Effect of EDT surface texturing on tribological behavior of aluminum sheet

Surface texturing, which fabricates micro dimples or micro channels on the surface of parts, is a growing technique for improving tribological characteristics of materials. Currently, electrical discharge texturing (EDT) technique, one surface texturing method suitable for mass production, is being used to texture aluminum sheets for the applications in automotive industry. It has been widely accepted in industry that EDT improves the forming behavior of aluminum sheets due to better friction behavior. However, how the textures on the surface of sheet metal change the friction behavior has not been investigated. In this paper, the influence of EDT on the friction behavior of aluminum automotive sheet at different contact pressures and sliding speeds is investigated based on both experimental studies and numerical simulations. To fully investigate the tribological behaviors, a flat-on-flat friction test device was built and a numerical code based on mixed lubrication theory was developed. It was found that EDT texturing can reduce the friction coefficient of contacting pair at high contact pressure, however, increase friction coefficient at low contact pressure. Numerical simulations confirmed this finding. Furthermore, the model provides valuable information for the prediction of friction behavior of EDT sheets and helps to optimize processing parameters for various forming processes using EDT aluminum sheets.