失效模式分析（ppt 68）

1、1An analytical tool for identifying Potential Failures in a product or process so that corrective action can be taken before the failures can reach the customer.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2An FMEA is a Structured Approach to:FMEA是結構式的方法 Identifying the ways in which a design or proce

2、ss can fail to meet the critical customer requirements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 Estimating the risk of specific causes with regard to these failures估計產生這些失效的特殊原因的風險 Evaluating the current controls for preventing these failures評估現有控制手段對這些失效的預防 Prioritizing the actions that must be taken to improve

3、the design or the process給那些用以改進設計和過程的措施排序3FMEA History 歷史 First used in the 1960s during the Apollo Moon Missions.最早被用於上世紀六十年代的阿波羅登月計劃. In 1974 MIL-STD-1629 was developed by the Navy for using FMEAs.1974年海軍為FMEA的應用制定了MIL-STD-1629. In the late 1970, adapted by the auto industry in response to higher

4、 liability costs and higher quality demands by customers.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.4FMEA is proactive, not reactive. Dont wait for the customer to complain if you can avoid it!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！ 5FMEA reduces the chance that a customer will see a failureFMEA通過以下措施減

5、少顧客遇到失效的情況:By defining failure in terms of what the customer wants and expects.針對顧客的要求和期望確定失效By showing where measures need to be taken to prevent failure.指出爲了防止失效，需要在哪方面採取措施 6Types of FMEAs 類型Design used to analyze product designs before they are released to production設計 - 用於在產品投產前對設計的分析 Process us

6、ed to analyze manufacturing processes過程 - 用於分析製程 System used to analyze systems in the early concept and design stages系統 用於分析早期的概念和設計階段的系統7Summary 概要Identifies known and potential failure modes;識別已知和潛在的失效模式Identifies the causes and effects of each failure mode;識別每一種失效模式的原因和後果Prioritizes the failure

7、modes (using the RPN); 利用風險序數 （RPN）給失效模式排序Should initiate corrective action where needed.必要時提出糾正措施8Timing of an FMEAFMEA的時機 FMEAs should be initiated when preliminary drawings of the design or process are available當初步的設計圖紙和工藝被制定出來時應開始做FMEA Updated as identified issues are resolved當被發現的問題解決後要更新FMEA C

8、an be used on existing products to improve quality可用於現有的產品以提高質量9System系統Wiring harness 線束Electronic module電控模塊Assembly總成System FMEA treats system as a“functional schematic”系統FMEA從“功能關係圖”入手來考慮SFMEA10An analytical tool used to identify system-level failure modes, and identify corrective actions to be

9、taken.是一種分析工具用來識別系統失效模式11It is similar to a Design FMEA, but focuses on the circuit schematic instead of physical failure of components.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。Take electrical systems as examples.以電氣系統為例。12Example:舉例：Failure mode at electrical system level 電氣系統失效模式Open circuit at ckt A回路A

10、出現開路Cause: 原因：Terminal unseated端子脫出Terminal unseated becomes a failure mode at the component level.端子脫出 是電氣元件的失效模式。13Rules of Design FMEA設計FMEA規則 Tool for design engineers and project team to improve the design in a preemptive manner (before failure occur)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) Used to est

11、ablished Critical to Quality features that effect the performance of the product用與那些影響產品性能的重要質量特性 Used to establish Critical to Life features that effect the life of the product用於確定影響產品壽命的重要壽命特性 Used to establish Critical to safety features用於確定重要安全特性14Purpose of Design FMEA設計FMEA的用途Establishes criti

12、cal features that must be controlled in manufacturing to satisfy customer requirements確定那些必須在生產中進行控制的特性以滿足客戶要求 Identifies deficiencies in the product design and associated action items找出產品設計中的不足和相應的措施 Helps evaluate the risk of design changes幫助評價設計變更的風險15Purpose of Design FMEA設計FMEA的用途 Identifies pr

13、ocess development needs確定開發工藝流程的需求 Dynamic document documents design alternatives and associated risks動態的文件 記錄可選擇的設計方案和相應的風險 Establishes bases for manufacturing and quality control plan建立製造和品質控制計劃的基礎16Design FMEA Inputs and Outputs 設計FMEA的輸入和輸出 Product drawings產品圖紙 Product models產品模型 Product specifi

