Flash Allowance - Zinc Die Casted Part 2

[CVPEngineering]

Hi all, my company purchases a zinc die casted part that recently has had a flash issue. The supplier states that the part meets drawing specs and is refusing to rework the parts unless we pay a service fee per part. As I reviewed the drawing I noticed that in one of our notes it states "FLASH ALLOWANCE TO 1.500 MAX". I'm trying to understand what this means. Is there a website or book that I can reference on how to correctly interpret this or update my drawing to correctly call-out flash acceptance? Thank you.

 

[hendersdc]

I hope you are working in mm and not inches. I would interpret that as the flash web can protrude 1.5 mm (or inches) and be of unspecified thickness.

We would typically have a second note similar to "parting line mismatch: 0.005 in max" to control the thickness of any flash.

 

[arunmrao]

Why should one leave behind extra metal on casting? 1.5mm across the parting line for a die cast part speaks poorly of the foundry. They must control it and not transfer their inefficiency to their customer.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[CVPEngineering]

Hendersdc, thank you for your response. Our drawing is dimensioned in inches, but I think that you are correct that 1.500 is more probably in mm.

 

[EdStainless]

Or is the part 1.490" wide and note means that the 'over the flash' dimension cannot exceed 1.500"?


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P.E. Metallurgy, Plymouth Tube

 

[racookpe1978]

No, in a contract drawing where money is already at an issue, and where the supplier has already said their beginning negotiation position is "Pay me more and I will consider fixing my defect in your part", you MUST be able to specifically clarify your units, your measurements and decimals, and your requirements.

If you cannoyt be clear about this specific phrase, you have lost your money trying to get this supplier to fix it.

 

[hendersdc]

arunmrao, flash is part of the process, not necessarily indicating a lack of capability on the part of the vendor. It is normally removed with a trim die or secondary machining/cutting but if you can live with it being present, and it won't affect the function or cosmetics of your part, it can be a cost saver to leave it there.

 

[hendersdc]

CVP, Ed makes a good point about your note referring to a specific dimension. It is also possible that the notes were copied over from a metric part and not updated to inches, that has happened to me before too.

 

[dik]

I would suggest your spec is wrong and should be fixed for the next issue... you have to be precise in what you are spec'ing... You 'bought' the baby and now have to live with it. Cleaning up the casting is either your work, or the supplier's. Once this contract has been completed, your next contract should reflect what you really need.

In the event of an ambiguity, the courts generally rule against the party that created the spec/contract.

Dik

 

[arunmrao]

I never give a part having flash to my customer. Also minimizing flash is in the interest of the foundry. It speaks poorly of the foundry, more so when they are die cast


"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[EdStainless]

arunmrao, and more so if the part has been made with acceptable levels of flash/miss-match in the past.
If the part has changed then either they are not maintaining tooling or they didn't set-up correctly.

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P.E. Metallurgy, Plymouth Tube

 

[MintJulep]

If the owner of the drawing (you) doesn't know what a note on the drawing means then it means nothing. Or worse, means something different to everyone that reads it.

At best this gives you the ability to reject parts coming in your door.

Regardless, your task now needs to be determine what is acceptable and how to properly define it on a drawing.

A bad vendor making parts to a bad drawing rarely has a good outcome.

 

[dik]

MJ...

"At best this gives you the ability to reject parts coming in your door."

only if the supplier prepared the document... If the owner (or rep) prepared it, then the owner/rep has little to stand on...

Dik

 

[MintJulep]

If the owner (or rep) prepared it, then the owner/rep has little to stand on..

"It's my drawing and my interpretation of the meaning is the correct one."

 

[dik]

Not necessarily from a legal point... if it's ambiguous, then it's likely the other guy's interpretation since you produced the ambiguity...

Dik