Physical insights about magnetic flux distribution and its effect on surface roughness in MR fluid based finishing process

Abstract

A novel magnetorheological (MR) fluid based experimental system was designed to finish Ti-6Al-4V cylindrical rods. Here, the finishing action is achieved by rotating the rod to be finished which is in contact with MR fluid (mixed with silicon carbide loose abrasives) while applying a magnetic field across the finishing zone. Magneto-static field analysis was carried out using finite element method to design the magnetic circuit and predict the flux density around the finishing area. Practical results showed that the magnetic flux density of 0.2 T with a workpiece rotation of 3000 rpm provided the maximum change in average surface roughness. This paper focuses on studying the influence of magnetic flux distribution on the uniformity of the surface roughness along the axial length of the finished rods. The experiments revealed that the surface roughness significantly varied throughout the finishing rod length. The maximum change in surface roughness was seen at the lower part of the finished rod and progressively reduced towards the top of the rod. The magnetic flux distribution controls the mechanism of material removal and reveals its role to achieve close final surface roughness tolerance. With this understanding, a strategy is proposed to reduce the non-uniformity of surface roughness along the entire length of the cylindrical rod.