Movement of powder bed material during the selective laser sintering of bisphenol-A polycarbonate

Purpose The purpose of this paper is to report on a study of the movement of the powder bed material during selective laser sintering (SLS) of bisphenol-A polycarbonate (PC) powder and its effect on the morphology of the sintered specimen. Design/methodology/approach Two sintering experiments, i.e. single-spot laser sintering and raster-scan laser sintering, were carried out and the material movement mechanisms were investigated in situ and subsequently by scanning electron microscopy. Findings During the raster-scan laser sintering process, the movement of the powder was found to be primarily perpendicular to the scanning direction. When sintering at a high laser power, it significantly affected the surface morphology of the sintered specimens and parallel surface bands occurred along the scanning direction. Research limitations/implications Experiments were carried out on a modified laser engraving machine rather than a commercial SLS machine. Practical implications A schematic model of the material movement mechanism for each of the sintering strategies is presented. Originality/value The results further the understanding of the sintering behaviour of the powder bed.