Nickel-Iron Pitting Problems
Q. We have a nickel-iron plating solution that functions reasonably well most of the time, but recently we have observed problems with pitting on our finished parts. We monitor surface tension and keep the value below 50 dynes/cm. The bath is agitated vigorously using a low-pressure air blower. Do you have any suggestions on how we might solve this problem?
A. Based on the little information you have included in your e-mail it is hard to give you a complete diagnosis of your problem. However, the area that I would concentrate on is filtration of the air supply and the plating solution.
Check the filters over the air intake to make sure they are properly fitted and changed and/or cleaned on a regular scheduled basis.
Your solution filtration setup should be examined on a regular basis. One of the common problems with almost all plating baths is that filtration systems are not maintained or adequately sized for the tanks and the solution chemistry. It is a good idea to have the filtration system inspected by a company that specializes in filtration systems. Names of vendors that specialize in filtration systems can be found in the Products Finishing Supplier Directory at www.pfonline.com.
It is important to remember that using an anti-pit agent to maintain low surface tension will not necessarily prevent pitting of your plated deposit.