FOR DIE CASTINGS
FOR STEEL PARTS
Zinc base die castings are plated with copper prior to plating with nickel and chromium for two major reasons: (1) copper metal is relatively inert to the acid nickel and chromium plating baths, and (2) copper plates in the recesses more readily than nickel or chromium. Better coverage in the recessed areas of the parts improves the corrosion resistance of plated zinc base die castings.
Most of the reasons for selecting copper for plating steel parts are self-explanatory. Copper is soft and is readily buffed. Although copper from acid plating baths has poor adhesion, plating of a copper “strike” from a cyanide bath solves the problems of adhesion and good coverage.