On-line control of machine tool vibration in turning operation using electro-magneto rheological damper

Abstract

Purpose of this work is to develop and implement an Electro-Magneto-Rheological damper that can be used to monitor and control the process dynamics of the cutting tool in hard turning operation. Magneto-Rheological (MR) damper consists of non-suspended magnetic iron particles and oil (MR fluid) whose viscosity and shearing stress can be controlled by changing the magnetic field around it with the help of current passing through the coils wrapped around the cylinder damper containing MR fluid. Study involved the characterization of MR fluid as well as vibration characterization of MR damper. MR damper provides variable stiffness and better damping ability and hence better control over the noise and frequency responsible for unstable machining. The experimental results show that dynamic response of the cutting tool system is improved by a maximum of 77% in terms of acceleration ratio with the Electro-Magneto-Rheological damper. Transmissibility approach and half power band width method in the paper was successfully used to analyse the signal amplitude ratio, the damping ratio and the time required by MR damper to settle down the frequency generated by dynamic fluctuation of cutting force. In addition, dynamic stability of the cutting tool holder was obtained with second mode of vibration using finite element software. The damper has improved the machining process in terms of better surface finish on the workpiece by 22.2%, reduced tool wear by 20%, reduced cutting force by 12.9% and enhanced productivity overall.