Abstract: A ball end mill in which a ball end cutting edge (3) has a convex shape in a tool rotation direction with respect to a line connecting a rotation center (O) and a radially outer end (3o) of the ball end cutting edge (3), in a front view of the tool. In the ball end mill, a rake angle (?) of each portion of the ball end cutting edge (3) is set in a range from ?10° to 0°, and the negative value of the rake angle (?) is increased from a tip of the ball end cutting edge (3) and a radially outer end (3o) of the ball end cutting edge (3) toward a middle point in the radial direction, and is maximized at approximately the middle point in the radial direction.

Abstract: 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 located in the second half-sector in a direction away from the first half-sector. The blended gash blends an end gash surface and flute rake surface of the corner radius end mill.

Abstract: A radius end mill including an end mill body which is rotated around an axis thereof; a chip discharge flute being provided at an outer periphery of a tip portion of the end mill body; a gash being provided at a tip portion of the chip discharge flute; a rake face being formed on a wall face facing an end-mill rotational direction in the chip discharge flute or the gash; a cutting edge being formed on the rake face; the cutting edge including an end cutting edge, an outer peripheral cutting edge, and a convex circular-arc-shaped corner cutting edge; the end cutting edge being formed at a side ridge portion on the tip portion of the rake face; the outer peripheral cutting edge being formed at a side ridge portion on the outer peripheral side of the rake face; the convex circular-arc-shaped corner cutting edge being formed at a corner side ridge portion formed by the end cutting edge and the outer peripheral cutting edge; wherein the corner cutting edge has a positive cutting edge inclination angle; and the por

Abstract: End mills are disclosed which may be made monolithically of ceramic or other materials. The cutting portions of the end mills have lengths of cut that are no more than twice their cutting diameters and cores which are at least 0.7 times their cutting diameters. Their axial blades have cutting edges with negative radial rake and are separated by helical flutes. Their cutting ends have negative axial rake and are gashed ahead of center and have radial cutting edges with negative rake. Such end mills also have radiused corners and gashes transitioning from radial to axial at a flute. Methods of milling materials using such ceramic end mills are also disclosed.

Abstract: An end mill comprising: an odd number of five or more outer peripheral cutting edges formed around a front end portion of the end mill body, the outer peripheral cutting edges being twisted about the axis to a rearward side of a rotational direction of the end mill from a front end of the end mill body toward a rear end side thereof and being arranged at intervals in a circumferential direction; and bottom cutting edges which are formed at the front end of the end mill body so as to respectively extend from tips of the outer peripheral cutting edges toward the axis, and wherein the outer peripheral cutting edges have different helix angles with respect to the axis between the outer peripheral cutting edges adjacent to each other in the circumferential direction.

Abstract: A dielectric structure including a metal foil, a dielectric layer and a conductor layer provided in this order, wherein the metal foil has a thickness of from 10 to 40 ?m, the dielectric layer has a thickness of from 0.3 to 5 ?m, and the conductor layer has a thickness of from 0.3 to 10 ?m. The dielectric structure has plural vias which are separated from each other, and which penetrate through both of the dielectric layer and the conductor layer. The vias of the dielectric layer have different diameters which are in a range of from 100 to 300 ?m, a diameter of each of the vias of the conductor layer is larger than a diameter of a corresponding via of the dielectric layer by 5 to 50 ?m, and a minimum via pitch is from 100 to 350 ?m.

Abstract: A face milling cutter has a shank portion adjoining a cutting portion. The cutting portion terminates in a plurality of cutting edges extending in a radial direction from a central axis of the face milling cutter. The cutting edges are convexly curved at least along a part of their length. A portion of the cutting edges proximate the central axis is nearer in an axial direction to the shank portion than a point, X, on the cutting edges that is farthest away from the shank portion. A distance Y, between the point, X, and the central axis is between 20% and 40% of a diameter, D, of the face milling cutter, and a central portion extends the distance, Y, and has a radius of curvature of about 110% of the diameter, D.

