Factors Affecting the Finishing Characteristics of an Internal Magnetic Abrasive Finishing Process for High Purity Fittings

Abstract

In the case of internal finishing of the bent section of a complex shaped tube, such as found in high purity fittings, by a magnetic abrasive finishing process, the magnetic field at the finishing area and, therefore, the finishing force are hardly uniform over the entire finishing area due to the geometry. This affects the abrasive behavior against the inner surface of the bent section, changing the finishing characteristics of SUS304 stainless steel fittings. In practice, non-uniformities in the surface finish remain at the bent section between the inside, outside, and lateral regions. This unevenness combines to cause difficulties in achieving uniform finishing. Magnetic abrasive is generally supplied with ferrous particles, and the ferrous particles experience greater magnetic force and play a role in pressing the magnetic abrasive against the target surface. This paper studies the finishing mechanism in view of the relationship between the magnetic field, the ferrous particles mixed with magnetic abrasive, and the finishing characteristics. The experiments identify the finishing conditions required for successfully diminishing the non-uniformity in the finished surface, and methods are recommended to satisfy the required conditions. The experiments using the proposed methods show the feasibility of producing a uniformly finished mirror surface.