Metal finishing Q&As since 1989

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Plating problems

We have built an automated grinding station that uses a CBN wheel. After the grinding process the part is moved to a flame hardening station. The problem that we are having is that after nickel plating the area that is flame hardened has a dark shadow appearance.

1. Is there a coolant for the grinding operation that would dissipate after the flame Hardening process?

Bruce McDougall
- DeWitt, Nebraska, USA
2002

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Bruce,

You ask for a coolant that will disipate after heat input. The first answer that comes to my mind is deionized water. It leaves only trace residues if at all. But its so obvious that I guess you have a different problem I couldn't understand. Does the plated nickel look dark on the heat affected zone or you are not getting any deposit in that zone?

Guillermo Marrufo
Monterrey, NL, Mexico
2002

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Thanks for the response. The dark appearance after plating is in the area of the flame hardening process but it goes beyond that wich leads me to believe its being caused by the coolant. This is an automated process that does not require an operator. We are currently doing the same process today with an operator and having no problems. The only difference between the two operations is the operator, the CBN wheel and the coolant. We also have to watch for a rust problem before plating.

Thanks again,

Bruce McDougall
- DeWitt, Nebraska, USA
2002