Influence of Process Damping on the Regenerative Instability of Guided Metal Circular Sawing

Circular saws are thin and hence they vibrate during cutting. Vibrations get imprinted on the side walls of the part being cut, with each tooth leaving its own imprint. When there is a phase shift of vibrations between two successive teeth, regenerative instabilities can occur. However, since the flank face of the tooth also rubs the vibration marks on the side wall, there can also be process-induced damping. Such damping is known to improve the stability of low speed cutting processes. Since metal circular sawing is a low-speed process, it is the aim of this paper to characterize the role of process damping, if any, on regenerative instabilities using an analytical model. The saw is modelled as an annular disc constrained by springs representing guides. The Muller method with deflation is used to solve the governing equations of motion. Model-based analysis suggests that process damping indeed plays a stabilizing role.