Kinematics of balls in magnetic fluid grinding (predictions of the onset of skidding motion between balls and driving shaft)

Recently magnetic fluid grinding has been developed as a new process which can remove materials in the finishing of ceramic balls fifty to one hundred times more rapidly than the conventional lapping process. The high removal rates occur when skidding motions are generated between balls and driving shaft. This paper offers a first attempt to model the mechanics of the process, to predict the onset of skidding motions. The model considers the force and moment equilibriums of the ball acted on by the forces and moments upon contacts with the driving shaft and other surfaces and by fluid drag moment. The friction coefficients relevant to the process and the viscosities of magnetic fluids containing abrasive grains were measured for use in the theory. As a result, it can be shown clearly that predictions of the skidding agree with measurements.