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Cadmium Lamination On Brass Bushing

2003

We are having issues with lamination of cadmium plating from our bushings. The cadmium appears to be coming away from the cadmium, as no copper is visible. Some background information (? means I don't understand..not a plating expert!)

Brass Bushing:
61.3% Cu
2.6% Pb
.10% Fe
REMAINING - Zinc

Plating
Bath with Carbon Treatment?, Copper strike, Activation?, Cadmium plating in barrel.

Use
The bushing is used in a mechanical switch. The bushing is rolled over at the top, where the issue is taking place. The plater has crushed the bushing without any problems at his facility, but if you take something sharp (even your fingernail at times) you can remove cad from the bushing.

The plater is attempting to rack the bushings instead of using the barrel plating method, but we are unsure if that will work. Any advice on what to attempt would be greatly appreciated.

Thank you in advance.

Chris Renis
mechanical switches - Chicago, Illinois, United States

In case anyone has the same issue, our solution was pretty simple. We changed to a tin/zinc plating (which may be taking the place of cadmium in the future) and we have no further issues with lamination.

Chris Renis
- Chicago, Illinois, USA
2003

Chris,

To get a good answer you must tell us by the pretreatment steps for the brass bushing. What is carbon treatment is it content sulfuric acid?

Regards,

Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
2003

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The lead is the problem. The lead is in the alloy to facilitate easy machining. Most job shop platers do not know how to prepare leaded brass for plating. The lead smears on the surface during machining and forms insoluble salts with the Hydrochloric or sulfuric that the typical job shop uses. Leaded brass must be treated in 50% Fluoboric acid (which does not form insoluble salts)immediately before plating. Better still "strike" the parts in a copper fluoboric plating solution before the cadmium.Get back to us and let finishing.com know what happened.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2003

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Hello and thank you for all of your input. When I gave the idea of using the fluoboric acid to treat the bushing before plating to our purchasing department, I was then separated from the issue for a week or so. I was told that the plater attempted to do this, without any success, and we began looking for alternatives. Not being able to deal directly with the plater took me out of the loop, which was disappointing. Your answer makes sense, but I was pushed out of the loop, and put back to working on the numerous other issues on my desk.

Once again I thank you all for your help on this issue, and if any other plating issues come up in our line of work, I will be sure to look to this web site for guidance.

Chris Renis
- Chicago, Illinois, USA
2003