Study On Magnetic Abrasive Finishing

Study on Magnetic Abrasive Finishing T. Shinmura, Utsunomiya University; K. Takazawa, Kanagawa Institute of Technology; E. Hatano, M. Matsunaga, Toyo-kenmazai Co./Japan - Submitted by T. Matsuo (1) Received on January 15,1990 ABSTRACT: This paper describes a new finishing process using magnetic abrasives in which the finishing pressure is generated by a magnetic field. The process principle and the finishing characteristics are described. Specifically, the effect of the magnetic abrasive particle size on stock removal and surface finish is invesligaled for cyliridrical tinishirig. Based 011 the results, diamond coated magnetic abrasives were newly made to finish Si N fine ceramic bars(l2mm in dia.) and its finishing performances were clarified. The surface roughnesa bf 0.45pmRa before finishing was improved to 0.04pmRa. It was also clarified that the precision edge finishing of about 0.Olmm in radius was performed easily by this process. KEY WORDS: Magnetic abrasive finishing, surface roughness, stock removal, magnetic abrasives, Eine ceramics, edge finishing 1. Introduction Manual operations are common in the surface finishing, deburring and precision chamfering of intricately shaped industrial parts. Recent trends, however, have necessitated the mechanization of these manual finishing processes. In order to enable surface and edge finishing of such parts, a new process "magnetic abrasive finishing"(Fig. 1) has been developed in East European countries [1,2]. In this process, granular magnetic abrasives (Fig.2) composed of both such ferromagnetic material as iron and such abrasive grain as aluminum oxide are used and the finishing pressure is generated by a magnetic field. So far as we know, the fundamentals of the finishing mechanism are not well understood, and more detailed research is strongly desired. The authors have been studying this process since 1980. This paper describes the process principles and a few finishing characteristics. Specifically, the influence of magnetic abrasive particle size on stock removal and surface finish was investigated for cylindrical finishing of SS41 steel, and a guide for selecting magnetic abrasives was developed. Based on the results, the various types of diamond coated magnetic abrasives (Fig.10) composed of both cast iron ball and diamond micron powder were newly made to finish Si N fine ceramic bars and its finishing performancgs4 were clarified. Finally, the experiments 011 the application t o edge finishing were carried out. 2. Process Principles The process principles of magnetic abrasive finishing is shown in Fig.1. The magnetic abrasives are joined to each other magnetically between magnetic poles N and S along the lines of magnetic force, forming flex