Abstract: Tool nose radius has an important affection on machining precision and cutting force. To research the affection on approach angle of tool nose radius, a geometry relation of tool elements is constructed. The four cutting conditions are catalogued according to the comparison between cutting depth and tool nose radius: ① tool nose radius < depth of cut, and approach angle is 90°; ② tool nose radius < depth of cut, and approach angle < 90°; ③ tool nose radius < depth of cut, and approach angle > 90°; ④ tool nose radius > depth of cut. The real approach angle is calculated caused by tool nose radius according to the geometry relation between tool nose radius and approach angle. The cutting force experiment has been conducted to verify the analysis result. Experimental approach angle is calculated by analyzing the angle between radial force and feed force. The experimental results show the tool nose radius lead to approach angle decrease.

Key words:  tool nose radius, approach angle, depth of cut, geometry relation, cutting force