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

An analytical tool for identifying PotentialFailures 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

An FMEA is a Structured Approach to: FMEA是結構式的方法 • Identifying the ways in which a design or process 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 the design or the process • 給那些用以改進設計和過程的措施排序

First used in the 1960’s 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 FMEA’s. 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 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. FMEA – History 歷史

FMEA is proactive, not reactive. Don't 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！

FMEA reduces the chance that a customer will see a failure FMEA通過以下措施減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

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 – used 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 Types of FMEAs 類型

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 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 Summary 概要

Timing of an FMEAFMEA的時機 • FMEA’s 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 • Can be used on existing products to improve quality 可用於現有的產品以提高質量

SFMEA System FMEA treats system as a“functional schematic” 系統FMEA從“功能關係圖”入手來考慮 • System系統 • Wiring harness 線束 • Electronic module 電控模塊 • Assembly 總成

An analytical tool used to identify system-level failure modes, and identify corrective actions to be taken. 是一種分析工具用來識別系統失效模式

Take electrical systems as examples. 以電氣系統為例。 • It 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。

Example: 舉例： • Failure mode at electrical system level 電氣系統失效模式 • Open circuit at ckt A • 回路A出現開路 • Cause: 原因： • Terminal unseated • 端子脫出 • Terminal unseatedbecomes a failure mode at the component level. 端子脫出是電氣元件的失效模式。

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 established 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 establishCritical 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 Rules of Design FMEA設計FMEA規則

Purpose of Design FMEA設計FMEA的用途 • Establishes critical 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

Purpose of Design FMEA設計FMEA的用途 • Identifies process 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

Design FMEA Inputs and Outputs 設計FMEA的輸入和輸出 • Identified Critical to • Quality 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 • Product drawings • 產品圖紙 • Product models • 產品模型 • Product specification • 產品規格

DFMEA Design FMEA looks at physical failure modes of components and design elements 设计FMEA着眼于元件及设计要素的物理失效模式 • Design 设计 • Components 元件 • Elements 设计要素

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 Rules of Process FMEA過程FMEA規則

Purpose 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

PFMEA 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 • Process 过程 • Manufacturing 制造 • Assembling 装配

Team approach 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 FMEA Team 小組

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 Definition of Terms 術語

Cause – Source(s) of process variation 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 thatensure 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 Definition of Terms 術語

Linking Failure Modes to Effects 失效模式和後果之間的聯繫 Failure Mode 1 Effect 1 Failure Mode 2 Effect 2 Effect 1 Failure Mode 1 Effect 2 Failure Mode 1 Effect 1 Failure Mode 2 Note 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

The output of 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 regarding RPN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以在影響客戶前覺察失效 Risk 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 sacred RPN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 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 Risk Priority Number 風險序數

Severity (of effect) – Importance to customer, may involve function, 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) Detection (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) Definition of RPN Terms RPN術語

Rating Scales 評分尺度

Examples of Occurrence scale 發生率評分的例子

Examples of Detection scale 探測度評分的例子

How well? 程度如何? How can this be found? 怎樣才可以發現? How well? 程度如何? What is the Effect on the output? 輸出的後果是甚麼? What is the input? 輸入是甚麼? What can go wrong with the input? 輸入會出甚麼錯? What are the causes? 原因是甚麼? What can be done? 可以做甚麼? How often? 頻繁程度

FMEA Model 模式 Prevention/預防 Prevention/預防 Prevention/預防 Cause/原因 Material or process input/原料或過程輸入 Failure Mode/ 失效模式 Process Step/工序 Effect/後果 External customer or downstream process step/外部客戶或下一工序 Controls/控制

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 key 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 General Steps in the DFMEA/一般步驟

List 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,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 General Steps in the DFMEA/一般步驟

Develop a Functional Block Diagram of The Product繪制產品功能結構圖 • A schematic representation, with 一種圖示法, 其中 • Components (or features) 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

Component 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

List The Function(s) of Each Component列出每個要素的功能 • Don't forget 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

A defect, flaw, or other unsatisfactory condition in the product that is caused by 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

Start with the previous two steps: 從前両個步驟入手: • Functions • 功能 • Quality requirements • 質量要求

In your own descriptive words, write down the following scenarios，用自己的語言描述下列假設： • 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

An 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 more 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

Determine 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 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！

Assess The Likelihood of Occurrence of Each Cause評估每種原因發生的可能性 If 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 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

There 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

Detection Rating (D): 探測度評分 9-10 Remote chance of detecting failure 察明失效的可能性極小 7-8 Very low chance，可能性很小 5-6 Low to moderate chance，可能性不大 2-4 Good chance，可能性較大 1 Will almost certainly detect failure (If 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)

To 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 • SpecialAttention if Severity = 9 or 10 當嚴重度為9或10時要特別注意

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