Magnetorheological fine finishing of steering rack bar for improving its functional operation

Abstract

Fine-finished external cylindrical surfaces in automotive manufacturing parts are of great importance for improving their performance. A finely finished external surface of steering rack bar leads to a decrease in its response time. So, in this work, the rotating core-based magnetorheological (MR) finishing process has been performed on the external surface of steering rack bar to improve its performance. In this work, the process parameters have been optimized to fine-finish the current workpiece with minimized efforts. The optimum conditions of process parameters are depicted using full factorial central composite design (CCD) under response surface methodology technique. The maximum contribution to the response, i.e. % change in surface roughness value is found from current (15.28%) and rotational tool speed (8.66%). Using the optimum finishing parameters, the average surface roughness value of the steering rack bar external surface achieved was 30 nm from 550 nm with finishing time of 90 min. Also, the fine finishing of steering rack bar's external surface was confirmed by a comparative study of scanning electron microscopic and mirror images of initial and final finished surfaces conducted in this study. Thus, this study advocated that the current process can be beneficial for fine finishing of industrial components such as rocker arm shafts, vacuum pistons, and cylindrical punches.