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Trivalent Black chromate on Zinc Die-cast part (Zamak 5) isn't consistent

2007

Hi,
This is my first time dealing with Zinc Die-cast parts with Trivalent Black Chromate and would like to know if it is able to achieve a good cosmetic finish?
Currently I'm seeing a non-uniform Finishing on my product which have patches of exposed metal which is unacceptable.
My plating house had claimed that Trivalent Black chromate could be easily "fades" due to handling issues, especially my parts need to go through a secondary machining process after plate. (To ensure the conductivity of the part).
Is there any ways to improve this situation?

Thanks,
Calvin

Calvin Lim
Engineering Assistant - Singapore

All things considered, the following may not be a great suggestion, but the best way to get consistent black chromate on the parts is to zinc-iron plate them first.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.
2007

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