On the improvement of process performance of hard turning using vibration-assisted machining

In hard turning, the cutting forces are large, which leads to tool wear and tensile nature of residual stresses. Vibration-assisted machining (VAM), where the tool is provided with a low amplitude vibration at significantly high frequency, might improve the process performance of hard turning in terms of cutting forces, residual stress, etc., as VAM helps in reduction of cutting forces and tool wear significantly. To improve the machining operation, a comparative study of VAM with conventional machining is undertaken to study and improve the hard turning performance. A two-dimensional (2D) finite element (FE) model is developed to understand the effect of process parameters better and to study the effect on machining performance by applying one-dimensional ultrasonic vibration to the tool. The model developed is validated with results from a previous work for continuous hard turning conditions. The effect of vibrations induced in cutting velocity direction is studied on the cutting forces and residual stresses induced on the machined workpiece. The ratio of cutting velocity to critical vibrating velocity is an important process parameter that affects the average cutting forces during hard turning using VAM. The nature of cutting force and temperature for a complete cycle of vibration is also studied. The simulation results establish that hard turning using VAM yields lower average cutting forces and more compressive residual stresses in comparison to conventional hard turning.