Occurrence matrix for PFMEA

arun007.chauhan · Mar 15, 2024

Can anyone explain me while reviewing PFMEA of a product, we need the occurrence data of 6 months but not all the dimensions and defects are checked or recorded on everyday basis. However, we check a certain amount of dimensions and defects on everyday basis but We do layout inspection twice an year of a product. So while reviewing the PFMEA, how can we change the occurrence rating of dimensions or defects that are not checked on everyday basis ?

Miner · Mar 15, 2024

This is one of the major weaknesses of Occurrence Ratings in an FMEA. In many cases, the Occurrence Rating cannot be quantified, but is literally guessed at by the team responsible. When it is quantified using field data, it is underestimated when customers do not report it.

John Predmore · Mar 15, 2024

Sometimes the best you can do is work with a cross-functional team of experienced people who design the process, people who maintain the equipment, people who inspect the parts, and people who fix things when they wear out. Be aware, wear is frequently not a linearly extrapolated phenomenon. If you are fortunate, your company has a track record with similar equipment or similar fabrication/assembly operations, where relevant historical data exists. Your assessment (educated guess, as @Miner points out) needs to be a consensus of all the perspectives, or maybe you want to err on the side of more pessimistic estimates.

arun007.chauhan · Mar 27, 2024

Miner said:
This is one of the major weaknesses of Occurrence Ratings in an FMEA. In many cases, the Occurrence Rating cannot be quantified, but is literally guessed at by the team responsible. When it is quantified using field data, it is underestimated when customers do not report it.

Thank you Sir. Got you. This is what we were doing till now.

arun007.chauhan · Mar 27, 2024

John Predmore said:
Sometimes the best you can do is work with a cross-functional team of experienced people who design the process, people who maintain the equipment, people who inspect the parts, and people who fix things when they wear out. Be aware, wear is frequently not a linearly extrapolated phenomenon. If you are fortunate, your company has a track record with similar equipment or similar fabrication/assembly operations, where relevant historical data exists. Your assessment (educated guess, as @Miner points out) needs to be a consensus of all the perspectives, or maybe you want to err on the side of more pessimistic estimates.

Thank you sir. This is really helping me a lot.

QualitySage · Apr 5, 2024

Based on your process capability studies and the trend of the dimensions/failure modes (SPC) that you are measuring on a daily basis, you should be able to give a good estimate of how those failure modes are performing. If any of those failure could affect form, fit and function you need to be sure that they are within the requirements even if they are not measured.

arun007.chauhan · Apr 24, 2024

QualitySage said:
Based on your process capability studies and the trend of the dimensions/failure modes (SPC) that you are measuring on a daily basis, you should be able to give a good estimate of how those failure modes are performing. If any of those failure could affect form, fit and function you need to be sure that they are within the requirements even if they are not measured.

Sure and Thank you for the reply.

Occurrence matrix for PFMEA

arun007.chauhan

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