Technical Committee Lubricants

Wear Behaviour of Small Module Gears lubricated with Greases of High Consistency

The aim of this research project is to determine the wear behavior of small module gears lubricated with high consistency greases. To achieve this goal, systematic experimental investigations are conducted with case-carburized gears of module mn = 1.0 mm and 0.6 mm using the FZG small module gear test rig. In the focus of these investigations are factors that affect the lubrication supply mechanism, e.g. rotational speed, lubricant fill-level and internal gearbox geometry. Additionally, the effect of different lubricant parameters and different material pairings is to be investigated. The experimental results show that the rotational speed of the gears strongly affects the lubrication supply mechanism and the wear behavior. At low rotational speeds the dominant lubrication supply mechanism is churning
With increasing rotational speed, wear initially decreases as expected until the lubrication supply mechanism changes from churning to channeling. This leads to a change in the wear behavior with both the additivated and the unadditivated greases. The additive package strongly affects the wear behavior during channeling. From the results of the wear investigations with both gear sizes, a first approach is proposed to give an estimation of the expected lubrication supply mechanism based on rotational speed and gear size. The shown approach, however, requires further validation and needs to be expanded to take into account the numerous complex influences on the lubrication supply mechanism. Furthermore, the results show that the wear behavior, especially at higher rotational speeds, can be influenced by the geometry of the gearbox as well as by the direction of gear rotation. Also, the material pairing was shown to clearly affect the wear behavior of grease lubricated small module gears.

The IGF project (17896 N) of the research association DGMK Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e.V., Überseering 40, 22297 Hamburg was funded by the Federal Ministry for Economic Affairs and Energy via the AiF within the framework of the programme for the promotion of joint industrial research (IGF) on the basis of a resolution of the German Bundestag.