A novel string-bead EDM mechanism for dressing of the conformal cooling channel fabricated by the SLM-additive manufacture

Abstract

Abstract The conformal cooling channel (CCC) fabricated by the SLM method is a unique technology contributed to plastic molds by additive manufacture technology (AM). This paper proposes a novel electrical discharge machining (EDM) mechanism to trim the surface of the inner channel made of the selective laser melting (SLM -AM) and assembles a new string-bead tool, a guide-wheel set, a wire tension adjustment mechanism, and innovative electrode design. The experiments verify the EDM machinability and stability of the driving mechanism in the channel and investigate the feasible EDM parameters. As a result, this method can completely dress a 30mm straight channel with a diameter expansion of about 10%. This mechanism effectively trims the contour into a flat and even smooth tube and the taper to 38/30000, from the entrance to the exit. After EDM dressing, the surface roughness is reduced from the original 15-26 μm to 5.9 μm Ra. But some sort of bamboo-nuts overcutting occurred around the apex, due to the string tension and stumbling of tool electrode motion.