Investigation of the effects of ultrasonic assisted face turning with CO2 cooling on cutting forces, residual stress, and surface quality

Ultrasonic assisted turning (UAT) has emerged in recent years as an advanced machining technique, leveraging high-frequency harmonic vibrations at the tool edge to enhance cutting performance. In this study, ultrasonic assisted face turn (UAFT) was employed to machine steel 1.7225 under various cutting conditions. Experiments were conducted at three spindle speeds, three feed rates, and under two cooling states: dry and cooling using CO₂ gas. All tests were performed in the UAFT mode. Machining forces were recorded using a dynamometer, and surface integrity was assessed through high-resolution imaging using a video measuring machine (VMM). Additionally, the influence of UAFT on the tensile residual stresses was thoroughly investigated. Tensile residual stresses, which can significantly affect the mechanical performance and service life of components, were analyzed as a critical output parameter alongside cutting forces and surface quality. The integration of ultrasonic vibrations with CO₂ cooling demonstrated a notable enhancement in process performance. Results indicated a reduction in cutting force by approximately 28.3 % and a decrease in tensile residual stress by nearly 35 % when using UAFT + CO₂ compared to UAFT + dry conditions. Furthermore, improved surface morphology and more favorable chip formation were observed under UAFT + CO₂ conditions, highlighting the synergistic benefits of combining ultrasonic assistance with CO₂ cooling.