Experimental study of electrical discharge-assisted turning for UD CFRP under low voltage condition

Abstract

CFRP (Carbon Fiber Reinforced Plastic) is prone to intensive tool wear due to the influence of carbon fibers contained as reinforcing materials, causing problems such as burrs and deterioration of finished dimensions. With the increased demand for microfabricated products using CFRP in recent years, the need for CFRP machining using lathes has also increased. Within previous investigations, the authors have already proposed Electric Discharge-Assisted Turning (EDAT) as a new processing method that combines atmospheric electrical discharge machining and conventional turning to reduce tool wear and residual fibers and burrs in turning CFRP. It is possible to cut carbon fibers using electrical energy, remove the cut carbon fibers along with the remaining matrix resin, and reduce the abrasive wear of cutting tools caused by carbon fibers. In this study, the authors explored the controllability of carbon fiber cutting depth through electric discharge, focusing on the impact of low voltage settings and widened discharge gaps. Parameters such as electrode material, shape, discharge voltage, frequency, discharge gap, duty ratio, and lathe setup were thoroughly investigated to elucidate their influence on the EDM (Electric Discharge Machining) process. Experiments were conducted using various combinations of feed rates and circumferential speeds. Consequently, the conditions for the discharge depth would be the shallowest, the residual fibers would be the shortest, and tool wear would be the lowest were investigated. Furthermore, the possibility of stable carbon-fiber cutting using an electric discharge at a lower voltage was confirmed. It demonstrated that the EDAT process could suppress the uncut fibers with fine surface quality and reduce the wear on the cutting edge and possibility of practical use of the EDAT under low voltage condition.