Investigation on the milling of support structures produced by laser-based powder bed fusion

Abstract In laser-based powder bed fusion (PBF-LB), support structures are often necessary to ensure the dimensional accuracy of components. However, these supports are not part of the final product and must be removed after the additive manufacturing process. This is done through subtractive post-processing. This study investigates the milling-based removal of Rod and Wall support structures made from AlSi10Mg. The analysis focuses on the removal mechanisms, resulting chips, forces, and surface topography of the workpiece. The results reveal that the geometry of the support structures plays a crucial role in their removability. The Rods were significantly deformed or even broken off during milling. This was not observed in the Wall supports. Milling the Walls resulted in a more stable cutting process in comparison to the Rods. However, highly fluctuating forces and significant vibrations were observed during the milling of both Rod and Wall supports. These vibrations are caused by the low stiffness of the supports and by the discontinuous tooth engagement due to the geometry of the support structures. The vibrations can be reduced by using suitable cutting conditions. Up milling in combination with low feeds per tooth has considerably decreased vibrations. Low-stiffness structures such as Rods require carefully selected cutting conditions to minimize deformation and prevent the supports from breaking, which can compromise the surface quality.