The prediction of 3D surface topography in a high-speed micro-milling process with aerostatic spindle

Aerostatic spindle has great importance to ultra-precision machine tools. Under different cutting parameters, the cutting force of aerostatic spindle will fluctuate and change discontinuously, which tends to cause a large vibration response of the spindle and leads to chatter phenomenon and machining surface failure. In order to improve the manufacturing efficiency and surface quality, a five-degree of freedom (5-DOF) dynamics model of aerostatic spindle is established, and the coupling effect between the rotor dynamics and micro-milling process is analyzed. In view of the dynamic vibration response of the tool tip in the micro-milling process, a prediction model of the three-dimensional (3D) surface topography of the workpiece is established. The effects of different cutting parameters (rotating speed, axial cutting depth and feedrate) and tool runout on the surface topography are quantitatively analyzed. The experimental results of 3D surface topography agree well with the simulated results. The results show that during the steady cutting process, the surface roughness is almost constant as the speed and cutting depth expand, but increases with the increase of the feed rate. When the tool tip runout amplitude is less than half of the feed amount per tooth, the workpiece surface roughness increases, otherwise, the workpiece surface roughness remains unchanged.