Magnetic Abrasive Finishing (MAF) of Flat thrust bearing surfaces and cylindrical shafts for ultra high speed cryogenic applications

Nano-finishing of flat thrust bearing and cylindrical shaft surfaces employed in ultra high-speed cryogenic applications with Magnetic Abrasive Finishing (MAF) would reduce friction, minimize wear and increase service life. A magnetic field applied across the machining gap containing a homogeneous mixture of abrasive (diamond paste (5 μm) and ferromagnetic iron particles), aligns the ferromagnetic particles to form a flexible magnetic abrasive brush (FMAB). A novel MAF setup has been developed that can finish both cylindhcal and flat surfaces. The FMAB can move in longitudinal direction as the workpiece rotates and can finish a cylindrical shaft to a roughness value of 0.023 μm (23 nm) R_a. A fiat bearing surface was also finished to a roughness value of 0.029 μm R_a and flatness value of about 5 μm with transverse feed of FMAB. Effects of such improvements in surface finish and flatness values on the performance of the rotor-bearing assembly are being studied.