Experimental Analysis of External Cylindrical Surfaces of Mild Steel Using Modified Turning Type Magnetorheological Finishing Tool

Abstract

The aim of thesis is to design a new turning type MRF tool which had uniform magnetic field density at the tool tip. At first simulation for curve tip type turning type magnetorheological finishing tool has been performed in MAXWELL ANSOFT V13 student version to analysis the magnetic flux density distribution at the tool tip and compared with the existing tool having flat tip surface. From, the magnetic simulations clearly seen that the magnetic flux density on curve type tool tip surface is much more uniform than the existing flat tool tip surface at same parametric conditions. The new curve tip turning type magnetorheological finishing tool has been fabricated with same dimensions of existing flat tool and attached at the selected lathe machine. To optimize the process performance of the present fabricated curve tip magnetorheological finishing tool, the design of experiments were carried out with major selected process parameters such as working gap, magnetizing current, workpiece rotating speed and abrasive mesh size. The experiments plan and analysis have been done by using DESIGN EXPERT- 10 software. The experimental responses were measured in terms of percentage change in Ra values. The experiments have been performed on each specimen at 60 minutes of finishing time. The best surface roughness value obtained on mild steel workpiece was 170 nm from the initial surface roughness value 680 nm at finishing condition as current 3.5A, working gap 1mm, workpiece rotational speed 300 rpm and abrasive 600 mesh size. It is found that the abrasive mesh size is most significant factor in affecting the percentage change in the roughness value of the mild steel workpiece. On the basic of experimental results, the optimum process parameters were predicted from the regression model for maximum percentage change in Ra value. The surface roughness reduction value on mild steel workpiece was 120 nm from the initial surface roughness value 720 nm at optimim finishing conditions as rotational speed of tool core 150 rpm, magnetizing current 3.5A, working gap 0.5 mm and abrasive 600 mesh size. The surface roughness was measured with Mitotoyo SJ-400 surface roughness tester. The scanning electron microscopy has been also used to know the final finished surface quality.