Effects of process parameters and scanning patterns on quality of thin-walled copper flanges manufactured by selective laser melting

Abstract

A thin-walled copper flange was prepared by the selective laser melting (SLM) method (with the average particle size of pure spherical copper powder of about 35 μm and the focal spot diameter of the single-mode fiber laser of 50 μm). The results show that the wall thickness (about 400 μm) of the obtained sample is significantly larger than that (200 μm, namely desired wall thickness) of the model set before the test. In this study, the wall thickness of the model was set as 50 μm and the linear scanning was adopted. On this basis, the influence laws of SLM parameters (laser power, scanning speed and hatch spacing) on forming quality (relative density, surface roughness and wall thickness) of the thin-walled copper flange sample were studied through an orthogonal test. Moreover, two groups of parameters of the sample with good forming quality were obtained. The thin-walled copper sample with the relative density of about 99.8%, wall thickness of about 200 μm and variance of height of rough surface morphologies (reflecting surface roughness) of 29–36 μm was obtained under linear scanning. Compared with SLM under linear scanning, the surface flatness of the sample is obviously improved and the variance of height of rough surface morphologies is reduced to 13–15 μm after SLM under circular scanning. In this way, the capability of SLM in preparing thinner components is significantly enhanced. The analysis shows that the area of a laser-heated region under scanning along the direction of wall thickness of the copper flange (linear scanning) is about 1.196 times that of the desired shape, and the heated region is wavy with several semicircles connected. Therefore, this is unfavorable for ensuring forming quality and dimensional accuracy of the sample prepared by SLM.