失效模式分析(1).ppt

1,2,AnanalyticaltoolforidentifyingPotentialFailuresinaproductorprocesssothatcorrectiveactioncanbetakenbeforethefailurescanreachthecustomer.,FMEA是一種識別產品或過程的潛在失效,以便在這些失效影響客戶之前採取措施的分析工具,3,AnFMEAisaStructuredApproachto:FMEA是結構式的方法,Identifyingthewaysinwhichadesignorprocesscanfailtomeetthecriticalcustomerrequirements識別設計或過程可能以何種方式失效而不能滿足客戶重要需求Estimatingtheriskofspecificcauseswithregardtothesefailures估計產生這些失效的特殊原因的風險Evaluatingthecurrentcontrolsforpreventingthesefailures評估現有控制手段對這些失效的預防Prioritizingtheactionsthatmustbetakentoimprovethedesignortheprocess給那些用以改進設計和過程的措施排序,4,FMEAHistory歷史,Firstusedinthe1960sduringtheApolloMoonMissions.最早被用於上世紀六十年代的阿波羅登月計劃.In1974MIL-STD-1629wasdevelopedbytheNavyforusingFMEAs.1974年海軍為FMEA的應用制定了MIL-STD-1629.Inthelate1970,adaptedbytheautoindustryinresponsetohigherliabilitycostsandhigherqualitydemandsbycustomers.在二十世紀七十年代末,為滿足客戶更高的責任成本和質量需求而被用於自動化工業中.,5,FMEAisproactive,notreactive.Dontwaitforthecustomertocomplainifyoucanavoidit!FMEA是預防性的，不是反應性的。應當儘量避免失效，而不是等著顧客提出申訴！,6,FMEAreducesthechancethatacustomerwillseeafailureFMEA通過以下措施減少顧客遇到失效的情況:Bydefiningfailureintermsofwhatthecustomerwantsandexpects.針對顧客的要求和期望確定失效Byshowingwheremeasuresneedtobetakentopreventfailure.指出爲了防止失效，需要在哪方面採取措施,7,TypesofFMEAs類型,Designusedtoanalyzeproductdesignsbeforetheyarereleasedtoproduction設計-用於在產品投產前對設計的分析Processusedtoanalyzemanufacturingprocesses過程-用於分析製程Systemusedtoanalyzesystemsintheearlyconceptanddesignstages系統用於分析早期的概念和設計階段的系統,8,Summary概要,Identifiesknownandpotentialfailuremodes;識別已知和潛在的失效模式Identifiesthecausesandeffectsofeachfailuremode;識別每一種失效模式的原因和後果Prioritizesthefailuremodes(usingtheRPN);利用風險序數（RPN）給失效模式排序Shouldinitiatecorrectiveactionwhereneeded.必要時提出糾正措施,9,TimingofanFMEAFMEA的時機,FMEAsshouldbeinitiatedwhenpreliminarydrawingsofthedesignorprocessareavailable當初步的設計圖紙和工藝被制定出來時應開始做FMEAUpdatedasidentifiedissuesareresolved當被發現的問題解決後要更新FMEACanbeusedonexistingproductstoimprovequality可用於現有的產品以提高質量,10,System系統Wiringharness線束Electronicmodule電控模塊Assembly總成,SystemFMEAtreatssystemasa“functionalschematic”系統FMEA從“功能關係圖”入手來考慮,SFMEA,11,Ananalyticaltoolusedtoidentifysystem-levelfailuremodes,andidentifycorrectiveactionstobetaken.是一種分析工具用來識別系統失效模式,12,ItissimilartoaDesignFMEA,butfocusesonthecircuitschematicinsteadofphysicalfailureofcomponents.同DFMEA相類似,系統FMEA側重於回路設計而不是元件的物理失效。,13,Example:舉例：Failuremodeatelectricalsystemlevel電氣系統失效模式OpencircuitatcktA回路A出現開路Cause:原因：Terminalunseated端子脫出Terminalunseatedbecomesafailuremodeatthecomponentlevel.端子脫出是電氣元件的失效模式。