Ultrahigh-Speed Micro-Milling End Mill with Shank Directly Supported by Aerostatic Bearings

Abstract

Recently, high-speed micro-milling has attracted considerable attention for effectively manufacturing fine and precise machine components with lower cutting resistance. However, as the tool diameter is reduced, higher rotational speeds of the spindle become necessary for machining components at the optimal cutting speed. We propose a new machining method in which an end mill cutter is directly supported by aerostatic journal and thrust bearings, and driven by air turbines to achieve high rotational speeds. We found that the proposed micro end mill spindle with a 4 mm shank could rotate at 400,000 min^-1 and cut grooves with depths of 30 µm to 40 µm on an aluminum alloy surface.