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Plating for aluminum

We are a manufacturer of hardware products.

The situation is that we have a solenoid component with a stainless steel plunger that is electroless nickel plated, with a rear aluminum (2011) end cap. The plunger OD is .141 and the hole ID in the rear cap is .145.

The aluminum rear cap is anodite plated. A process I am not so familiar with. The problem is after so many life cycles the plunger develops a black residue, that gums up the plunger, preventing it from continuing to travel through the cap hole.

We are attempting to prevent corrosion and white dust build up on the aluminum cap, and to increase its hardness against wear.

We are looking for any suggestion of an alternative process by which we can achieve both the desired results and not have any accumulative material build up.

Thank you,

Gary Ferguson
- Bronx, New York
2001

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2001

Well if you are not "so familiar" with 'anodite plating' you are still a few steps ahead of me because I've never heard the term :-)

I think there are two things to remember in wear situations: first that one material should be appreciably harder than the other, and secondly that bare aluminum is so prone to galling and snagging that it totally sucks. You could probably address the second problem by hard anodizing the aluminum, possibly with teflon incorporated as well, but that leaves you with two very hard surfaces rubbing against each other. Is there a downside to electroplating the aluminum with a soft and lubricous material like tin?

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