Research on material removal model and processing parameters of cluster magnetorheological finishing with dynamic magnetic fields

Abstract

Based on fluid mechanics and Preston equation, the influences of various technological parameters (including rotational speeds of workpieces, magnetic poles, and polishing disk and the machining gap) on polishing pressure on workpiece surfaces were investigated. On this basis, a material removal rate (MRR) model of cluster magnetorheological finishing (CMRF) with dynamic magnetic fields was established. Moreover, three pieces of single-crystal silicon substrates were subjected to synchronous polishing on the CMRF devices with dynamic magnetic fields in order to analyze the influence of different technological parameters on the MRR. It is showed that the theoretical simulation results favorably agree with the experimental results. The single-crystal silicon substrates with the initial surface roughness (Ra) of 0.48 μm were polished for 5 h on the optimal technological conditions: the machining gap and the eccentricity of magnetic poles are 0.9 mm and 6 mm, respectively; the workpieces are oscillated in Y direction for 40 mm at the oscillation speed of 600 mm/min; the rotational speeds of the polishing disk, magnetic poles, and workpieces are 50 r/min, 90 r/min, and 350 r/min, respectively. In this way, the super-smooth uniform surfaces with the roughness of Ra 2.4 nm were acquired.