Material With Very Low Coefficient of Friction

First of two simultaneous responses--

A. The materials with lowest coefficients (<0.2) that I know are graphite, diamond-like-carbon (DLC) and diamond. There might be some other compounds. The coefficient also depends on the ambient gas, moisture and temperature conditions. DLC is a thin coating and not a block of solid.

Second of two simultaneous responses--

A. Rupesh,

While you are looking for a surface with a low coefficient of friction, you will also need a surface with good wear resistance because of its contact with newsprint. I know of a metal coating which can be applied to metal surfaces which can achieve this coefficient of friction. This material is Electroless Nickel infused with Teflon. This combination of Nickel and Teflon gives great Wear Resistance and has a low coefficient of friction (I think it is about 0.06).

A. DEAR RUPESH:

I TEND TO AGREE MORE WITH TONY'S RESPONSE BECAUSE EVEN THOUGH FROM THE THEORETICAL POINT OF VIEW GRAPHITE IS INDEED VERY SLIPPERY, IT WEARS OUT VERY FAST AND WILL STAIN OR CONTAMINATE MOST SURFACES IN CONTACT. WHEREAS DIAMOND AND DIAMOND-LIKE COATINGS WILL PROBABLY BE TECHNICALLY SUITABLE BUT EXPENSIVE.

ON THE OTHER HAND, NICKEL COMPOSITES WITH TEFLON OR WITH INORGANIC PARTICLES IS AFFORDABLE, WEAR RESISTANT AND WILL NOT LIKELY STAIN OR CONTAMINATE ANY SURFACE APPRECIABLY. IT CAN BE OBTAINED FROM SEVERAL SOURCES IN THE U.S.

ONE OF THEM IS SURFACE TECHNOLOGY, INC. IN TRENTON, NJ. UNDER THE NAME OF ELECTROLESS NICKEL 500 SERIES, OR NISLIP.

GOOD LUCK.

A. In our powder coating facility we have used a product by Anzo-Nobel called XP666-7 that has a high teflon content and a very low coefficient of friction that we applied to some sheet metal plates that we produced for a Ink Jet Printer OEM. They come into contact with the printer paper and allow the paper to be driven over it by use of friction wheels. It is a powder that is applied with common electrostatic powder coating equipment and run through a curing oven at a temperature of 385 °F.

A. Hi, according to the National University of México, hard chrome has a friction coefficient of 2.0 when lubed and an abrasive wear of 2.0; 932 °F heat treated electroless nickel has a 0.25 FC and 2.7 in abrasive wear. There is a nickel-cobalt-boron alloy called DOX that can be electrodeposited, it has a 0.16 FC and a 1.09 abrasive wear. Of course teflon has a 0.04 FC, but wear abrasion is way too high.

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2004

Thanks, Amilcar, but there is a typographical error there ; coefficients of friction are rarely higher than one, and hard chrome is rather slippery. Chromium on steel has been reported as ranging from 0.16 to about 0.2, dry, so that's probably what you meant. But in practice it's difficult to draw a clear line between dry coefficient and lubed coefficient of friction because it depends on configuration, and casual lubrication is so commonplace.

In plating school years ago an instructor brought in a hard chrome plated cone with a fine knurling, set it on its base on his desk, and defied any student to pick it up.

Naturally, with the low coefficient of friction, the unavoidable casual lubrication from your fingers, and the "squirting" action as you pressed your fingers on the cone, it was indeed impossible to pick up :-)

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

A. With normal operating temperatures to 550 °F, Vespel is a polymide with the lowest coefficient of friction that I know of. GM is using it for bushings in the "A" arms of their Corvettes.
Easily machinable, it is easily the material of my choice.
Cons; This material is staggeringly expensive. ex; 1/4" dia. x 1" long rod is about $23.00.

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Thanks Harry. I don't think it's the virgin Vespel per se that is so low friction, though. Rather, graphite, teflon, and molybdenum disulfide can be impregnated into it for extremely low friction.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
November 27, 2012

A. Hi Theo. Most plating shops have a "lot" charge of $50-$200, and maybe a little more. There are no "standard" costs for plating because it depends on so many factors, leaving you with the option to request a quote, or guess. I'd guess that for electroless nickel plating with occluded teflon particles that $1 per square inch is as justifiable as any other guess :-)

But maybe a plating shop which offers the finish will chime in with a better guess. Good luck.

Regards,

A. I would suggest bright nickel electroplating on mirror polished surface, with trivalent chromium top layer. If that doesn't give you a low enough friction consider topping it off with a diamond-like carbon (DLC) coating or a molybdenum disulfide PVD coating.