Q. I am having a problem with burning on my nickel-plated parts. On some jobs, 75 to 85 percent of the parts come out with burnt areas. Do you have any suggestions as to what the cause of this might be? S.D.
A. The solution to your problem goes back to having better control of your plating bath. The most common cause of burnt areas of a plated part is due to poor control of current density. A well-managed plating bath will have a consistent current density, within a range of values, on all areas of the part being plated. When you are operating within range, you are much less likely to have burning of parts. However, on a given part, current density can be much higher on edges and corners. For example, if you are plating a flat rectangular plate, you will find that the current density on the corners and edges of this plate is higher than that of the flat surface. This results in a thicker deposit in these areas and, in more extreme cases, burning.
Your problem can be solved by decreasing the current that flows through your plating bath or, in some cases, raising the temperature of the plating bath. Other things that can be done include modifying the way parts are racked and the placement of anodes in the plating bath.
Other causes of burning that are sometimes overlooked include low nickel content and low chloride concentration.
You can find more information on nickel plating by searching PFonline.com. I also will email a copy of the Nickel Tank Doctor, which offers some trouble-shooting information for the Watt’s nickel bath.