Study of the surface quality in multi track to Selective Laser Melting with CoCrMo powders

The layers produced by Selective Laser Melting (SLM) are created when a laser beam interacts with a layer of metallic powder creating melting zones in successive tracks which together form the layer. Any overlapping between these tracks leads to a degree of re-melting of a previous track, thus affecting the overall geometry of the piece. The objective of this experimental work is to evaluate the surface quality of a layer of CoCrMo. The parameters were selected in order to achieve sufficient energy density to create a layer of sufficient length to assess the repeatability of the process. The results reveal that when the energy density is from 89 to 100 J/mm(3), the quality is the best with an overlapping from 10 to 50%. It has been shown that an increase in scanning speed and scanning space causes the appearance of irregularities, such as sharp peaks and valleys on the surface. At the highest energy density (200 J/mm(3)), a surface roughness, Ra, of 23.09 +/- 6.60 m was achieved. This was doubled when the energy density was 25% lower.