Friction Testing (What Code Do I use?)

[JakeAdkins]

I have two rollers in Hertzian contact. One roller is driving the other. I put a coating on one roller and want to determine how much it helps. I have the ability to determine the RPM & torque of both rollers.

This seems like a simple enough case that it could be tested with some ASTM code, but I can't find one. There should be no slip between the rollers.

 

[CoryPad]

I recommend reviewing ASTM G 115 Standard Guide for Measuring and Reporting Friction Coefficients. It may not have exactly what you need, but it is a good beginning on this subject.

 

[Ron]

First, ASTM is not a "code". The ASTM publications are standards, standard practices, standard procedures, etc. promulgated by committees representing various groups.

Why not measure relative rotation of the rollers at startup? If one is slipping against the other, then you have two choices...increase the contact stress or increase the relative friction between the two. If you know your contact stress and you know the torque required at start up, you can compute the amount of static friction required for movement.

Most ASTM standards address static coefficients of friction. Your condition is more of a kinetic or kinematic coefficient to maintain the same speed of the rollers by hertzian contact.

You didn't give the materials used for the rollers, but be sure to check fatigue considerations as you increase the contact stress if you indeed have to do that.