MODELING AND PROCESS ANALYSIS OF FREE AND FORCED VIBRATIONS IN MILLING

Milling is an important machining operation for production of prismatic components using multipoint cutting tools both in vertical and horizontal spindle orientations at low speeds to very high speeds. These cutting tool edges progressively penetrate into work piece producing harmonic forces. The cutting operation is modeled as forced vibration system where as idle running of machine as free vibration. Unbalanced forces (belt tensions) in Main spindle drive and gear forces lead to set up natural vibrations in idle running of the machine tool. In this paper, free and forced vibrations study is conducted experimentally in complex milling operations to characterize process parameters. The machine tool-work piece system behaves like a damped spring mass system. Amplitude and velocity measurement are done using vibrometer during machining. Further Matlab code is developed to generate process parameter response plots in 2D and 3D envelop for the amplitude of vibrations in time domain for universal milling machine to identify sudden changes during metal removal at entry and exit of cutting tool on to the work piece.