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Brass Plating over Nickel Plating

Q. We are using steel screws for the brass neutral link or brass terminals bars used for earthing in electrical wiring.

Our customer wants these steel screws with brass plating. We buy these screws and so not aware of the process. As far as I know, the screw is acid cleaned and then copper is flashed before nickel plating and then brass flashing.

The problem is that after few days the brass (yellow) color gets red and black if kept open. The shelf life of these parts are very crucial and hence would like to know the following.

1) Is there any grade of steel which is less corrosive? (Not Stainless Steel)
2) Is there any particular method to be followed for acid cleaning of these screws before they are copper flashed?
3) Same before nickel plating
4) And finally brass flashing
5) Is there any coating required on the top of brass flashing?

These screws are then fastened on the terminals by hand. It has been noted in the past that the sweat on hands were the reason, but then we use cloth gloves. The problem is reduced, but not solved.

Can anyone suggest a proper full proof method?

Regards
JACOB

Jacob Ebanezer
Mechanical Engineer - Jamnagar, Gujarat, India
August 29, 2010

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Some nickel plated screws aren't getting their brass plating

Q. Sir I am facing a problem that is after nickel plating on iron screws when we try for brass plating. some of screws missing in brass or some material not covered with brass plating. This problem is coming last few days. Before one month there was not problem about any missing.

I'm adding brass salt, ammonia ⇦ this on eBay or Amazon [affil links] , and cyanide also.
18 °C and pH 11.6

Vikas girdhar
Ishmeet polish industry - Amritsa,Punjab/india
February 11, 2019