Magnetic Parts

Q I am having problems with parts that are magnetic. Can you give me any information concerning magnetized steel and the effect on plating adhesion? W.A.

A. I last addressed this problem more than 15 years ago. Normally, the major concern with magnetic parts is roughness of the plated deposit caused by the magnetic part attracting suspended particles in the plating solution. For this rea-son, many shops routinely demagnetize steel parts before putting them through the plating process. Here is what I wrote:

“Surprisingly, there does not seem to be a lot of solid information regarding the effect of a magnetized substrate on plating adhesion. There is one report of a magnetic substrate causing problems with cadmium plating of the part, L. Dur-ney, Products Finishing, Volume 58, #12, September, 1994, Pages 20-24. Prior to demagnetizing of the steel parts, bare areas appeared on the surface. After demagnetizing, the parts plated in a normal manner.

There have been other cases reported in which magnetic base materials played a role, but most are not well documented. You might try posting your question at finishing.com and see if other individuals have had experience with this prob-lem.

The bottom line is this: It is always good practice to demagnetize your parts be-fore starting the cleaning and plating process.”