Abstract: A polishing method that uses an auxiliary magnetic field is proposed, in which magnetic polymer microspheres/SiO2 composite abrasives are anchored on a smooth glass tool plate by the magnetic force, and the dependence between diameter of composite abrasive and morphology of tool plate is reduced. The auxiliary magnetic field is established by NdFeB permanent magnets with 8 mm diameter and different heights. The finite element method (FEM) analysis shows that the magnetic field with a concave-down columnar section has a uniform distribution of the force of magnetic field HdH/dz. Force analyses on magnetic polymer microspheres indicate that the magnetic force could help the magnetic polymer microspheres enter the polishing area from near-polishing area, and material is polished by magnetic composite abrasives in two-body abrasion wear mechanism. Experiments of polishing silica wafer, using a glass tool plate of Ra 0.5 μm surface roughness, have shown the superior characteristics with the assistance of the magnetic field. The material removal rate is increased from 66 nm/min to 179 nm/min，and the surface roughness of wafer is decreased from Ra 405.860 nm to Ra 0.490 nm.

Key words: Auxiliary magnetic field, Chemical mechanical polishing, Magnetic composite abrasives, Slurry