Experimental Investigation of Unbonded Magnetic Abrasive Polishing (UMAP) of Silicon Nitride Balls
Abstract
New technique known as "Unbonded-Magnetic-Abrasive-Polishing"(UMAP) was designed and built in-house, to polish silicon-nitride balls in an economical-way. UMAP is based on the combination of underling principles of magnetic float polishing, magnetic abrasive finishing and lapping. Balls to be finished were loaded between a polishing-plate and a beveled-spindle by spring action. This was placed in a chamber mounted horizontally on a lathe, containing unbonded magnetic abrasive and non-magnetic viscous fluid. Magnetic field gradient generated around the balls concentrates abrasive particles in the polishing region. Polishing action occurs due to relative-movement of balls and abrasives between the polishing-plate and the spindle, rotating in opposite directions. A bevel of less-than 25 degree with the groove was essential for improving the sphericity and surface-finish. MRR upto 1.2 micrometer/min/ball with average sphericity of 0.77 micrometer and finish of 11.6nm were obtained. The best ball measurements achieved were 0.5 micrometer sphericity and 10.4nm finish.
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- OSU Theses [15752]