A ball end mill, which includes long and short cutting edges alternately formed, shows excellent chip discharge performance without sacrificing strength. An even number of cutting edges are formed at intervals in a circumferential direction on a front end of an end mill body rotated about an axis and have rotation trajectories formed around the axis that form a hemispherical shape. The cutting edges adjacent to each other in the circumferential direction with one cutting edge interposed are long cutting edges that intersect with each other on the axis. The other cutting edges adjacent to each other in the circumferential direction with one cutting edge interposed are short cutting edges that include inner peripheral ends at positions distant from the axis. A gash of the long cutting edge and a gash of the short cutting edge connect with each other on a front end side of the end mill body.

A formed rotary cutting tool includes a cutting edge defining a cutting edge diameter that is increased and reduced in a direction of an axis of the tool, so as to have at least one neck portion in which the cutting edge diameter is minimized. The cutting tool includes a roughing portion which is provided on a periphery thereof and which is constituted by a succession of protrusions and recesses arranged in the direction of the axis. The roughing portion includes (i) a fine roughing portion that is provided in at least one of the at least one neck portion, and (ii) another portion that is provided in a portion that is other than the at least one of the at least one neck portion. The fine roughing portion of the roughing portion is different in characteristics from the above-described another portion of the roughing portion.

A tool arrangement with a screw-in tool and a tool receiver, the screw-in tool having a thread for engagement in a counter thread on the tool receiver. The counter thread and the thread have different thread contours and therefore, in the screwed condition, these adapt to one another by elastic deformation.

A ball end mill comprises a gash provided at a front end portion of a main end mill body rotated about an axis; and at least one cutting edge which has a rotational trajectory around the axis that forms a convex hemispherical shape having a center on the axis. The cutting edge is formed at a peripheral edge portion of a wall surface of the gash. A difference between a first and second included angles is within ±7°, where the first included angle is formed between the axis and a straight line connecting the center with a cutting edge position at which a depth of the gash is maximal in a cross-section orthogonal to the cutting edge, and the second included angle is formed between the axis and a straight line connecting the center with a cutting edge position at which a rake angle of the cutting edge is maximal.

A corner radius end mill includes a blended gash extending along a cutting edge. The blended gash is formed in a corner sector of the end mill. The corner sector has a first half-sector and a second half-sector defined on opposite sides of an imaginary bisection line of the corner sector, the first and second half-sectors subtending equal angles about the imaginary bisection line. The blended gash extends from a first extremity and blends an end gash surface and flute rake surface of the corner radius end mill. The blended gash is spaced from a radial tangent point by a predetermined distance, and extends to a second extremity which is spaced apart from the axial line and the second half-sector.

A rotary cutting tool includes a shaft having and outer surface and having a longitudinal axis, a plurality of helical flutes formed in the shaft about the longitudinal axis, a plurality of helical cutting edges formed at an interface with the outer surface and a respective helical flute about the longitudinal axis, and a plurality of end cutting edges located on an axial distal end of a cutting portion of the shaft, the end cutting edges being contiguous with a corresponding one of the plurality of helical cutting edges and forming a corner in the transition between each of the end cutting edges and the corresponding one of the plurality of helical cutting edges. A hone edge extends along a portion of each of the end cutting edges, the associated corner and a portion of the corresponding one of the plurality of helical cutting edges.

A method for forming dimples on a workpiece includes providing a rotary cutting tool. The rotary cutting tool includes a cutting edge that protrudes in a leading direction parallel to a longitudinal axis of the tool. The cutting edge extends from a position at the leading end of the rod-shaped main body that is radially offset from the longitudinal axis. The rotary cutting tool is set such that the longitudinal axis of the rotary cutting tool is inclined relative to a line perpendicular to the processing surface of the workpiece. The rotary cutting tool is moved along the processing surface while the rotary cutting tool is rotated about the axis. The processing surface is cut by the cutting edge to form the dimples, which are spaced apart from each other on the processing surface.

The radial run-out tool (2), particularly a drill or a cutter, has a basic body (12) extending in an axial direction (4) and comprises at least two chip grooves (14), to which a guide chamfer (22) is connected in the rotational direction (24), with a ridge (15) being formed between them. A radial clearance is connected to the guide chamfer (22). In order to enable simple and economical production of such type of radial run-out tool (2), an unprocessed rod (30) is ground non-concentrically, in a first process step, such that a radius (R) of the unprocessed rod (30) varies, depending on the angle, between a maximum radius (R2) and a minimum radius (R1). In a second process step, the chip grooves (14) are grounded down such that the guide chamfers (22) are formed at the positions with the maximum radius (R2) and the radius (R) is subsequently reduced downstream of the respective guide chamfer (22) in order to form the radial clearance (28).

A method for forming dimples on a workpiece includes providing a rotary cutting tool. The rotary cutting tool includes a cutting edge that protrudes in a leading direction parallel to a longitudinal axis of the tool. The cutting edge extends from a position at the leading end of the rod-shaped main body that is radially offset from the longitudinal axis. The rotary cutting tool is set such that the longitudinal axis of the rotary cutting tool is inclined relative to a line perpendicular to the processing surface of the workpiece. The rotary cutting tool is moved along the processing surface while the rotary cutting tool is rotated about the axis. The processing surface is cut by the cutting edge to form the dimples, which are spaced apart from each other on the processing surface.

[Object] To provide a ball end mill in which it is possible to improve wear resistance in the vicinity of the central axis at the tip of a ball-nosed end cutting edge and to suppress vibration of a tool body during machining. [Solution] A ball end mill 10 includes: a tool body 1 that rotates about a central axis O; and an arc-shaped ball-nosed end cutting edge 2 in a side view which is provided to start from the central axis O side on a tip side of the tool body 1 toward a rear side thereof. The ball-nosed end cutting edge 2 has a radius of curvature r that becomes gradually smaller from the central axis O side toward a periphery Q side.