Chatter vibration suppression effect of variable pitch and variable helix milling cutters

Regenerative self-excited chatter vibrations during metal cutting degrade the machined surface finish, damage the tool, and reduce the machining accuracy. To ensure the quality of machined components, it is essential to suppress chatter vibrations. Many studies have been conducted to determine the conditions that lead to their occurrence. The control of the regenerative loop effectively suppresses regenerative chatter. Variable pitch and variable helix cutters suppress chatter by adjusting the time interval between consecutive cutting teeth. In this study, Stone’s stability theory for variable helix cutters was extended and dimensionless stability charts were derived for both variable pitch and variable helix cutters. The effects of variable pitch and variable helix angles on chatter stability are illustrated using diagrams that visually clarify these effects. Turn milling experiments were conducted using a multi-tasking machine to evaluate the effectiveness of variable pitch and variable helix cutters. The stability characteristics of the variable pitch and variable helix cutters, including increased stability at low speeds and improved stability at specific rotational speeds, agreed reasonably well with the analytical chart.