PURPOSE: To continuously form a cutting line for a contour following the generated tip lines of an outer contour by arranging a plurality of cutting inserts on continuous teeth at intervals relatively staggeringly on each tooth against other teeth, and providing rotary paths where inserts intersect.

CONSTITUTION: Cutting inserts are installed at prescribed intervals to cover the front faces of teeth, and the front faces of the inserts are arranged in the radial plane of a disk. The inserts of another tooth of the disk are staggeringly arranged, and a double-chain body is formed when the insert seatings of two adjacent teeth are combined, thus forming a composite pattern constituted of inserts 1-8 including the inserts 1, 3, 5, 7 on a generated contour contained in one tooth and the inserts 2, 4, 6, 8 contained in the other tooth. The seatings of the inserts are arranged to cover and protrude from the contour outer face of the cutting operation formed by the rotary surface wiped by the actual cutting edge tip line in the initial polygon, the inserts are fitted at the regular positions, and the actual cutting edge tip lines form a contour line 112. A precise contour outer shape is finished by a cutting tool, and the molded cutting edge tip line capable of securing precision is obtained.