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Nickel plating surface face prior to hard chroming for large bore engine piston rings

A continuous problem when hard chrome plating the face of cast iron engine piston rings is "shading". This is where a small area fails to chrome on f the outside surface of a fixture deigned to hold several piston rings sandwiched between two aluminum plates causing a majority of the product to be scraped. To achieve consistency quality and reliability a flash coat of nickel is applied so their is a clean accurate surface to hard chrome plate.

Are their any complication or adverse conditions created when a thin nickel flash coat is applied to cast iron prior to applying a hard dense chrome? Will the hard chrome plate adhere to the nickel better than directly to the cast iron?

Tim Coons

2006

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First of two simultaneous responses --

Not enough information and too many ambiguous words to be of much help. A nickel strike is used on cast by some operators with success, but the strike has to be good and the transfer to the chrome has to be rapid.
If you are not using conforming anodes, you might want to consider the benefits of them.

James Watts
Navarre, Florida
2006

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Second of two simultaneous responses --

There are many obvious complications. Two baths instead of one means more chemical control, intermediate rinses, possibility of dragouts, passivation, contamination, reduced options for rack materials to withstand both chemistries. In my opinion, if the chrome operation is well designed a nickel underplate is not required.

Guillermo Marrufo

2006