Abstract: Taking the single crystal nickel-based superalloy DD98 as research object， the material removal mechanism of single crystal superalloy was analyzed from its microstructure. The glide plane of DD98 is its close-packed plane 111， while the glide direction is its close-packed direction <110> with minimum resistance force and easy slip. The orthogonal experiment was implemented for micro-milling single crystal nickel-based superalloy DD98 by using two-edged micro-milling tool. The effect of cutting parameters on the micro-milling forces was obtained through range analysis. The result showed that the influence of spindle speed is the greatest， the feed rate is the secondary， and the milling depth is the smallest affecting factor. The ideal cutting parameters were obtained using minimum micro-milling forces， i.e.， with the spindle speed of 36000r/min， milling depth of 5μm and the feed rate of 20μm/s. The reasons affecting on micro-milling forces were deeply analyzed， and the test results may provide certain theory reference and test basis for understanding the micro-milling mechanism of single crystal superalloy.

Key words: micro-milling force, single crystal superalloy, DD98, microstructure, orthogonal experiment