An analytical elastic-plastic contact model for process damping prediction in milling

Process damping is mainly caused by the dynamic extrusion between the flank face of the tool and the wavy machined surface of workpiece. An accurate description of process damping is critical for predicting stability and optimizing chatter-free cutting parameters. Existing process damping models neglect the extrusion deformation state in the indentation force calculation, and thus cannot reveal the dynamic deformation behavior of the extrusion. This paper presents a general analytical process damping model based on the elastic-plastic contact deformation. The proposed model analyzes three stages of contact deformation, i.e. the elastic regime, mixed elastic-plastic regime, and fully plastic regime, and calculates the indentation force separately for each stage, which avoids additional coefficient identification. Then, the equivalent viscous damping is derived from energy balance to linearize the indentation force and predict stability. The new model is validated by scratching tests and milling experiments, which can predict stability accurately and replace the traditional model.