How do you determine what is acceptable base on an FMEA RPN

[kuyakut]

Hi guys,

I'm just new in the FMEA, the auditor had question me on the RPN.
In our FMEA rating's we put 1~ 64 is acceptable , 65 ~124 is broadly acceptable. The auditor ask me where did I get this reference number.
Is there a table of reference where it was stated what is acceptable RPN number? And what rpn number need to take action?


Thanks,

Kuyakut

[qusys]

In Reply to Parent Post by kuyakut

Hi guys,

I'm just new in the FMEA, the auditor had question me on the RPN.
In our FMEA rating's we put 1~ 64 is acceptable , 65 ~124 is broadly acceptable. The auditor ask me where did I get this reference number.
Is there a table of reference where it was stated what is acceptable RPN number? And what rpn number need to take action?


Thanks,

Kuyakut

Hi you can search in this links in this forum being already treated as a topic:
http://elsmar.com/Forums/showthread.php?t=8071

[Cikgu IK]

Hi Kuyakut,
There is no indicator in the manual to take actions based on RPN. It depends on the company to indicate and important is Customer no complaint during audit. From my experience, usually company will use RPN >100, 125, 150 but for FMEA 4th edition, using RPN is not recommended. To take actions, you and use Severity 9 or 10 and also Severity(5 to 8) X Occurrence(4 to 10).

[Jim Wynne]

In Reply to Parent Post by Cikgu IK

Hi Kuyakut,
There is no indicator in the manual to take actions based on RPN. It depends on the company to indicate and important is Customer no complaint during audit. From my experience, usually company will use RPN >100, 125, 150 but for FMEA 4th edition, using RPN is not recommended. To take actions, you and use Severity 9 or 10 and also Severity(5 to 8) X Occurrence(4 to 10).

Welcome to the Cove, and good first post.

As qusys suggests, there's been much discussion around this subject, but I think most people agree that threshold RPN values are not a good thing. Look at the RPNs as relative values and understand that there are times when regardless of Severity or Occurrence ratings there isn't much that can be done that hasn't been done already. By the same token, there might be worthwhile improvements that can be made for relatively low-risk issues.

[Bev D]

The short answer to your question: There is no recommendation or guideline for the RPN values...One issue with setting some threshold for RPN is that different companies and even different teams within a company will use different definitions for each level. They will also use different thinking and resolution rules for assigning the levels. Some teams will even deliberately rationalize a lower score to stay out of the 'must take action zone'. So the same RPN number for one project will not have the same meaning as for another project. (not to mention the whole mathematical problem with multiplying logarithmic and ordinal numbers)

Beyond that difficulty, the intent of the RPN number was never to have a threshold but to always be working on the highest values. Continual improvement...

Modern thinking has recognized the mathematical drawbacks that lead to misleadign results. there are ways to get a higher RPN on a less serious problem than on a very serious problem. So now most sources recommend using only the severity and the occurence ratings. moderate occurence and moderate severity and above get the first attention.

[kuyakut]

Thanks guys .. for the explaination...


Kuyakut

[Cikgu IK]

Hi Kuyakut,

You are welcome.