Determination of the removal function is an important step in magnetorheological finishing (MRF) of optical materials. However, the removal function is difficult to determine if a spot sample of the same material as that needing polish is unavailable, thus preventing establishment of an MRF process plan. A method to resolve this issue is proposed, wherein an MRF process plan for an item of a differing optical material is migrated. The theoretical basis for migration is investigated, and simulations reveal that narrow nonlinear regions of the source and target materials’ removal functions are a necessary condition for adequate convergence rate. The proposed method is experimentally verified by finishing a ZnS part with the process plan of a BK7 optical part of the same geometry, with a convergence rate of 45.7% after four iterations.

In magnetorheological finishing (MRF), predicting the size of a removal function plays an important role in determining the efficiency of optical material removal. The size of the removal function can be adjusted for different immersion depths of optical parts into the MRF ribbon, which enables the development of multiple MRF-processing algorithms: dwell-time calculation, path planning, or dynamic control of MRF instruments. However, few methods for such algorithms have been developed to dynamically approximate the size of removal functions with respect to various immersion depths. Thus, the ability to dynamically approximate the size of the MRF removal function is indeed of significance. A dynamic approximation method is designed after analyzing the generation mechanism of removal function and its size; establishing the equations for size, which are further numerically analyzed and simplified for common MRF configurations; and approximating the length and width of removal function dynamically. The approximation accuracy is verified through experimental tests where UBK7 optical parts are polished on a PKC1000-Q2 MRF installation. It is revealed that the approximation errors for the length and width are less than 6% and 8%, respectively.