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1、1設計失效模式及效設計失效模式及效应应分析分析Design Failure Mode & Effect Analysis (DFMEA)2FMEA Definition / FMEA 定义An FMEA can be described as a systemized group of activities intended to: 失效模式及效应分析是一组有系统的行为, 其目的是:(a)Recognize and evaluate the potential failure of a product/process and its effects 辨别与评估产品及其工艺的潜在失效模式, 以及
2、由此产生的效应(b)Identify actions which could eliminate or reduce the chance of the potential failure occurring, and 找出行动方案来避免潜在失效的发生, 或降低其可能性(c)Document the process 将以上过程记录在案3FMEA Flow / FMEA 流程Boundary DiagramInterface MatrixP-DiagramFMEA (with Robustness Linkage)Robustness & Reliability ChecklistDesign
3、Validation Plan (DVP)Qualifies and clarifies the relationships between systemsIdentifies and quantifies the strength of system interactionsIdentifies noise and control factors and error statesSummarizes error states, noise factors, and associate design control4Magna Closures Required FMEA Related Do
4、cuments Boundary Diagram P-Diagram CC / SC / KC Product Characteristic Matrix FMEA Checklist Interface Matrix DFMEA Process Flow Diagram PFMEA DVP&R5A Boundary Diagram Example (U204 Liftgate Latching System)Liftgate Latch AssemblyAjar SwitchBrainplateLock ActuatorPlastic Security ShieldGlass LatchO/
5、S Handle Assembly w/ RodWire HarnessGEMAssembly PlantOwner/OperatorVehicle BodyInner Door TrimWater ShieldDoor Seal System (door effort)Striker AssemblyC-pillar sheet metal with paintFastenersWindow Glass clearanceSheet Metal OuterFCSD (Service)Fasteners6A P-Diagram Example (U204 Liftgate Latching S
6、ystem)U204 Liftgate Latching SystemSignal Factors1) Door Slam Engergy2) Handle release effort Liftgate3) Handle release travel Liftgate4) Handle release effort Glass5) Handle release travel Glass6) Outside release handle cyclingControl FactorsLatch material selections - Frameplate - Housing - Ratche
7、t & PawlRatchet & pawl heat treat: 36-42 HRCComponent finishSpring material selectionIdeal Function Response1) Latch releases2) Latch retains striker fullyError State Response1) Latch no function2) Striker not aligned with latch3) Striker not properly engaged4) Gap issues with trim5) High/low releas
8、e effort6) High/low release travel7) Inside/outside release handle not functioningNoise FactorsPiece to piece:1) Handle effort 68.6 N Max2) Handle travel 20 29 mm3) Door panel hole tolerance4) Door dimensional variation5) Release rod6) 4-way locator bodyCustomer Usage:1) Handle cycle loads / Abuse2)
9、 Door slam speedSub-system interaction:1) Inner/outer sheet metal2) Latch assembly3) Outside release handle assy4) Linkage5) Electrical connectorAging / Wear Effect:1) Fatigue2) Creek3) Impact durability4) CorrosionEnvironment:1) Temperature2) Humidity3) Dust4) Vibration5) Ice7An Interface Matrix Ex
10、ample (Headlamp)InterfaceInterfaceMatrix:Matrix:Example ofHeadLamp-1 -2 -1 -12 -2-1 -2-1 -1 -1 -1-1 -1 -1 -122 -2 -1 -12HeadlampHeadlamp HousingHoodGrill Opening PanelBodyConnectorWiring/Electrical SystemScrew/FastenerScrew/FastenerWiring/Electrical SystemConnectorBodyGrill Opening PanelHoodHeadlamp
11、 HousingHeadlampPEIMP: Physical touching E: Energy Exchange I: Information Exchange M: Material ExchangeNumbers in each corner represent the above interface types, with value denoting the following:+2: Interaction is necessary for function+1: Interaction is beneficial; but not absolutely necessary f
12、or functionality 0: Interaction does not affect functionality-1: Interaction causes negative effects but does not prevent functionality-2: Interaction must be prevented to achieve functionalityNegative values are analyzed for recommended functions.8DFMEA设计失效模式及效应分析设计失效模式及效应分析Design Potential FMEA is
13、: 设计潜在失效模式及效应分析是:an analytical technique used primarily by Design-Responsible Engineer/Team 由负责设计的工程师/小组采用的分析技术to identify potential failure modes用作辨别潜在失效模式to identify associated cause/mechanisms辨别相关原因/机理to support the design process in reducing the risk of failures支持设计过程, 减少失效风险apply to system, sub
14、system, and component应用于系统、 子系统及部件9Customer of DFMEA顾客的定义顾客的定义Customer for a Design FMEA顾客的定义 End user 通常是指“最终使用者” Manufacturing/Process-responsible engineer 也可以是更高一层设计司，制造或装配生产工程司10Team Effort 小组的努力小组的努力 Design 设计 Manufacturing 制造 Quality 品质 Material 材料 Reliability 可靠性 Sub-contractor 分供方11DFMEA 设计失
15、效模式及效应分析设计失效模式及效应分析Design FMEA is LIVING document and should设计FMEA是一份动态的文件 be initiated before or at design concept finalization 在一个设计概念最终形成之时或之前开始 be continually updated在产品开发的各个阶段, 发生更改或获得更多的信息时, 持续予以更新 be fundamentally completed before production drawing release在产品加工图样完工之前全部完成12DFMEA 设计失效模式及效应分析设计
16、失效模式及效应分析Potential failure modes during production “Need Not” but “May Be” included制造的失效模式“不需”但“也可能”包括DFMEA not rely on process controls to overcome design weaknessDFMEA不依靠过程控制来克服潜在的设计缺憾DFMEA considers technical limits of manufacturingDFMEA考虑制造的限制 Mold drafts 拔模斜度 Assembling space 装配空间 Tolerances / capability 公差 / 过程能力13Development of a Design FMEA 设计设计FMEA的开始的开始 First Step of DFMEA: IDENTIFY DESIGN INTEND第一步 : 确定设计意图“Listing of what design is expected to do andwhat is expected not to do”“列出设计期望
