Laser polishing parameter optimisation on selective laser sintered parts

Abstract

This paper presents the effect of the laser-polishing process applied to parts built-up by selective laser sintering (SLS). One of the main drawbacks of the SLS technique is the high surface roughness of resulting parts. Therefore, a final polishing process is necessary to be valid for operation conditions. Polishing processes are usually carried out by manual abrasive techniques. In the present paper, a surface polishing method based on laser irradiation is presented to automate the polishing operation. The laser polishing process is based on a surface microscopic layer melting, which re-solidifies under shielding gas protective conditions, resulting on a smoother surface. Laser-polishing tests for lines, horizontal areas, inclined planes and a sample real part were performed, with satisfactory results in all the cases. The experimental tests were carried out on LaserForm ST-100© sintered test parts with an initial roughness of 7.5 to 7.8 μm Ra. Experimental results present final surface roughness below to 1.49 μm Ra, which represent a reduction of the mean roughness over 80%.