Fundamentals of magnetorheological fluid utilization in high precision finishing

Magnetorheological finishing (MRF) is an enabling technology that may produ ce surface accuracy on the order of 30 nm peak to valley (p-v) and surface micro-roughness less than 10 Angstrom rms. In MRF, mechanical energy for ma terial removal over the portion of the workpiece surface is generated by th e magnetically controlled hydrodynamic flow of a magnetorheological polishi ng fluid. A fundamental advantage of MRF over existing technologies is that the polishing tool does not wear, since the recirculated fluid is continuo usly monitored and maintained. Perishing debris and heat are continuously r emoved. The technique requires no dedicated tooling or special setup. A unique attribute of the MRF process is its determinism that is attained t hrough the use of a well-defined material removal function to eliminate kno wn surface error. The efficiency of material removal and the removal process stability are th e crucial factors in MRF. In turn, they are primarily dependent on MR polis hing fluid stability. It is shown that the joint use of physicochemical and rheological factors along with specially developed methods of the slurry h andling, pumping, and in-line monitoring and maintaining provides a level o f MR slurry stability that is quite adequate for high precision finishing. Attention is given to methods of MR slurry property measurements.