FMEA失效模式及其影响分析

1、Failure Mode and Effect Analysis失 效 模 式 及 其 影 响 分 析1Module Objectives课程目的Describe FMEA principles and techniques. 描述FMEA的法则及技巧。Summarize the concepts, definitions, application options and relationships with other tools.摘要概念、定义、应用的选择和其他工具的关联。Perform a FMEA执行一个FMEA。FMEA: Failure Modes and Effects Anal

2、ysisFMEA is a systematic approach used to examine potential failures and prevent their occurrence. It enhances our ability to predict problems and provides a system of ranking, or prioritization, so the most likely failure modes can be addressed. FMEA是用来检查潜在失效和预防它再次发生的系统性方法.它增强了我们预测问题的能力,并提供了一个排序或区分

3、优先次序的系统,因而使得最可能的失效模式得以确定.FMEA is generally applied during the initial stages of a process or product design. Brainstorming is used to determine potential failure modes, their causes, their severity, and their likelihood of occurring. In Six Sigma, we apply FMEA to know failure modes. Our main intere

4、sts are the cause and likelihood of occurrence, for which we have actual data and do not need to rely on brainstorming.FMEA通常应用在工艺及产品设计的初期，自由讨论决定潜在失效的模式、原因、严重度及发生的可能性。在6S中，我们应用FMEA去了解失效的模式。我们主要感兴趣的是原因及发生的可能性。FMEA is also a valuable tool for managing tasks during defect/failure reduction projects.FME

5、A也是一个在失效缩小的管理任务的有价值的工具。FMEADefinition of FMEA 定义recognize and evaluate the potential failure modes and causes associated with the designing and manufacturing of a new product or a change to an existing product.认识和评估新产品的设计和制造时或对现有产品做出改变时相关的潜在失效模式和原因identify actions which could eliminate or reduce the

6、 chance of the potential failure occurring,确定消除或减少潜在失效发生机会的行动document the process.使过程形成文件FMEA is a systematic design evaluation procedurewhose purpose is to: 是系统的设计评估程序Failure to perform a defined function执行既定功能的失效Something occurring that you dont expect, or want发生了你不希望或不想要的事情Wrong application应用错误A

7、Failure Mode is . . .失效模式是FMEA Use by Black / Brown / Green BeltsTo identify potential failure modes and rate the severity of their effectsTo identify critical characteristics and significant characteristicsTo rank potential design and process deficienciesTo help all of us focus on eliminating produ

8、ct and process concerns and prevent problems from recurringReduce the product development timing and costBackgroundDeveloped in early 60s by NASA to “fail-proof” Apollo missions.Adopted in early 70s by US Navy .By late 80s, automotive industry had implemented FMEA and began requiring suppliers do th

9、e same. Liability costs were the main driving force.Used sporadically throughout industry during 1980s.Adopted by MSI in ? Six Sigma is the catalyst.NASA used FMEA to identify Single Point Failures on Apollo project (SPF = no redundancy & loss of mission). How many did they find?420and we thought we

10、 had problems!Types of FMEAsSYSTEM DESIGNPROCESSSystem FMEA is used to analyze systems and subsystems in the early concept and design stages.Design FMEA is used to analyze products before they are released to productionProcess FMEA is used to analyze manufacturing, assembly and administrative proces

11、sesWhen is the FMEA Started?“Do the best you can with what you have”AS EARLY AS POSSIBLE!Guideline:When to Start ?When new systems, products and processes are being designedWhen existing designs and processes are being changedWhen carry-over designs or processes will be used in new applications or e

12、nvironmentsAfter completing a Problem Solving Study, to prevent recurrence of a problemBeginning and EndEffect of FMEA on Process and Design changesDesign StartDevelopmentProduction ReleaseProduction TimeNo of Engineering ChangesTraditional approachFMEA approachProcess FMEA FormJL ExampleElements of

13、 FMEAFailure Mode Any way in which a process could fail to meet some measurable expectation.Effect Assuming a failure does occur, describe the effects. List separately each main effect on both a downstream operation and the end user.Severity Using a scale provided, rate the seriousness of the effect

14、. 10 represents worst case, 1 represents least severe.Causes This is the list of causes and/or potential causes of the failure mode.Occurrence This is a ranking, on a scale provided, of the likelihood of the failure occurring. 10 represents near certainty; 1 represents 6 sigma. In the case of a Six

