An alternative model of process damping in milling based on Hertz theory

Process damping is a common phenomenon improving the stability in machining. The main source of process damping is the extrusion between the tool flank and the wavy machined workpiece surface. For most process damping models, the indentation force coefficient needs identification to predict the indentation force, which requires cumbersome experiments or simulation. In this paper, a new process damping model without identification is presented based on the Hertz theory. The indentation force is the function of the depth of contact. The contact boundary is estimated by the cutting-edge geometry and wavy machined surface. The process damping coefficient is related to the cutting parameters, cutting geometry, vibration frequency and amplitude, and the mechanical properties of the workpiece material. The dynamical equation with process damping is solved using the numerical integration method (IM). It is experimentally proved that the stability with the proposed process damping model has better predictive accuracy compared with the classical models.