Vibration Analysis and Stability Studies in Milling of Thin-Walled Workpieces

Abstract

Milling is one of the most commonly used machining processes. Now-a-days, aeronautical and automobile industries require preparation of thin walled components. Machining of such components is very difficult task, because of high work flexibility, which in turn causes undesirable deformation that compromises the tolerances given on the workpiece. Focus of the present work is to design and analyze the milling process with flexible workpiece considerations via an interactive cutting force model. The tool and workpiece considered are having two degrees of freedom each in X and Y direction and further analysis has done in time domain by solving both the coupled delay-differential equations. The vibrational amplitudes and corresponding cutting force components from a four-fluted milling tool at different cutting speeds are observed. The Fast Fourier Transform (FFT) of the time domain signals show the dominant chatter frequencies, which is of main concern in determining the process stability. The FRF of the signals are also predicted from the FFTs of X and Y displacements and corresponding forces. It is found out that the chatter frequency varies with spindle speed. The effect of stiffness of workpiece on vibration response is also studied. The inter-dependent effect of the tool and workpiece model is studied with a varying stiffness model of the workpiece and the behavioral change of the system with respect to different parameters is observed.