Machining chatter is a self-excited vibration occuring between the cutting tool and workpiece. Large amplitude vibrations caused by chatter may lead to damaging the cutting tool and/or the inability to hold part tolerance. It follows that the onset of chatter is a significant limiting factor in material removal rates when machining. To maximize the productivity of the machining process, chatter must be avoided through laborious tuning of the tool stiffness and spindle speed.
A high-speed AMB boring spindle at the Center for Rotating Machinery Dynamics and Control (RoMaDyC) serves as the platform for this research. The μ-synthesis technique has been used to design a robust MIMO controller for magnetic levitation and chatter prevention. Uncertainties are utilized in the cutting force model, maximizing the chatter-free region over the entire running speed of the spindle. The resulting controller is compared to a nominal robust controller designed without the cutting force model. A significant increase in the critical feed-rate before the onset of chatter is found, indicating that the chatter prevention controller enables faster feed rates. This increase can be seen in the comparison of the experimental stability lobe diagrams for each AMB controller.
Student: Alex Pesch
Faculty: Dr. Jerzy T. Sawicki
Cleveland State University
RoMaDyC – Center for Rotating Machinery Dynamics and Control