14、cation產品規格 Identified Critical toQuality failures確定的重要質量特性 Actions to prevent the causes of failures防止失效原因的措施 Actions to detect failure modes發現失效模式的措施 History of actions and Responsibilities措施和責任人的記錄17Design 设计Components 元件Elements设计要素Design FMEA looks at physical failure modes of components and des

15、ign elements设计FMEA着眼于元件及设计要素 的物理失效模式DFMEA18Rules of Process FMEA過程FMEA規則 Tool for process engineers and project team to improve the manufacturing process in a preemptive manner 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 Used to prioritize actions to ensure attention to critical processes that effect customers用與區分先

16、後順序以確保那些影響客戶的重要工藝Used to document process improvements用於工藝改進 Dynamic document for continuous improvement持續改進的動態文件19Purpose of Process FMEA過程FMEA的用途 Assists in the analysis of new manufacturing process幫助分析新的製造工藝 Establishes the bases for manufacturing process instructions and control sheets建立製造工藝文件和控

17、制文件的基礎 Identifies new manufacturing process needs確定新製造工藝的需求 Helps evaluate the risk of process changes幫助評估工藝更改的風險20Process 过程Manufacturing 制造Assembling装配Process FMEA looks at product failures caused by the process failing to meet requirements过程FMEA着眼于因加工過程不符合要求所造成的产品 失效PFMEA21FMEA Team 小組 Team appro

18、ach is necessary.需要團隊的方式 Responsible for Design FMEA Design Engineer設計工程師負責設計FMEA Responsible for Process FMEA Manufacturing Engineer製造工程師負責過程FMEA Recommended representatives:推薦人選:Design / 設計Manufacturing Engineers / 製造工程師Quality Engineers / 質量工程師Reliability / 可靠性Materials / 原材料Suppliers / 供應商22Defi

19、nition of Terms 術語Failure Mode The way in which a specific input requirement fails and if not detected, corrected or removed will cause an Effect to occur.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 Effect Impact on customer requirements 後果 對客戶要求的影響23Definition of Terms 術語Cause Source(s) of process vari

20、ation that causes the Failure Mode to occur.原因 造成失效模式發生的過程變差的起源 Current Control (proposed controls)當前的控制 (建議的控制)Design elements that ensure function確保功能的設計要素Mistake proofing, automated controls, set up instructions, 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24

21、Linking Failure Modes to Effects失效模式和後果之間的聯繫Failure Mode 1Failure Mode 2Effect 1Failure Mode 1Effect 2Effect 1Failure Mode 1Failure Mode 2Effect 1Note that the relationship between the Failure Mode and Effect is not always 1-to-1 請注意失效模式和後果之間的關係不總是一對一Effect 225Risk Priority Number 風險序數 The output of

22、 a FMEA is the “Risk of Priority Number” - RPN一個FMEA的輸出是“風險序數”-RPN The RPN is a calculated number based on information provided regardingRPN是根據下面的資料計算出來的 The potential failure modes,潛在失效模式The effects, and後果The current or planned ability to detect the failure before it reaches the customer現有的和已計劃的能力可

23、以在影響客戶前覺察失效26Risk Priority Number 風險序數 It is calculated as the product of three quantitative rating 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 The RPN is not sacredRPN不是神聖的 Scaling for Severity, Occurrence, and Detection are locally developed嚴重度,發生頻度,探測度的尺度由自己制定 Other

24、 categories may be added to suit need根據需要可以加上其他類型 High Risk Priority Numbers are significant to the success of the product design - actions must be taken to prevent failures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27Definition of RPN Terms RPN術語Severity (of effect) Importance to customer, may involve functio

25、n, safety, reliability, or life of product (1= not severe, 10 = very severe)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 (of cause) Frequency with which a given Cause may occur (1= not likely to occur, 10= very likely to occur)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)De

