Magnetorheological finishing machine and technique based on two-polishing-head

Aiming at some deficiencies of traditional one-polishing-head magnetorheological finishing (MRF) technique, a new two-polishing-head MRF method was studied and a two-polishing-head computer controlled MRF machine with 8 axes was developed . The machine has the ability to produce large aperture flat, asphere and continuous phase plate with high figure accuracy and high material removal rate . Material removal characteristic and figure correction ability for each of large and small polishing heads were studied. Each of two heads individually acquired stable and valid polishing removal function and ultraprecision flat sample . After a single polishing iteration using small polishing head , the figure error peak value(PV) in 45 mm diameter of a 50 mm diameter small plano optics significantly improved from 0.21 to 0.08 (0.053 to 0.015 root-mean-square). After three polishing iterations using large polishing head,the figure error in 410 mm410 mm of a 430 mm430 mm large plano optics significantly improved from 0.40 to 0.10 PV (0.068 to 0.013 RMS). These results show that the two-polishing-head MRF machine has good material removal stability and excellent figure correction capability.