Integrated design optimization of a motorized active magnetic bearing spindle for micro-milling applications

Contact or air bearings are commonly used in micro-milling spindles. However, active magnetic bearing (AMB) enables high-speed and contact-free rotation with active control of spindle dynamics. Many studies focus on either AMB or motor only and therefore lack a thorough consideration of mutual influence of both elements on spindle performance. In contrast, our approach integrated these elements in a design optimization framework. This framework was built upon a comprehensive set of numerically-corrected multiphysical analytical models considering the electromagnetic, rotordynamic, and mechanical performance of spindle. Using a multi-objective optimization algorithm, a Pareto front was developed allowing designers to choose from alternative optimal spindle dimensions depending on the specific application requirements. We further suggested design modifications accounting for the often-neglected coupling between the fields of motor and AMB by constructing a 3D finite element model. The presented design framework should allow for novel miniaturized AMB spindle designs based on multiphysical modeling capabilities.