PROBLEM TO BE SOLVED: To provide a high-service life CBN (cubic boron nitride) small-diameter ball end mill which can suppress vibration and chattering of a tool during cutting work, has high bending-breakage strength, and can provide a good cutting surface, particularly a small-diameter ball end mill which, even in the case of a long neck having a length L of the neck which is five times or larger the diameter D of the cutting edge, is less likely to cause vibration and has no possibility of bending-breakage.;SOLUTION: The small-diameter CBN ball end mill has a cutting edge diameter D of not more than 3 mm and includes a ball cutting edge, which constitutes a cutting part and has an arcuate radius of R mm, and a peripheral cutting edge formed of CBN. In the small-diameter CBN ball end mill, the rake face of the ball cutting edge and the rake face of the peripheral cutting edge which is not less than R/5 of the length of the peripheral cutting edge are provided on the same plane, the peripheral cutting edge is formed in a right hand cut left hand helix form, and the axial rake angle of the ball cutting edge is -5° to -25°.;COPYRIGHT: (C)2010,JPO&INPIT
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