Podcasts

07 FMEAs from an Expert s Point of View

A Discussion on FMEAs with Fred Schenkelberg

You arrive in the office early Monday morning, and you receive an email from your boss.  It is one that you have been dreaded for days.  You have been told that you are participating in a Failure Mode Effect Analysis for the next week.

Failure Mode Effect Analysis are often feared and avoided by many.  Mainly because they are not well understood or people have been forced to sit through FMEAs that were not facilitated properly.

06 What is a FMEA and How Can It Help?

Failure modes and effects analysis (FMEA) is a step-by-step approach for identifying all possible failures in a design, a manufacturing or assembly process.

Failure modes means the ways, or modes, in which something might fail. Failures are any errors or defects, especially ones that affect the customer, and can be potential or actual.  They typically include the component, the damage or problem with it and the cause of it

Effects analysis refers to studying the consequences of those failures.

Does the age of equipment increase the probability of failure?  That was the conventional wisdom until Nowlan & Heap discover that components have six different types of failure patterns;

• Bathtub – 4%
• Wear Out – 2%
• Fatigue Related – 5%
• Rapid Increase to Random – 7%
• Random Level of Failure – 14%
• Infant mortality – 68%

This means only 11% of failures are age related 89% are not age related – so why do PM Programs still rely on time-based maintenance (Replacements, Overhauls) they only address 11% of failures.

There are 3 primary types of maintenance strategies utilized;

• Condition Based Maintenance (CBM)
• Time-Based Maintenance (TBM)
• Run to Fail (RTF)

The strategy utilized depends on heavily upon the nature of the failure.  Meaning does it wear out with age or is a random failure independent of time?  Condition based maintenance is acceptable for the random failures, while Time based maintenance works for wearing out type failures.  Lastly Run to Failure is acceptable when there are no significant consequences in the event of a failure.

Determining the frequency […]