Effective polishing of inner surfaces of additive manufactured inserts for polymer extrusion using Plasma Electrolytic Polishing

While additive manufacturing enables fast production of parts with high geometrical complexity, the post-processing step for obtaining high-quality surfaces of these parts is getting increasingly difficult. In addition, not all state-of-the-art polishing techniques are capable of achieving satisfactory results. Moreover, many of them are extremely environmentally unfriendly. In this study it was demonstrated that effective and more environmentally friendly polishing of inner surface of parts additively manufactured from maraging steel 1.2709 powder could be achieved by employing immersion-based plasma electrolytic polishing. In total two parts having different gap size were investigated. After 10 min of polishing the inner surface roughness was reduced from maximum Ra = 6.53 μm to minimum Ra = 0.53 μm.