26、tection (Capability of current or planned Controls) Ability to detect the cause (1= likely to be detected, 10= not likely to be detected)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)28Rating Scales 評分尺度Rating得分 Degree of Severity/ 嚴重程度 1Customer will not notice the adverse effect or it is insigni

27、ficant/客戶不會注意到或該不利後果不重要 2Customer will probably experience slight annoyance/可能對客戶有輕微的影響3Customer will experience annoyance due to the slight degradation of performance/由於輕微的性能下降可能給客戶帶來麻煩 4Customer dissatisfaction due to reduced performance/由於性能下降使客戶不滿意 5Customer is made uncomfortable or their produc

28、tivity is reduced by the continued degradation of the effect/客戶不滿意或受持續降級的影響使他們的生產力降低 6Warranty repair or significant manufacturing or assembly complain/保修或者重大的製造或組裝的投訴 7High degree of customer dissatisfaction due to component failure without complete loss of function. Productivity impacted by high s

29、crap or rework levels/零件雖未完全失去功能但引起客戶較大的不滿;由於高報廢,高返工率影響生產力 8Very high degree of customer dissatisfaction due to the loss of function without a negative impact on safety or government regulation/由於零件喪失功能而引起客戶極大不滿但尚未違反安全或國家規定 9Customer endangered due to adverse effect on safe system performance with w

30、arning before failure or violation of governmental regulations/安全系統的不利影響使得客戶處於危險當中但在失效前有警告或違反國家規定 10Customer endangered due to adverse effect on safe system performance without warning before failure or violation of governmental regulations/安全系統的不利影響使得客戶處於危險當中而且失效前沒有警告或違反國家規定 29Rating Scales 評分尺度Rat

31、ing得分 Likelihood of Occurrence/ 發生的可能性1Likelihood of occurrence is remote/ 發生的可能性極小2Low failure rate with support documentation/ 有書面證據證明發生的可能性很低3Low failure rate without support documentation/發生的可能性很低但沒有書面證據證明4Occasional failure/ 偶爾失效5Relatively Moderate failure rate with supporting documentation/有書

32、面證據證明中等的失效可能性6Moderate failure rate without supporting documentation/沒有書面證據證明中等的失效可能性7Relatively high failure rate with supporting documentation/有書面證據證明高度的失效可能性8Relatively high failure rate without supporting documentation/沒有書面證據證明高度的失效可能性9Failure is almost certain based on warranty data or signific

33、ant testing/ 根據保修數據或重要試驗幾乎可以肯定失效會發生10Assure of Failure based on warranty data or significant testing/ 根據保修數據或重要試驗可以肯定失效會發生30Rating Scales 評分尺度Rating得分 Ability of Detect/ 可探測度 1Sure that the potential failure will be found or prevented before reaching the next customer/確定潛在失效可以在到達下一個客戶前被發現或預防2Almost

34、certain that the potential failure will be found or prevented before reaching the next customer/幾乎可以肯定潛在失效可以在到達下一個客戶前被發現或預防3Low likelihood that the potential failure will reach the next customer/潛在的失效到達下一個客戶的可能性很低4Controls may detect or prevent the potential failure from reaching the next customer/控

35、制手段可以防止潛在失效到達下一個客戶5Moderate likelihood that the potential failure will reach the next customer/潛在的失效到達下一個客戶的可能性中等6Controls are likely to detect or prevent the potential failure from reaching the next customer/控制手段不太可能防止潛在失效到達下一個客戶7Poor likelihood that the potential failure will be detected or preven

36、ted before reaching the next customer/在潛在失效到達下一個客戶前發現或預防的可能性較低8Very poor likelihood that the potential failure will be detected or prevented before reaching the next customer/在潛在失效到達下一個客戶前發現或預防的可能性非常低9Current controls probably will not detect the potential failure/現有控制手段可能探測不到潛在失效10Absolute certainl

37、y that the current controls will not detect the potential failure/完全肯定現有的控制手段無法探測潛在失效31Examples of Occurrence scale發生率評分的例子Scale Value分值Occurrences perWeek週Day日Shift班Hour小時107001003349500712438350501727200291016100145157511445072325412711132Examples of Detection scale探測度評分的例子Scale Value/分值Percent of