Abstract: An end mill for machining titanium includes a cutting portion having blunt teeth alternated with flutes. Each flute includes, in order from the cutting edge, a rake surface, a concavely shaped bending portion, a convexly shaped ejecting portion and a tooth relief edge. The convexly shaped ejecting portion has an ejection height E, which is measurable between an apex of the ejecting portion to an imaginary straight line extending from a nadir of the adjacent bending portion of the flute to the adjacent tooth relief edge. In a plane perpendicular to a rotation axis of the end mill, the ejection height E and a cutting portion diameter DE, fulfill the condition 0.010DE<E<0.031DE.

Abstract: An end mill for machining titanium includes a cutting portion having blunt cutting edges alternated with flutes. Each flute includes, in order from the cutting edge, a rake surface, a concavely shaped bending portion, a convexly shaped ejecting portion and a tooth relief edge. The convexly shaped ejecting portion has an ejection height E, which is measurable between an apex of the ejecting portion to an imaginary straight line extending from a nadir of the adjacent bending portion of the flute to the adjacent tooth relief edge. In a plane perpendicular to a rotation axis of the end mill, the ejection height E and a cutting portion diameter DE, fulfill the condition 0.010DE<E<0.031DE.

Abstract: To provide a tool that can reduce the maximum value of cutting resistance when adjacent peripheral edges cut a workpiece simultaneously. A lead L of a spiral flute 21, a waveform pitch P, the number of edges N of peripheral edges 22, and a natural number m are set to satisfy L/N=m×P?P/N±P/2 or L/N=m×P+P/N±P/2, the waveforms of adjacent ones of the peripheral edges 22 at the positions where they contact a workpiece simultaneously are in an anti-phase relationship when the adjacent peripheral edges 22 cut the workpiece simultaneously. Therefore, there is an effect that the length of the cutting edges that contact the workpiece simultaneously is shortened to reduce the maximum value of cutting resistance.

Abstract: A multi-flute endmill including a cutting edge part having multiple cutting edges and flutes formed between adjacent cutting edges in a rotation direction around the tool axis O. A rake face of each cutting edge is formed from a rake face of an end cutting edge from the tool axis O side to the outer peripheral side of a shank, an adjacent rake face of a corner R edge that forms a surface different from the rake face of the end cutting edge, and an adjacent rake face of a peripheral cutting edge that forms a surface different from the rake face of the corner R edge. A gash is formed between the rake face of the end cutting edge and a flank of an end cutting edge that is adjacent on a forward side thereof in the rotation direction R.

Abstract: An end mill having a plurality of teeth configured for both roughing and semi-finishing applications, the teeth being alternated with a plurality of flutes. At least one tooth of the plurality of cutting teeth is a serrated tooth formed with serrations along a relief surface thereof and at least one other tooth is free of serrations. Each tooth of the plurality of cutting teeth includes an actual internal cutting angle formed at an intersection of a rake cutting sub-surface and a relief surface. The actual internal cutting angle of each tooth has a greater value than an imaginary internal cutting angle formed at an intersection of imaginary extension lines of a rake recessed sub-surface and a relief surface of the same tooth.

Abstract: 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 located in the second half-sector in a direction away from the first half-sector. The blended gash blends an end gash surface and flute rake surface of the corner radius end mill.

Abstract: A milling tool (21) includes a tool body (23) having a longitudinal axis (A) and a first end (25), a plurality of flutes (27) provided in the tool body (23) and extending to the first end (25) of the tool body (23), and a plurality of cutting edges (29r, 29u), each cutting edge being associated with a respective one of the plurality of flutes (27), each cutting edge being substantially identical to each other one of the plurality of cutting edges except that at least one but not all of the cutting edges is a recessed cutting edge (29r) and at least one but not all of the cutting edges is a non-recessed cutting edge (29u), each recessed cutting edge (29r) beginning at a non-zero distance from the first end (25) of the tool body (23) and each non-recessed cutting edge (29u) extending to the first end (25) of the tool body (23).

Abstract: A rotary cutting tool or end mill is provided, the tool comprising a plurality of pairs of diametrically-opposed, symmetrical, helical flutes formed in a cutting portion of the tool body, wherein the pitch between at least one pair of adjacent helical flutes is less than or greater than the pitch of at least one other pair of adjacent helical flutes in at least one radial plane along the axial length of the flutes, a plurality of peripheral cutting edges, wherein at least one of the peripheral cutting edges has a radial rake angle different from radial rake angle of a peripheral cutting edge of a different helical flute.

