THE EFFECT OF ION-IMPLANTATION ON THE LIFETIME OF PUNCHES

The electronics industry demands stamped parts with high performance. Therefore, punching tools like cutting punches with very high precision have to be used. In the case reported, the punches are mounted in a modular system and have to be resharpened or replaced after a certain number of strokes. To increase the lifetime of the punches made of Vasco Wear steel, implantations with carbon, nitrogen, boron and titanium, and co-implantation with titanium and carbon were performed at energies from 50 keV to 200 keV and 600 keV and 700 keV with different doses in the region of several times 10(18) cm-2, measured perpendicular to the ion beam. A maximum increase in lifetime of a factor of 3.6 was reached. The surface roughness had a large influence on the increase in lifetime and the improvement caused by specific ion species. The maximum improvement was obtained for the lowest surface roughness (R(a) = 0.04-mu-m). Therefore, when performing the implants, punches with low surface roughness should be used. The most successful ion species were boron and nitrogen for the lowest surface roughness used (R(a) = 0.04-mu-m), and after changing the polishing procedure (R(a) = 0.14-mu-m) titanium and nitrogen at medium energies (100-200 keV). High energy implantation (700 keV) resulted in an increase of a factor of 2.1 at lower doses (5.6 x 10(17) cm-2), but is uneconomical owing to the low current density. In laboratory wear tests (ball on disk) no improvement by ion implantation could be found. These results prove that it is difficult to compare field tests and laboratory tests because of different testing conditions.