38、 potential failures prevented預防潛在失效的比率190%280%370%460%550%640%730%820%910%100%33ProcessStep/InputPotential Failure ModePotential Failure EffectsSEVPotential CausesOCCCurrent ControlsDETRPNActions Recommended0000000000000000What is the input?輸入是甚麼?What can go wrong with the input?輸入會出甚麼錯?What is theE

39、ffect onthe output?輸出的後果是甚麼?What arethe causes?原因是甚麼?How well?程度如何?How canthis be found?怎樣才可以發現?How often?頻繁程度What can be done?可以做甚麼?How well?程度如何?34FMEA FAILURE MODE EFFECTS ANALYSISProduct:ProcessStep/InputPotential Failure ModePotential Failure EffectsSEVPotential CausesOCCCurrent ControlsDETRPNA

40、ctions RecommendedResponsibilityWhat is the step or input under investigation?In what way does the key input go wrong?What is the impact on the key output variable (customer requirement or internal requirement)How severe is the impact on the customer?What causes the key output to go wrong?How often

41、does cause of failure mode happen?What are the existing controls and procedures (inspection and testing) that prevent either the cause or the failure mode? Include shop operating procedure number How well can the failure mode of cause be detected?RPN = SEV * OCC * DETWhat are the actions for reducin

42、g the occurrence of the cause or improving detection? Should have actions on all high RPN numbers.Who is responsible for implementing the recommended actions?000035FMEA Model 模式Prevention/預防Prevention/預防Prevention/預防Cause/原因Effect/後果Failure Mode/失效模式Controls/控制Material or process input/原料或過程輸入Proces

43、s Step/工序External customer or downstream process step/外部客戶或下一工序36General Steps in the DFMEA/一般步驟 Select design FMEA team 組建設計FMEA小組List customer requirements 列出客戶的要求 For each customer requirement list the key design elements that satisfy the customer requirements 針對客戶的每一個要求列出滿足該要求的關鍵設計要素 For each ke

44、y design element list ways that the design element could vary, Potential Failure Modes 列出每一個關鍵設計要素的變化,潛在的失效模式 List Effects of each Failure mode on the customer requirement 列出每個失效模式的對客戶要求的影響 List Causes for each failure Mode 列出失效模式的原因37General Steps in the DFMEA/一般步驟 List current controls for each ca

45、use 列出每個原因的現有控制手段 Assign Severity, Occurrence, and Detection ratings to each cause給每個原因的嚴重度,頻度,可探測度評分 Calculate RPNs 計算風險序數 Recommend actions to reduce high RPNs 提出降低風險序數的措施 Take appropriate action 採取適當的措施 Recalculate RPNs 重新計算風險序數38A schematic representation, with 一種圖示法, 其中 Components (or features)

46、 shown as blocks, 用方塊表示各元件(或特性)Interactions between components shown as lines, 用直線表示各元件之間的關係At the appropriate level of detail詳細到恰當的程度 Develop a Functional Block Diagram of The Product繪制產品功能結構圖39Component元件Component元件Component元件Component元件Component元件Component元件Block Diagram 結構圖Examples例如40Dont forge

47、t auxiliary functions as well a primary functions主要功能和輔助功能都要考慮Often, components work together to perform a function 經常是幾個零件共同實現一個功能Hint: Use the Block Diagram!提示: 利用結構圖List The Function(s) of Each Component列出每個要素的功能41A defect, flaw, or other unsatisfactory condition in the product that is caused by

48、a design weakness 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Typical Failure Modes: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42Start with the previous two steps: 從前両個步驟入手: Functions 功能Quality requirements質量要求43In your own descriptive words, write down the following scenarios，用自己的語言

49、描述下列假設：Failure = No function， 失效 = 無功能Failure = Not enough function， 失效 = 功能不足Failure = Too much function， 失效 = 功能過強Similarly,同樣：Failure = No quality requirement失效 = 未達到質量要求44An effect can be ，後果可能是：Complete loss of function，功能完全喪失Degradation of performance or quality性能或質量下降Many failure modes have m

