FMEA - Failure Modes and Effects Analysis - Page 2 of 2: The Risk Priority Number

Custom Search

Failure Modes and Effects Analysis (FMEA) - Page 2

Please refer to the FMEA Procedural Guide for more details on how FMEA is usually performed.

The most critical information on the FMEA Table is the Risk Priority Number (RPN), which is the numerical rating given to the level of risk associated with a failure mode, and therefore denotes the urgency of addressing that failure mode.

The RPN is actually the product of three (3) factors, namely, the severity of the effect of the failure mode (SEV), the probability of the occurrence of the cause of the failure mode (PF, for probability factor), and the effectiveness of the controls for detecting and preventing the failure mode (DET). Thus, RPN = SEV x PF x DET. The SEV, PF, and DET are also documented in the FMEA Table.

The FMEA Table is a living document, constantly changing from the time of its first release when the product or process is still being designed until its archiving after the product or process has been obsoleted.

Critical times or events that require an update to the FMEA Table include the following:

1) when a new product or process is being designed or introduced;

2) when a critical change in the operating conditions of the product or process occurs;

3) when the product or process itself undergoes a change;

4) when a new regulation that affects the product or process is instituted;

5) when customer complaints about the product or process are received; and

6) when an error in the FMEA Table is discovered or new information that affects its contents come to light.

Many published standards on FMEA procedures and reporting formats now exist. Among them are the SAE J1739, the AIAG FMEA-3, and the Mil-Std-1629A.

See also: FMEA Process Guide; Failure Analysis

HOME