Analysis of high-speed milling dynamic stability through sound pressure, machining force and tool displacement measurements

Abstract

High-speed milling is a manufacturing process that has great economical potential owing to high material removal rate, accuracy and quality of machined workpieces. However, chatter might arise especially in situations where there is lack of dynamic stiffness of the system composed by the machine tool, the cutting tool and the workpiece. This work analyses the dynamic stability of the high-speed end milling process. The evaluation of stability is based on sound pressure, machining force and tool displacements measured during the process. In order to investigate the transition from stable cutting to cutting with chatter, the experimentally measured tool displacements are used as input data into a computer simulation to estimate the chip thickness variation during the process. It was found that for unstable cuts, the tool shaft motions are elliptical, process dynamics are dominated by power at the chatter frequency and other vibration modes of the system can resonate with the harmonics of the chatter frequency. Through the computational simulation of the estimated chip thickness variation, it was possible to observe the transition from stable cutting to cutting with chatter, the phase differences between undulations left by subsequent teeth and their consequences in machining forces.