Novel magnetic field array optimization method for the chemical magnetorheological finishing of Ti-6Al-4V alloy with SiO2 abrasive and Fe3O4 magnetic particles.

The Ti-6Al-4V alloy is an important material used in many high-end devices, such as medical, aerospace, petrochemical, and sports equipment. Thus, the feasibility of producing Ti-6Al-4V with mirror surface quality through magnetic polishing was assessed in this study. One of the extremely challenging aspects of magnetic polishing for Ti-6Al-4V alloys is the generation of a magnetic field suitable for surface-quality finishing. Moreover, machined material residue cannot be completely removed, the alloy has limited application, and uniform surface quality on a large workpiece surface cannot be achieved because generating strong and suitable magnetic field is currently infeasible. To create a polishing process with a highly efficient magnetic field source for improving material removal rate and surface quality, a linear variable magnetic field array was proposed by Halbach. Finite element simulation processes combined with experimental validation provide an efficient polishing model with high field area and intensity generated by an improved Halbach magnet array. The magnetic force generated by the improved Halbach array and the force distribution process on the Fe3O4 magnetic particle were analyzed. Thus, material removal and the distribution and pressure of abrasive SiO2 particles acting on the polished surface were examined. The influences of technological factors on surface quality and material removal ability were systematically studied. The proposed chemical–magnetorheological finishing model showed a considerably increased magnetic field generation compared with the previous model (1.7 times that of the conventional Halbach array), thereby efficiently removing materials. Polishing models established for Ti-6Al-4V alloy markedly improved surface quality after 80 min of treatment, and an ultrafine workpiece surface showed an Ra of 1 nm, which had an initial roughness of approximately 500 nm. [ABSTRACT FROM AUTHOR]