High-Quality Surface Finishing of Industrial Three-Dimensional Metal Additive Manufacturing Using Electrochemical Polishing

Three-dimensional (3D) additive manufacturing technologies are useful for building various and complicated shapes. Representative technologies include laser metal deposition and selective laser sintering that make metal powders melt in order to form diverse 3D structures. Although numerous well-known advantages of 3D additive manufacturing, they still have some difficulties in surface quality improvement for further applications such as food or biomedical industries because they cause rough surfaces, discoloration, unmelted particles by repeated instant dissolution and solidification of metal particles. This paper introduces an electrochemical polishing (or electropolishing, ECP) process as a possible finishing process for 3D printed parts. Conventional finishing processes including mechanical finishing can hardly polish 3D curved surface readily. In ECP, the tool electrode and the work sample are not in contact with each other. All electrically connected surface exposed to electrolyte are subject to be polished. The printed product performs in a current density region higher than the conventional current density, thereby activating the electrochemical reaction and promoting the dissolution of the metal surface, thereby smoothly polishing a very rough surface. Surface quality including roughness, splashed particle spots, smoothness, brightness, light reflection and corrosion resistance were improved by ECP. Experimental results were analyzed by scanning electron microscopy, optical and detailed atomic force microscopy images according to various ECP electrical conditions.