Neda Mohammadian, Master Student, Polytechnique de Montreal
Sylvain Turenne PhD, Professor, Ecole Polytechnique de Montreal
Little is understood about how to improve the interior surface quality of complex parts produced by the additive manufacturing techniques. Two surface-related problems can be highlighted: 1. The presence of semi-welded particles and 2. A significant surface roughness and texture. Semi-welded particles could cause pollution in the fluid system of an engine part, whereas a significant surface roughness and texture could compromise fluid flow. This study was to design, manufacture and validate an innovative finishing technique combining chemical and abrasive flow polishing of interior surfaces of tubular IN625 parts designed for aerospace industry. The synergetic effect stemmed from the combined use of chemical and abrasive flow action were investigated by studying four polishing techniques: static chemical polishing, abrasive flow polishing, chemical flow polishing, and combined chemical-abrasive flow polishing. Considering the complexity of additively-manufactured parts, the effect of SLM build orientation on internal surface finish was also characterized. Roughness and three-dimensional topography of the polished surface of IN625 parts for four SLM building orientations were assessed using profilometry and optical interferometry. The results indicate by employing the combined chemical-abrasive polishing, semi-welded particles on the interior surfaces of IN625 components can be completely removed and the surface roughness and texture significantly improved.