Using RPN to Confirm Risk Reduced to an Acceptable Level

Rou|Model · Sep 8, 2022

Tagin said:
Multiplying SxOxD is gibberish: it confuses the use of a number as an ordinal for a value usable in multiplication.

Thanks Tagin - I have read that article from Wheeler many times!

qualprod · Sep 8, 2022

Rou|Model said:
Hi all,

Just wanting to survey the professional crowd if your organizations utilize RPN (S x O x D) value for Nonconformances this way:
1) To quantity initial risk (characterized by a Cause --> Failure Mode --> Effect).
2) Then develop mitigation actions that address the SOD values, and
3) Then project the new RPN value (assuming the actions have been taken).
Purpose for this is to confirm if the proposed actions will reduce risk to the acceptable level (designated threshold).

This is not part of an FMEA project, but supposedly to integrate quality risk management into the NC process. But this risk assessment is solely being used to confirm that proposed risk mitigation actions would sufficiently reduce risk to an acceptable level. I haven't come across RPN being used this way, and eager to hear what others have to share.

Thanks

In 9001, I use Risk value= PxI, probability x Impact
Based on this, a get the risk value, then I implement action plans to mitigate the risk, after actions have been performed
I evaluate residual risk, doing the same calculation.
If the new value is what I expected, Then I close out the risk, if not, I add other actions or continue with the same actions monitoring if
risk is lowered.
All the details of the treatment are explained in the procedure " Risk management"

Hope this helps.

Bev D · Sep 9, 2022

It looks like the process you describe is far too complex and basically meaningless.
why wouldn’t you just use real actual data to determine the cause of the NC, determine and test a solution validate that it causes no other problems (again with data from an experiment) and then assess the actual occurence rate (and detection effectiveness if applicable) with actual data? The thing here is that the customer and you will experience the actual situation not some ordinal rating that is disconnected from reality.

Using RPN to Confirm Risk Reduced to an Acceptable Level

Rou|Model

Registered

qualprod

Bev D

Heretical Statistician

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