Patent ID: 7322774

Claim:
A soft-materials-cutting end mill being configured to rotate in a cutting direction about a central, rotational axis and cut soft materials such as free-cutting steel, non-ferrous metals, and plastics, said end mill comprising: a shaft portion being configured to be gripped by a tool; a cutting portion comprising a plurality of flutes and a plurality of cutting teeth; each pair of adjacent flutes of said plurality of flutes being configured and disposed to define a cutting tooth disposed therebetween; each of said cutting teeth comprising: a peripheral land surface being disposed to run substantially along the outermost periphery of said end mill from a leading flute disposed ahead of said peripheral land surface in the cutting direction to a trailing flute disposed behind said peripheral land surface in the cutting direction; a cutting edge being formed at the intersection of said land surface and said leading flute; a corner being formed at the intersection of said land surface and said trailing flute; said land surface comprising: a relief section extending from said cutting edge opposite the cutting direction; and an arcuate tooth-backing section extending opposite the cutting direction from said relief section to said corner; said tooth-backing section being substantially longer than said relief section; in a plane perpendicular to the rotational axis of said end mill, said corner being disposed a first distance from the rotational axis of said end mill and said cutting edge being disposed a second distance from the rotational axis of said end mill, which said first distance being in the range of sixty to one hundred percent of the amount of said second distance; and each of said flutes having a cross-sectional volume of sufficient size to provide both: (i) sufficient flow of chips during a cutting operation; and (ii) maximized size of said cutting teeth to extend a substantial portion of said cutting teeth and their corresponding land surfaces to at least said first distance from the rotational axis of said end mill to provide sufficient material adjacent the outer periphery of said end mill to both: (a) maximize the polar moment of inertia with respect to the rotational axis of said end mill and thus maximize the torsional rigidity of said end mill; and (b) maximize the resistance to bending of said end mill.