Aluminium Die Casting DFMEA example wanted

A

akhsan

#1
Dear all

Now we have porosity problem in alluminium part. And we find a solution for this problem by creating DFMEA to define the real cause.

But I'm confuse how to define the occurance value? Because we validate the possible cause by simulation software.

for example.

We thought that this problem caused by hot spot area on the aluminium die casting duo to worse cooling system.
So we made simulation by changing the cooling system and the result seen that hot spot become smaller than previous.
So how to judge the occurance value for above possible cause?

Thank you for your kind answer.

Best regards
Akhsan
Jakarta
 

Marc

Captain Nice
Staff member
Admin
#2
Are you looking for help with a process problem? I'm not knowledgeable in aluminum but I thought porosity was a process issue, not a design issue. Maybe someone else here can speak about Aluminum Porosity
 
A

akhsan

#3
Thanks Marc, but we know that aluminum porosity especially in High pressure die casting also be able caused by worse design it self not only process.
 

Chennaiite

Never-say-die
Trusted
#4
Thanks Marc, but we know that aluminum porosity especially in High pressure die casting also be able caused by worse design it self not only process.
Couple of things I wanted to mention (Hope you are aware)

When PFMEA is done, the Product design is not to be suspected and vice versa. Based on your posts, you seem to be suspecting the Product design for the Failure mode-Porosity, if I am correct. But Design being based on the Material, dimensional, functional, performance requirements, the process designer shall achieve the Porosity target with the given product design. Nevertheless, if you really suspect the Product design and look forward to modifying the same, which seems to be exactly your case, the product requirements shall also be taken into account, apparently.

Now coming back to your original question of setting up Occurrence value, you know for yourself what percentage of Casting was rejected for porosity due to wrong design, before you reacted with corrective action. For example, if you had produced 1000 castings and 50 rejected due to porosity due to wrong design, the rating is 9 as per AIAG manual.
Clarify me, if I am wrong.
 

Jim Wynne

Super Moderator
#5
Dear all

Now we have porosity problem in alluminium part. And we find a solution for this problem by creating DFMEA to define the real cause.

But I'm confuse how to define the occurance value? Because we validate the possible cause by simulation software.

for example.

We thought that this problem caused by hot spot area on the aluminium die casting duo to worse cooling system.
So we made simulation by changing the cooling system and the result seen that hot spot become smaller than previous.
So how to judge the occurance value for above possible cause?

Thank you for your kind answer.

Best regards
Akhsan
Jakarta
I'm not sure it's a good idea to do an ex post facto DFMEA. You're closing the barn door when the horse is two miles down the road. The best thing to do, imo, is not be concerned with the S-O-D ratings because they're relative, not absolute. What you need to do is consider all of the variables (from the design and process) that could contribute to the problem at hand and evaluate them one at a time. The likelihood of one cause or another being the culprit is a matter of experience, part geometry, tool construction and process variables, so the way that you home in on probable causes and remedial actions won't be helped by saying that one is a six and another's an eight.
 
A

akhsan

#6
Thanks Chennaiite

I think We are talking about different thing. The design that I have mentioned was the die casting die design it self (tool/mold for making part), not product design. Cause we cant change the given product design. We are die/mold maker, so the quality of part that produce by our die/mold depend on my design,the runner lay out, cooling channel lay out etc influence the result part. To achieve the part requirement quality (including no porosity), we take some die/mold design simulation software to place runner, and cooling channel. But now, we found that by using my die/mold design produce part with high rejection rate by porosity.

So we want to check again our die/mold design to get the root cause that make high rejection.

May be it can be a few information to know what the real problem I get.
 

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