Improving the wear resistance of metal forming tools by ion implantation

A facility for wear tests under simulated production conditions was installed. These tests permit variations in essential parameters of the forming processes 'backward can extrusion' and 'upsetting between flat parallel dies', which were investigated in this work. For measuring sufficient wear, 10 000 to 20 000 workpieces had to be pressed. To reduce the time, in some cases a short-time testing procedure based on a radionuclide technique was used. In this, thin surface layer of the tool was activated by deuteron irradiation. During the wear process the activity of the tool decreased because of loss of material. This enabled the determination of wear after only 2000-3000 manufactured workpieces. By applying nitrogen-ion-implanted tools, wear decreased down to the level of conventionally nitrided tools. The great advantage of the former process is the low temperature of treatment; so the roughness and structure of the material are not affected and tools can be machined to their final dimensions before ion implantation. The results of nitrogen implantation are compared with those of nitrogen plus silver ion implantation and nitrogen plus tin ion implantation. A comparison of the two forming processes, different tool materials and various surface treatments should contribute to economic application of optimized wear-resistant tools in bulk metal forming processes. (orig.)