Analysis and optimisation of vertical surface roughness in micro selective laser melting

Surface roughness is a major disadvantage of many additive manufacturing technologies like selective laser melting (SLM) compared to established processes like milling or drilling. With recent advancements the resolution of the SLM process could be increased to layer heights of less than 10 mu m leading to a new process called micro selective laser melting (mu SLM). The purpose of this paper is to analyze the influence of the mu SLM process parameters and exposure strategies on the morphology of vertical surfaces. Contour scanning using varying process parameters was used to increase the surface quality. It is shown that it is possible to achieve average surface roughness of less than 1.7 mu m using low scan speeds compared to 8-10 mu m without contour scanning. Furthermore it is shown that a contour exposure prior to the core exposure leads to surface defects and thus increased roughness.