15、Sigma project, occurrence is generally derived from defect data.Current Controls All means of detecting the failure before product reaches the end user, are listed under current controls.Detection The effectiveness of each current control method is rated on a provided scale from 1 to 10. A 10 implie

16、s the control will not detect the presence of a failure; a 1 suggests detection is nearly certain.Process Failure ModeThe potential failure mode is the manner in which the process could fail to perform its intended function. The failure mode for a particular operation could be a cause in a subsequen

17、t (downstream) operation or an effect associated with a potential failure in a previous (upstream) operation. FAILUREMODEEFFECTPREVIOUSOPERATIONCAUSENEXTOPERATIONProcess Causes Process FMEA considers process variability due to:OPERATORSET-UPMACHINEMETHODENVIRONMENTMEASUREMENTCurrent ControlsAssessme

18、nt of the ability of the control to detect the failure before the item leaves the manufacturing area and ships to the customer.Capability of all controls in the process to prevent escapesSPCProcess CapabilityGage R&RSamplingTestingDOETypes of MeasuresSEVERITYAs it applies to the effects on the local

19、 system, next level, and end userOCCURRENCELikelihood that a specific cause will occur and result in a specific failure modeDETECTIONAbility of the current / proposed control mechanism to detect and identify the failure modeTypically, three items are scored:Risk Priority NumberRPN = O x S x D Occurr

20、ence x Severity x DetectionOSD xx= RPNShortcomings of RPNA 8 4 3 96B 4 8 3 96SAME RESULTFailure ModeSeverityOccurrenceEffectivenessRPNSeverityOccuranceDetectionIt is conducted on a timely basisandIt is applied by a product teamandIts results are documentedFMEA is Most Effective When What Is A Good A

21、pplication?Involve new technology Have changed from previous Are chronically in trouble Have a high degree of operator control Have a high degree of variationChoose designs or processes which . . .Involve new technologyHave changed from previousAre chronically in troubleHave a high degree of operato

22、r controlHave a high degree of variationChoose designs or processes which.FMEA ProcessManufacturing EngineerBuyerProcessOperatorProcess KnowledgePrevious ExperiencePast ProblemsChronic ProblemsReliabilityEngineerProcess Functions, Potential Failure ModesEffects, Causes, Current ControlsAction Priori

23、tyActions to Eliminate or Reduce Failure ModeWarranty ClaimsBasic Steps1. Develop a Strategy1. Develop a Strategy2. Review the design /process EFFECTCAUSESBasic StepsBasic Steps1. Develop a Strategy2. Review the design /process3. List functionsDevelop a StrategyReview the design/processList function

24、s1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modesBasic StepsBasic Steps:1. Develop a strategy2. Review the design/process3. List functions4. Brainstorm potential failure modes1. Develop a Strategy2. Review the design /process3. List functions4.

25、 Brainstorm potential failure modes5. Organize potential failure modesBasic StepstopictopicAffinity Diagram1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. Organize potential failure modes6. Analyze potential failure modesBasic Steps1. Develo

26、p a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. Organize potential failure modes6. Analyze potential failure modes7. Establish risk priorityVITALFEWTRIVIALMANYBasic Steps1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm

27、 potential failure modes5. Organize potential failure modes6. Analyze potential failure modes7. Establish risk priority8. Take action to reduce riskBasic Steps1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. Organize potential failure modes6.

28、 Analyze potential failure modes7. Establish risk priority8. Take action to reduce risk9. Calculate resulting RPNsBasic StepsO*S*D=RPN1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. Organize potential failure modes6. Analyze potential failur

29、e modes7. Establish risk priority8. Take action to reduce risk9. Calculate resulting RPNs10. Follow upBasic StepsTesting the RelationshipsIFTHENHOW DOI KNOW?CAUSEFAILURE MODEEFFECTActionsThe design or process must be improved based on the results of the FMEA study.A well-developed FMEA will be of li

30、mited value without positive and effective corrective actions.Module ObjectivesDescribe FMEA principles and techniques. Summarize the concepts, definitions, application options and relationships with other tools.Perform a FMEADescribe FMEA principles and techniques. Summarize the concepts, definitio

