Structuring of tribological active surfaces for reduction of frictional losses

Surfaces in a wide range of engineering applications are subject to tribological loads. Many of these surfaces have a profound effect on the efficiency of manufacturing processes and products during service. This paper focuses on the effect of surface microstructure geometry on the friction coefficient between lubricated sliding partners. Initially, the Computational Fluid Dynamics (CFD) package COMSOL. Multiphysics was used to determine the effect of geometry parameters of semispherical cavities on hydrodynamic pressure. The simulations showed that surface microstructures act as micro pressure chambers that would allow the sliding partners to reach hydrodynamic lubrication at lower operating speeds. Patterns of the microstructure that showed the highest pressure build-up in the simulations were then manufactured by Jet-ECM and tested in a tribometer. It was determined that patterned spherical segment cavities 10 ìm deep and 500 ìm wide yield a friction coefficient reduction of up to 35 %.