Metal finishing Q&As since 1989

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Looking for tough, low friction, biocompatible plating

I'm trying to find a way of drastically increasing the lubricity of some stainless steel parts, while maintaining a tough finish that will be on dry wear surfaces. I have run across many shops that can co-deposit PTFE with nickel. This sounds like a perfect solution, but this is a medical device. We are very hesitant to use nickel, because it is generally not biocompatible and may lead to larger problems with the FDA. We have tried teflon coating, but it does not stand up to the abuse, and is removed after a few machine cycles. Is anyone aware of a PTFE co-deposit process with other more suitable metals - chromium, perhaps. Another alternative may be hard chrome plating. Can anyone shed some light on the subject?

Aaron Brown
mechanical engineering / medical - Los Gatos, California, USA
2004

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2004

I realize that nickel is a skin irritant to some percentage of the population (whether it be 6 percent as the industry claims or some higher percentage). I also understand that it is an irritant like Poison Ivy whereby intolerance can develop over time. But then I start getting confused because I know that some biomedical items like stents, catheters, and even dental appliances are made of nickel or are electroless nickel plated.

So my only advice is that if teflon impregnated electroless nickel is ideal from an engineering standpoint, don't dismiss it on rumors and suspicion. Make sure it is a real problem (either physical or regulatory) before writing it off.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Dicronite works well as dry lubricant. Try it directly on the stainless steel or over a hard chrome if you need more wear resistance.

Ken Sherwood
- Allentown, Pennsylvania, USA
2004