Process Effect on Part Surface Roughness in Powder-Bed Electron Beam Additive Manufacturing

Surface roughness is an inherent attribute of parts fabricated by Powder-Bed Electron Beam Additive Manufacturing (PB-EBAM) process. The wide application of PB-EBAM technology is affected by the part surface quality and therefore needs to be studied and optimized so as to establish PB-EBAM process among other manufacturing processes. Therefore, in this study, the build surface of fabricated parts built with different speed function (SF) is analyzed using white light interferometry. The results show that, in general the build surface roughness along the beam moving direction slightly increases with the scanning speed. On the other hand, the hatch spacing noticeably affects the surface roughness in the transverse direction. The experimentally acquired average surface roughness increased with increasing speed function from about 3 μm for SF20 case to 11 μm for SF65 case. In addition, a 3D VOF model has been attempted to predict the surface formation during the PB-EBAM process. Thus simulated SF36 case was able to predict different surface features and was in good agreement with experiment which shows that surface roughness analysis with numerical model may be a possible approach.