Friction and wear behaviour of rapid prototype parts by direct metal laser sintering

Abstract

Rapid prototyping and manufacturing (RP/M) is one of the proven tools for product development owing to its advantages such as short product cycle, high quality product and possibility of fabricating functionally gradient materials. Several RP/M techniques do exist. Among them, direct metal laser sintering (DMLS) method is quite popular as near net shape components with high dimensional accuracies can be manufactured. Meager information is available as regards the tribological behaviour of laser built parts, although this is vital in judging the suitability of built-up parts for applications where sliding is inevitable. In the light of the above, the present investigation is aimed at building parts by DMLS technique of RP/M using 50 μm iron powder and characterising its density, microstructure, microhardness, tensile strength, friction and wear behaviour under sliding conditions. The effect of laser speed on the above properties of built-up parts has been studied. The build layer thickness was maintained at 50 μm. Laser diameter of 0˙4 mm, laser power of 180 W and hatch spacing of 0˙2 mm were adopted. However, the laser speed was varied from 50 to 125 mm s^–1 in steps of 25 mm s^–1. Laser speed had a profound influence on density, microstructure, microhardness, tensile strength, friction and wear behaviour of built-up parts. Lesser laser speed resulted in higher density, microhardness, tensile strength and wear resistance while higher laser speed promoted lowering of coefficient of friction.