The Wear Behavior of Small Module Gears Lubricated with NLGI 1 Grease

Small module gears (m_n ≤ 1 mm) are increasingly important in power transmitting gear applications due to ever more rigorous requirements regarding, for example, performance and weight. They can be found in numerous applications that are subject to very different operating conditions. Often, small module gear applications are grease lubricated. This results in the lubrication supply mechanism (i.e., circulating and channeling) playing an important role in regard to the resultant gear failure mode. In the experimental investigations conducted herein, the focus was on gear sliding wear. The influence of the operating conditions and the grease composition on the lubrication supply mechanism, and thus wear behavior, was investigated using case-carburized, small module gears (m_n = 1 mm). The investigations show that the rotational speed has a significant effect on gear wear behavior. Increasing rotational speed does not necessarily lead to more favorable wear behavior of grease-lubricated gears. Furthermore, the grease composition was shown to affect wear behavior.