AIAG FMEA 4th Ed "Design Assumption" - I Need Examples

[Carmine]

I think that assuming that the design is correct It means that I don't have to consider the possibility of having a wrong design, so I don't have to consider Design Failure mode but just Preocess ones. AmI wrong?

[Carmine]

I think that assuming that the design is correct It means that I don't have to Process Failure mode coming from a wrong design. But actually I they can be as Miner suggestin his examples. Do you agree?

[Jim Wynne]

In Reply to Parent Post by Carmine

I think that assuming that the design is correct It means that I don't have to consider the possibility of having a wrong design, so I don't have to consider Design Failure mode but just Preocess ones. AmI wrong?

Thanks for the clarification. You're doing a design FMEA, not a process FMEA.

Think of it this way: If the design is "correct," the task is to try and understand potential design/product failure modes with that assumption in mind.

BUT, in the course of the DFMEA process, it might be discovered that there is something questionable about the design, despite the assumption of correctness. That discovery should be reported to the proper design authority.

[Carmine]

I am doing a PFMEA and the manual gives this assumption.This is a Process FMEA assumption. I am reading the manual right now. Read at page 81 bout Process Failure Mode the two assumption
1) About incoming material to be correct

2)About Design to be correct

See carefull it

[Jim Wynne]

In Reply to Parent Post by Carmine

I am doing a PFMEA and the manual gives this assumption.This is a Process FMEA assumption. I am reading the manual right now. Read at page 81 bout Process Failure Mode the two assumption
1) About incoming material to be correct

2)About Design to be correct

See carefull it

It would have been good to give the specifics in the beginning. If you're doing a PFMEA, assume the design is correct but notify the design authority if you see something that doesn't seem right. See Miner's examples.

[Carmine]

Thanks so much guys!

[Chennaiite]

In Reply to Parent Post by Jim Wynne

Thanks for the clarification. You're doing a design FMEA, not a process FMEA.

Think of it this way: If the design is "correct," the task is to try and understand potential design/product failure modes with that assumption in mind.

BUT, in the course of the DFMEA process, it might be discovered that there is something questionable about the design, despite the assumption of correctness. That discovery should be reported to the proper design authority.

Why would someone report the design flaw discovered in DFMEA to the Design authority, given that the authority himself shall be the owner of the DFMEA process and hence is very much part of the discovery?

Moreover, I don't agree with the concept of assuming Design correctness for DFMEA. I would say DFMEA per se is the process of questioning the Design and its robustness in order to evaluate risk. That is why Design changes become the outcome of DFMEA depending on the risk involved, cost constraint, technical feasibility, etc. I agree that the team shall not start questioning the design 'concept' which are supposed to be evaluated and frozen before even DFMEA begins. For instance, when the concept is frozen for a Rear Engine Vehicle, the DFMEA team shall not pitch in and question the positioning of Engine. But in real time scenario there are even occasions when Design concept is questioned.

[Jim Wynne]

In Reply to Parent Post by Chennaiite

Why would someone report the design flaw discovered in DFMEA to the Design authority, given that the authority himself shall be the owner of the DFMEA process and hence is very much part of the discovery?

Moreover, I don't agree with the concept of assuming Design correctness for DFMEA. I would say DFMEA per se is the process of questioning the Design and its robustness in order to evaluate risk. That is why Design changes become the outcome of DFMEA depending on the risk involved, cost constraint, technical feasibility, etc. I agree that the team shall not start questioning the design 'concept' which are supposed to be evaluated and frozen before even DFMEA begins. For instance, when the concept is frozen for a Rear Engine Vehicle, the DFMEA team shall not pitch in and question the positioning of Engine. But in real time scenario there are even occasions when Design concept is questioned.

There was some confusion here. The OP, as it turned out, was referring to PFMEA, not DFMEA.