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PFMEA Severity - What is Process FMEA Severity estimation based on?

  • Thread starter Matthew_Hopkins
  • Start date

Helmut Jilling

Auditor / Consultant
#12
Re: Severity estimation in a PFMEA is confusing - What is Severity estimation based o

hjilling, What FMEA book are you referring to?

best regards,

I was not looking at the book when I wrote the reply. But, it would be the current version - 3rd ed. I believe. They changed the Severity table in the Process PFMEA section to show two columns - one for End User and one for customer, which is explained in the narrative to mean the assembly plant.

Been a while since I read it, but I am pretty certain of the information.

Why do you ask?
 
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Matthew_Hopkins

#13
Re: Severity estimation in a PFMEA is confusing - What is Severity estimation based o

Because I assumed you were suggesting me to read an unspecified FMEA book. Is it some fundamental book used in the automotive industry? I guess I'm not enlightened since I'm not working with vehicles, and in a way I envy quality people in the automotive industry for having all the quality tools quite prepared for their needs...
 

Helmut Jilling

Auditor / Consultant
#14
Re: Severity estimation in a PFMEA is confusing - What is Severity estimation based o

Because I assumed you were suggesting me to read an unspecified FMEA book. Is it some fundamental book used in the automotive industry? I guess I'm not enlightened since I'm not working with vehicles, and in a way I envy quality people in the automotive industry for having all the quality tools quite prepared for their needs...
So sorry, sometimes we get a little too brief on the Cove with our acronyms and all.

AIAG.com is the website for the Big 3 US automotive companies. They published a FMEA guide manual that is a very useful document for anyone who want to use FMEAs as a planning tool, automotive or not. They will sell to the public as well. You do not need to be a member.
 
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Matthew_Hopkins

#15
Re: Severity estimation in a PFMEA is confusing - What is Severity estimation based o

So sorry, sometimes we get a little too brief on the Cove with our acronyms and all.

AIAG.com is the website for the Big 3 US automotive companies. They published a FMEA guide manual that is a very useful document for anyone who want to use FMEAs as a planning tool, automotive or not. They will sell to the public as well. You do not need to be a member.
OK. I will see what they got and perhaps order their book as well. Thanks.
 

Jim Wynne

Super Moderator
#17
Re: Severity estimation in a PFMEA is confusing - What is Severity estimation based o

For example, a dull stamping die could leave a sharp burr. That burr could have a significant impact on either the assembly plant or possibly the end user, when that part is assembled on the vehicle. So, it would get a fairly high Severity number.
If a burr can cause problems downstream, it's the responsibility of the designer(s) to make sure that the potential problem is addressed in the specifications. If it is, then it's possible that there's nothing to be gained by giving potential burrs a high severity number in the PFMEA.
 

Helmut Jilling

Auditor / Consultant
#18
Re: Severity estimation in a PFMEA is confusing - What is Severity estimation based o

If a burr can cause problems downstream, it's the responsibility of the designer(s) to make sure that the potential problem is addressed in the specifications. If it is, then it's possible that there's nothing to be gained by giving potential burrs a high severity number in the PFMEA.
1. In my example, the burr was caused by a dull punch die. That is a tooling issue and should be addressed by sharpened the tooling. In some cases, the designer could reduce and ameliorate the potential effect, but not always.

2. It is unlikely you could persuade a customer engineer to give that request any attention. It is difficult enough to get them to pay attention to root causes they are respnsible for.


:)
 
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prototyper

#19
The whole point of a PFMEA is to focus attention on the most important functional areas of the product.
If a poor weld would result in a wheel falling off a car then the consequences of failure are far more important than something cosmetic, like scratched paintwork. The weld may have a specification, but a specification won’t stop you making bad parts.
The reason for having a severity rating is to ensure that features which are of a safety critical nature are properly controlled.
The severity ratings must, therefore, consider implications to the end user as well as downstream processes.
 
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