Abstract: Embodiments of the disclosure provide a drill bit including a drill bit body having a central axis. A first cutting edge is disposed on the drill bit body at a first radial distance from the central axis as measured within a plane normal to the central axis. And a second cutting edge is disposed on the drill bit body at a second radial distance from the central axis as measured from within the plane. The first radial distance is less than the second radial distance.

Abstract: A variable lead end mill has a plurality of peripheral cutting edges with different helix angles, the variable lead end mill having a flute bottom diameter of a plurality of helix flutes making up rake faces of the plurality of the peripheral cutting edges, the flute bottom diameter increasing in an axial direction from a tool tip toward a shank.

Abstract: An end mill including multiple spiral flutes in a helical shape around an axis that are formed in a periphery of the top portion of an end mill body which rotates on the axis. Cutting edges are formed at peripheral side ridge portions of wall surfaces of the flutes facing a front side in an end mill rotating direction. Honing is applied along each peripheral cutting edge such that the cutting edge has a variable honing width in the direction of the axis.

Abstract: In the tip section of an end mill body, a plurality of end cutting edges are formed. In the outer peripheral section of the end mill body, a plurality of peripheral cutting edges are formed. Some of the plurality of end cutting edges are long end cutting edges. The angle which is formed by the straight line that connects the axis to a peripheral cutting edge continuous with a long end cutting edge and by the straight line that connects the axis to a peripheral cutting edge continuous with the end cutting edge positioned in forward of the long end cutting edge in the end mill rotation direction, is larger than the angle which is formed by the tangent lines at the inner ends of the long end cutting edge and the end cutting edge positioned in forward of the long end cutting edge in the end mill rotation direction.

Abstract: A combination milling bit and cutter employed to machine a distal end of a workpiece is provided, in which the milling cutter includes a handle and a cutting portion formed on an end of the handle. The cutting portion includes two cutting edges; at least one of the two cutting edges comprises one cutting sub-edge for milling the distal end of the workpiece to form an end surface, and another cutting sub-edge for chamfering the distal end of the workpiece at both an annular outer chamfering surface and an annular inner chamfering surface on the distal end. The combination milling and cutting cutter device carries out both milling and cutting actions in a single operation.

Abstract: A rotating cutting tool (10, 110) includes a body (12, 112) with a longitudinal axis (14, 114) and at least one flute (16, 116) and one active part (18, 118). Each active part has a peripheral surface including: a radial cutting edge (20, 120) that is at a cutting distance (Rc) from the longitudinal axis, a clearance face (30, 130) that is at a final clearance distance (Rd) from the longitudinal axis, and a control face (40, 140) that is at a penetration control distance (Rp) from the longitudinal axis. These distances satisfy the relation: 0<?p<?d, with ?p=|Rc?Rp| and ?d=|Rc?Rd|.

Abstract: Providing an end mill for reducing the use of the cutting fluid to prevent the environmental pollution. Because the end mill 1 includes the openings 5a which open along spiral grooves 4, and the openings 5a communicate with the aperture on the rear end surface of the shank 2 via the intake path 5, the chips generated in the cutting are aspirated forcibly from the openings 5a when air intake is performed via the intake path 5, and the aspirated chips can be discharged from the aperture on the rear end surface of the shank 2. As a result, because the use of cutting fluid for discharging the chips can be reduced (or unnecessary) in comparison with conventional products, environmental pollution can be prevented.

Abstract: End mills are disclosed which may be made monolithically of ceramic or other materials. The cutting portions of the end mills have lengths of cut that are no more than twice their cutting diameters and cores which are at least 0.7 times their cutting diameters. Their axial blades have cutting edges with negative radial rake and are separated by helical flutes. Their cutting ends have negative axial rake and are gashed ahead of center and have radial cutting edges with negative rake. Such end mills also have radiused corners and gashes transitioning from radial to axial at a flute. Methods of milling materials using such ceramic end mills are also disclosed.

Abstract: The present invention relates to an end mill, which comprises a bottom edge, which is composed of an arc-shaped cutting edge that is curved when seen from a direction perpendicular to the tool axis and a linear or curved medium-to-low inclination cutting edge, and a peripheral edge, wherein, when seen from a direction parallel to the tool axis, the arc-shaped cutting edge and a rim at the rearward side of the rotation at a flank of the arc-shaped cutting edge are curved with radii of curvatures, and the radius of curvature of the arc-shaped cutting edge is smaller than the radius of curvature of the rim at the rearward side of the rotation at the flank of the arc-shaped cutting edge.

