Suitability of Pristine Carbon Nanotube Yarn Tool for Material Removal by Electrical Discharges

High-intensity electrical discharges are used in the unconventional technique known as electrical discharge machining (EDM) to machine metals of any hardness. Due to their extraordinary conductivity and strength, carbon nanotubes (CNTs) have recently been explored in EDM too. However, material removal with CNT yarn (CNTY) has not been studied thoroughly. This work advocates the use of a pristine CNTY as an EDM tool. The feasibility is examined through characterization and material removal experiments. The measurements show that the CNTY (< 100 µm in diameter) has an electrical conductivity and current carrying capacity of 2.66 × 10⁴ S/m and 1.76 × 10³ A/cm², respectively. Steel and aluminum are the workpieces for machining experiments conducted in air and hydrocarbon oil dielectrics, respectively. Significant material removal and extended tool life are obtained in the air dielectric. It is suggested that the oxidation of steel increases material removal in the air while reducing tool life. The effect of tool thickness is also investigated. Thicker (> 100 µm) multi-ply tools extend tool life and, therefore, machining time by more than 14 s in the air and nearly 2.5 s in the oil. Other factors that restrict machining include intensified discharges and the shielding effect of the carbide layer formed on the workpiece.