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Fluoborate Cadmium Chipping Problem

I am new to the plating business and am having a problem with H-11 steel fasteners being plated per NAS 672. Interestingly enough, I did some work on the process and reduced the problem somewhat but we are still having a problem with the plating chipping off. The fasteners are small bolts and the head is chipping at the radius between the top and the side of the head. Our bath chemistry conforms to NAS 672. Prior to plating, we alkaline degrease, powder blast with alumina, and electroclean. We activate in nitric acid.

Pat Reid
technical services - Costa Mesa, California
2005

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Stop using nitric acid to "activate". Use 30% Hydrochloric Acid or 10$ Sulfuric Acid.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2005

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How long should we activate in HCl? We have been activating for a very short period of time (5-10 seconds). We tried HCl for that short time and it did not seem to help. I do have some further info. First, we are barrel plating. Second, the area that is chipping is on the edge of an acute angle between the flat of the head and the tapering side wall(like the head of a countersunk screw). The parts with rectangular cross section heads do not seem to be having the problem. Next, the problem seems to get worse with increasing voltage and amperage. We also tried ultrasonic cleaning before powder blast to no avail.

Any further suggestions or clarifications would be greatly appreciated.

Pat Reid
- Costa Mesa, California
2005

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3 minutes at 30% HCl. If that does not work, then the steel is a high strength (probably nickel and chrome bearing), so go on to a Nickel Chloride Strike(2 #/gal Nickel Chloride, 2 quarts per gallon HCl, cathodic at about 12 volts in a barrel for 5 minutes.)

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2005