Material Combos with High Stick, Low Slip Friction

[MikeMech]

I'm looking for a material pair that has a high coefficient of static friction and low coefficient of sliding friction. The actual coefficients are not critical, it's the difference between the two that I want to maximize. I'd prefer dry contact unless there is a lubricant available that exacerbates the difference between the two coefficients.

The application is a constant force spring counterbalance. While I can approximate the necessary counterbalance force required with the spring (about 10 lbs), the load varies somewhat during its travel. I'm thinking of using a spring loaded friction disc pressing against the spring drum to achieve a holding force of about 30% of the nominal load. Space is tight and the spring drum is only about 3" diamter.

Any suggestions are appreciated, also any leads to constant force spring manufacturers.

Thanks in advance,
Mike

 

[sjwilson]

Associated spring SPEC
Evesham Worcestershire (UK)
01386 443366
theres also a company called Tensator who make tool balances and similar equipment with constant force spring assemblies, they may be able to help - last time I contacted them tehy were in teh Milton Keynes area I think.
Steve