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"Nickel Electroplating is peeling off Stainless Steel dental instruments"
March 17, 2010
We manufacture dental instruments and have stainless steel parts partially nickel electroplated (about half way up on the shaft of the part). Some parts had the nickel "shell" come off of the part. The part does vibrate when it is being used, but what would cause the plating to come off as a unit like it did? Of course, our supplier's plating is proprietary and subject to little questioning without some solid questions to ask them. Can you suggest some questions I can propose so we can figure this out?
Manufacturing technologist - York, Pennsylvania, USA
First of four simultaneous responses -- March 18, 2010
It is normal to insist that your supplier provide a plated product with good adhesion. The key to plating on stainless steel is the pretreatment steps before the plating tank. The pretreatment consists of alkaline cleaning, acid activation, and a "strike" which is a thin preplate formulated especially for plating on stainless, and of course intermediate rinsing. If anything is wrong with any of the pretreatment steps, then the result is likely going to be poor adhesion. That being said, there are many specific possibilities. The two things that I usually look at first are poor cleaning and contamination in the strike bath. A Wood's strike, a common pre-plate chemistry, is especially vulnerable to copper contamination that may dissolve off of the cathode or anode bars. That should give you a start. Good luck.
Jon Barrows, MSF, EHSSC
Second of four simultaneous responses -- March 18, 2010
We suspect that your plater has allowed the nickel metal to creep up in the nickel chloride strike therefore converting it from a inefficient "strike" to an efficient plating solution which does not bond.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
Third of four simultaneous responses -- March 18, 2010
I doubt that vibration has anything to do with the peeling unless the nickel deposit is stressed. If this was the case you would normally see cracking of the deposit, but peeling is a remote possibility. Nickel Sulphamate has lower deposit stress characteristics than nickel sulfate baths. Which bath are they using? Another possible cause would be in the pre-clean cycle, poor rinsing, or nickel strike. If your plater wants your business they will take some corrective action to get to the root of the problem. You could ask them to do rigorous adhesion testing before they ship the parts.
process engineer - Malone, New York
Fourth of four simultaneous responses -- March 19, 2010
No questions. Just tell him to do it again and do it right. If he is knowledgeable enough to have proprietary processes he must be able to identify the problem and correct it.Guillermo Marrufo
Monterrey, NL, Mexico