Smoothening of the down-skin regions of copper components produced via Laser Powder Bed Fusion technology

Additive manufacturing (AM) is revolutionizing the industrial scenario. Four copper samples have been printed via Laser Powder Bed Fusion (LPBF) at DIAM Laboratory (INFN - Sezione di Padova, Padova, Italy). Samples had different geometrical characteristics, to test the feasibility of the AM as a productive technique for the creation of unsupported copper structures that are characterized by surfaces with a very small inclination angle, where supports cannot be placed. Parts have been printed successfully even in case of 18° of inclination of unsupported walls with respect to the horizontal plane, and on the same samples, surface finishing treatments (performed by Rösler Italiana S.r.l. and INFN-LNL) have been performed to reduce the roughness of the down-facing surfaces. Indeed, the down-skin regions are the most critical areas of AM parts. Several surface treatments are under investigation: mass-finishing treatments (mechanical and chemically assisted mechanical processes), chemical polishing and electropolishing, and for some of them, the results are extremely positive: from an initial roughness (Ra) of 30-35 μm, the treatments allowed us to achieve a Ra value lower than 1 μm. The study here exposed presents a good way to rapidly reduce the roughness of 3D-printed parts, reaching a mirror-like aspect.