Polishing Parameters of Magnetorheological Finishing for High-Precision Optical Surfaces

Seven parameters,such as viscosity of magnetorheological(MR) fluid,intensity of magnetic field,flow rate of MR fluid,wheel speed,ribbon height,depth into ribbon and spot,which should be considered and controlled in the process of polishing high-precision optical surfaces with magnetorheological finishing (MRF), are analyzed and optimized. Inherent relationship always exists between material removing and these seven parameters on the condition of single factor. Based on the analysis and optimization of these parameters in MRF process,one flat part(K4,100,mm in diameter)was polished by KDMRF-1000 that we developed before. After two iterations of polishing about 200 min,residual surface error decreased from peak-to-valley(PV)of 262 nm and root-mean-square(RMS)of 49 nm to PV of 55 nm and RMS of 5.7 nm . The convergence of surface error in the experiment illustrates that we can take full advantage of MRF technique and offer reliable insurance for finishing high-precision optical surfaces as long as we master the law for these seven parameters in the process of MRF.