50、ore than one effect!許多失效模式不止有一個後果！Effects of failure often show up as a chain of events, from immediate effect to the ultimate effect on the customer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45Determine Potential Cause(s) of Each Failure Mode確定每種失效模式的潛在原因A cause of failure is a design weakness that leads

51、to the failure mode造成失效的原因是由於設計缺陷 引起Inherent in the way the product was designed是產品設計所固有的Relative to the usage of the product與產品的使用方法有關Many failure modes have multiple causes! 許多失效模式有多個起因！46If the design as-is were to go into production.如果依據現有設計進行生產的話Use historical data，利用歷史資料Take improvements into

52、account，參考已有的改進Consider the lifespan of the product，考慮產品的壽命Use reliability models and comparison with similar products，利用可靠性模型並與類似產品比較Assess The Likelihood of Occurrence of Each Cause評估每種原因發生的可能性47There are three types of design controls:設計控制有三種類型：(1) Those that prevent the cause of failure; 預防產生失效的

53、原因；(2) Those that detect the cause(s) of failure; 覺察產生失效的原因；(3) Those that detect the failure mode(s) 檢測失效模式48Detection Rating (D): 探測度評分9-10Remote chance of detecting failure察明失效的可能性極小7-8Very low chance，可能性很小5-6Low to moderate chance，可能性不大2-4Good chance，可能性較大 1Will almost certainly detect failure(I

54、f it passes this, it will not fail)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)49To reduce severity - design change to control the effect降低嚴重度 通過設計更改來控制後果To reduce occurrence - design change to control the cause減少發生頻度 -通過設計更改來控制原因To improve detection - improved testing or simulation methods增強探測度 改進測試和模擬方法Special Att

55、ention if Severity = 9 or 10當嚴重度為9或10時要特別注意50General Steps in the PFMEA/一般步驟 Select process FMEA team 組建過程FMEA小組 Develop a Process Map and identify all process steps 做一個流程圖確定過程的所有步驟 List all the Key Process Outputs to satisfy internal and external customer requirement 列出所有的滿足內部和外部客戶要求的關鍵過程輸出 For eac

56、h process step, list Key Process Input Variables 列出每一步的關鍵過程輸入變量 For the Process Define C&E matrix relating Key Outputs to Key Process Input Variable 用因果圖分析關鍵過程輸入和關鍵輸出的聯繫 Rank the KPIVs according to importance 根據重要程度給關鍵過程輸入變量分級 Start the process FMEA 開始做過程FMEA51General Steps in the PFMEA/一般步驟 For eac

57、h process input, list ways that it can vary (failure Modes) and identify associated effects 對每一個過程的輸入,列出其可能的變化和相應的後果 List all Causes for each Failure Mode 列出失效模式的所有原因 List the current Controls for each cause 列出每個原因的現有控制手段 Assign Severity, Occurrence, and Detection ratings to each cause 給每個原因的嚴重度,頻度,

58、可探測度評分 Calculate the RPN for each potential Failure Mode scenario 計算每個潛在失效模式的風險序數 Determine recommended actions to reduce High RPNs 提出降低風險序數的措施 Take appropriate actions 採取適當的措施 Recalculate RPNs 重新計算風險序數52Use the Process Flow Diagram format 適用流程圖的格式Identifies fabricate, move, store and inspect operat

59、ions 識別四種作業類型,製造,移動,儲存,檢驗Identifies Key Characteristics識別關鍵特性A function is what the operation does 功能系指該操作所起的作用 State the function as /说明功能为：Verb + Object + Qualifier 动词+宾语+修饰词 Mold part /成型零件 Crimp terminal onto cable /電線上壓接端子 Form bend in part /零件彎曲成形53A customer want or desire顧客的希望或要求 Could serio

60、usly affect customer perception有可能嚴重影響顧客的看法 Could lead to a customer complaint有可能導致顧客投訴 A defect, flaw, or other unsatisfactory condition in the product that occurs when the process fails to meet the process requirements由於過程未達到要求而導致的産品缺陷、瑕疵等不良狀態 Failure modes should be written in terms of the condit