Influence of post-processing and build orientation on the micro-machinability and chip formation during micro-drilling of L-PBF AlSi10Mg

Abstract

The requirement of micro holes or features on the additively manufactured (AM) components attract machinability investigations on Laser Powder Bed Fused (L-PBF) components, and directional anisotropy is one of the critical problems with parts made using L-PBF. As a result, the current study compares the machinability properties during the micro-drilling of several samples, including cast and L-PBF-produced AlSi10Mg. Moreover, the impact of T6 solution heat treatment and build orientation on microstructure, thrust force, cutting torque, surface roughness, and cutting temperature is analyzed. It was found that at a feed of 8 µm/rev and 5000 rpm, the force requirement perpendicular to the build direction (PPBD) was 23.11 % higher than parallel to the build plane direction (PBD). The force required is reduced after heat treatment because of the reduction in hardness. Similarly, a difference of 31.36 % in cutting torque requirement was observed, which increased to 46.82 % after heat treatment. At the same time, the difference in chip temperature in the as-built AlSi10Mg was less between PPBD and PBD. It was also observed that there is a reduction in the chip temperature with feed rate. The chip formation was further studied using a high-speed camera, and four stages of chip formation were identified. From the SEM analysis of the chips, microchips of different lengths and morphology can be identified, which are dissimilar to one another.