Abstract: In a shank portion of an end mill which is chucked by a tool holder, flat surfaces are formed at a plurality of circumferential positions in the outer periphery of the shank portion so that the flat surfaces abut on side lock bolts attached to a body of the tool holder.

Abstract: This aims to provide a ball end mill capable of preventing the occurrence of a ‘pluck’ off a work face. The ball end mill (10) is equipped with two cutting edges (11 and 12) formed at its spherical tips. The rake face (11a) of the cutting edge (11) has its inner circumference end arranged at a position offset farther forward of a rotating direction than a spindle. The rake face (11a) of the cutting edge (11) has its inner circumference end arranged at a position protruding by a predetermined distance from the spindle to the opposite side of the cutting edge forming side in the radial direction. The portion of the cutting edge (11) from a connecting portion (11f), which is formed midway of a ridgeline (11c) or a boundary line between the rake face (11a) of the cutting edge (11) and a flank (11b), to the outer circumference end of the cutting edge (11) is a main cutting edge (11m).

Abstract: A rotating tool includes a tool body including a first end and a second end. A plurality of first helical flutes extend from the first end of the tool body, each first helical flute of the plurality of helical flutes defining a respective first cutting edge. A plurality of second helical flutes intersect with the first helical flutes at non-zero distances from the first and the second ends of the tool body, each second helical flute of the plurality of second helical flutes defining a respective second cutting edge. The first helical flutes and the second helical flutes are of opposite hands. The first helical flutes have a first pitch and the second helical flutes have a second pitch. A plurality of chip divider recesses are formed along each first cutting edge.

Abstract: An end mill includes first cutting edges which spiral in a direction defining a positive helix angle and second cutting edges which spiral in a direction defining a negative helix angle, the first cutting edges and the second cutting edges being disposed at positions shifted in a circumferential direction. The first cutting edges and the second cutting edges are each configured to be continuous over an effective cutting edge length. At an axially forward end of the end mill, a first phase angle between one of the first cutting edges and its adjacent second cutting edge located adjacent to the first cutting edges in an opposite direction to a tool rotation direction is set to be different from a second phase angle between the second cutting edge and its adjacent first cutting edge located adjacent to the second cutting edges in the opposite direction to the tool rotation direction.

Abstract: An end mill body wiih a corner cutting edge forming a convex arc shape of which the rotation locus becomes convex toward the tip outer peripheral side is formed at a side ridge portion of the corner cutting edge rake face, a gash is formed on the inner peripheral side of the corner cutting edge rake face, and an end cutting edge connected to the corner cutting edge and extending toward the inner peripheral side is formed at a tip-side side ridge portion of the end cutting edge rake face. An intersection line between the corner cutting edge rake face and the end cutting edge rake face is located closer to the radial inner peripheral side with respect to the axis than the center of the convex arc that the corner cutting edge forms in the rotation locus.

Abstract: A cutter for milling of workpiece includes a cutter body, a first cutting portion, and a second cutting portion formed between the cutter body and the first cutting portion. The first cutting portion carries out primary machining on the workpiece. The first and second cutting portions extend in opposite twists or helixes along a central axis of the cutter body and are rotated in opposite directions during machining.

Abstract: A method of removing an end-surface burr of a formed groove cut into a workpiece by rotationally driving around an axial center and moving a formed rotary cutting tool relative to the workpiece in a direction orthogonal to the axial center, by using a formed rotary cutting tool for chamfering acquired by deforming a radial shape of the formed rotary cutting tool used in cutting of the formed groove according to a predefined chamfer angle, and by rotationally driving around an axial center and moving the formed rotary cutting tool for chamfering relative to an end surface of the formed groove in a direction perpendicular to the axial center along an axial center movement locus forming the chamfer angle relative to an axial center movement locus of the formed rotary cutting tool in the cutting of the formed groove, chamfering for removing a burr on the end surface is performed.

