Investigating the machinability of 34CrNiMo6 steel in hybrid ultrasonic-plasma assisted turning

This study examines the synergistic effects of plasma-assisted heating and ultrasonic vibration on the hard turning of 34CrNiMo6 steel, aiming to minimize tool flank wear. While cubic boron nitride (CBN) and tungsten carbide tools were evaluated, CBN demonstrated superior wear resistance, with statistical analysis confirming that the tool material was the most significant factor influencing wear. A hybrid machining approach was developed, integrating a plasma system for localized workpiece softening and ultrasonic vibration to reduce cutting forces through intermittent tool-workpiece contact. Using Taguchi-designed experiments, the optimal parameters for minimal flank wear were identified: CBN tools operating at reduced cutting conditions (0.50 mm depth of cut, 0.08 mm/rev feed, 40 m/min speed) combined with controlled plasma current (25 A) and maximum vibration amplitude (10 µm). Results revealed a dual-phase plasma current effect, initial force reduction followed by thermal wear at excessive current, and demonstrated that vibration amplitude significantly lowers wear.