Applicability of Blasted Blanks for Adaption of Tribological Conditions in Sheet-bulk Metal Forming

Manufacturing by sheet-bulk metal forming (SBMF) leads to varying stress and strain states that significantly influence the geometrical component accuracy. To improve the product quality, control of the material flow is needed. A suitable approach is given by adapting the surface properties of tool and/or workpiece and the associated tribological conditions. The study investigates blasted blanks as a method to achieve suitable frictional behavior. The influence of different grit sizes and pressures during abrasive blasting on the surface integrity was analyzed. Based on these results, the tribological behavior of the blasted blanks was evaluated using a pin extrusion test. Finally, functional cause-effect relationships to identify the mechanism of blasted blanks regarding a control of the material flow during SBMF processes were derived. The results revealed that a pressure increase and growing grit sizes lead to an enhanced material removal rate during blasting and thus a roughening of the surface. The strengthening increases with increasing blasting pressures and grit size. The surface integrity significantly influences the frictional behavior and thus the material flow. Thus, blasted blanks with rough surfaces and a high strengthening in the near surface area positively affect the material flow what improves the process results of SBMF processes.