The research work reported in this paper is focused on the use of magnetic fluids as active elements in seals for improving sealing capacity and minimizing friction torque, with application to the spindles of high precision machine tools. The prototype design was optimized following numerical computation of the magnetic field in the rings of the seal. Two magnetic fluids were analysed for their use in the seals: a ferrofluid and magnetorheological fluid. The sealing capacity of the MRF based seals was higher than 45kPa per ring, but the friction of the seal in the bearing was 8 N•m, too large for the use in precision spindles of machine tools. The ferrofluid seal achieved sealing capacity around 9kPa per ring, good enough to be used in the spindles of machine tools, with a friction 0.25 N•m. The feasibility of using ferrofluids for developing high performance seals for high precision spindles and the validity of the simulation models has been demonstrated experimentally.

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The research work reported in this article is focused on the use of magnetic fluids as active lubricant for improving the performance of hybrid journal bearings, with application to high-precision machine tools. Prototype design was optimized following numerical computation of Reynolds equation and computational fluid dynamics calculations, in both cases with Herschel–Bulkley model for the magnetorheological fluid. This fluid (LORD Corp. MRF 122-2ED) was experimentally characterized in detail. The improvement of the hydrodynamic effect in journal bearings was demonstrated with 50% higher load capacity and stiffness, mainly at half of shaft eccentricity 0.4 <  ε < 0.7. Active hydrostatic lubrication achieved quasi-infinite stiffness within working limits (load and speed), at low frequencies. For high dynamic response, the active lubrication based on magnetorheological valves did not show good response. The feasibility of using magnetic fluids for developing high performance machine tool spindles and the validity of the simulation models was demonstrated experimentally.

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