,14,RulesofDesignFMEA設計FMEA規則,Toolfordesignengineersandprojectteamtoimprovethedesigninapreemptivemanner(beforefailureoccur)是設計工程師和項目小組的工具用來提高設計的前瞻性(在問題發生前)UsedtoestablishedCriticaltoQualityfeaturesthateffecttheperformanceoftheproduct用與那些影響產品性能的重要質量特性UsedtoestablishCriticaltoLifefeaturesthateffectthelifeoftheproduct用於確定影響產品壽命的重要壽命特性UsedtoestablishCriticaltosafetyfeatures用於確定重要安全特性,15,PurposeofDesignFMEA設計FMEA的用途,Establishescriticalfeaturesthatmustbecontrolledinmanufacturingtosatisfycustomerrequirements確定那些必須在生產中進行控制的特性以滿足客戶要求Identifiesdeficienciesintheproductdesignandassociatedactionitems找出產品設計中的不足和相應的措施Helpsevaluatetheriskofdesignchanges幫助評價設計變更的風險,16,PurposeofDesignFMEA設計FMEA的用途,Identifiesprocessdevelopmentneeds確定開發工藝流程的需求Dynamicdocumentdocumentsdesignalternativesandassociatedrisks動態的文件記錄可選擇的設計方案和相應的風險Establishesbasesformanufacturingandqualitycontrolplan建立製造和品質控制計劃的基礎,17,DesignFMEAInputsandOutputs設計FMEA的輸入和輸出,Productdrawings產品圖紙Productmodels產品模型Productspecification產品規格,IdentifiedCriticaltoQualityfailures確定的重要質量特性Actionstopreventthecausesoffailures防止失效原因的措施Actionstodetectfailuremodes發現失效模式的措施HistoryofactionsandResponsibilities措施和責任人的記錄,18,Design设计Components元件Elements设计要素,DesignFMEAlooksatphysicalfailuremodesofcomponentsanddesignelements设计FMEA着眼于元件及设计要素的物理失效模式,DFMEA,19,RulesofProcessFMEA過程FMEA規則,Toolforprocessengineersandprojectteamtoimprovethemanufacturingprocessinapreemptivemanner是工藝工程師和項目小組的工具,用來提高製造工藝的前瞻性Usedtoprioritizeactionstoensureattentiontocriticalprocessesthateffectcustomers用與區分先後順序以確保那些影響客戶的重要工藝Usedtodocumentprocessimprovements用於工藝改進Dynamicdocumentforcontinuousimprovement持續改進的動態文件,20,PurposeofProcessFMEA過程FMEA的用途,Assistsintheanalysisofnewmanufacturingprocess幫助分析新的製造工藝Establishesthebasesformanufacturingprocessinstructionsandcontrolsheets建立製造工藝文件和控制文件的基礎Identifiesnewmanufacturingprocessneeds確定新製造工藝的需求Helpsevaluatetheriskofprocesschanges幫助評估工藝更改的風險,21,Process过程Manufacturing制造Assembling装配,ProcessFMEAlooksatproductfailurescausedbytheprocessfailingtomeetrequirements过程FMEA着眼于因加工過程不符合要求所造成的产品失效,PFMEA,22,FMEATeam小組,Teamapproachisnecessary.需要團隊的方式ResponsibleforDesignFMEADesignEngineer設計工程師負責設計FMEAResponsibleforProcessFMEAManufacturingEngineer製造工程師負責過程FMEARecommendedrepresentatives:推薦人選:Design/設計ManufacturingEngineers/製造工程師QualityEngineers/質量工程師Reliability/可靠性Materials/原材料Suppliers/供應商,23,DefinitionofTerms術語,FailureModeThewayinwhichaspecificinputrequirementfailsandifnotdetected,correctedorremovedwillcauseanEffecttooccur.失效模式一個特殊的輸入要求失敗的方式或者由於未被發覺,糾正或消除而帶來的後果EffectImpactoncustomerrequirements後果對客戶要求的影響,24,DefinitionofTerms術語,CauseSource(s)ofprocessvariationthatcausestheFailureModetooccur.原因造成失效模式發生的過程變差的起源CurrentControl(proposedcontrols)當前的控制(建議的控制)Designelementsthatensurefunction確保功能的設計要素Mistakeproofing,automatedcontrols,setupinstructions,gauges防錯,自動化控制,機器設定指導書,量具Audits,checklists,inspections,PM,etc.