ASSIGNMENT 8

Failure Mode and Effects Analysis (FMEA)

                Failure mode and effects analysis (FMEA) is a team – based methodology for identifying potential problems with the new or existing designs. It is the first step of a system reliability study. FMEA is the core task in reliability engineering, safety engineering, and quality engineering. FMEA involves reviewing as many components, assemblies, and subsystem as possible to identify failure modes, and their causes and effects. In order to determine the components of the process that are most in need of change, FMEA includes the following steps:

1.      Steps in the process.

2.      Failure modes (What could go wrong?)

3.      Failure causes (Why would the failure happen?)

4.      Failure effects (What would be the consequences of each failure?)

            Three factors that are considered in developing a FMEA:

1.      The severity of the failure.

2.      The probability of occurrence of failure.

3.      The likelihood of detecting the failure in either design or manufacturing, before the product is used by the customer.

            Different types of FMEA analysis:

1.      Functional,

2.      Design, and

3.      Process FMEA.

            Major benefits derived from a properly implemented FMEA are as follows:

1.      It provides documentation in selecting design with high probability of successful operation and safety.

2.      A uniform documentation method of assessing potential failure mechanism, failure modes and their impact on system operation, resulting in a list of failure modes ranked according to seriousness of their system impact and likelihood of occurrence.

3.      Early identification of single failure points (SFPS) and system interface problems which may be critical to mission success and/or safety.

4.      An effective method for evaluating the effect of proposed changes t the design and/or operational procedures on mission success and safety.

5.      A basis for in – flight troubleshooting procedures and for locating performance monitoring and fault – detection devices.

6.      Criteria for early planning of tests.

Example of FMEA analysis for car tire:

Keywords:

SEV – severity

OCC – occurrence

DET – Detection

RPN – Risk Priority Number

Criteria for FMEA Analysis

            FMEA is analyzed based on three criteria:

1.      Severity effect on customer.

2.      Occurrence of failure.

3.      Easy to detect.

            It is then ranked from 1 (low) to 10 (high) for each criterion.

Table 1: Severity, Occurrence and Detection Ratings

Formula for RPN is:

RPN = severity x occurrence x detection