BALL END MILL

摘要

PROBLEM TO BE SOLVED: To enhance surface roughness of a cut surface to accuracy 1.6μm or less in Rz when performing cutting work on hardened steel, etc. SOLUTION: A cutting edge of this ball end mill is made of a polycrystalline hard sintered body containing cubic system boron nitride by 20 to 95 volume %. A radius of cross-sectional curvature R of a cutting edge ridgeline part 14 is 5 to 30μm. A flank 12 and a face 13 or a negative land surface 11 of the cutting edge smoothly continue on the radius of curvature R of a cross-section. The surface roughness of the cutting edge ridgeline part 14 is formed in 0.1 to 1.0μm in ten-point average roughness (Rz).