Within examples, systems and methods for forming a hole through at least one layer of a material are provided. An example cutting tool for forming such a hole may include a body, and a first portion of the body having a first diameter and a first radial rake angle. The cutting tool also includes a second portion of the body adjacent the first portion, the second portion having a second diameter and a second radial rake angle, wherein the second diameter is different than the first diameter, and wherein the second radial rake angle is different than the first radial rake angle.

A ball-end mill includes arcuate cutting edges each extending from a tip end to a peripherally outermost point along a S shape curve when viewed from the front side, spirally-shaped, peripheral cutting edges each smoothly connected to each arcuate cutting edge, and a convex rake face of each arcuate cutting edge protruding forward in a rotation direction. Each arcuate cutting edge has a radial rake angle satisfying <, where is a radial rake angle at a radial angle of 5, is a radial rake angle at a radial angle of 90, and is a radial rake angle at a rotationally most projecting point of the arcuate cutting edge. The radial rake angle has the maximum value at a radial angle in a range of 12-40 and continuously decreases in a range from the rotationally most projecting point to the peripherally outermost point.

A cutting insert includes: a polygonal shaped upper surface; a lower surface; a side surface connected to each of the upper and lower surfaces; and an upper cutting edge located at the intersection of the upper surface and the side surface. The upper surface alternately includes three major corners and three minor corners. The upper cutting edge includes: a corner cutting edge; a minor cutting edge inclined toward the lower surface as separating from the corner cutting edge at a first inclination angle; and a major cutting edge inclined toward the lower surface as separating from the minor cutting edge at a second inclination angle. The corner cutting edge, the minor cutting edge and the major cutting edge are located sequentially from a first major corner to each of first and second minor corners, both of which are adjacent to the first major corner.

An indexable roughing end mill having a peripheral surface provided with a plurality of spiral grooves. When the positions of cutting inserts (40) arranged in each spiral groove (28) are defined as a first segment to an n.sup.th segment from a leading end surface (22) side of a tool body (20) toward a base end surface (21) side, all of the angles 1 . . . m between lines connecting a rotational axis (O) and the cutting inserts (40) in the first segments of the respective spiral grooves (28) are different from each other, as viewed from the leading end, and an angle (t) between the cutting insert (40) in the first segment and the cutting insert (40) in the uppermost n.sup.th segment in a spiral groove 28 is different from any of the angles 1 . . . m between the lines, as viewed from the leading end.

Within examples, systems and methods for forming a hole through at least one layer of a material are provided. An example cutting tool for forming such a hole may include a body, and a first portion of the body having a first diameter and a first radial rake angle. The cutting tool also includes a second portion of the body adjacent the first portion, the second portion having a second diameter and a second radial rake angle, wherein the second diameter is different than the first diameter, and wherein the second radial rake angle is different than the first radial rake angle.

A corner radius end mill includes a tooth adjacent a helically extending flute. The tooth includes axial and radial relief surfaces connected by a corner relief surface, as well as rake surface having a rake ridge. The rake ridge is continuously curved from a bisector line until at least an axial location rearward of the corner relief surface.

A bur with features that minimize the application of substantially identical forces to the tissue against which the bur is applied. One of these features is the arrangement of the flutes so that one pair of flutes projects outwardly from the tip at an acute angle that is greater than the angle at which the other flutes project outwardly from tip. Consequently at the equator of the bur head, the location along the bur head where the bur head has a maximum diameter, the flutes define a perimeter that is non-circular in shape.

A cutting element for use in a cutting operation, comprising a cutting edge (CE) capable of cutting out material from a workpiece during the operation, to form therein a workpiece corner of angle alpha. There exists at least one view of the cutting edge in which a portion of the cutting edge is delimitable by a first (L1) and a second (L2) line oriented tangentially to the portion of the cutting edge portion at respective tangency points A and B. The lines form therebetween a cutting angle corresponding to the workpiece corner angle alpha and have a vertex 0. For a bisector of the cutting angle intersecting the portion of the cutting edge at the point C, the projection C of the point C of the portion of the cutting edge on a line OL passing through the vertex 0 perpendicularly to the plane of the one view is located between projections A1 and B of the respective points A and B of the portion of the cutting edge on the line OL.

A tool for machining a stacked material workpiece includes a tool body having one or more helical flutes extending to a forward end of the tool body. Each helical flute has a width defined by a first cutting edge and a second edge, a surface of the flute adjacent the first cutting edge facing the forward end of the tool body and a surface of the flute adjacent the second edge facing away from the forward end of the tool body. Each helical flute can include a first portion having a first negative pitch angle and a second portion having a second negative pitch angle different from the first negative pitch angle, the first portion extending from the forward end of the tool body to the second portion. The tool has only negative pitch angles. A method for machining a stacked material is also disclosed.

A cutting insert includes: a polygonal shaped upper surface; a lower surface; a side surface connected to each of the upper and lower surfaces; and an upper cutting edge located at the intersection of the upper surface and the side surface. The upper surface alternately includes three major corners and three minor corners. The upper cutting edge includes: a corner cutting edge; a minor cutting edge inclined toward the lower surface as separating from the corner cutting edge at a first inclination angle; and a major cutting edge inclined toward the lower surface as separating from the minor cutting edge at a second inclination angle. The corner cutting edge, the minor cutting edge and the major cutting edge are located sequentially from a first major corner to each of first and second minor corners, both of which are adjacent to the first major corner.