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Electroplating Finishes for Zamak Parts

April 9, 2009

I have some Zamak-5 zinc die cast parts in a project I'm designing. Per my customer, I need to specify some different surface finishes for these parts, and I have a few questions.

For one component, I need a "matte stainless steel" appearance, and I need to keep the cost down, whatever I do. I think the best approach here is an electroless nickel finish. Is anyone aware of any other finishes I ought to consider for this application? I've found ASTM B733, which covers electroless nickel. Are there any other industry standards that specifically pertain to plating on zinc parts?

For another component, I need a black finish, similar to black oxide. I saw the previous post about Hubbard-Hall's Black Magic finish, but I would really like to stay away from proprietary finishes on this component. I understand that conversion coatings (of which black oxide is one) work well on Zamak parts. I'm having trouble finding a specific conversion coating process that can give me the flat black look I need. Can anyone recommend such a process? Preferably non-proprietary, and preferably something with an ASTM or other similar industry standard that I can refer to on the drawing.

Thanks!

Tim Giauque
Product Designer - Columbia, SC USA

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Hi, Tim. Optical black chrome plating is used for anti-glare coatings in microscope and telescope tubes, etc., so it's about as matte as you can get -- but it's expensive, which doesn't fit your needs. Black zinc may do it. We have the question of why electroplated finishes? Does this rule out electrophoretic coatings and autophoretic coatings, or only paint and powder?

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 20, 2009