Tool wear process monitoring by damping behavior of cutting vibration for milling process

Tool wear process is a complex thermo-mechanical coupling dynamic process. Tool wear will cause the change of the dynamic property of the cutting process, namely the process damping. A new method for monitoring tool wear by on-line recognition of damping behavior of cutting vibration is presented. By modeling the milling force of worn tools, the influence of tool wear on milling force and cutting vibration is analyzed. For accurately identify the time varying process damping with tool wear increases, the vibration component near the dominant mode of cutting system is extracted from cutting vibration signal, and the local mean damping ratio is calculated using the instantaneous frequency (IF) and the instantaneous amplitude (IA). The method performance is demonstrated through experimental data of milling. The results indicate that the local mean damping ratio of milling vibration increases with tool wear, which can clearly indicate the wear progression of tool. The method provides an effective monitoring index for tool wear monitoring in machining.