I'm working on a database which involves geometric design parameters, forces analysis and efficiency and losses for wormgear reduction design systems.

To determine the tangential and axial forces applied to the gear reduction system, I need to relate the Sliding velocity with the friction factor for different materials combination.

I found this graphic chart in a technical paper. This graphic is exactly what I'm looking for, but I need a curve for steel worm and a polymer (Copolymer Acetal precisely) worm gear:

enter image description here

I would be grateful if someone can help to find that material curve.

  • $\begingroup$ You have the chart, so use it... Or do you want it as a formula or list of numbers? $\endgroup$
    – Solar Mike
    Aug 8, 2019 at 21:31
  • $\begingroup$ In my case, most of the worm gears are made of plastics (POM). A case hardened steel worm and plastic/polymer worm gear curve is what I need. $\endgroup$ Aug 8, 2019 at 21:53
  • $\begingroup$ So if that curve does not exist, then build a test rig and confirm these curves then change the gears for the materials you want and get the results... $\endgroup$
    – Solar Mike
    Aug 8, 2019 at 22:06

1 Answer 1


See "Friction and wear behaviour of acetal and nylon gears", 2009, Wear 267 p. 639 for some torque-speed curves (acetal-acetal).

Another source is "Friction and wear of acetal: A matter of scale", 2005, Wear 259, p. 697.

A google scholar search will lead you to many other sources of useful data. Whether you will get the data in the form of friction coefficient vs. sliding velocity is unclear from the papers I've looked at.


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