This document provides an introduction and overview of Failure Mode and Effects Analysis (FMEA). It defines FMEA as a procedure for analyzing potential failure modes within a system and classifying them by severity and likelihood. The document outlines the FMEA cycle and provides an example FMEA with ratings for severity of effect, probability of occurrence, and likelihood of detection. It explains that various organizations have established standardized rating systems for these factors.
2. FMEA
Introduction
To
FAILURE MODE
EFFECTS & ANALYSIS
3. defination
FMEA is a procedure in product development
and operations management for analysis of
potential failure modes within a system for
classification by the severity and likelihood of
the failures.
8. Example of FMEA
Severity of Effect
10 May result in safety issue or regulatory violation without
warning
9 May result in safety issue or regulatory violation with warning
8 Primary function is lost or seriously degraded
7 Primary function is reduced and customer is impacted
6 Secondary function is lost or seriously degraded
5 Secondary function is reduced and customer is impacted
4 Loss of function or appearance such that most customers
would return product or stop using service
3 Loss of function or appearance that is noticed by customers
but would not result in a return or loss of service
2 Loss of function or appearance that is unlikely to be noticed by
customers and would not result in a return or loss of service
1 Little to no impact
Some organizations such as SAE, AIAG, ISO 9000, and ISO/TS
16949:2002 have established severity ratings.
11. Example of FMEA
Probability of Occurrence
10 1 in 2
9 1 in 10
8 1 in 50 Similar to the ratings for Severity, each
7 1 in 250 organization like AIAG and ISO 9000 have
their own ratings for occurrence.
6 1 in 1,000
5 1 in 5,000
4 1 in 10,000
3 1 in 50,000
2 1 in 250,000
1 1 in 1 Million
14. Example of FMEA
Likelihood of Detection
10 Absolutely uncertain that failure will be detected
9 Very remote chance that failure will be detected
8 Remote chance that failure will be detected
7 Very low chance that failure will be detected
6 Low chance that failure will be detected
5 Moderate chance that failure will be detected
4 Moderately high chance that failure will be detected
3 High chance that failure will be detected
2 Very high chance that failure will be detected
1 Almost certainty that failure will be detected