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 The New Elsmar Cove Forums
 FMEA and Control Plans
 What comes first?
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louie Forum Contributor Posts: 19 |
posted 01 March 2000 11:19 AM
  
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.
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Spaceman Spiff Forum Contributor Posts: 64 |
posted 01 March 2000 01:35 PM
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. IP: Logged |
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Sarang unregistered |
posted 01 March 2000 02:20 PM
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?? IP: Logged |
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Marc Smith Cheech Wizard Posts: 4119 |
posted 01 March 2000 02:26 PM
Igenerally start with a control plan - enter customer critical characteristics. Then DFMEA, then the Trilogy (PFMEA, CP and Process Flow. Have you reviewed Elsmar.com/pdf_files/APQP_Q.pdf ? IP: Logged |
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Sarang unregistered |
posted 01 March 2000 02:29 PM
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? IP: Logged |
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Marc Smith Cheech Wizard Posts: 4119 |
posted 01 March 2000 02:43 PM
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. IP: Logged |
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Laura M Forum Contributor Posts: 299 |
posted 01 March 2000 02:45 PM
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. IP: Logged |
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Spaceman Spiff Forum Contributor Posts: 64 |
posted 02 March 2000 08:20 AM
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. IP: Logged |
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Sam Forum Contributor Posts: 244 |
posted 02 March 2000 09:33 AM
The APQP manual provides guidance on the sequence of events for document preparation; DFMEA,(PFD,PFMEA) and Control Plans. IP: Logged |
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Kevin Mader Forum Wizard Posts: 575 |
posted 02 March 2000 02:31 PM
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? Regards, Kevin IP: Logged |
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Eric Sleeckx Lurker (<10 Posts) Posts: 3 |
posted 02 March 2000 04:29 PM
(May be I don't understand the discussion quite well.) I think an efficient control plan should focus in the first place on "critical" issues. These critical issues can be identified by an FMEA. The most logical order would then be FMEA, next control plan. Bye the way by nature of an FMEA it results in an action list, what could well be a control plan. Without a critical analysis your control plan hangs in the air, I'm afraid... IP: Logged |
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Spaceman Spiff Forum Contributor Posts: 64 |
posted 02 March 2000 05:02 PM
Kevin, RPN reduction is normally through design and/or process improvement at the pre-production phase. However, since FMEA is a living document, you are absolutely right in saying FMEA RPN reduction is result of control plan. IP: Logged |
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Dawn Forum Contributor Posts: 245 |
posted 02 March 2000 09:22 PM
Flowcharts come first; FMEAs are created from the flowchart; control plans are created from the FMEA. IP: Logged |
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Marc Smith Cheech Wizard Posts: 4119 |
posted 04 March 2000 01:08 PM
quote:Sometimes at the Design FMEA stage the process flow is not known or defined. As Laura said: "...it was in all practicality a simultaneous activity..." The chicken came first... IP: Logged |
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Marc Smith Cheech Wizard Posts: 4119 |
posted 04 March 2000 01:17 PM
quote:I'm sorry if I didn't make that clear. Before you do anything you have to get your customer requirements - which is why a control plan (sequentially) is an early (sometimes the first) document. And remember, the control plan, like the other documents, 'evolve'. In QS there is a requirement for 3 'levels' of the control plan (sometimes all three ar the same but that's another topic...). Whether or not you start the control plan right away, or after you do the design FEMA, you need to know the customer requirements including critical characteristics. You can't (in my opinion) do a design FMEA unless you have the customer requirements including critical (and safety, etc.) characteristics. IP: Logged |
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Brian Dowsett Forum Contributor Posts: 35 |
posted 15 March 2000 11:36 AM
Folks, I'd say find out customer requirements, use a QFD or cause and effect matrix to decide what process or design inputs have most effect on these requirements, then do your fmea(s) to get to potential failures. After all this good stuff you'll know what to include on your control plan. Where the confusion sets in is that the control plan will quite often include some product based controls that were specified by the customer right from the start. If you want to pencil these in on a control plan form, right from day one -what the heck! Who cares as long as you end up with control of the product characteristics that the customer specified, plus all the process based inputs that will have an effect. Cheers Brian IP: Logged |
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Marc Smith Cheech Wizard Posts: 4119 |
posted 06 August 2000 06:03 PM
quote:Agreed. IP: Logged |
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