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1、潜在的失效模式及其效应分析（FMEA）培训员: 王运良内容课程目的什么是FMEAFMEA的起源为什么要用FMEAFMEA的分类什么时候用FMEA特殊特性在FMEA怎样做FMEA怎样降低过程的风险（RPN）FMEA中常见的问题缺陷树分析和FMEA课程目的 明白FMEA的角色和作用 明白过程FMEA（DFMEA）的概念和技术以及怎样应用 明白设计FMEA（DFMEA）的概念 了解缺陷树分析（FTA） 了解零缺陷质量控制和防错法的概念以及他们对FMEA的含意什么是FMEA? 潜在的失效模式及其效应分析 潜在的 而不只是现有的 失效模式 研究的对象 效应 （后果） 失效模式的影响 是一个前期质量策划的
2、工具用来评估潜在的失效模式和失效模式产生的原因 区分失效的优先次序。根据失效模式的风险和所采取的行动来消灭和减少发生的几率。 提供一个方法用来分析制程并持续改进。 FMEA必须与别的质量工具结合才能更好的解决问题，如DOE， SPC，因果分析图等 FMEA 的焦点是通过问题的前摄来达到预防的目的而不是解决现有的问题。什么是FMEA?FMEA的分类三种类型的 FMEA 系统FMEA (SFMEA) 设计FMEA (DFMEA) 过程FMEA (PFMEA)FMEA的起源 FMECA （Failure Mode Effects and Criticality Analysis） 失效模式的后果及其
3、危险程度分析 起源于20世纪50年代 航空航天业以及美国军工业 分类和等级 目标是预防致命的问题的发生 特别强调安全问题 FMEA 失效模式及其效应分析- 1960s 和 70s 首先使用FMEA的是可靠性工程师 为什么要用FMEA? 欧美发达国家制定的质量责任的有关法律法规的条款 FMEA的“严重度”第10等级体现了这一点 违反法律法规违反法律法规 人身安全人身安全 案例： 针对Ford汽车的索赔案 三菱帕杰罗刹车故障案 Ford和凡士通的官司事关企业的存亡！ 汽车行业汽车行业QS9000 和TS16949APQP手册 过程安全管理行动过程安全管理行动 (PSM) （美国职业安全健康局）CF
4、R 1910.119999999 列出PFMEA是六种方法中的一种用来评估危险性 FDA （美国药品管理局）- GMPs设计FMEA是其中一个工具用来评估一个新的设计。 ISO 9001预防行动的要求. FMEA是一个很好的持续改进的工具来符合这个条款的要求。 ISO14000可以用来评估有害物质的风险。为什么用FMEA？一个早期的 FMEASFMEA从概念开发的开始阶段到正式的设计方案开始前。 用于评估系统的失效风险DFMEA从概念开发的后期阶段开始到设计方案完成。用于评估设计的失效风险PFMEA从设计开发完成开始到产品的试产前。用于评估制造过程的失效风险。什么时候做FMEA？FMEA 的时
5、间表 DFMEA: 从过程的早期开始. 设计的草图完成后，在任何的工具设计开始前。 PFMEA: 从过程开发的早期阶段开始，已经大致确定了过程的初步方案。应在量产的方案确定之前或量产批准前。概念设计 设计 设计完成 试生产 产品和过程批准 量产开始PFMEADFMEASFMEA三种 FMEA之间的关系SFMEAPFMEADFMEA失效模式后果原因来自SFMEA中的问题的原因来自SFMEA有着更好定义的中的后果对设计失效的新的根本原因来自DFMEA中的问题的原因与DFMEA相同的后果对过程失效模式的特定的根本原因问题的分支问题问题的原因系统系统设计设计制程制程零件零件 子系统子系统 主系统主系统
6、人员人员 机器机器 方法方法 物料物料 测量测量 环境环境零件零件 子系统子系统 主系统主系统把系统失效模式的后果最小化焦点把设计的失效模式的后果最小化焦点最大化系统的质量，可靠性，成本和可维护性目标最大化设计的质量，可靠性，成本和可维护性目标机器工具， 工作岗位，生产线，员工培训，制程，量具把整个制程的失效模式的后果最小化焦点最大化整个制程的质量，可靠性，成本和可维护性目标三种 FMEA之间的关系典型的汽车产品发展的三步曲产品流程产品流程图和产品图和产品的工程规的工程规格格PFMEA控制计划控制计划输入输入输出输出过程过程客户的要求客户的要求是什么？是什么？典型的汽车产品发展的三步曲PFME
7、A（包括所有的过程）关键特性和失效的后果DFMEA过程的控制计划（来自PFMEA的关键过程）关键特性和特性的控制可能被包括的一些元素流程图（包括所有的过程）APQP时间表典型的汽车产品发展的三步曲过程的流向及清单检查客户的要求选择每一个“关键”的过程到FMEA表中评估每一个过程的FMEA项目发展包含了特殊特性的控制计划仔细考虑所选的“关键”过程用适当的RPN数值和一些别的意见来决定关键的特性 （过程）发展针对特殊特性的控制机制仔细考虑控制计划的各个阶段：样板试产量产注意：注意：FMEA还还应当包含对产品特应当包含对产品特殊特性的评估。殊特性的评估。Some Key FMEA TermsCust
8、omer InputTeam - Team Selection (Cross-Functional)Ranking - Ranking of DecisionsRisk Priority Assessment Design Process Production ProcessAutomotive Acronyms: AIAG: Automotive Industry Action Group APQP: Advanced Product Quality Planning DFMEA: Design Failure Mode and Effects Analysis DOE: Design of
9、 Experiments FMA: Failure Modes Analysis FMEA: Failure Mode and Effects Analysis KCC: Key Control Characteristic KPC: Key Product Characteristic PFMEA: Process Failure Mode and Effects Analysis PPAP: Production Part Approval Process PSW: Product Submission Warrant QFD: Quality Function DeploymentAut
10、omotive Madness特殊特性产品的特殊特性 尺寸，性能参数 。 影响产品的功能，可靠性，寿命，耐用性，安全性 可能影响法律法规的符合性 一般由客户指定，图纸上用特殊的符号标出。如 “ ”， “”等。特殊特性过程的特殊特性 可能产品的影响产品的功能，可靠性，寿命，耐用性，安全性，或可能影响法律法规的符合性或产品后续生产过程的制造过程参数。 一般通过FMEA评估产生，由制造商自己指定。产品和过程的特殊特性都应当包含在控制产品和过程的特殊特性都应当包含在控制计划中。计划中。Characteristics ICharacteristics IICharacteristics IIIChara
11、cteristics IVCharacteristics V怎样用FMEA评估过程的风险？1. 什么是失效模式1.一般指的产品的失效（缺陷）。这些缺一般指的产品的失效（缺陷）。这些缺陷可能是功能，装配，外形方面的问题，陷可能是功能，装配，外形方面的问题，对客户满意度有不同程度的影响。对客户满意度有不同程度的影响。2.注意：不一定是外部客户，有可能指的是内部客户。怎样用FMEA评估过程的风险？1. 失效模式的风险度1.一般用一般用 RPN（风险度序数）来表示过（风险度序数）来表示过程的风险度，程的风险度，RPN最小为最小为1， 最大是最大是1000。RPN越大，被评估过程的风险越越大，被评估过程
12、的风险越大。大。 怎样用FMEA评估过程的风险？1. 失效模式的严重度 （S）1.一般用一般用S（严重度）来表示产品的缺陷（严重度）来表示产品的缺陷对最终使用，或下道工序，以及客户满意对最终使用，或下道工序，以及客户满意度的影响程度。度的影响程度。D最小为最小为1， 最大是最大是10。D越大，产品的缺陷越严重，越大，产品的缺陷越严重， 缺陷造成的缺陷造成的后果后果 越严重。越严重。怎样用FMEA评估过程的风险？1. 失效模式的发生频率 （O）1.用用 O（发生频率）来表示产品的缺陷的（发生频率）来表示产品的缺陷的可能性。可能性。 O最小为最小为1， 最大是最大是10。O越大，越大，产品的缺陷发
