Study of Internal Finishing Process for Capillary using Magneto-rheological Fluid

Abstract

Capillaries, whose internal diameters are under 0.3 mm, are used for an injection pipe in medical field, an instrument in chemical and biological field. These capillaries are being required to be finished smoother to prevent a contamination etc. This paper studied a new finishing process using Magneto-rheological Fluid (MRF) of such capillaries, which are difficult to be finished by general processing techniques. In our previous study, we developed the MRF-based slurry, which is the composite of MRF and abrasive, and demonstrated the basic finishing characteristics and the finishing mechanisms. In this paper, we applied the MRF-based slurry to the internal finishing of capillaries using the motion of axial direction, and demonstrated the finishing characteristics and the finishing mechanisms. The higher magnetic flux density of the finishing area increased the finishing force and the dragged motion of the slurry by the magnetic poles; improved the finishing performance. And the edge effects of magnetic flux density also accelerated the finishing performance was found. The slurry showed the high dragged motion when the supplied amount of the slurry was accommodated to the area of high magnetic flux density. The higher velocity of magnetic poles decreased the dragged motion of the slurry; declined the finishing performance. The internal surface of SUS316L stainless steel tube (0.8mmID, 0.4mmID) could be finished smooth by the MRF-based slurry was confirmed.