Comparative study on near-dry wire-cut electrical discharge machining process using moistened wire

In high-speed reciprocating wire electrical discharge machine, the dry process can solve the problem of disturbance of flushing to the electrode wire that existed in conventional top and bottom flushing process. However, the surface of the processed part is prone to be burned. A novel dielectric fluid feeding method (moistened wire method) with near-dry process was proposed to improve processing quality. Firstly, the dielectric fluid was poured onto the drum, then the dielectric fluid was packed into the discharge gap by the moistened high-speed running molybdenum wire to form a gas-liquid double-layer dielectric for discharge machining, cooling and cleaning the working material. On this basis, the SiC nanofluids were added in the dielectric fluid to further improve processing quality. The effects of the conventional top and bottom flushing with emulsion, the dry with atmospheric, the moistened wire with emulsion and the moistened wire with emulsion-SiC nanofluids during the finishing process on the kerf width, average cutting speed, surface roughness, surface morphology, and corner accuracy of the Cr12MoV die steel was studied. Compared to the conventional top and bottom flushing process, the processing quality was obviously enhanced by the moistened wire processes, and the Ra values machined by moistened wire with emulsion and emulsion-SiC nanofluid processes were decreased by 39.8% and 45.8%, the inner circle radius was decreased by 4.1% and 4.9%, and outer circle radius was decreased by 3.4% and 10.3%, respectively. Meanwhile, the high cutting speeds were maintained. Compared with the moistened wires with emulsion process, the moistened wires with emulsion-SiC nanofluid process further improved processing quality with lower surface roughness and corner error. The moistened wire process improved the processing quality without sacrificing the cutting speed due to their moderate discharge gaps.