Pre-selection of laser-processed materials for dry forming tools by means of a dry oscillating ball-on-disc test

Abstract

The aim of this paper was to characterize different classes of materials, light metals, steels, cobalt–chromium-based and ceramic materials under tribological stress and to determine the reproducibility of the measurement results by monitoring the production, processing and analysis of the test materials. The results were used to ensure pre-selection of materials for use in the dry forming process. To depict real conditions at the edges of a forming process surface pressures of 10–200 N/mm² need to be adjusted. For this purpose, the friction and wear properties were determined in a dry ball-on-disc test. The functional surfaces were produced by laser-cladding, selective laser melting, chemical vapor deposition (CVD) and laser hardening. The tested and selected classes of materials were steel (42CrMo₄, X110CrMoVAl 8-2), light metals (aluminum 6082, C95300 aluminum-bronze), cobalt–chromium alloys (Stellite 12, Stellite 21), ceramic (S₃N₄) and polycrystalline CVD diamond. The test setup of the dry ball-on-disc test included 10 N contact force, 10 mm traversing distance, 10 mm/s average speed, 40 % humidity and 24 °C ambient temperature. The resulting wear map includes five orders of magnitude of different wear rates and one order of magnitude of different coefficient of friction. An eligibility number is introduced for a better differentiation of the combined properties of the tribosystem of a tool material.