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The present work investigates the variation of the surface roughness due to the build position of specimens with respect to the inert gas flow direction and re-coater movement direction. Selective laser melting (SLM) method was used to study this effect using Inconel 718 as workpiece material. A total of 21 samples were placed equidistant from each other on the built plate to observe the effect of gas flow and re-coater movement. The effect of these parameters on the printed samples was analyzed in terms of the profile surface roughness parameter such as Ra and Rz in the build direction. The result showed that samples placed near the gas inlet and the re-coater starting position had larger roughness as compared to the samples placed further from the gas inlet and re-coater end position. The result showed that the profile average roughness parameter values varied from Ra = 5.02 µm to 14.7 µm and profile maximum height surface parameter varied from Rz = 47.61 µm to 118.3 µm for all the printed samples. Surface topography of the samples was also studied which showed common printing defects such as cracks, micropores, local solidified melt pools, and dimples. The study opens an avenue to explore and optimize the placement of the printing sample on the build plate with respect to the inlet gas flow and re-coater movement directions for better surface roughness.
GAUTAM et al. (Mon,) studied this question.