Friction Joint

[bvanhiel]

I don't have any experience in clutch design, and I'm looking for some material recommendations to improve the performance of a friction joint.

I have a custom friction clutch designed for an application that currently uses alternating disks (about 1.5" dia) of stainless steel and delrin. Tension is held on the clutch pack using a compression spring. I'm using about 7 clutch pairs and ~5-10lb of force on the spring. I know I can increase the # of clutchs or the force, but I'd like to improve the performance by changing the materials. The clutch only has to have a relatively short life (~30,000 cycles), but I'd like to get consistant performance.

Any ideas?

Thanks,

-b

 

[ornerynorsk]

Is heat buildup during slippage going to cause problems with delrin? You may just want to use clutch facing material. I've also used rubber filled cork and sbr flange gaskets in the past for low load applications.

 

[bvanhiel]

Heat won't be a problem, as it won't cycle frequently. These will be built in low quantity, so I'm looking for an easily available material. I'll check on your recommendations.

Thanks,

-b

 

[GregLocock]

What sort of friction coefficient are you getting? most dry friction materials seem to have a mu of 0.35 on steel.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[bvanhiel]

I haven't measured it myself, but the given values for mu are .2-.3 for delrin and steel. I've ordered some brake liner material to play with, the given values are for mu are .45-.55. My fear with the liner material is that it will be too weak to transmit the torque without being bonded to a substrate (something I'm not doing with the delrin).

-b

 

[Philrock]

Try Turcite A or Turcite X as a friction material. Both are made by Busak + Shamban.

For most consistent performance, keep ratio of inside contact dia to outside contact dia as large as possible.

For longevity, keep PV low. Increase capacity by no. of discs and contact dia.