GRP

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#11
Thank you for your thorough answer.
It makes sense what you said. If I understood well all YS/YC in DFMEA are listed in SCCAF. Then the tier 1 receives this document from FORD let's say and manufacturer should agree to enter those in PFMEA also as SC/CC only if recognized as such. Normally the plant recognizes YS from DFMEA as SC in SCCAF and PFMEA when the probability of occurence is more than 4 correct ?

Thanks for the good discussion.
YC = sev 9,10. If this becomes CC, you have to have special controls in control plan.
YS = sev 5-8 anc OCC 4-10. If this becomes SC, special controls. In pfmea OCC is also 4-10.

In principle, the more you can prove your manufacturing process eliminates failure modes or reduces the likelihood of producing NOK parts the less special characteristics you would have to confirm, e.g. YS in dfmea becomes blank in pfmea due to a 100% automatic control in station which yields a ranking of OCC 2 (in the opinion of the team and as per applicable ranking table).

I´d be interested in knowing if someone has managed to avoid confirming a YC.
 
#12
Just to add in my $0.02 on this. Your customer (Ford in this case) determines certain features/characteristics as significant (YS) or critical (YC) to the intended function of the part. These SHOULD be carried through onto the released part print, and from there onto your documentation (Process Flow, PFMEA, Control Plan, etc). Since the DFMEA may not always be provided to you for review, then you have to go by the information provided on the part print.
HOWEVER you may choose to self-designate features within your process as critical or significant TO YOUR MANUFACTURING PROCESS although this is not mandatory.
I have have never heard of a case where the manufacturing plant can justify 'not recognizing' a YS/YC designation, no matter WHAT the occurrence is.
 

GRP

Involved In Discussions
#13
Just to add in my $0.02 on this. Your customer (Ford in this case) determines certain features/characteristics as significant (YS) or critical (YC) to the intended function of the part. These SHOULD be carried through onto the released part print, and from there onto your documentation (Process Flow, PFMEA, Control Plan, etc). Since the DFMEA may not always be provided to you for review, then you have to go by the information provided on the part print.
HOWEVER you may choose to self-designate features within your process as critical or significant TO YOUR MANUFACTURING PROCESS although this is not mandatory.
I have have never heard of a case where the manufacturing plant can justify 'not recognizing' a YS/YC designation, no matter WHAT the occurrence is.
Well Ron, on a certain occasion my organization got away with not confirming dozens of YS´s based on Ppk´s > 6 measured with CMM. Of course, this Tier 1 still imposed quite a lot more control characteristics than we originally intended.
 

toniriazor

Starting to get Involved
#14
Hello to all involved,

We had a meeting with our customer and we did not recognize some of the potential YS in the DFMEA. The reason for that is that our process is capable to ensure product characteristics meets customer requirements on 100% and occurence was low - OCC. 2, please see below example:
DFMEA - wire/type/size (YS)
Specification tolerance
- as specified on engineering drawing
PFMEA -> Process Control Method -> 100% scanning system to control wire/type/size

This way we proved to our customer that what they have listed as a YS in DFMEA is covered on 100% by our process which is Poka-Yoke and therefore it should not be in the PFMEA as (SC)

They agreed.

But then one questions popped up in my head and it was after trying to convice the customer that another product characteristic should not be (SC) in the PFMEA. The question was:
Why just we don't put all YS from DFMEA as SC in the PFMEA. Really what the difference would be ? I could not answer to myself.
In both scenarios we have controls put in place for that very product characteristic and we are applying them throughout the manufacturing process to ensure product integrity, so whether it is SC or not in the PFMEA does not really matter and does not create more work for the supplier, does it ?

If someone is able to explain my question above I'd be really grateful, because there's always pressure during audit times especially on this topic.

Thank you all for involving.
 

GRP

Involved In Discussions
#15
Hello to all involved,

We had a meeting with our customer and we did not recognize some of the potential YS in the DFMEA. The reason for that is that our process is capable to ensure product characteristics meets customer requirements on 100% and occurence was low - OCC. 2, please see below example:
DFMEA - wire/type/size (YS)
Specification tolerance
- as specified on engineering drawing
PFMEA -> Process Control Method -> 100% scanning system to control wire/type/size

This way we proved to our customer that what they have listed as a YS in DFMEA is covered on 100% by our process which is Poka-Yoke and therefore it should not be in the PFMEA as (SC)

They agreed.

But then one questions popped up in my head and it was after trying to convice the customer that another product characteristic should not be (SC) in the PFMEA. The question was:
Why just we don't put all YS from DFMEA as SC in the PFMEA. Really what the difference would be ? I could not answer to myself.
In both scenarios we have controls put in place for that very product characteristic and we are applying them throughout the manufacturing process to ensure product integrity, so whether it is SC or not in the PFMEA does not really matter and does not create more work for the supplier, does it ?

If someone is able to explain my question above I'd be really grateful, because there's always pressure during audit times especially on this topic.

Thank you all for involving.
When you say you did not recognize the YS because you had a 100% automatic control (scanning system), in fact you have already done something in terms of manufacturing process design. So if you tell your client you do not recognize it, because you have the control, obviously the client will not pursue the matter anymore. If they had been thorough they should have told you to leave it as SC and fill the form with the special control.

For me, rejecting a YS implies not including a special control. From my experience, let's say we had a product with about 200 dimensions with YS and YC. During development we proved that a lot of those characteristics had really high Ppk. Based on this evidence we rejected several YS and the plant did not deploy resources to monitor those characteristics during series production.

So that is the answer: the situation doesn't make sense because, regardless of what you say, you are accepting the YS. Rejecting a YS implies no special controls, the YS goes to blank, and maybe you just inspect those characteristics with the full layout and annual requalification.
 

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