Active Damping of Boring Bar Vibration With a Magnetic Actuator

Boring bars with a large length-to-diameter ratio chatter under productive cutting conditions, which leads to poor surface finish and violation of part tolerances. This paper presents an active damping method of boring bars with an in-house designed magnetic actuator. The actuator has been designed to have a linear force output relative to the input current, and instrumented to control boring bar vibrations. Four different H_∞ optimal controllers are designed to shape the boring bar dynamics and improve the chatter stability. The proposed active damping method is experimentally tested on a CNC lathe. The dynamic stiffness of the boring bar is increased considerably, leading to a significant increase in the chatter-free material removal rates.