Active damping of milling chatter vibration via a novel spindle system with an integrated electromagnetic actuator

Self-excited vibration, widely referred to as chatter, has always been a limitation and challenge in machining. To suppress milling chatter vibration and improve surface finishes, a novel spindle system is proposed in this study. A noncontact electromagnetic actuator with two degrees of freedom is developed and integrated into the designed spindle system compactly. A differential driving mode is utilized for the electromagnetic actuator to obtain a linear output of actuator force, making the actuator more applicable for vibration control. Displacement sensors mounted near the actuator measure the vibration of the rotating spindle shaft and provide feedback signals for the developed proportional-derivative controller. The active damping performance of the designed spindle system with an integrated electromagnetic actuator, in both x and y directions, is also validated with impact tests and milling experiments, and a maximum increase (by factors of 3.67 and 2.89 in x and y directions, respectively) of dynamic stiffness at the first modal frequency is obtained. Milling experiment results with and without active damping also illustrate that milling chatter vibration has been well damped actively with the developed spindle system.