Identification of the process damping coefficient in dry and wet machining of steel

Flank face chamfers are an effective way to suppress vibrations and increase the productivity of milling processes. The underlying process damping mechanism is the so-called indentation effect. The effect describes the process damping as a result of an additional force due to the indentation of workpiece material under the flank face. In literature, this force is commonly modeled by the volume indented under the flank face and a process damping coefficient. To determine the process damping coefficient, various approaches with partly contradictory results exist. In this paper, a novel method to calculate the process damping coefficient based on process forces measurements in orthogonal cutting is applied for steel machining. The method considers ploughing effects of flank face chamfer and cutting edge rounding as well as plastic deformation effects. In the current investigation, the approach is applied to different cooling strategies, chamfer widths, and cutting speeds. The results show that the cutting speed has the most significant influence on the process damping coefficient. With increasing cutting speed, the process damping coefficient increases, which can be attributed to strain rate hardening effects