Patent ID: 7306408

Claim:
A rotary cutting tool comprising: a body having a cutting portion and a shank portion; a plurality of diametrically-opposed, symmetrical, helical flutes formed in the cutting portion of the body, wherein adjacent helical flutes form an index angle therebetween in each radial plane along the axial length of the flutes, and a first index angle between at least a first pair of adjacent helical flutes is less than or greater than a second index angle between at least a second pair of adjacent helical flutes in at least one of the radial planes; a plurality of peripheral cutting edges, the peripheral cutting edges formed along an intersection of a circumferential surface of the cutting portion of the body and a portion of an inner surface of a respective one of the helical flutes facing in a direction of rotation of the body; wherein at least one of the peripheral cutting edges has a radial rake angle different from radial rake angle of a peripheral cutting edge of a different helical flute.