Effect of the coefficient of friction on gear-tooth root fatigue for both dry and lubricated running polymer gears

S. Matkovič, M. Kalin

Tribology International 194 (2024) 109525 1-9

Abstract

Polymer gears are increasingly popular for a variety of applications due to their improved performance, light weight, ease of manufacture and low cost. However, the design of polymer gears and predictions of their useful operating lifetimes require refinements based on a better understanding of all the influential parameters. For example, do dry and lubricated running polymer gears operating with the same tooth-root temperature and under the same load/torque experience different fatigue lifetimes? To investigate this question, the fatigue lifetimes of dry and oil-lubricated polymer/steel gear pairs were experimentally evaluated under three different loads (0.8, 1.0 and 1.2 Nm) and two different tooth-root temperatures (25 and 80 °C). For all the experimental conditions, the finite-element method was employed to gain a better insight into the observed differences. Finally, the decomposition of the loads acting on the gears was used to understand the effect of friction, which is different for dry and lubricated conditions, and changes direction before and after the pitch point. The lower friction in the lubricated conditions results in up to 13% less maximum stress in the tooth-root, which can have a non-linear effect on the polymer’s lifetime, resulting in a 2–5.2-times-longer fatigue life compared to dry-running gears under the same load/torque and temperature.

URL: https://doi.org/10.1016/j.triboint.2024.109525

Keywords: polymer gear, fatigue, friction, temperature

Open access URL SLO: https://repozitorij.uni-lj.si/IzpisGradiva.php?id=156258&lang=slv

Open access URL ENG: https://repozitorij.uni-lj.si/IzpisGradiva.php?id=156258&lang=eng

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