Improved dynamic cutting force model with complex coefficients at orthogonal turning

Self-excited vibration (chatter) is determined by the relation between the vibrating system and the cutting process. In current theories, the dynamic cutting force model in a form suggested by Tlusty and Polacek in the 1950s is still used. However, this model oversimplifies the dynamic cutting process by trying to express all processes using a single cutting force coefficient. Measurement results presented in this article clearly show that such simplification of the cutting process is unacceptable. This work follows upon the original measurement method by Tlusty and Polacek using controlled tool vibration. The method was intended to research the cutting process dynamics. However, the original Tlusty and Polacek method ignored the impact of the length of the workpiece surface wave. The original method is innovatively developed by taking into account the impact of the chatter frequency. The new method allows to better understand the processes occurring during dynamic cutting. As opposed to the original method, current advanced measurement equipment allows for more precise examination of the cutting process in dependence on the chatter frequency. The article shows that results obtained by the new method can be utilized for modeling the cutting force with greater precision in order to better predict the cutting process stability.