Parametric Optimization for Nano-Finishing of the External Cylindrical Surfaces Using Rotating Core Magnetorheological Finishing Process

A rotating core magnetorheological finishing process has been developed to finish the external cylindrical surfaces at nano-level as the conventional finishing processes like grinding cannot meet the extreme precise requirement. The quality of finished cylindrical components estimated through its geometrical accuracy, material assets, and mechanical features. The macaroni making machine driving shaft is made up of mild steel where high quality of surface finish is required. In plastic toy industries, the mild steel punches are used where a high level of surface finish is required to increase the appearance of the products and to improve its geometrical accuracy. The MR finishing process can improve the external surface quality of the cylindrical components very precisely. This result in the improvement of prolongs functional performance of the components. In the present work, the optimum process parameters are experimentally investigated for nano-finishing of the mild steel cylindrical external surfaces using the rotating core magnetorheological (MR) finishing process. The rotation of tool core, the rotation of the cylindrical workpiece, the current, and the working gap are the control process parameters which affect the finishing performance i.e. percentage change in surface roughness value. So, the effects of these process parameters on the process response such as percentage change in surface roughness value have been analyzed using signal-to-noise ratios and mean response data. The current and the rotational speed of the tool core have been found as a considerable role for increasing the percentage change in roughness value. Further, the optimum magnitude of the process parameters are predicted as the current 3A, the rotational speed of tool 500 rpm, the rotational speed of the cylindrical workpiece 80 rpm and the working gap of 0.6 mm. With the finishing of these optimum process parameters on the present developed process, the average roughness R_a value of the external surface of the mild steel cylindrical is reduced to 60 nm from the initial R_a value of 600 nm in 90 minutes of finishing. The results of scanning electron microscopy test, mirror images and roughness graphs of the finished surface have confirmed that the present finishing process can fulfil the extreme precise requirement of surface quality which is not possible by the conventional finishing processes. The extreme precise requirement of the surface quality of the external cylindrical workpieces are dealing with mild steel punches in plastic toy industries, dies, and molds, macaroni making driving shafts, armature shaft, and shafts used in gear etc.