Consecutive sub-sector scan mode with adjustable scan lengths for selective laser melting technology

In an effort to optimize the manufacture of near fully dense metal parts, we have developed a sub-sector scan mode for selective laser melting (SLM) technology. The working process of such a scan mode is realized by the way that the contour polygons of a three-dimensional (3D) metal part obtained by slicing layer by layer are enclosed in a small quadrangle box, specifically an encasing box, and sub-boxes (sub-sectors) in square are then divided by the enclosed quadrangle box with short scan lengths on each side. Then these sub-sectors are hatched with bidirectional scanning lines which are normal with right-angles in adjacent sectors. The algorithm is presented in this paper. In the SLM processes, this scan pattern helps to increase the temperature in small sub-sectors and melt metal powder more effectively. Parts with complex structures from stainless steel 316 L were manufactured with this new scan mode.