FMEA Basics - Failure Mode and Effects Analysis


FMEA Basics - Failure Mode and Effects Analysis

Neural Blog, 29th Aug 2006

Comprehensive Analysis Tool for FMEA and FMECA
FMEA Basics, FMECA Books, FMEA Information
Comprehensive Analysis Tool for FMEA and FMECA
FMEA Basics - Failure Mode and Effects Analysis

FMEA Basics - Failure Mode and Effects Analysis

Software for FMEA and FMECA

FMEA and FMECA Analysis

FMECA and FMEA Basics, FMEA and FMECA Failure Mode and Effects Criticality Analysis is a systematic approach that identifies potential failure modes in a system, product

FMECA and FMEA Basics

FMEA is intended to document a Failure, the failure's mode, it's effect when it fails. By conducting a FMEA analysis or going through a FMEA process one can identify the cause-effect for a number of situations where a piece of equipment or a system might fail.

The idea behind the FMEA process is to identify risks and to initiate dedicated efforts to control or minimize risks. Identifying these risks can make your project plan more realistic. FMEA seems to work best, when a team documents its known knowledge about known cause and effect relationships.

FMEA Basics, starting point

It is suggest to work out the timely sequence of failure events first, before entering results into a FMEA sheet. A number of different methods may be used to document this, e.g. Ishikawa or flow diagrams. The use of cards or post-it notes or even UML to document and organize items into a logical sequence of events.

FMEA Basics, operational modes and scenario

Identifying a scenario or operational mode would be the starting point for a FMEA or FMECA analysis. Then address the key functions your process/product has to perform or undergo. Identify external effects and conditions that could effect these functions in a malicious way. Next identify ways to deteriorate those key functions (modes and causes).

FMEA Basics, identify risks

Only few people seem to be able to anticipate unknown risks and unknown failure mechanisms. It is suggest to use an AFD (Anticipatory Failure Determination) when you need to analyze subtle failure mechanisms or have to predict future failures from your process/product.

You need to stay very disciplined in cause and effect thinking to create strong FMEA results. Unfortunately many available FMEA sheets are open ended and do not enforce a structured way of thinking.

Here is a simple example of a motor controller

component investigated is the Position Controller
its function is to "receive a demand position"
one failure mode is "loosing cable connection"
which is caused by "wear and tear"
this results in "motor fails to move"

The logical thought process of a failure for this simple FMEA study

cable wears and tears => cable connection is lost => motor fails to move => function to receive a demand position is deteriorated.

Please note the that many FMEA worksheets do not encourage timely order of events, as columns are ordered in a different ways depending on the study, industry and business requirements.

Finally, once you have good input to enter into your FMEA sheet identifying the ranks for severity, occurrence probability etc. should be easy to do. These values are obtained form two dimensional graphs, x-axis depicting the probability of failure, with the y-axis depicting the severity of failure.

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