The authoritative public forum
  for Metal Finishing since 1989
-----

Low friction coating for sliding parts

Hi,

I have an application whereby a small pin (1.2mm diameter * 8mm long), slides in a sleeve of equal dimension. It is being driven by a 2" diaphragm underneath which moves under low pressure (3-4PSI) The diaphragm is attached to the pin.
Currently, it is difficult to shift the pin.

I am potentially looking at a very thin coating with low friction. Cycles will probably be up to 60 times per minute. Currently using stainless steel, but would be willing to change.

Thanks

James Tinker
pneumatics - Littleton, Colorado
2005

---

I am bothered by the statement that it slides in a tube of equal dimension. Typically, the pin needs to be about 0.003 smaller or you have an interference fit-IE it will stick.
That said, a pin with a UHMW polyethylene head or cap should do the deed very nicely as it is inert and low friction. Could be ribbed to give the effect of ring seals.

James Watts
- Navarre, Florida
2005

Chrome is a very thin coating that has little friction. maybe even electroless nickel might work.

Peter Van de Luecht
- Melbourne, Vic, Australia
2005

Have you considered nickel-Teflon ?

Bo Kønig
- Odense, Denmark
2005

---

When the 1955 Chevrolet 8 cylinder first came out there was a squeaky problem with the stamped steel valve rocker arms. In the little dirty job shop I worked in at that time, we barrel cadmium plated those rocker arms, the word got out, and we received rocker arms from all over the country. Then they redesigned and got the squeak out without cadmium.

Also, the main problem the industry (particularly Boeing) is having in eliminating cadmium is that zinc/nickel, zinc/cobalt, and all the other approaches, do not have the lubricity of cadmium electroplate.

There are shops in North Carolina that still do Cadmium.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2005

A teflon coating will work great for this application!

Jordi Pujol
- Barcelona, SPAIN
2005

---

2005

Depending other parameters involved:
1) Strength
2) Electrical Conductivity
3) Thermal Conductivity
4) Operation Temperature

consider: one or both components to be fabricated of same material:

- Pure Graphite, Graphite reinforced Carbon Graphite
- Boron Nitride
- Teflon

Anthony F. van Belle
- Bunschoten, Netherlands