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Bright nickel is flaking from "toggle locking" operation

We are plating a steel part with bright nickel with a minimum of .0004 thickness over .0001 copper flash.

Our customer is assembling this part to another steel part by a process called Toggle locking which is put into a press at pressure of 35 ton.The impression from this tool is approx. .25 diameter by .35 deep. After this process is done the nickel is coming off on about 20% of the parts around the toggle lock area it self. We have preformed a scribe test next to what they say is a failure with excellent results of adhesion. I am looking for information that may explain that the finish will not hold up to the process that they are doing to these parts.

Vince Wheeler
Customer service/Sales plating shop - Forest Lake, MN, USA
2007

Several things would seem obvious. Firstly does the nickel deposit exhibit high levels of tensile stress? This can be readily verified by taking a 2 amp 5 minute Hull Cell panel and bending it 90 degrees. If you hear a snap or crackle you have high stress in you nickel. This can be due to high organics (including secondary brighteners), low carrier or improper pH. Secondly, the nickel deposit may not have sufficient grain elongation for the operation. Finally and most importantly, is the nickel separating from the copper or is the copper nickel separating from the base metal? The answer to this can lead to a discussion of surface prepartion and plating cycle.

Gene Packman
process supplier - Great Neck, New York
2007