Metal finishing Q&As since 1989

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Foreign particles on Chrome Plated parts

I have been facing this problem for quite a long time , whenever we take the job out of the hard chrome plating vat and do the final buffing , there are small holes that are created due to the foreign particles (Foreign ferrous particles), in a job of 3 mtr these particles are at 2-4 places , but job is rejected due to these particles, what should I do to take these ferrous particles out of plating vat.

Vicky Nagpal
Plating Shop Incharge - New Delhi, India
September 21, 2009

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September 21, 2009

Hi, Vicky. It is possible to continuously filter a chrome plating solution, and it has been done for critical operations. But due to the aggressively corrosive and oxidizing nature of concentrated chromic acid, it is not cheap or easy. If at all possible, it is better to keep the ferrous particles out of the tank. I suspect that the parts are not fully cleaned, or are not demagnetized before going into the chrome plating tank.

Regards,

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

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September 21, 2009

It could be burs from the machining/grinding operation that are raised by the pretreatment steps.

Enter and exit the tank slower. You are probably stirring up the sludge on the bottom of the tank. On a Friday evening, hoe all of the trash off of the bottom of the tank and do that on a schedule.
Depending on your solution, you can get about 1 week out of polypropylene wound filters with the chrome at 140F. Some proprietary chrome solutions will not last that long. If you filter, I would try for a greater thru put of solution so would try a 25 micron filter first. I would not go below 10 micron.

James Watts
- Navarre, Florida