13、生的可能性越大。产品的缺陷发生的可能性越大。怎样用FMEA评估过程的风险？1. 失效模式的不可探测度 （D）1.用用 D（不可探测度 ）来表示产品的缺陷）来表示产品的缺陷的被发现的可能性。的被发现的可能性。 D最小为最小为1， 最大是最大是10。D越大，产品的缺陷越难以被探测到越大，产品的缺陷越难以被探测到的可能性越小。的可能性越小。怎样做PFMEA？1. 成立一个跨部门的小组1. 制造（工艺）工程师制造（工艺）工程师2. 设备工程师3. 设计工程师4. 品质工程师5. 生产工程师/主管6. 可靠性工程师7. 工业工程师8. 等。1.在开始FMEA前，把小组的人员先写在FMEA表格的上边。一般
14、是组长怎样做PFMEA？1.2. 定义所涉及的产品的特殊特性：1.客户图纸2.规格书3.等。4.必要时应与客户沟通，以确保领会客户的要求。练习 11.指定一个产品，并定义产品的特殊特性。怎样做PFMEA？1.3. 画出产品的生产流程图.PROCESS FLOW DOCUMENT Flow CHART, Preliminary ProcessDescription of anticipated manufacturing processdeveloped from preliminary bill of material andproduct/process assumptions. (P10
15、#1.10 APQP) & (P104 APQP) Flow DIAGRAM, ProcessDepicts the flow of materials through the process,including any rework or repair operations. (P50 PPAP)How To Use The Flow Chart Use to help determine who should be involved by identifying all the work areas in a process Use as a job aid to remind peopl
16、e about process standards Use as a check list to collect data on where problems occur Use to investigate why rework is occurring at a certain place in the process Use the ideal process flow chart data to communicate your proposed solutionFlow Chart Tips If a process step or box has two output arrows
17、, consider whether a decision box is needed Remember that the people closest to the work know it best. Make sure people are involved in developing the flow chart Software packages make flow chart production easy.怎样做PFMEA？1.4. 把出对产品的特殊特性有影响的过程先标出来，这些过程应当优先评估。2.5。把对下道工序有影响的工序标出来，这些过程也应当优先评估。3.6。把每道工序的
18、功能写下来。4. 思考：想一下，为什么？练习 21.画出产品的生产流程图.2.把出对产品的特殊特性有影响的过程先标出来，这些过程应当优先评估。3.把对下道工序有影响的工序标出来，这些过程也应当优先评估。4.把每道工序的功能写下来。怎样做PFMEA？1.7. 列出每一个过程的失效模式， 即每一个过程可能可能产生的缺陷。1.注意：是可能发生的缺陷，是潜在的，不一定是已有发生的。2.8. 评估每一个缺陷可能造成的后果，根据FMEA的规则对后果进行评分。即S的分数。FMEA Rating of S, O, DRecommended Actions When the failure modes have
19、 been ranked by their RPN, corrective actions should be first directed at the highest ranked concerns and critical items identified. The intent of any recommended action is to reduce one or more (or all) of the occurrence, severity and/or detection rankings. Only a design revision can bring about a
20、reduction in the severity ranking. If no actions are recommended for a specific cause, this should be indicated. A reduction in the occurrence ranking can only be effected by removing or controlling one or more of the causes of the failure mode through a design revision. An increase in design verifi
21、cation actions will result in a reduction in the detection ranking ONLY. Design FMEA doesnt rely on process controls to overcome potential weaknesses in the design; however, it does take technical and physical limitations of a process into consideration (Design Rules)The Process Potential FMEA Ident
22、ifies potential product-related failure modes Assesses the potential customer effects of the failures Identifies the potential internal and external manufacturing or assembly process causes and identifies process variables on which to focus controls for occurrence reduction and/or detection of the f
23、ailure condition(s) Develops ranked list of potential failure modes, thus establishing a priority system for corrective action considerations Documents the results of the manufacturing or assembly processProcess Potential FMEA A Process Potential FMEA is an analytical tool utilized by a Process FMEA
24、 team as a means to ensure potential failure modes and their associated causes are identified, considered and addressed. Teams should be run by the owner of the process or someone who understands the process well. Defines reasons for rejection at specific operations. In preparation for the FMEA, the
25、 assumption should be made that the incoming parts and materials are correct. A comparison of similar processes and a review of customer claims relating to similar components is a recommended starting point. A knowledge of the purpose of the design is necessary. It can be cause-associated with a pot
