Study of the surface modification resulting from an internal magnetic abrasive finishing process

Abstract

An internal magnetic abrasive finishing process was proposed for producing highly finished inner surfaces of tubes used in critical applications including clean gas or liquid piping systems. Most of the previous research has explored the process characteristics and mechanism from a macroscopic point of view making use of surface roughness profiles. However, those approaches did not adequately characterize the behavior of abrasive cutting edges acting against the surface to remove material in the process. This paper examines the microscopic changes in the surface texture resulting from processing. In addition to the surface roughness measurement, atomic force and scanning electron microscopy were used to characterize the material removal process and provide a fundamental understanding of the process mechanism. The observed surface texture shows that the process is an accumulation of the micro-scratches from the abrasive cutting edges, generating a characteristic magnetic abrasive finished surface. Moreover, the surface is finished by removing the material from not only the peaks but also the valleys of the surface, as far as the cutting edges of the magnetic abrasive are introduced into the valleys. However, the relatively longer wavelength components of the roughness profile tend to remain on the surface after processing; this shows that the magnetic abrasive finishing process belongs to the category of pressure-copying processes.