Ultra-precision machine tools for fabricating optical lens and lens molds require highly accurate positioning. However, one concern is that, depending on the workpiece size, fly-cutting using conventional machine tools can often require a large amount of time. To solve this problem, we have developed an ultra-precision 5-axis machine tool, and evaluated its processing performance during free-form, high-speed surface machining of a workpiece with high-precision contour control. We successfully demonstrated a non-rotational cutting process that resulted in a surface roughness of within 2 nm and a form accuracy of within 0.1 μn. The processing time was less than half that required by a conventional fly-cutting process. The performance of the machine tool and the results of an evaluation of the machined mold are reported in this paper.