26、ential failure mode in asubsequent operation or an effect associated with a potential failure in a previous operation. Each potential failure mode for the particular operation should be listed in terms of a part or process characteristic.Process FMEA FociCustomers include: End User Next Manufacturin
27、g or Process Step Process Engineers Assembly Engineers Repair Functions Test Engineers Product Analysis Dealership or other Sales OutletProcess FMEA Benefits As a systematic approach, the Process Potential FMEA parallels and formalizes the mental discipline that an engineer goes through in any manuf
28、acturing planning process. The Process Potential FMEA identifies potential product related process failure modes. The Process Potential FMEA assesses the potential customer effects of the failures. The Process Potential FMEA identifies potential manufacturing and/or assembly process causes. The Proc
29、ess Potential FMEA identifies significant process variables to focus controls for occurrence reduction and detection of failure conditions. The Process Potential FMEA develops a list of potential failure modes ranked according to their affect on the customer, thus establishing a priority system for
30、corrective and preventive action considerations.More Process FMEA Considerations The Process FMEA is a living document. The Process FMEA should be continually updated as changes occur throughout all phases of product development and on into and through to the end of production. The Process FMEA shou
31、ld begin with a flow chart of the processes - from receiving through shipping and warehousing. The Potential Failure Modes/Causes which can occur during manufacturing or assembly process are covered by the Process FMEA but some information (severity rankings, identification of some effects) may come
32、 from the Design FMEA.A reduction in occurrence ranking can only be achieved byimplementing a process change that controls or eliminatesone or more causes of the failure mode.General Rating of S,O, D1. Omitted processing2. Processing errors3. Errors setting up work pieces4. Missing parts5. Wrong par
33、ts6. Processing wrong work piece7. Mis-operation8. Adjustment error9. Equipment not set up properly10. Tools and/or fixtures improperly prepared11. Poor control procedures12. Improper equipmentmaintenance13. Bad recipe14. Fatigue15. Lack of Safety16. Hardware failure17. Failure to enforce controls18
34、. Environment19. Stress connections20. Poor FMEA(s).Process Failure Causes1. Standardized work instructions/procedures2. Fixtures and jigs3. Mechanical interference interfaces4. Mechanical counters5. Mechanical sensors6. Electrical/Electronic sensors7. Job sheets or Process packages8. Bar coding wit
35、h software integration and control9. Marking10. Training and related educational safeguards11. Visual Checks12. Gage studies13. Preventive maintenance14. Automation (Real Time Control)Controls can beprocess controls such as fixture foolproofing or SPC, or can be post-process inspection / testing.Ins
36、pection / testingmay occur at thesubject operation orat subsequentoperation(s) that candetect the subjectfailure mode.Process Control ExamplesTypical Process Documents SPC records Visual aides Work instructions Inspection instructions/records Equipment operating instructions Training records Traceab
37、ility recordsRecommended Actions Corrective Action should be first directed at the highest concerns as rank ordered by RPN. The intent of any recommended action is to reduce the occurrence, severity and/or detection rankings. If no actions are recommended for a specific cause, then this should be in
