The effect of overhang and recoater angles on the quality of laser powder bed fusion produced parts with contactless supports

This experimental study focuses on the effect of overhang and recoater angles on the surface roughness of overhang specimens produced by laser powder bed fusion (LPBF) process from CoCr material and by using contactless support structures. The inclination of overhang surface with respect to build platform and the orientation of the specimens with respect to recoater direction were selected as design inputs and the average and the maximum surface roughness of overhang surfaces were selected as design outputs. Experimental studies revealed that decreasing overhang angle increased the surface roughness. 90-degree orientation of the part with respect to recoater direction resulted in minimum average surface roughness. It was also observed that contactless support didn’t give enough structural strength to 20-degree overhang surface which failed to be manufactured. Thermomechanical modelling-based process simulations were also performed, and very good correlation was found between numerical and experimental results. It was shown that thermomechanical modelling is very useful to be performed before LPBF process to mitigate recoater jam risks.