Influence of surface finishing on the tribological application behavior using the example of cylindrical gears

Surface finishing has a considerable impact on the application behavior and lifetime of bearings and gears. Using the example of cylindrical gears, it is shown that the tribological behavior in tooth flank contact is influenced through variations in grinding, polishing or milling of the gear pair. For this purpose, three identical tooth flanks with varying surface finishes were measured and digitized using a confocal microscope. Furthermore, these surfaces were used for micro-hydrodynamic simulations conducted with the software Tribo-X from Tribo Technologies to ascertain the solid contact pressure curve and the pressure as well as the shear flow factors in x- and y-direction. Subsequently, these characteristic curves which are necessary for the cylindrical gear simulations. In this analysis, the gear geometry, the interacting surface, the load and the lubricant are taken into account. As a result, e.g. the maximum solid contact pressure, minimum film thickness, coefficient of friction, frictional power and maximum temperature are obtained. In terms of increasing efficiency, resource-efficient production and sustainability, these results are important indicators. For example, the surface finish can be optimized to possess ideal properties with regard to the necessary material processing (costs) and the required tribological properties (efficiency). Another interesting research focus is the comparison of the surface textures of conventional manufacturing technologies such as gear polishing and grinding with those produced by innovative technologies such as the precise electrochemical machining (PECM). The approach enables a direct comparison of these machining processes with their specific surface textures to the tribological application behavior of gears. Our objective is a cross-technology evaluation of machining processes to facilitate optimal selection based on energy, production technology and resource efficiency.