Electropolishing of surfaces in metallic parts obtained by Additive Manufacturing

In this paper a study of the process of Electropolishing (EP) to be applied to metallic parts obtained by Additive Manufacturing is presented. The roughness of parts obtained by Additive Manufacturing is not acceptable in many applications and consequently they require a postprocessing stage to improve the surface roughness of these parts. If the material hardness is very high, like in Stainless Steels, the process of mechanical grinding is not suitable, since there is an important wear in the tool and residual stresses can be generated in the part. EP is a process in which the roughness required is obtained without tool-part contact. The conditions for this process in 17-4PH and 316 Stainless Steel parts with a Tungsten or Lead electrode are worked out in order to achieve a fast and effective smoothing process. DC voltage and an electrolyte of H3PO4 and H2SO4 are used between the tool, which acts as the cathode, and the part, which is the anode. A micropositioning system is used to set the interelectrode gap to the optimum value. Decrease in roughness Ra from 12 m to values about 3 m with this process was achieved.