Connection between DFMEA and PFMEA - What must be transferred to the PFMEA?

M

mahoc

Someone could tell me what is the DFMEA information that must or may transfer to the PFMEA?
Do you know if there are any manual that I canverify this data?:
- All the DFMEA causes must be moved to the PFMEA like Potential Failure Modes
- For these Pot. Failure Modes I must put the same DFMEA Effects?
- The severity for theses effects must be the DFMEA ones?

Waiting your comments. Regards
 
M

maosm

My norm interpretation is:
The connection between DFMEA y PFMEA is important as reference such as other PFMEA, because works like a preliminar PFMEA and improvement efficiency the final results.
If DFMEA is available, the connection must be done, even though the norm said "should".
 
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D

dokes

dFMEA and pFMEA connections

Primary info that is same in both FMEAs is the Effect and the related Severity rating. It doesn't matter if, for example, a radius was designed undersize or manufacturered undersize, the effect on the product/customer will be the same. Since the effect is the same the severity of the impact is the same.
 
Q

qualitygoddess - 2010

Differences

mahoc said:
Someone could tell me what is the DFMEA information that must or may transfer to the PFMEA?
Do you know if there are any manual that I canverify this data?:- All the DFMEA causes must be moved to the PFMEA like Potential Failure Modes
- For these Pot. Failure Modes I must put the same DFMEA Effects?
- The severity for theses effects must be the DFMEA ones?

Waiting your comments. Regards

There are many books and references on the subject. Typically, Design FMEA and Process FMEA are different documents, since the design process is typically different from the process to make something. I suppose each one could contain the same or similar information, depending on the product or service that is being designed or processed. I would recommend that you take a look at some reference books. If you are working with an automotive customer, ask them for a copy of the FMEA manual from Automotive Industry Action Group (AIAG). This is very helpful to understand the difference between DFMEA and PFMEA.

Otherwise, you can pick up books on FMEA from a technical library on a college campus or do a search on ASQ's website.
 
C

chalapathi

mahoc said:
Someone could tell me what is the DFMEA information that must or may transfer to the PFMEA?
Do you know if there are any manual that I canverify this data?:
- All the DFMEA causes must be moved to the PFMEA like Potential Failure Modes
- For these Pot. Failure Modes I must put the same DFMEA Effects?
- The severity for theses effects must be the DFMEA ones?

Waiting your comments. Regards
Designer's limitations are passed on to Process FMEA team. For example, a scotter design engineer is analyzing "Flat Tyre" as a failure. He can give tube less tyres, but that will increase the cost and he can not do (this is a design constraint). Can some thing be done in the process to take care of this constraint.

Similarly, when doing Process FMEA, they may have some failure, which designer can modify the design to eliminate the cause or reduce the cause or reduce the impact. For example, if there is problem in loding components correctly in a machine. The designer can provide some kind of fixture/jigs.

Hope I could clarify some of your questions.
 

antoine.dias

Quite Involved in Discussions
PFMEA versus DFMEA

The AIAG manual on FMEA is describing the differences and the connections.
you may also find SAE J 1739 useful to understand the differences and connections.

Best regards,

Antoine
 
M

Michael Walmsley

The primary connection is in the area of special characteristics, if applicable.

eg In a design component FMEA we may have a diameter that is critical such that it has a special characteristic associated with it (along with showing up on the print). You then need find in the PFMEA where the diameter is machined or manufactured. At this point where the station and operation is defined , the characteristic had better be assigned.

In general,Severity of effects may differ in the DFMEA and PFMEA. In the DFMEA the effect is to the end user. In the PFMEA the effect is to the process (unless of course you would like to embed the effect to end user also for traceability purposes).

If the severity of effect to the process is greater than the severity to the end user , you may have a different characteristic assigned.

See attached
 

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Jim Wynne

Leader
Admin
Michael Walmsley said:
The primary connection is in the area of special characteristics, if applicable.

eg In a design component FMEA we may have a diameter that is critical such that it has a special characteristic associated with it (along with showing up on the print). You then need find in the PFMEA where the diameter is machined or manufactured. At this point where the station and operation is defined , the characteristic had better be assigned.

In general,Severity of effects may differ in the DFMEA and PFMEA. In the DFMEA the effect is to the end user. In the PFMEA the effect is to the process (unless of course you would like to embed the effect to end user also for traceability purposes).

If the severity of effect to the process is greater than the severity to the end user , you may have a different characteristic assigned.

See attached

Good advice :agree1: especially about differentiating effects between the D- and PFMEAs. I'll add that sometimes there's no access to a DFMEA when a PFMEA is done, so the customer's critical characteristics must be identified on the drawing. If the DFMEA is done properly, and the specifications are properly constructed and communicated as a result, it's not necessary to have access to the DFMEA when doing the DFMEA, especially in the case of job shops.
 
T

The Kidd

Consider the DFMEA a design system element. Consider the PFMEA a process sytems element. In linking system elements: Failure Modes in higher level system elements are Effects in lower level system elements. Failure Modes in lower level system elements are Causes in higher level system elements. Do not violate the incoming quality rules and you can link any number of sytem, subsystem, components down to the manufacturing process.
 
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