Analysis of forces in ultrasonically assisted turning

Many modern engineering materials are very difficult to process with conventional machining methods. Ultrasonically assisted turning (UAT) is a new technology, where high frequency vibration (frequency f≈20 kHz, amplitude a≈15 μm) is superimposed on the movement of the cutting tool. Compared to conventional turning (CT), UAT allows significant improvements in processing many intractable materials, such as high-strength aerospace alloys and composites, by producing a noticeable decrease in cutting forces and a superior surface finish. Vibro-impact interaction between the tool and workpiece in UAT during the chip formation leads to a dynamically changing cutting force in the process zone as compared to the quasistatic one in CT. The paper presents an experimental study and computational (finite-element) model of both CT and UAT. Forces acting on the cutting tool in UAT are studied, and their dependence on vibration amplitude, frequency and vibration direction as well as on cutting parameters, such as feed rate and cutting speed, are investigated.