Elucidation of the polishing mechanism by the magnetic polishing brush

Nowadays, a free-form surface, such as molding die surface, is required to be finished by reducing the environmental burden. Therefore, a novel polishing technology is needed with a less abrasive slurry,for the reduction of which a magnetic abrasive finishing method is attracting attention. However, it is well known that a conventional magnetic polishing method is unstable and insufficient to obtain the required surface roughness. In the present paper, we discuss the reasons causing instability in conventional magnetic polishing. We systematically investigate the magnetic pressure distribution characteristics and measure the pressing force distribution of the magnetic brush during machining. Furthermore, to observethe impact of an iron particle shape on the pressing force, we used steel balls (steel-ball brush) and abrasive slurry. Moreover, we compared this brush with a brush that uses iron powder paste (employed in the conventional magnetic polishing method). Thus, we determined the possibility of the wide range control of the pressing force by changing the shape and size of the magnetic material. The setting of the approach conditions should be sufficient because it could deteriorate the shape accuracy through very high pressure.