PFMEA Scope - Oversized Special Characteristic

[Crimpshrine13]

We had a 3rd party audit this summer and I'm still working on one of the minor NC that was issued by the auditor.

There was an internal deviation on one of the dimensions in our process at the time of the audit, and that was a deviation to our internal control limit, but not to the customer/end-user specification. The dimension was intentionally running oversized to compensate the other dimension going undersized as a final product, but the oversized deviation was still well within customer/end-user specification, which poses no risks to its functionality. Because of this reason, this was not listed on our PFMEA, but the auditor said, "Production has an ongoing problem with oversize major diameter, which is a special characteristic. A quality alert was issued to allow a deviation. However, the FMEA does not indicate analysis of risks for oversize major diameter." and that "If Major Diameter is a SC, then an FMEA should address at least the obvious risks of being too small or too big – not just one."

Does anyone know if this is a valid statement? My understanding was that the scope of PFMEA was identifying the potential issues and how that affect the customer/end-user. Based on the process, the major diameter never becomes oversized to customer/end-user specification. And not identifying it on PFMEA is a NC?

I'm stuck with corrective action as to how to respond to this.

 

[Golfman25]

We had a 3rd party audit this summer and I'm still working on one of the minor NC that was issued by the auditor.

There was an internal deviation on one of the dimensions in our process at the time of the audit, and that was a deviation to our internal control limit, but not to the customer/end-user specification. The dimension was intentionally running oversized to compensate the other dimension going undersized as a final product, but the oversized deviation was still well within customer/end-user specification, which poses no risks to its functionality. Because of this reason, this was not listed on our PFMEA, but the auditor said, "Production has an ongoing problem with oversize major diameter, which is a special characteristic. A quality alert was issued to allow a deviation. However, the FMEA does not indicate analysis of risks for oversize major diameter." and that "If Major Diameter is a SC, then an FMEA should address at least the obvious risks of being too small or too big – not just one."

Does anyone know if this is a valid statement? My understanding was that the scope of PFMEA was identifying the potential issues and how that affect the customer/end-user. Based on the process, the major diameter never becomes oversized to customer/end-user specification. And not identifying it on PFMEA is a NC?

I'm stuck with corrective action as to how to respond to this.

I hate when auditors substitute their judgment for your's, the expert. You cannot possibly explain the complexities of the interaction of your process and dimensions to an auditor in the timeframe of an audit, or in this post.

My question is whether the diameter in question is a SC and if it was addressed at all on the PFMEA? If not, then you probably need to add something. If so, and it was just not to the auditor's liking, then you may need to wordsmith it to get it thru. In fact, it sounds like you guys did your thinking and due diligence, but just didn't document it. Good luck.

 

[Englishman Abroad]

Hi Crimpshine,

I think that the NC is a bit confused with internal control limits and deviations compared to the issue of PFMEA.

The NC says (from your post) "the FMEA does not indicate analysis of risks for oversize major diameter" and "If Major Diameter is a SC, then an FMEA should address at least the obvious risks of being too small or too big"

So is this a true reflection of your FMEA? (forget about actual process capability, internal control limits etc. for the moment)

Is the risk that the Major diamter is too big and too small listed on the FMEA?

Perhaps the severity of diameter too big will be different from the severity of diameter too small?

Also as well as final end user effects, the PFMEA should consider effects on the next (and further downstream) steps in the operation.

So if you diameter is too big, it may not assemble and hence have no final customer effect, but will have a manufacturing scrap effect, etc.

 

[Crimpshrine13]

I hate when auditors substitute their judgment for your's, the expert. You cannot possibly explain the complexities of the interaction of your process and dimensions to an auditor in the timeframe of an audit, or in this post.

My question is whether the diameter in question is a SC and if it was addressed at all on the PFMEA? If not, then you probably need to add something. If so, and it was just not to the auditor's liking, then you may need to wordsmith it to get it thru. In fact, it sounds like you guys did your thinking and due diligence, but just didn't document it. Good luck.

Golfman25

Thanks for your reply. It is internally assigned as SC, but not on customer drawing. This was something that was noted by previous 3rd party auditor who mentioned that we did not list any SC on our PFMEA or Control Plan that we should review our product drawing and if it has significant importance to the quality of the product, we should internally assign SC regardless of our customer drawing. Since then, we assigned thread to be SC, but his finding was stating "Production has an ongoing problem with oversize major diameter, which is a special characteristic. A quality alert was issued to allow a deviation. However, the FMEA does not indicate analysis of risks for oversize major diameter." This is the same auditor who complained about our internal deviation last year not having expiration date, in which the ISO/TS 16949 standard does not require to assign an expiration date on internal deviation (only external deviation to the customer requiring the expiration date). We challenged the finding to the CB that his finding was invalid. He appears to have issues with our internal quality alert each year.

Our PFMEA had listings of potential failure for PD being oversized or undersized, and MD being undersized, but MD being oversized was not listed on our PFMEA at the time of the audit.

 

[Crimpshrine13]

Hi Crimpshine,

I think that the NC is a bit confused with internal control limits and deviations compared to the issue of PFMEA.

The NC says (from your post) "the FMEA does not indicate analysis of risks for oversize major diameter" and "If Major Diameter is a SC, then an FMEA should address at least the obvious risks of being too small or too big"

So is this a true reflection of your FMEA? (forget about actual process capability, internal control limits etc. for the moment)

Is the risk that the Major diamter is too big and too small listed on the FMEA?

Perhaps the severity of diameter too big will be different from the severity of diameter too small?

Also as well as final end user effects, the PFMEA should consider effects on the next (and further downstream) steps in the operation.

So if you diameter is too big, it may not assemble and hence have no final customer effect, but will have a manufacturing scrap effect, etc.

Englishman Abroad

Thanks for the reply.

No, our customer won't have any effect because they are just putting together their product with our product, and the threads are not going to engage with anything until the final assembly at OEM. Also, our internal control limit is way stricter than the customer limit, which in this case the internal deviation we made (oversized up to 0.02mm) does not affect either our customer or the OEM. This was why I didn't like that our auditor said "A quality alert was issued to allow a deviation. However, the FMEA does not indicate analysis of risks for oversize major diameter." as if that the deviation was due to the bad quality (this was intentional deviation to make sure that the MD to be within the customer limit at every spot it was measured because one of the spot was getting undersized MD after plating).