31、ns, application options and relationships with other tools.Perform a FMEAModule Objectives.Organizational Learning and Systems Thinking 组织学习和系统思维A Management System43Building Organizational MemoryEyelash Learning CurveABILITY TODO JOBTIMEOLD EMPLOYEE LEAVESWITH KNOWLEDGENEW EMPLOYEE BEGINSThere is n

32、o organizational memory to allow people to start where their predecessors left offNothing in place to capture the new or improved methods that produce results*Rapid Learning CurveABILITY TODO JOBTIMENEW EMPLOYEE COMES ONAND PICKS UP ALMOST WHEREPREVIOUS EMPLOYEE LEFT OFFOrganization continues to adv

33、ance its knowledge by preserving the lessons each learnsRapid learning = less waste, less complexity, higher customer value, lower costs*How Do We Create Rapid Learning?Two key ingredients:1. Having best known methods documented2. Training people on what those methods areWho to train?New employeesMa

34、nagersExperienced employees*Six SigmaPros and Cons of Standard Methods Advantages: 优点Customer progress is more visible and can be tracked over time 顾客进步更可见而且可以随时间跟踪Capture and share lessons learned吸取和分享教训System itself does not become a source of variation系统自身不会成为变异的来源 Leads to efficient practices 导致

35、有效率的实践 *Pros and Cons of Standard MethodsDisadvantages: 缺点Stifle creativity and lead to stagnation 抑制创造力导致停滞不前Interfere with customer focus 干涉客户的焦点Add bureaucracy and red tape 助长官僚作风Make work inflexible and boring 使工作欠缺灵活性，使人容易感到厌烦Only describe the minimal acceptable output只描述最小的可接受输出Finding a Balan

36、ce 寻找平衡The difficulty we face is . . . .the arguments for and against standardization are both true 公说公有理，婆说婆有理To achieve a balance, develop standards judiciously - where it matters the mostWhen effectively managed, standards provide the foundation for improvement Effective Standardization 有效的标准Comp

37、anies that use standardization effectively operate very differently:The company knows why it is developing standards and how they contribute to its overall purposeManagement uses best-known methods themselves and strongly supports and checks usageEmployees understand how different facets of their wo

38、rk affect the products and services Employees know which elements/functions are critical to producing high-quality outputCreate Standards Judiciously 明智地创造标准Leverage Point: A place where a little change has a great impact 支点：小小的变化就能有巨大的影响的地方。三两拨千斤？“ . every job, every process, has within it high-lev

39、erage points that we must standardize if we want to achieve consistently high performance, and low-leverage points where standardization is superfluous, serving only to restrict flexibility.”Know What Is and What Is Not Important“Knowledge about what is not important is almost as valuable as knowled

40、ge about what is important. It frees our attention to better focus on the few things that make a difference.” “This kind of flexibility shows up in all jobs.” “As a rule of thumb, keep the degree of standardization as low as possible but do not neglect any leverage points.” Leverage Point Thinking -

41、 How Do You Turn the Ship? Knowing the leverage points is critical for determining priorities and strategies for improvementVital FewTrivial ManyPareto Principle 80% of the problems are caused by only about 20% of the contributing factors*Whats the Connection? 联系Companies run into trouble because th

42、ey change their methods before they understand why the methods are there in the first place. 陷入麻烦的公司是因为他们在不了解现有方法存在的原因之前就盲目改变它。They eliminate safety nets in their processes without controlling the factors that made them essential.Resist the temptation to change until we determine: Are the documented

43、 standards the best? What is the impact on the rest of the system? Are the methods actually being followed?Whats the Connection?Employee Responsibility 员工的责任Before anyone can be held responsible for the quality of their own work, they must:1. Know the job 了解工作Is the job clearly documented?Are goals

44、and targets visible?Has adequate training been done?Do workers know how product is used?2. Know the standard 了解标准Output must be measurable with immediate feedback on performance. Dont be vague or require interpretation (i.e. words like flat, smooth, etc.)Employee Responsibility (cont)3. Have the abi

45、lity to regulate 拥有调节的能力When the job does not meet the standard, are there reaction procedures?Are best practices leveraged?Must have all 3 - in order!(See Appendix A for Checklist)CAP-Do - Determine the Need for Standardization1. CheckMake sure we know why the work is being done See if the purpose is clearly documentedCompare actual practice with documented methodsIf no documented methods exist, compare different practices among peo