稽核,檢查表,檢驗,設備維護,等,25,LinkingFailureModestoEffects失效模式和後果之間的聯繫,FailureMode1,FailureMode2,Effect1,FailureMode1,Effect2,Effect1,FailureMode1,FailureMode2,Effect1,NotethattherelationshipbetweentheFailureModeandEffectisnotalways1-to-1請注意失效模式和後果之間的關係不總是一對一,Effect2,26,RiskPriorityNumber風險序數,TheoutputofaFMEAisthe“RiskofPriorityNumber”-RPN一個FMEA的輸出是“風險序數”-RPNTheRPNisacalculatednumberbasedoninformationprovidedregardingRPN是根據下面的資料計算出來的Thepotentialfailuremodes,潛在失效模式Theeffects,and後果Thecurrentorplannedabilitytodetectthefailurebeforeitreachesthecustomer現有的和已計劃的能力可以在影響客戶前覺察失效,27,RiskPriorityNumber風險序數,Itiscalculatedastheproductofthreequantitativerating它是用三個級數計算出來的RPN=Severity*Occurrence*Detection風險序數=嚴重度*發生頻度*探測度TheRPNisnotsacredRPN不是神聖的ScalingforSeverity,Occurrence,andDetectionarelocallydeveloped嚴重度,發生頻度,探測度的尺度由自己制定Othercategoriesmaybeaddedtosuitneed根據需要可以加上其他類型HighRiskPriorityNumbersaresignificanttothesuccessoftheproductdesign-actionsmustbetakentopreventfailures高風險序數對產品設計的成功來講很重要-需要採取措施來防止失效,28,DefinitionofRPNTermsRPN術語,Severity(ofeffect)Importancetocustomer,mayinvolvefunction,safety,reliability,orlifeofproduct(1=notsevere,10=verysevere)嚴重度(後果的)對客戶的重要程度,可包括功能,安全,可靠性,產品壽命等方面.(1=不嚴重,10=很嚴重)Occurrence(ofcause)FrequencywithwhichagivenCausemayoccur(1=notlikelytooccur,10=verylikelytooccur)發生頻度(原因的)一個特定的原因可能發生的頻度(1=不可能發生,10=很可能發生)Detection(CapabilityofcurrentorplannedControls)Abilitytodetectthecause(1=likelytobedetected,10=notlikelytobedetected)探測度(現有的或已計劃的控制能力)覺察原因的能力(1=有可能發覺,10=不可能發覺),29,RatingScales評分尺度,30,RatingScales評分尺度,31,RatingScales評分尺度,32,ExamplesofOccurrencescale發生率評分的例子,33,ExamplesofDetectionscale探測度評分的例子,34,Whatistheinput?輸入是甚麼?,Whatcangowrongwiththeinput?輸入會出甚麼錯?,WhatistheEffectontheoutput?輸出的後果是甚麼?,Whatarethecauses?原因是甚麼?,Howwell?程度如何?,Howcanthisbefound?怎樣才可以發現?,Howoften?頻繁程度,Whatcanbedone?可以做甚麼?,Howwell?程度如何?,35,36,FMEAModel模式,Prevention/預防,Prevention/預防,Prevention/預防,Cause/原因,Effect/後果,FailureMode/失效模式,Controls/控制,Materialorprocessinput/原料或過程輸入,ProcessStep/工序,Externalcustomerordownstreamprocessstep/外部客戶或下一工序,37,GeneralStepsintheDFMEA/一般步驟,SelectdesignFMEAteam組建設計FMEA小組Listcustomerrequirements列出客戶的要求Foreachcustomerrequirementlistthekeydesignelementsthatsatisfythecustomerrequirements針對客戶的每一個要求列出滿足該要求的關鍵設計要素Foreachkeydesignelementlistwaysthatthedesignelementcouldvary,PotentialFailureModes列出每一個關鍵設計要素的變化,潛在的失效模式ListEffectsofeachFailuremodeonthecustomerrequirement列出每個失效模式的對客戶要求的影響ListCausesforeachfailureMode列出失效模式的原因,38,GeneralStepsintheDFMEA/一般步驟,Listcurrentcontrolsforeachcause列出每個原因的現有控制手段AssignSeverity,Occurrence,andDetectionratingstoeachcause給每個原因的嚴重度,頻度,可探測度評分CalculateRPNs計算風險序數RecommendactionstoreducehighRPNs提出降低風險序數的措施Takeappropriateaction採取適當的措施RecalculateRPNs重新計算風險序數,39,Aschematicrepresentation,with一種圖示法,其中Components(orfeatures)shownasblocks,用方塊表示各元件(或特性)Interactionsbetweencomponentsshownaslines,用直線表示各元件之間的關係Attheappropriatelevelofdetail詳細到恰當的程度,DevelopaFunctionalBlockDiagramofTheProduct繪制產品功能結構圖,40,BlockDiagram結構圖,Examples例如,41,Dontforgetauxiliaryfunctionsaswellaprimaryfunctions主要功能和輔助功能都要考慮Often,componentsworktogethertoperformafunction經常是幾個零件共同實現一個功能Hint:UsetheBlockDiagram!