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DFMEA/PFMEA and SCCAF alignment

GRP

Involved In Discussions
#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.
 
#16
From the DFMEA...all YC's & YS's become CC's & SC's on the PFMEA. Any feature determined as Critical or Significant is based on the part application. Being statistically capable of maintaining a feature is great, but it will not change the classification.

Originally CC's and SC's were called out on the part blueprint, but this limited Ford's ability to make changes....because a drawing change can be a time consuming and costly process. So Ford developed the SCCAF form to communicate CC's and SC's, and no longer puts these designations on the part blueprints. Unfortunately for Tier-1 Suppliers this allows Ford to make frequent changes whenever it suits them.

We make safety critical parts for Ford. We make a suspension component that for years had 13 features designated as SC's. Then suddenly Ford revised the SCCAF form and added 40 more SC's....yes....40 more! They said that we needed to be statistically capable on all or have 100% inspection in place. Some of the new SC's were things like chamfer angles, surface finishes, threads, etc....it was just insane.

We recently had our IATF Audit, and the Auditor noted that one of our process controls did not match up with the SCCAF. What happened was that over time with historical data, we determined that could relax a check frequency from each shift to once daily. But the SCCAF was not updated to reflect this. Our corporate program management believed that the SCCAF is an initial launch type of document, and may not always be in alignment with the latest process controls, etc. Our Ford STA says it is up to us to keep the SCCAF current, however we recently processed an update issued by Ford and the SCCAF was not included in the documents to be updated, despite numerous changes on the drawing? I'm trying to get to the bottom of this issue now.....
 

toniriazor

Starting to get Involved
#17
From the DFMEA...all YC's & YS's become CC's & SC's on the PFMEA. Any feature determined as Critical or Significant is based on the part application. Being statistically capable of maintaining a feature is great, but it will not change the classification.



Originally CC's and SC's were called out on the part blueprint, but this limited Ford's ability to make changes....because a drawing change can be a time consuming and costly process. So Ford developed the SCCAF form to communicate CC's and SC's, and no longer puts these designations on the part blueprints. Unfortunately for Tier-1 Suppliers this allows Ford to make frequent changes whenever it suits them.

We make safety critical parts for Ford. We make a suspension component that for years had 13 features designated as SC's. Then suddenly Ford revised the SCCAF form and added 40 more SC's....yes....40 more! They said that we needed to be statistically capable on all or have 100% inspection in place. Some of the new SC's were things like chamfer angles, surface finishes, threads, etc....it was just insane



We recently had our IATF Audit, and the Auditor noted that one of our process controls did not match up with the SCCAF. What happened was that over time with historical data, we determined that could relax a check frequency from each shift to once daily. But the SCCAF was not updated to reflect this. Our corporate program management believed that the SCCAF is an initial launch type of document, and may not always be in alignment with the latest process controls, etc. Our Ford STA says it is up to us to keep the SCCAF current, however we recently processed an update issued by Ford and the SCCAF was not included in the documents to be updated, despite numerous changes on the drawing? I'm trying to get to the bottom of this issue now.....
Hello,
Not all YC's and YS's become CC's and SC's. This has to be confirmed by PFMEA and respective severity/occurence ratings given in SCCAF. It is quite strange that FORD just assigned you 40 SC's on a mass production project. According to what I know all YS's and YC's are being decided during the develpment phase of the product and project. Did you had a meeting with your STA to confirm/ reject these SC's or you just accepted all of them ?
Another thing to consider is that PFMEA/SCCAF/ Control Plans are living documents and they shall be updated whenever is needed. You have to explain this to your STA and request a support from that person.
 

GRP

Involved In Discussions
#18
Hello,
Not all YC's and YS's become CC's and SC's. This has to be confirmed by PFMEA and respective severity/occurence ratings given in SCCAF.
I concur with this statement. The screenshot below is from the SCCAF brochure from Ford for suppliers (v1. 2015).
1562250282773.png


It can be seen on the last line that the YS was not confirmed by the PFMEA and bears no class symbol. That never seems to be the case for YCs.

I understand boxer12 you have had a different experience. Hopefully our experience is helpful to you and others for benchmarking.

We make a suspension component that for years had 13 features designated as SC's. Then suddenly Ford revised the SCCAF form and added 40 more SC's....yes....40 more
This event deserves a thread of its own. I am not saying it is easy, but I would try to submit a new part price to the client based on the new requirements.
 
#19
I need to clarify the circumstances regarding the massive increase SC's. We have made this suspension knuckle since 2013, and when Ford revised the design, we quoted it (same vehicle application) and at that time the original SCCAF was just carried over. A few months into the launch process the 40 additional SC's were communicated to us via a new SCCAF. Our complaint was that we've made this knuckle for 6 years with no major issues, and we asked what the rationale was for this? Ford said..."we are simply adopting the standard European SCCAF format". Our corporate engineering folks did not sign off on the new SCCAF's for 2 months but eventually caved in, then it landed on my desk. I said there is no way I would sign off without having data to determine our capability, or if not capable, a method of 100% gaging the feature. After several weeks, the Ford Program Manager in Europe called me at home one evening (yep!), and said I needed to sign off on the SCCAF's....as I was holding up the implementation process. I voiced my concerns, and we discussed various methods of quality verification and eventually decided to use batch & hold until such time as we could prove capability. So then I signed off. Over time we managed to get capable on most of the items, but a few where we weren't capable - we had to purchase special gages. So we will be going back to Ford to get the SCCAFs revised - which is likely to be a huge ordeal.

While I can appreciate that fact that not all YC's and YS's become CC's and SC's....that has not been our experience. I reviewed 6 different SCCAFs we have on file and every single item on the DFMEA was carried over the PFMEA.

Regarding the SCCAF's, it has always been unclear how the form is kept current. In the past we have treated the SCCAF as an initial launch type of document used during product development. During a recent IATF Audit we had a finding where the SCCAF did not exactly match up with our control plan. We asked our STA about the process of keeping the SCCAF updated, and he said it's our job. This requires us to get the appropriate Ford sign-offs every time we make a change, no matter how insignificant that change may be. Oh the joy....
 
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