Manufacturing of surface microstructures for improved tribological efficiency of powertrain components and forming tools

The performance and energy efficiency of mechanical components is strongly influenced by the tribological behaviour of their surfaces. This paper investigates the design and manufacturing of microstructured surfaces for improved wear resistance of forming tools and reduced friction in powertrain components. The potential of microstructures in the improvement of adhesion strength and resistance to delamination of hard coatings under the severe thermomechanical service conditions of hot forging tool surfaces is discussed. In the case of powertrain components, the ability of surface structures to reduce friction between lubricated bearing surfaces was investigated numerically and experimentally. The COMSOL Multiphysics Computational Fluid Dynamics (CFD) package was used to estimate the effect of geometric parameters of patterned spherical-segment cavities on hydrodynamic pressure. Electrochemical Machining by closed-electrolytic-free Jet (Jet-ECM) was used to manufacture the microstructures. Tribological ring-on-disc tests with structured surfaces were performed. It was determined that surface microstructures in the form of patterned spherical-segment cavities generate additional lift pressure which allows the surfaces to reach hydrodynamic lubrication at lower operating speeds.