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Coating for Springs

 

I am looking for a coating for carbon steel springs that is corrosion resistant, has low friction characteristics, cost effective, and will not cause hydrogen embrittelment or decrease the compressive stresses on the spring (put there by shot peening). It is a fatigue life critical application.

I have thought of chrome plating, nickel plating, black oxide, and e-coating. Are one of these better than the others?

It seems that everything I look at has some of the above characteristics, but not all.

Any suggestions would be greatly appreciated.

David Krafsur
- Knoxville, TN

In my own humble opinion, the coating with the most desirable characteristics (and the fewest bad) is the black oxide - the only negative being the low friction. The low friction can be overcome though, by using a torque reducing wax, or a good quality RP that will leave an oily finish that can bolster lubricity. Black oxide is also far and away the most cost effective of your choices.

Dan Brewer
chemical process supplier - Gurnee, Illinois
 

I would look at either a PTFE (Teflon) coating or one of the new stearate coatings such as PoluLube BPL211 for these springs.

Mike Gyokeres
- Warren, Michigan, USA