Selecting the right plating finish
I work for a metal stamping company and I am in charge of suppliers, of which electroplating is a large portion. I have a customer that is requesting an MfZn8C specification, but the salt spray requested is 240 to white and 360 to red. They are also requesting that the plating meet the new environmental requirements. I suggested alternative coatings. They agreed, but now I have to find a plating that will fit. Color, or lack of it, is not a problem. I thought about Tin Zinc, or Zinc Chromate. I also need to choose the most cost-effective option. Any suggestions? Need help ASAP!
- Grand Rapids, Michigan, USA
The most cost-effective plating is zinc plating with a conventional clear chromate, but this offers nowhere near 240 hours of salt spray resistance to white rust (more like 1/20 of that).
If the coating need not be conductive, zinc plating with a new generation trivalent chromate and a topcoat should be able to do it though.
Tin-zinc is a fine finish, but it is not as decorative as plain zinc and is much more expensive because it is about 80 percent tin. Zinc cobalt and zinc nickel are possibilities, but also significantly more expensive than plain zinc.
Ted Mooney, P.E.
Pine Beach, New Jersey
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