Control Plan or FMEA - Which comes first?



The company I'm currently with begins their Control Plan prior to beginning their FMEA. After they identify critical characteristics on the CP, they do FMEAs on the critical characteristics. We have a new person at our company that says we CAN NOT start our Control Plans until our FMEAs are complete.

Why Not? Am I missing something?

Appreciate your comments.

Spaceman Spiff

The sequence of events is: Design FMEA, Process FMEA, and then Control Plan. FMEAs determine what characteristics need to be controlled and the Control Plan describes how to control it. Ford's Dynamic Control Plan actually combines the PFMEA and the Control Plan.


I agree with Spaceman. I was really shocked when I first read the starter. I have been doing my FMEAs for the last couple of months and was listing down the critical characteristics so as to be included in the control plan and what I read was exactly the opposite of what I was doing.. I am not still sure about whether the sequence specified by Spaceman "DFMEA, PFMEA and control plan" is the right one, but as far as my knowledge goes, its FMEAs first and then the control plan. As described, come out with your process flow chart and diagrams, do FMEAs for all your processes and also your designs, identify the critical processes and then include these critical processes in your Control Plan to control them. Thats what the name suggests.
Any comments about this SENIORS???


How do you identify the critical characteristics Marc? I already told the way I have planned to do it and have been doing it for the last two months. Am I going wrong? Is this not the best approach? Do you suggest me to change my approach and catch another path?


Fully vaccinated are you?
Your control plan evolves. As I said, I start a control plan first and put customer defined critical characteristics on it. To get your critical characteristics you look at everything from industry standards on. Y9ou might machine a part and for that part to go in an assembly it may require a hole be placed within a certain area. It may be that area is critical, or it may not. You simply have to use your judgement and experience. There is no list you can go to.

I don't think the path is that critical. There is almost always overlap - as the DFMEA is being done quite often a PFMEA team (or person {reality, folks} is doing the Process FMEA. You have to understand the process, however. Sometimes there are DFMEA entries that are carried over to the PFMEA (not often, but it does happen from time to time).

I prefer to have a projected process flow diagram before starting the PFMEA as I believe you have a better idea of what to look at.

I wouldn't let the sequence bog you down. If you do the PFMEA before the DFMEA (which is very, very common - but I would say it is not the 'smartest way' to do it), it's a matter of reviewing the two together and checking to see if anything from the DFMEA should be added to the PFMEA.

If you review the APQP document I linked above and still have questions, come on back and ask more questions.

Gotta run. I'm leaving for Tampa in a couple of hours.

Laura M

We always did PFD, PFMEA, then PCP. DFMEA was provided by design as the first document. In reality the PFMEA requires you identify "current process controls" so it was in all practicality a simultaneous activity. Alot depends on whether you are looking at an existing process or developing a new one.

Spaceman Spiff

Marc, it's not often I disagree with you... the customer's critical characteristics should be the "Input" in Phase 1 of APQP. Those characteristics are part of the design consideration, thus included in the Design FMEA.

Kevin Mader

One of THE Original Covers!
My 2 cents:

While performing an FMEA, you need to have some idea of how a failure mode is controlled, even if the FMEA comes first in your sequence of events. Additionally, is a low RPN value as a result of the preliminary (?) control plan activity?


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