EXPERIMENTAL EVALUATION OF VIBRATIONS IN THE MICRO-MILLING PROCESS OF TITANIUM ALLOY

Abstract

Micro-milling is widely recognised as an advanced micro-manufacturing process due to its high flexibility and capability to generate complex micro-geometrical features with superior dimensional accuracy. Nevertheless, the reduction of tool diameter and cutting depth has been shown to significantly decrease tool stiffness and increase the sensitivity of the process to dynamic effects. Vibrations arising in the cutting zone directly influence surface integrity, dimensional accuracy, tool wear, and overall process stability. Consequently, a reliable experimental assessment of vibration behaviour under different cutting conditions is of considerable scientific and practical importance, particularly for machining difficult-to-cut titanium alloys. The present study constitutes an experimental investigation of the vibration characteristics exhibited during micro-milling of VT1-0 titanium alloy under varying cutting parameters. The experiment employed a two-flute carbide end mill with a diameter of 1 mm and a TiAlN coating. Vibration signals were measured using a piezoelectric accelerometer. The vibration intensity was quantified using the root mean square (RMS) value of vibration acceleration, calculated from time-domain signals corresponding to the cutting stage with full radial engagement of the cutting tool. Fast Fourier Transform analysis was conducted to ascertain the predominant frequency components and to evaluate the spectral distribution of vibration energy. The development of a regression model incorporating interaction effects between cutting parameters was informed by experimental data. Variance analysis demonstrated that cutting speed is the dominant factor affecting vibration level, contributing more than half of the total variance of RMS values. Axial depth of cut exhibited a secondary yet statistically significant influence, while feed per tooth did not demonstrate a significant effect within the investigated range due to the size effect and ploughing-dominated cutting regime. The obtained results provide practical recommendations for selecting cutting parameters to ensure improved vibration stability and enhanced machining performance in micro-milling of titanium alloys.