“Life calls not for perfection, but for completeness.” Carl Jung
One of the common FMEA questions that comes up is: When is an FMEA complete? You’d think it would be simple, but many organizations and practitioners get it wrong.
In this article, I’ll begin with the purpose of Design and Process FMEAs, and from there, we’ll examine two very different approaches to completing an FMEA.
What is the purpose of Design FMEA?
The purpose of Design FMEA is to analyze the product design, focusing on potential design-related deficiencies, with emphasis on improving the product design and effectiveness of tests, helping to ensure product operation is safe and reliable during useful life.
What is the purpose of Process FMEA?
The purpose of Process FMEA is to analyze the manufacturing or assembly process, focusing on potential process-related deficiencies, with emphasis on improving the manufacturing process, helping to ensure manufacturing operations are safe and reliable during production.
When is an FMEA complete (wrong answer)?
Some people think that an FMEA is complete when all the columns in the FMEA are filled out. That is the wrong answer. Yet, it is the way many companies and practitioners apply FMEA. They go about filling out the form, all the way to the last column. When all the columns are filled out, they think they are done.
Too often, what passes for FMEA training is to cover each column, with definitions and examples. Although this is helpful, it misses a crucial point. Why are we doing FMEAs? It is not merely to fill out the form.
Example of wrong way
For an example of the wrong way to “complete” an FMEA, I’ll use a fictitious and truncated Design FMEA of a projector lamp. As you can see from the example, the FMEA is “complete” because the form was filled out, even though there is still unacceptable risk.
When is an FMEA complete (right answer)?
An FMEA is completed when risk, as represented by all the different combinations of severity, occurrence and detection, is reduced to an acceptable level. Until then, it should be continued.
Example of right way
For an example of the right way to complete an FMEA, I’ll continue using the same fictitious and truncated Design FMEA of a projector lamp. As you can see from the example, the FMEA is complete when the FMEA team continues recommending actions until risk is reduced to a level that is acceptable to the FMEA team and management.
What is “acceptable risk”?
The word “acceptable” means “able to be agreed on; suitable.” An acceptable level of risk is the combination of S, O, and D that is agreed upon as acceptable by the FMEA team and management.
The FMEA is continued until the risk, as represented by each of the S, O, and D combinations, is reduced to a level that is deemed acceptable by the company, considering input or requirements from the customer. In some cases, acceptable risk is when each of the SOD combinations are “Low,” as assessed from the Action Priority Table. In some cases, acceptable risk is determined by the customer. This is up to company management and FMEA policy. However it is determined, the FMEA team needs to continue the FMEA until risk is deemed acceptable.
What about design changes?
The FMEA is performed for a given level of design. It can be and should updated when designs are changed, and it can even kept open as a “living FMEA” (see below).
As stated above, for a given level of design, an FMEA is finished when risk is reduced to an acceptable level. When the design is changed or modified, the FMEA needs to be reviewed and updated, so that risk from the design change (or modification) can be assessed, and reduced, as needed.
Can you ever achieve zero risk?
Zero risk is not possible to achieve. What is possible is for risk to be low, and product designs to be safe and reliable.
What about “living FMEA”? A “living FMEA” is an FMEA that is kept open as a repository for design changes, field failures, and any other changes from when the FMEA was originally completed. The use of “living FMEA” and alternatives are covered in the FMEA Preparation Series.
Summary
FMEA is not a “fill out the form” activity. It is an analysis to engage the thinking of a cross functional team to identify and address design and test risk (for Design FMEAs), and manufacturing risk (for Process FMEAs). The point is to continue the FMEA until an acceptable level of risk is reached, in support of safe and reliable product designs or manufacturing processes.
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