Abstract: The present invention relates to a rotary cutting tool assembly comprising a combination of a single ball nose cutting insert of a generally elongated configuration. The ball nose cutting insert is fixed into a holding body provided with a slot adapted to securely and non-movably hold the insert. The single ball nose cutting insert has at least one fill ball nose cutting end having a cutting edge of a continuous spiral fluted configuration. The fill ball nose cutting end comprises a cutting face consisting of two radius cutting edges meeting at a center or tip of the full ball nose cutting end forming a web. The cutting face forms a true helical path made of a continuous curve following a spiral shape, and helix angles of the radius cutting edges are between 3 to 45 degrees with respect to a longitudinal axis of the ball nose cutting insert in both right and left directions.

Abstract: A cutting insert having helically arranged teeth, each comprising a six sided block having two major parallel rhomboid-shaped plane surfaces constituting a seating face and a clearance face respectively, two opposed minor side surfaces constituting cutting faces extending between the seating and clearance faces, each cutting face forming an acute angle with the clearance face and forming a cutting edge along the intersection therewith, and two minor parallel plane end faces extending between the seating face and the two cutting faces. Each cutting face has a concave curvature located centrally of its major dimension, and a convex curvature at each end of its major dimension to define a serpentine cutting face and cutting edge.

Abstract: A rotary cutting tool blank comprises a cutting portion having a longitudinal axis and a plurality of teeth extending the length of said cutting portion, with each of the teeth having a cutting face and a trailing face and a land surface bridging the cutting and trailing faces. The land surfaces are interrupted by a plurality of spaced transverse depressions of relatively large radius arcuate cross section to form a plurality of cutting edge portions at the junction of the cutting face and the uninterrupted portions of the land surface. The cutting edge portions have a positive rake angle, and the trailing and cutting faces of each tooth have surfaces which undulate generally sinusoidally from one end of the cutting portion to the other so that the rake angle of each cutting edge portion varies continuously along its length. The cutting tool blank can be transformed to a cutting tool ready for use simply by suitably relieving the land surfaces to form cutting edges at the aforementioned cutting edge portions.