An experimental study on non-linear characteristic of vibration signal in micro-end-milling process

Micro-end-milling is a dominant method of micro-cutting because of its three dimensional micro-machining ability. Compared to conventional macro-scale milling, the relationship between machining effect and machining parameter inclines to more un-corresponding which can be described as non-linear in micro scale end-milling. Based on this, the vibration signals, under which normal surface and surface with macroscopic ripple are obtained, were sampled with high impedance tri-axial accelerometer respectively. The fluctuation processes of vibration signal characteristics such as energy, deviation, power spectrum frequency band and energy distribution in micro-end-milling were described by parameters such as root mean square (RMS) and kurtosis K in time-domain, spectral frequency center (FC), root mean square frequency (RMSF) and root variance frequency (RVF) in frequency-domain. The investigated results show that non-linear phenomenon in micro-end-milling process is mainly caused by the unstability; the main frequency band is most sensitive to status change of the feed direction of milling cutter, the direction of milling depth is second and the axial direction is the most inertia.