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May 17, 2010

Failure Mode and Effects Analysis (FMEA) Basics

Failure Mode and Effects Analysis (FMEA) or FMECA is an analysis technique which facilitates the identification of potential problems in a design or process by examining the effects of lower level failures. Recommended actions or compensating provisions are made to reduce the likelihood of the problem occurring, and mitigate the risk, if in fact, it does occur.

The FMEA team determines, by failure mode analysis, the effect of each failure and identifies single failure points that are critical. It may also rank each failure according to the criticality of a failure effect and its probability of occurring. FMECA is the result of two steps: 1) Failure Mode and Effects Analysis (FMEA), and 2) Criticality Analysis (CA). Or in other words, FMECA is just FMEA with Criticality Analysis.

There are many different types of FMEA. There are Conceptual or Functional FMEAs, Design FMEAs, and Process FMEAs. Sometimes during a Design FMEA the analysis will look at a combination of functions and hardware. Sometimes it will include just hardware, and sometimes the analyst will take a detailed look at the system down to a piece-part level, especially when critical functions or hardware are involved.

Why is FMEA or FMECA Important?

There are a number of reasons why this analysis technique is so valuable. Here are just a few:

1) FMEA provides a basis for identifying root failure causes and developing effective corrective actions.

2) The FMEA identifies reliability and safety critical components.

3) It facilitates investigation of alternatives at all stages of the design or process.

4) FMEA provides a foundation for maintainability, safety, testability, and logistics analyses.

When to conduct an FMEA

1- Early in the process improvement investigation
2- When new systems, products, and processes are being designed
3- When existing designs or processes are being changed
4- When carry-over designs are used in new applications
5- After system, product, or process functions are defined, but before specific hardware is selected or released to manufacturing


FMEA / FMECA Background and History

FMEA or FMECA is an offshoot of Military Procedure MIL-P-1629, titled Procedures for Performing a Failure Mode, Effects and Criticality Analysis, dated November 9, 1949. It was originally used as a reliability technique to determine the effect of system and equipment failures. Failures were classified according to their impact on mission success and personnel/equipment safety.

FMECA was further developed and applied by NASA in the 1960's to improve and verify reliability of space program hardware. The procedures called out in MIL-STD-1629A are probably the most widely accepted methods throughout the military and commercial industry, although SAE J1739 is a very prevalent FMEA standard used in the automotive industry.

Summary

This article just scratches the surface of FMEA. It is a valuable analysis technique, and has proven its worth time and time again throughout many industries. There are a number of good books and other resources where you can find out more about FMEA. Both large and small companies will benefit as they make FMEA an integral part of their quality programs.