Preparation and processing performance of high steady-state magnetorheological finishing fluid

Magnetorheological finishing fluid (MRFF), as the transfer medium of magnetorheological finishing, is mainly composed of magnetic particles, base carrier fluid, abrasives and additives, etc. The MRFF with stable performance and good polishing effect is an important factor to achieve magnetorheological deterministic finishing. The magnetic particles with low bulk density are stably suspended in the MRFF, while the micro-structure on the outer surface of the magnetic particles can enhance the holding strength of the magnetic chain bundles on the abrasives in magnetorheological finishing. Highly stable MRFF was prepared by combining solvothermal and calcination reactions to produce flower-like Fe₃O₄ as magnetic particles, and its settling stability and polishing performance were tested. The stability test results showed that the settling ratio of 64.2% for the flower-like-Fe₃O₄ MRFF was better than that of 14.2% for the spherical Fe₃O₄. Compared with the spherical-Fe₃O₄ magnetic chain bundles, the COMSOL Multiphysics finite element simulation results showed that the magnetic chain bundles composed of flower-like Fe₃O₄ had a stronger holding force under the magnetic field and a 10.37% increase in shear force during the polishing process. The processing results showed that the polishing depth of flower-like Fe₃O₄ polishing increased with the gradual reduction of polishing gap, and the polishing with flower-like-Fe₃O₄ MRFF could obtain deeper material removal depth compared with spherical-Fe₃O₄ MRFF, and the maximum removal depth increased by 41.5% under the same conditions.