Effect of processing parameters on dimensional accuracy and bending strength of graphite flake/phenolic resin powder mixture in SLS process

Abstract

Graphite flake/phenolic resin powder mixture had been prepared via selective laser sintering process. A dimensional analysis involving radial and axial deviation was performed, and the effect of SLS process parameters (laser power, scan spacing, scan speed, layer thickness) in both radial and axial directions were investigated. Laser power is found to be the most significant process variable in radial dimensional accuracy, while in axial direction layer thickness and laser power are the most significant process variable by range analysis based on orthogonal experiment. The optimum combination of parameters in graphite flake/phenolic resin powders mixture SLS process for high dimensional accuracy in radial direction was laser power, scan speed, scan spacing, and layer thickness of 20 W, 1500 m/s, 0.1 mm, and 0.1 mm, respectively, while the optimum combination of parameters in axial direction was laser power, scan speed, scan spacing, and layer thickness of 20 W, 2000 mm/s, 0.1 mm, and 0.15 mm, respectively. Energy density was introduced to better incorporate the processing parameters with dimensional accuracy and mechanical properties, and both dimensional accuracy and bending strength were analyzed under varying energy density and layer thickness, and results showed that in the range of energy density of 0.075–0.15 J/mm2, layer thickness of 0.1–0.2 mm, a graphite flake/phenolic resin laser sintered part with appropriate bending strength and dimensional accuracy could be prepared.