Parametric analysis of an improved ball end magnetorheological finishing process

Abstract

A novel surface finishing method using an improved ball end magnetorheological finishing tool was developed for nanofinishing of flat, as well as three-dimensional workpiece surfaces. An improved magnetorheological finishing tool is the main part of the present finishing process, which has been made up of the central rotating core and stationary electromagnet coil integrated with a copper cooling coil. A magnetically generated ball end finishing spot of magnetorheological polishing fluid was used as a finishing segment at the tip surface of the rotating core. In this research, detailed study through statistical design of the experiments was conducted for nanofinishing of ferromagnetic workpieces by the proposed ball end magnetorheological finishing process. Response surface methodology has been used to plan and analyze the effect of rotational speed of the tool core, magnetizing current and working gap on percentage change in surface roughness. The experimental results were discussed and the best finishing conditions were identified within the experimental range of variables. Analysis of experimental data showed that the percentage change in surface roughness was highly influenced by the working gap, followed by magnetizing current and rotational speed of the tool core. The best surface finish obtained on the ferromagnetic workpieces was as low as 27.6 nm from the initial value of 142.9 nm in 30 min of finishing time. In order to study the finished surface morphology, scanning electron microscopy and atomic force microscopy were also conducted.