We specialize in decorative chromium using the classic copper/nickel/bright nickel/chromium process. We find that over time our nickel plating baths become contaminated with high levels of zinc. We process both steel and zinc diecasts in this line. What can we do to ret rid of this problem? F.S.
This is a classic problem that usually can be cleared by improved housekeeping. We can start out with something very simple. First, remove fallen parts from the bottom of your nickel tanks as well as all of the other process tanks. This should be a routine scheduled process and not just be performed when your plating racks can no longer be properly immersed in the plating tank. If your parts are small you can use netting material, which is resistant to the plating bath chemicals to catch the drops. The netting should be lifted carefully out of the tank, and the dropped parts retrieved on a daily basis. If parts are larger you may have to suffice with raking.
Next, setup an off-line or sidestream "dummying" tank. Instead of dummying the plating baths once a week, do it continuously. Continuous dummying allows you to control the "tramp" metals, such as zinc, at a minimum and to a constant level.
Last, make sure that the above is carried out all the time. Good housekeeping is a "hot button" for me personally. I see too many shops where good standards are in place but never followed. Our industry can do better!