1、本資料來源,FMEAFailure Mode and Effects Analysis,Adapted from presentation by Dr. Stamper,Outline,Failure Mode and Effects Analysis What is it? Motivation FMEA Methods Example FMEA in-class exercise,What is an FMEA?,Description: A procedure that examines each item in a system, considers how that item can

2、 fail and then determines how that failure will affect (or cascade through) the system Acronyms FMEA: Failure Modes and Effects Analysis FMECA: Failure Modes and Effects and Criticality Analysis,Motivation for Conducting a FMEA,Improves design by discovering unanticipated failures Highlights the imp

3、act of the failures Potentially helpful during legal actions Provides a method to characterize product safety Often required (e.g. FDA and DOD procurement),Method to Conduct an FMEA(taken from ASM Handbook Vol. 11),Identify all components or systems at given level of the design hierarchy. List the f

4、unction of each identified component or system. Identify failure modes for each component/system. Typically there will be several ways in which a component can fail. Determine the effect (both locally and globally) on the system.,Method to Conduct an FMEA(taken from ASM Handbook Vol. 11),Classify th

5、e failure by its effects on the system operation. Determine the failures probability of occurrence. Identify how the failure mode can be detected (may point out what needs to be inspected on a regular basis). Identify any compensating provisions or design changes to mitigate the failure effects.,Oth

6、er Variations of the Method,DESIGN FMEA (DFMEA),The Design FMEA is used to analyze products before they are released to production. It focuses on potential failure modes of products caused by design deficiencies. Design FMEAs are normally done at three levels system, subsystem, and component levels

7、This type of FMEA is used to analyze hardware, functions or a combination,PROCESS FMEA (PFMEA),The Process FMEA is normally used to analyze manufacturing and assembly processes at the system, subsystem or component levels. This type of FMEA focuses on potential failure modes of the process that are

8、caused by manufacturing or assembly process deficiencies.,What to Do,Function comes from Functional Analysis, Functional Decomposition Potential Failure Mode comes from things that have gone wrong in the past, concerns of designers, and brainstorming. Possible considerations are partial function, in

9、termittent function, excess function. Potential Effects are consequences to the design, the user, and the environment. Safety and regulation noncompliance are critical issues.,IN-CLASS PROBLEM 1,Most cars have a fuel filter between the fuel tank and the engine. Consider the consequences of a) Anti-f

10、unction (opposite of filtering) b) Partial function c) Intermittent function d) Excess function,What to Do,Potential Causes of failure should be engineering related such as incorrect material, corrosion, wear and human related such as inexperience, misuse, etc. Current Design Controls are things lik

11、e inspections, testing, poke yoke, and other design checks that are intended to prevent the problem.,What to Do,Assign values to Severity, Occurrence, and Detection using the tables on the next three pages. Determine the Risk Priority Number (Severity* Occurrence * Detection) Develop an action plan

12、Implement an action plan,Risk Guidelines,Occurrence Ranking,Detection Ranking,IN-CLASS PROBLEM 2,Suppose you were the designer of cars before air bags and seat belts. Suppose your function is “Protect occupants during head-on collision at less than 40 mph.” Estimate numbers for Severity, Occurrence,

13、 and Detection for the “before airbag/seatbelts” and after “airbags/seatbelts” cases.,Partial Example,Partial Example (Cont.),IN-CLASS PROBLEM 3,For the cordless a screwdriver we have previously considered generate a partial FMEA a) List the three most significant functions of the case. b) For most potentially troublesome function, name Potential Failure M