FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA manual

Chennaiite

Never-say-die
Trusted Information Resource
#1
Dear Coves,

I need some clarity in the Potential Manufacturing effect mentioned in the AIAG MAnual. As we know, it speaks about line stoppage, decrease in line speed, 100% rejection, Portion rejection, off line rework, blaw, blaw. My problem is in correlating the failure mode with these aforesaid statements. How do a CFT conclude, whether a potential failure mode has the potential to stop the Carmaker line or decrease the Carmaker line or result in 100% scrap or portion scrap or offline rework so so. For me, these are incident based and cannot be generalised. I request the PFMEA facilitators across this forum to support me with some good examples.
(Finally, I beg your pardon, if related thread exists for this post)
Thanks.
 
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Stijloor

Staff member
Super Moderator
#2
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

Dear Coves,

I need some clarity in the Potential Manufacturing effect mentioned in the AIAG MAnual. As we know, it speaks about line stoppage, decrease in line speed, 100% rejection, Portion rejection, off line rework, blaw, blaw. My problem is in correlating the failure mode with these aforesaid statements. How do a CFT conclude, whether a potential failure mode has the potential to stop the Carmaker line or decrease the Carmaker line or result in 100% scrap or portion scrap or offline rework so so. For me, these are incident based and cannot be generalised. I request the PFMEA facilitators across this forum to support me with some good examples.
(Finally, I beg your pardon, if related thread exists for this post)
Thanks.
What is CFT?

Stijloor.
 

harry

Super Moderator
#3
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

Used in this context, my guess is - cross functional team (CFT)
 
D

DrM2u

#4
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

Dear Coves,

I need some clarity in the Potential Manufacturing effect mentioned in the AIAG MAnual. As we know, it speaks about line stoppage, decrease in line speed, 100% rejection, Portion rejection, off line rework, blaw, blaw. My problem is in correlating the failure mode with these aforesaid statements. How do a CFT conclude, whether a potential failure mode has the potential to stop the Carmaker line or decrease the Carmaker line or result in 100% scrap or portion scrap or offline rework so so. For me, these are incident based and cannot be generalised. I request the PFMEA facilitators across this forum to support me with some good examples.
(Finally, I beg your pardon, if related thread exists for this post)
Thanks.
You have to consider the failure modes and effects from the perspective of both the internal and external customers, not only external. Let's say for example that you have a multiple-step process where each process step has a 'pokey-dokey' in place to prevent the use of 'bad' parts from the previous step. In such an instance you do not have to consider the external customer (until the last process step is completed) only how a failure will impact the next process step. Also, there is no black-and-white rule on how to apply the rating system. My preference is to look at all potential impacts/effects and consider the highest combined ratings for effect and occurence, regardless if the customer is internal or external. The idea is to prevent and control the worst scenario.

Another piece fo advice: the product severity & occurence ratings can be changed only through product redesign, and process redesign applies to process ratings. The changes in controls only affect detection.

The use of a CFT is a very wise idea! I wish more organizations would do that ...
 

Jim Wynne

Staff member
Admin
#5
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

How do a CFT conclude, whether a potential failure mode has the potential to stop the Carmaker line or decrease the Carmaker line or result in 100% scrap or portion scrap or offline rework so so. For me, these are incident based and cannot be generalised.
Assuming that "CFT" is cross-functional team, there are times when you just can't know what the effects on a customer process might be. A lot of the AIAG FMEA stuff assumes (a) a continuum from DFMEA to PFMEA and (b) that both the DFMEA and PFMEA are locally controlled. In actual practice, suppliers rarely have access to customer DFMEAs and must rely on the customer's documented specifications for guidance in doing PFMEAs.

This is the primary reason that I think it's basically wrong to expect suppliers to consider end-use issues in doing their PFMEAs--it results in a lot of useless guessing. Better to use the specifications as the guide in process design, because it must be assumed (in the absence of knowledge to the contrary) that if you meet the design requirements, design intent will be fulfilled.

My advice to you is don't guess. If you don't know how a given nonconforming condition will contribute to a line shutdown, or scrap, or anything else in the customer's process or assembly, concentrate on meeting the specifications.
 

Chennaiite

Never-say-die
Trusted Information Resource
#6
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

My advice to you is don't guess. If you don't know how a given nonconforming condition will contribute to a line shutdown, or scrap, or anything else in the customer's process or assembly, concentrate on meeting the specifications.
CFT (Cross Functional Team) do understand how a given non conformity will contribute for line shutdown, but then again it will be incident based. If a supplier delivers one bad part with a particular non conformity, the line doesnot stop. On the other hand, if he delivers one full batch of bad parts, it does in fact stop the line. These can be two different incidents with same non conformity. If the CFT considers the second case, which is the most serious effect, for giving severity rating, there may be some exaggeration of risk in the process.
Thanks.
 
M

marcus arelius

#7
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

It pays dividends to be able to relate any failures / reject parts causing line delays by cross referencing against previously collated delay results collected over the production lines lifetime (or similar lines with the same issues), this can make it easier to calculate production delay using PPM percentages etc. If this is a new line you can only calculate FMEA severity with previously acquired failures / reject parts knowledge on similar lines, and adjust the severity as issues arise. The choosing of a highly knowledgeable CFT that will sit and thrash out issues at the writing of the initial FMEA can resolve many problems before they even arise, although SQA is externally out of your control, processes must be put in place with suppliers to enable easier resolution of issues (so cutting down delay time).

Never rest the FMEA is a living document that must be revisited regularly (the auditor will always come back and bite you!)


"Working with quality engineers that question what you say is a joy, it make reaching the root cause a lot quicker and easier"
 

Stijloor

Staff member
Super Moderator
#8
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

<snip>Never rest the FMEA is a living document that must be revisited regularly (the auditor will always come back and bite you!)
I absolutely agree with the first part! :agree1:
:topic:
The second part concerns me; I have never bitten anyone! :mg: :D

Stijloor.
 
M

marcus arelius

#9
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

I absolutely agree with the first part! :agree1:
:topic:
The second part concerns me; I have never bitten anyone! :mg: :D

Stijloor.
Stijloor, you are obviously a rare commodity - an auditor with a sense of humour :lol:

Joking apart I hope we all recognise the only time we see the auditor as the enemy is when we have not done our jobs correctly.
 

Jim Wynne

Staff member
Admin
#10
Re: FMEA Severity Rating for Potential Manufacturing Effect mentioned in the FMEA man

Stijloor, you are obviously a rare commodity - an auditor with a sense of humour :lol:

Joking apart I hope we all recognise the only time we see the auditor as the enemy is when we have not done our jobs correctly.
Or when the auditor is a mope. Those are fairly rare, thankfully.
 
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