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Cadmium plating vs surface finish

I have a problem with cadmium plating. I need a surface finish of 32 RMS or better on 4340 Steel (260 to 280 ksi) and the surface has to be cadmium plated (0.00015 to 0.0005 inch per drawing).

I measured RMS finishes between 130 and 240 RMS after cadmium plating and 68 to 150 RMS before plating (after grit blast). We have tried honing the surface with scotchbrite, but cadmium plating is too soft and thin for this operation, it comes off easily. Is there any way to solve this problem? Any ideas?

Thanks!

Dominic Bazinet
- Montreal, Quebec, Canada
2003

Increasing the cyanide content a bit will smooth it out a tiny bit, but you can not hope that the plate will be better than the surface finish it started with. If you need 32 out, you need at least 32 in and closer to 25.

James Watts
- Navarre, Florida
2003