THROWAWAY TYPE BALL END MILL

PROBLEM TO BE SOLVED: To prevent the shift and fall of a tip by fully resisting even when excessive load is applied during cutting. SOLUTION: The tip 5 is mounted to a tip mounting seat 4 at the tip of a tool body 1. The tip 5 is formed with a mounting hole 10 through which a clamping screw 6 is inserted, circular cutting edges 8 and linear cutting edges 9, and recessed groove parts 15 at a lower face 14. The tip mounting seat 4 is formed with a threaded hole 18 into which the clamping screw 6 is screwed, and projecting parts 20 that can be engaged with the recessed grooves 15, at the bottom face 16. In the state of the tip 5 being mounted to the tip mounting seat 4 by the clamping screw 6, the recessed grooves 15 abut on the projecting parts 20 at the side faces 15A, 20A on one side, and a peripheral surface part 12B in line with one circular cutting edge 8, and a peripheral surface part 12A in line with one linear cutting edge 9 can abut on wall surface parts 17A, 17B of the tip mounting seat 4.