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Clear coating for a cosmetic zinc die cast part?

October 13, 2010

We are currently using a zinc die cast part that is then chrome plated (copper, nickel, chrome) and used on a food processors. The issue with the existing plating is that this part requires a cosmetic finish and comes in contact with the base of a plastic container, which eventually will wear through the chrome and nickel plating, exposing the copper layer. Functionally, this isn't a problem. But the visible copper tends to give the false impression that the part is rusting.

So I am looking for options to clear coat or conversion coat this zinc part to eliminate the copper, nickel, chrome plating. This would minimize the change to the appearance of the part in the areas that tend to wear. The coating has to be abrasion and stain resistant. Any suggestions?

I really appreciate any help you can offer!

Brad Hanson
Product Designer - Orem, Utah, USA

October 14, 2010

Hi, Brad. Copper-nickel-chrome plating routinely lasts a decade and more in the severe service environment of a truck bumper or automobile grill. Are you sure you have a good handle on the issues involved in this failure?

Alternatives include heavier chrome plating (wear parts on thousands of high speed machinery components are hard chrome plated) or electroless nickel plating. Electroless nickel plating would be fine alone, or can be subsequently nickel-chrome plated without involving copper. You can apply a thin e-coating to the zinc and get good corrosion resistance, but I don't think the wear resistance of any organic coating compares to chrome plating. Although exposed zinc does not rust, it will pit and bloom in pretty ugly and unsanitary fashion.


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

October 15, 2010

It will cost a small fraction more to put double the amount of chrome on the part which will give you a far greater lifetime out of the part. Labor is the greatest cost of your plating and leaving it in the chrome tank longer adds very little to the labor.

James Watts
- Navarre, Florida

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