail.Determinetheeffect(bothlocallyandglobally)onthesystem.,MethodtoConductanFMEA(takenfromASMHandbookVol.11),Classifythefailurebyitseffectsonthesystemoperation.Determinethefailuresprobabilityofoccurrence.Identifyhowthefailuremodecanbedetected(maypointoutwhatneedstobeinspectedonaregularbasis).Identifyanycompensatingprovisionsordesignchangestomitigatethefailureeffects.,OtherVariationsoftheMethod,Mil-STD-1629A,Fig101.3http:/www.fmea-,DESIGNFMEA(DFMEA),TheDesignFMEAisusedtoanalyzeproductsbeforetheyarereleasedtoproduction.Itfocusesonpotentialfailuremodesofproductscausedbydesigndeficiencies.DesignFMEAsarenormallydoneatthreelevelssystem,subsystem,andcomponentlevelsThistypeofFMEAisusedtoanalyzehardware,functionsoracombination,PROCESSFMEA(PFMEA),TheProcessFMEAisnormallyusedtoanalyzemanufacturingandassemblyprocessesatthesystem,subsystemorcomponentlevels.ThistypeofFMEAfocusesonpotentialfailuremodesoftheprocessthatarecausedbymanufacturingorassemblyprocessdeficiencies.,WhattoDo,FunctioncomesfromFunctionalAnalysis,FunctionalDecompositionPotentialFailureModecomesfromthingsthathavegonewronginthepast,concernsofdesigners,andbrainstorming.Possibleconsiderationsarepartialfunction,intermittentfunction,excessfunction.PotentialEffectsareconsequencestothedesign,theuser,andtheenvironment.Safetyandregulationnoncompliancearecriticalissues.,In-ClassProblem1,Mostcarshaveafuelfilterbetweenthefueltankandtheengine.Considertheconsequencesofa)Anti-function(oppositeoffiltering)b)Partialfunctionc)Intermittentfunctiond)Excessfunction,WhattoDo,PotentialCausesoffailureshouldbeengineeringrelatedsuchasincorrectmaterial,corrosion,wearandhumanrelatedsuchasinexperience,misuse,etc.CurrentDesignControlsarethingslikeinspections,testing,pokeyoke,andotherdesignchecksthatareintendedtopreventtheproblem.,WhattoDo,AssignvaluestoSeverity,Occurrence,andDetectionusingthetablesonthenextthreepages.DeterminetheRiskPriorityNumber(Severity*Occurrence*Detection)DevelopanactionplanImplementanactionplan,RiskGuidelines,OccurrenceRanking,DetectionRanking,In-ClassProblem2,Supposeyouwerethedesignerofcarsbeforeairbagsandseatbelts.Supposeyourfunctionis“Protectoccupantsduringhead-oncollisionatlessthan40mph.”EstimatenumbersforSeverity,Occurrence,andDetectionforthe“beforeairbag/seatbelts”andafter“airbags/seatbelts”cases.,PartialExample,PartialExample(Cont.),In-ClassProblem3,ForthecordlessascrewdriverwehavepreviouslyconsideredgenerateapartialFMEAa)Listthethreemostsignificantfunctionsofthecase.b)Formostpotentiallytroublesomefunction,namePotentialFailureModesc)ForeachPotentialFailureMode,namePotentialEffectsd)ForeachPotentialFailu