Control of Pressing Force in Magnetic Abrasive Finishing Using Permanent Magnet End-Mill Tool

The magnetic abrasive finishing (MAF) process is well known because of its high efficiency in yielding a mirror gloss finish zone. Clarification of the high efficiency machining mechanism has indicated that this high efficiency is obtained by iron particle cutting and the simultaneous polishing of alumina abrasives. This process yields unevenness, which is often evident on the workpiece surface. In a previous report, we compared magnetic polishing brushes consisting of iron powder paste (commercial paste) or steel balls (uniform size), and found that a large variation was generated when the magnetic polishing brush approached the workpiece surface in both cases. In this paper, we make slight changes to the steel-ball shape, obtaining saddle and barrel-shaped iron particles via stamping processing. The aim is to observe the control factor of the pressing force for these three different iron particle shapes and for different particle numbers, using a force sensor and a high-speed camera. The relationship between the iron particle shape, the iron particle number and the pressing force control is also explored in an attempt to discuss the mechanism behind the iron particle shape effect on the frictional force generation between the iron particles. It is found that the force variation can be reduced by adjusting the particle shape and number, which effectively reduces the damage caused when the brush approaches the workpiece surface.