A Meso-Scale Micro-Turning Machine With Modular Linear Air-Bearing Stages

In this paper, we describe the design, fabrication, and evaluation of a compact-sized diamond turning machine built with two air-bearing stages and a spindle. The two stages were developed to achieve the precise positioning required for submicron-level machining and miniaturization by introducing air bearings and a linear motor sufficient for mesoscale precision machine tools. The linear motor contained two permanent magnets and was designed to generate a preload force for the vertical air bearings and a thrust force for the stage movement. The size of the single-axis miniature stage was 120 × 120 × 50 mm³, and the footprint of the turning machine was 200 × 350 mm², which is small enough for a tabletop. The positioning repeatability of the each linear axis was measured to be 0.05 μm, and the machining error and was evaluated by cutting various depths of an aluminum alloy mirror with a single-crystal diamond. The estimated workpiece–tool stiffness was lower than that with conventional ultraprecision machine, but a form error of less than 0.16 μm and a surface roughness (R_z) of 0.08 μm were achieved by the finishing cut using a small depth of cut. This reveals that miniaturized machines can be used successfully for precision machining of small precision parts.