Abstract: An end mill includes a plurality of peripheral cutting edges having a cutting diameter that is constant over their entire cutting length. The plurality of peripheral cutting edges, which are adjacent to each other, are defined by curved teeth. Each of the curved teeth is twisted in a twist direction that is changed irreversibly and smoothly from one of rightward and leftward directions to the other of the rightward and leftward directions in the entire cutting length so as to be reversed right and left on its way. Each of the curved teeth has a curved shape curved in an arcuate or arched manner in a development view of an outer circumferential surface of the end mill around an axis such that a corresponding one of the peripheral cutting edges is provided on a concave side of the curved shape.

Abstract: An end mill includes a plurality of peripheral cutting edges that are defined by three types of teeth including a right-handed helical tooth that is twisted rightward, a left-handed helical tooth that is twisted leftward, and a curved tooth which is twisted in a direction reversed right and left on a way thereof and which has a curved shape curved in an arcuate or arched manner in a development view of an outer circumferential surface of the end mill around an axis such that a corresponding one of the peripheral cutting edges is provided on a concave side of the curved shape. Each adjacent pair of the peripheral cutting edges adjacent to each other are defined by the respective teeth that are different in type from each other.

Abstract: An end mill includes a plurality of peripheral cutting edges have respective helix angles which are equal to each other and which range from 0° to 5°. Each of the plurality of peripheral cutting edges is defined by one of four types of teeth A-D consisting of (a) teeth A-C each defining a partially-uneven cutting edge that includes an uneven edge portion consisting of a nicked portion or a roughing portion and (b) a tooth D that does not define the uneven edge portion. The peripheral cutting edges are defined by at least two of the four types of teeth A-D, such that each adjacent pair of the peripheral cutting edges adjacent to each other are defined by the teeth that are different in type from each other.