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Ask the Expert Question-and-Answer Archive
(Hard Chrome Plating)

by Randy Taylor, Advanced Tooling Corporation.
March, 2009

Rough Finish at Outside in Rings

Q. The problem is that we get roughness at outside in rings with dia 36, 38 and 40mm in Hard Chrome Plating ( around 1%). Nowadays, we are facing frequent power interruption due to which we are plating the component with interrupted current supply in the bath. The power interruption lasts up to 5 minutes maximum and we again regain the power which goes twice or thrice for a single load.

We want to know whether this practice is advisable and will this interrupted power supply affect in any way with the roughness which inturn affects the plated quality.

We would also like to putforth that the other parameters are kept within the permissable limits including the current density.

We request your kind suggestion regarding this issue.

Thanks with Regards,

A. First I have several questions about your process.
1.) what is the base material (substrate material)?
2.) what dry preparation(s) are you performing on the metal before chrome plating, i.e., polishing, grit blasting, shot peening,
3.) which wet preparation(s) are you performing (if any) before immersion into chromium?
4.) what is your exact start up procedure now, i.e., warm up, reverse etch, first applications of forward current at which settings, i.e. amps & voltage.
5.) Size of plating area per part in Square inches, number of parts plated at a single time, on a single rack or on hooks?
6.) Describe the type anodes used in detail, size, configuration, material, and most importantly "spacing" of anodes to cathodes?

My primary suspicions are:
1.) Pre-plating preparation of the parts/ material
2.) Pre-plate etch

Interrupted Power supply is not a primary concern at this point, but we can discuss that after we discuss the questions above.

If you'll take the time to answer my questions, I may be able to offer some useful suggestions.

Randy Taylor





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