38、dicated. Only a design revision can bring about a reduction in the severity ranking. To reduce the probability of occurrence, process and/or specification revisions are required. To increase the probability of detection, process control and/or inspection changes are required. Improving detection con
39、trols is typically costly. The emphasis should be placed on preventing, rather than detecting, defects. Fault-tree analysis is a deductive process Especially useful for Analyzing failures, when the causes of failures have not been identified Reliability engineering Tool Motor FailureThe Role and Fun
40、ction of FTAMotor FailureFault Tree Symbols The EllipseThe top event, the ellipse, contains the description of the system-level fault or undesired event. This symbol appears at the head or top of the tree and is included only once in any tree. The input to the ellipse is from a logic gate. The Recta
41、ngleThe fault event, the rectangle, contains a brief description of a lower-level fault.This description should be short without being vague. Fault events appearthroughout the tree and have both their input and output from a logic gate. Logic GatesLogic Gate inputs and outputs, except for the Inhibi
42、t Gate, which is addressedbelow, have similar connections. The output from a logic gate is to any faultevent block or to a Transfer Out function. The input is from any fault event block or from a Transfer In function. The AND Gate is the logic gate in which the output occurs only if all inputs exist
43、.The OR Gate is the logic gate in which the output occurs only if one or more of the input events occur.Fault Tree Fundamentals1. Defining the Undesired Event(s) (Major Fault(s)a. The undesired event is most often the fault which, upon occurrence, results in complete failure of the system, the failu
44、re of a back-up system, degradation, or an undetected failure. This is considered catastrophic failure. The major fault is a failure which causes loss of availability through the degradation or systemshut-down and/or poses a safety hazard to operators and/or maintenancepersonnel. The undesired event
45、, however, may be an unusual failure at a subsystem level, the root cause of which is unknown. Any observable event may be chosen as the “undesired event”. The analyst must recognize that the FTA will not identify failures unrelated to the chosen event.b. To define the undesired event, the normal sy
46、stem operation and environment must be known in order to allow the analysis to show the undesired event as a failure. When defining the undesired event, care must be taken to prevent the range of the faults from becoming too broad. For example, “Failure to complete trip”, for an automobile, is not s
47、pecific enough to allow for ease of analysis. This is because failure could vary from an air conditioning fault, which caused discomfort, to loss of engine power, which caused loss of mobility. Both faults could be considered failure; however, loss of mobility is obviously a much more severe fault t
48、han losing air conditioning.Fault Tree Fundamentals(Continued 1)2. Defining Types of FaultsFaults fall into two basic categories: operational and component.Operation FaultThe operational fault is one which occurs when a component is operating as it was designed to, but at an inappropriate time or pl
49、ace. An example is a failure of a control valve to close or to interrupt the introduction of a reactant into a chemical process due to an inappropriate signal from another device.Component FaultThe component fault can be further divided into two sub-categories: primary and secondary. A Primary compo
50、nent fault occurs when a component fails tofunction in its intended environment. Example: A radar unit designed for use in aircraft which fails due to vibration. A Secondary component failure occurs when a component fails to function in an environment other than the environment for which it is inten