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Designing a zinc license plate frame to be chrome plated

I have designed a license plate frame for production in zinc, to be triple chrome plated.

To narrow down manufacturing methods, I need to know the degree of surface roughness that can be tolerated to achieve a good chrome finish.

For example, if rubber/plaster casting can achieve only 125 micro-inch finish, per manufacturer, that option is ruled out, and I have no option besides die casting.

It seems sand casting also gets ruled out, for surface roughness, and investment casting gets ruled out for excessive labor costs.

Thank you, in advance, for your comments.

Your questions are good ones, Karen, but I think they just slightly miss the heart of the matter. Almost anything can be nickel-chrome plated via some procedure or other, but you need the plating to be adherent, corrosion resistant, aesthetic, and cost effective.

On diecastings this usually involves either vibratory finishing or a very light scratch brush, and it requires higher quality diecastings than some other finishes might require. For example, if the casting has even a very small coldshut it is not plateable. On other types of castings, porosity is a big issue and vacuum impregnation may be required; this is doable, but license plate frames usually must be quite cheap. My experience is limited, but stamped steel and zinc diecastings are the only way I've seen them done in production.

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

Thank you for your response. Most especially, I appreciate the tip to look out for the diecasting issues you raise that affect the plated outcome.

adv.
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