Flaky Cadmium

Question:

Our company plates small parts used in the aircraft industry. We have successfully plated cadmium for more than 10 years but recently started having problems. The bath was changed late last year, and shortly after that we started seeing flaking and adhesion failure using a bend test. We also observed that the parts require longer times to plate with this new solution compared to the old discarded solution. The parts and test coupons are barrel plated. The failures are not consistent. What can cause this problem? (Additional information on the process was included with the e-mail.) S.C.

Answer:

The problem reared its ugly head after the cadmium plating solution was changed. This is where you should start your troubleshooting. Excess brightener in the plating bath can cause peeling and poor adhesion. Another cause can be improper acid dipping of the parts. This can cause hydrogen absorption, which can cause peeling. The problem with the longer plating times can be caused by a plating bath with too high a cyanide concentration or a low metal content.

Also determine if everything is okay with your barrels and danglers. Were they changed or modified during the same time period? Are all electrical contacts clean and free of corrosion?

In short, do a thorough inspection of the entire cadmium plating process. Do it when you are wide awake! You have a better chance of spotting problems when “bright-eyed and bushy-tailed!” Get a copy of Trouble in Your Tank, 3rd Edition, by Lawrence J. Durney available from Products Finishing Hanser Gardner Publications, 800-950-8977. The book can be a tremendous help.