Improved Tribological Properties of Blanking Punches for Copper Alloys Utilizing Deterministic Surface Texturing by Machine Hammer Peening

Constant efforts to increase resource efficiency, productivity, and output quantities, as well as growing product requirements, result in high tribological loads on forming tools. The manipulation of the tribological properties of blanking punches by deterministic texturing using machine hammer peening on the lateral surface is a solution to ensure an extended service life. For this purpose, rotationally symmetrical blanking punches were textured using a specially developed texturing center. The machine hammer peening center allows surface texturing with positioning accuracies of less than 2% for individual indentations by controlling a rotary and feed axis in combination with frequency control of the machine hammer peening setup. A modified hammer head with a micro-tip was used as the texturing tool. Different coverage ratios with the same aspect ratio were applied to the surface. These punches were then tested on an industrial high-speed press. To evaluate the effectiveness, the force curves were analyzed and the evolution of the textured topography was continuously evaluated. The experiments showed that the withdrawal force could be reduced by 38% due to microtexturing with a coverage ratio of 18%. Other coverage ratios resulted in an increase. By texturing the lateral surfaces of blanking punches using machine hammer peening, the service life was also significantly improved.