Finite Element Analysis of Electromagnetic Field of Superconductive-Assisted Machining (SUAM) Using Superconducting Tapes and Halbach Array Permanent Magnets

A magnetic-levitation tool using a superconductor (Superconducting Assisted Machining: SUAM) is a promising technology that enables noncontact finishing of hollow or complex-shaped structures by exploiting flux pinning. However, conventional SUAM has faced the issue of insufficient repulsive force required for polishing. To address this, we replaced the conventional ring-shaped arrangement of permanent magnets with a Halbach array to enhance the repulsive force. In finite element method (FEM) analysis, we computed the repulsive force for a ring-shaped one-sided 4-pole magnet with a surface field of 450 mT (Ring-model) and for a Halbach array (Halbach-model) composed of five bar magnets with the same 450 mT surface field, and found that the Halbach-model yielded a larger repulsive force than the Ring-model. In experiments, we measured the repulsive force using a 450 mT ring magnet and a 391 mT Halbach array and obtained comparable forces despite the different surface flux densities. FEM under the same conditions exhibited the same trend. These results indicate that optimizing the magnet arrangement is effective for improving SUAM performance and that FEM, even when limited in reproducing absolute values, is useful for comparing arrays and extracting design guidelines.