提示:利用結構圖,ListTheFunction(s)ofEachComponent列出每個要素的功能,42,Adefect,flaw,orotherunsatisfactoryconditionintheproductthatiscausedbyadesignweakness由於設計缺陷造成的產品缺陷,瑕疵或其它令人不滿意的情況,TypicalFailureModes:典型的失效模式-Breaks-Cracks破碎裂紋-Corrodes-Sticks腐蝕粘結-Deforms/melts變形/熔化,43,Startwiththeprevioustwosteps:從前両個步驟入手:Functions功能Qualityrequirements質量要求,44,Inyourowndescriptivewords,writedownthefollowingscenarios，用自己的語言描述下列假設：Failure=Nofunction，失效=無功能Failure=Notenoughfunction，失效=功能不足Failure=Toomuchfunction，失效=功能過強Similarly,同樣：Failure=Noqualityrequirement失效=未達到質量要求,45,Aneffectcanbe，後果可能是：Completelossoffunction，功能完全喪失Degradationofperformanceorquality性能或質量下降Manyfailuremodeshavemorethanoneeffect!許多失效模式不止有一個後果！Effectsoffailureoftenshowupasachainofevents,fromimmediateeffecttotheultimateeffectonthecustomer失效模式的後果經常表現為對客戶的一連串的影響,包括直接的後果和最終的後果,46,DeterminePotentialCause(s)ofEachFailureMode確定每種失效模式的潛在原因,Acauseoffailureisadesignweaknessthatleadstothefailuremode造成失效的原因是由於設計缺陷引起Inherentinthewaytheproductwasdesigned是產品設計所固有的Relativetotheusageoftheproduct與產品的使用方法有關Manyfailuremodeshavemultiplecauses!許多失效模式有多個起因！,47,Ifthedesignas-isweretogointoproduction.如果依據現有設計進行生產的話Usehistoricaldata，利用歷史資料Takeimprovementsintoaccount，參考已有的改進Considerthelifespanoftheproduct，考慮產品的壽命Usereliabilitymodelsandcomparisonwithsimilarproducts，利用可靠性模型並與類似產品比較,AssessTheLikelihoodofOccurrenceofEachCause評估每種原因發生的可能性,48,Therearethreetypesofdesigncontrols:設計控制有三種類型：(1)Thosethatpreventthecauseoffailure;預防產生失效的原因；(2)Thosethatdetectthecause(s)offailure;覺察產生失效的原因；(3)Thosethatdetectthefailuremode(s)檢測失效模式,49,DetectionRating(D):探測度評分9-10Remotechanceofdetectingfailure察明失效的可能性極小7-8Verylowchance，可能性很小5-6Lowtomoderatechance，可能性不大2-4Goodchance，可能性較大1Willalmostcertainlydetectfailure(Ifitpassesthis,itwillnotfail)失效幾乎都可以被査到(如果通過這樣的檢查就不會有失效),50,Toreduceseverity-designchangetocontroltheeffect降低嚴重度通過設計更改來控制後果Toreduceoccurrence-designchangetocontrolthecause減少發生頻度-通過設計更改來控制原因Toimprovedetection-improvedtestingorsimulationmethods增強探測度改進測試和模擬方法SpecialAttentionifSeverity=9or10當嚴重度為9或10時要特別注意,51,GeneralStepsinthePFMEA/一般步驟,SelectprocessFMEAteam組建過程FMEA小組DevelopaProcessMapandidentifyallprocesssteps做一個流程圖確定過程的所有步驟ListalltheKeyProcessOutputstosatisfyinternalandexternalcustomerrequirement列出所有的滿足內部和外部客戶要求的關鍵過程輸出Foreachprocessstep,listKeyProcessInputVariables列出每一步的關鍵過程輸入變量FortheProcessDefineC&EmatrixrelatingKeyOutputstoKeyProcessInputVariable用因果圖分析關鍵過程輸入和關鍵輸出的聯繫RanktheKPIVsaccordingtoimportance根據重要程度給關鍵過程輸入變量分級StarttheprocessFMEA開始做過程FMEA,52,GeneralStepsinthePFMEA/一般步驟,Foreachprocessinput,listwaysthatitcanvary(failureModes)andidentifyassociatedeffects對每一個過程的輸入,列出其可能的變化和相應的後果ListallCausesforeachFailureMode列出失效模式的所有原因ListthecurrentControlsforeachcause列出每個原因的現有控制手段AssignSeverity,Occurrence,andDetectionratingstoeachcause給每個原因的嚴重度,頻度,可探測度評分CalculatetheRPNforeachpotentialFailureModescenario計算每個潛在失效模式的風險序數DeterminerecommendedactionstoreduceHighRPNs提出降低風險序數的措施Takeappropriateactions採取適當的措施RecalculateRPNs重新計算風險序數,53,UsetheProcessFlowDiagramformat適用流程圖的格式Identifiesfabricate,move,storeandinspectoperations識別四種作業類型,製造,移動,儲存,檢驗IdentifiesKeyCharacteristics識別關鍵特性Afunctioniswhattheoperationdoes功能系指該操作所起的作用Statethefunctionas/说明功能为：Verb+Object+Qualifier动词+宾语+修饰词Moldpart/成型零件Crimpterminalontocable/電線上壓接端子Formbendinpart/零件彎曲成形,54,Acustomerwantordesire顧客的希望或要求Couldseriouslyaffectcustomerperception有可能嚴重影響顧客的看法Couldleadtoacustomercomplaint有可能導致顧客投訴Adefect,flaw,orotherunsatisfactoryconditionintheproductthatoccurswhentheprocessfailstomeettheprocessrequirements由於過程未達到要求而導致的産品缺陷、瑕疵等不良狀態Failuremodesshouldbewrittenintermsoftheconditionoftheproduct失效模式體現在産品上,55,TypicalFailureModes/幾種典型失效模式Diameteroutofspec./直径超差Missingseal/漏裝密封墊Cutstrands/切破線皮Miss-orientedpart/部件方向錯Insufficientsolder/焊劑不足Toomuchsolder/焊劑過量NFO,Flash/未充滿,飛邊Theramificationsoffailure/後果是失效模式的衍生事件Theeffectcanbeon/可能影響Theultimatecustomer/最終用戶Orintermediatecustomer(OEM,etc.)/中間用戶Agovernmentregulation/政府法規Thenextprocessstep/下工序,56,Customercomplaintsareausefulsourceofinformation顧客抱怨是非常有用的資訊來源Aneffectcanbe/後果可能是Completelossoffunction/功能完全喪失Degradationofperformanceorquality/質量或性能下降Damageofprocessequipment/設備受損Injurytoanoperator/員工受傷Shut-downofanassemblyline/停線Effectsoffailureoftenshowupasachainofevents,fromimmediateeffecttotheultimateeffectonthecustomer/失效的後果通常表現爲從對顧客的直接影響到最終影響等一系列連鎖反應ItisrecommendedthatthesechainsbedevelopedforeachfailuremodeandrecordedontheFMEAform/建議針對每一種失效模式找出這些連鎖反應，並記錄在FMEA表上,57,Acauseoffailureishowthefailurecanoccurintheprocess失效原因就是過程爲何會失效Shouldbewrittenintermsofsomethingintheprocessthatcanbecorrectedandcontrolled應表述爲可糾正或可控制的因素Considerhumanerror,wear-outoftools,ambientconditions,andinteractionsoffactors如人的過失，工裝磨損、環境條件以及因素間的相互作用,58,Effectsontheprocess/對過程的影響9-10Mayendangermachineoroperator/可能導致設備或人員受損6-8Scrap/報廢4-5Sortandrework/篩選和返工2-3Reworkon-line/在線返工1Noeffect/無影響,ConsiderAlsotheEffectsontheCustomer还要考虑对顾客的影响,59,Usehistoricaldata(asabaseline)/利用歷史資料Takeimprovementsintoaccount考慮改進9-10Failurealmostinevitable/失效幾乎不可避免7-8Similarprocessesthathaveoftenfailedinthepast以前類似過程常常失效4-6Similarprocessesthathaveoccasionalfailures類似過程偶爾失效1-3Similarprocessesthathaveexperiencedisolatedfailures/類似過程僅有過個別失效,60,Cause-and-EffectChain因果鏈,ToolIsWorn夾具磨損,ToolNotReplaced夾具未更換,LackofMaintenanceProcedure/沒有保養程序,ClampCracksatBend夾子在彎曲處裂紋,BundleFallsOut線束散開,RattlingNoise卡嗒聲噪音,CAUSEchain原因鏈,EFFECTchain後果鏈,RadiusOutOfSpec半徑超差,61,CrossedWire交叉的電線,NoFunction沒有功能,CausesTree/原因樹,EffectsTree/後果樹,FireinPlant工廠起火,OperatorInjury員工受傷,DamagedEquip設備損壞,MustRepairVehicle必需維修車輛,PoorInstruction指導書不足,NotTrained未培訓,OperatorError操作員錯誤,BoardError電路板錯誤,OperatorTired操作人員疲勞,CrossedWire交叉的電線,62,Processcontrolscatchthedefectbeforetheproductreachesthecustomer/程序控制當在産品到達顧客前發現缺陷