Abstract: A cutter element (100) for a rotary machine tool having an axis of rotation, the cutter element comprising a plurality of cutting edges (110) defined by at least one cutter structure (120) comprising superhard material, consecutive cutting edges being spaced apart by at most 10 mm and configured operable to cut a body when moved in a direction that is substantially non-aligned with the axis of rotation.

Abstract: An unequal helix-angle end mill includes a cutting part and a handle part. The cutting part is provided with a plurality of flutes, each spirally extending from the bottom end to the handle part. The face of each flute facing the cutting rotation direction is a rake face, wherein the rake face and an outer peripheral face of the cutting part are intersected to form an outer peripheral blade, and the helix-angle of at least one of the peripheral blades is different from those of the other peripheral blades. A face joined with the peripheral blade among the outer peripheral face of the cutting part is a rear face. The width B of the edge flap of each peripheral blade is equal on a plane orthogonal to a rotating axis of the end mill. The unequal helix-angle end mill has high strength, and enhances the cutting depth and durability.

Abstract: To provide a rotary cutting tool in which a satisfactory cut state in which burrs and uncut portions are absent is obtained, even when counterboring is applied to a composite honeycomb member.

Abstract: Disclosed herein is an end mill capable of preventing an increase in cutting resistance, chipping, or damage due to cutting chip clogging from being generated in each bottom cutting edge having a small pitch in a rotational direction side of the end mill even when the pitches between the bottom cutting edges in a circumferential direction of each thereof differ from one another. An end mill includes an end mill body which is rotated about an axis thereof; an odd number of five or more outer peripheral cutting edges formed around a front end portion of the end mill body; and bottom cutting edges which are formed at the front end of the end mill body so as to respectively extend from the tips of the outer peripheral cutting edges toward the axis, wherein the outer peripheral cutting edges have different helix angles with respect to the axis.

Abstract: A rotary cutting tool or end mill is provided, the tool comprising a plurality of pairs of diametrically-opposed, symmetrical, helical flutes formed in a cutting portion of the tool body, wherein the pitch between at least one pair of adjacent helical flutes is less than or greater than the pitch of at least one other pair of adjacent helical flutes in at least one radial plane along the axial length of the flutes, a plurality of peripheral cutting edges, wherein at least one of the peripheral cutting edges has a radial rake angle different from radial rake angle of a peripheral cutting edge of a different helical flute.

Abstract: A milling cutter includes a shank portion and a cutting portion having a cylindrical outer surface. The milling cutter includes a plurality of major cutting edges extending from an end face toward the shank portion, and a plurality of minor cutting edges disposed at the end face of the cutting portion. A relief surface is formed in the cylindrical outer surface proximate a corner of the milling cutter such that the primary cutting edges forms an angle equal to 90° with respect to the end face of the milling cutter. As a result, the milling cutter is capable of cutting a perfect 90° shoulder in a workpiece.

Abstract: The invention provides an end mill having an improved chip discharging performance and capable of carrying out excellent cutting machining. The end mill includes an end cutting edge (2) provided on a front end of a tool body (1) which rotates around a central axis, a peripheral cutting edge (4) provided on an outer periphery of the tool body (1), a rake surface of the end cutting edge (2) and the peripheral cutting edge (4), and at least one recess (6), which locally breaks the continuity of the end cutting edge (2) is provided, wherein a wall section (8) which extends toward the rear of the outer peripheral side is provided at least in that area of the rake surface (3) which is closer to the outer peripheral side than the recess (6).

Abstract: A rounded nose end-mill modified by optimization of geometrical parameters of both the rake angle and relief angle along the cutting edge of the rounded portion, wherein the rake angle and the relief angle gradually increase along the cutting edge from the full diameter of the rounded portion to the tip.

Abstract: Disclosed are systems and methods of beveling gripping holes of bowling balls. A method includes creating a bevel at an edge of a hole of the bowling ball by removing material from the bowling ball using a rotary tool equipped with a shaping bit that extends into the hole.

Abstract: Provided is an end mill wherein: the generation of burrs can be controlled according to the various machining conditions and/or to the board thicknesses of the various work pieces to be machined; and smooth machining work can be carried out, with good chip removal performance, and with a finished surface of excellent quality. In this end mill, an end mill body 1 rotatable on an axis O has a cutting edge section 3 which provides first peripheral cutting edges 4A which are handed and helically shaped around the axis O, and second peripheral cutting edges 4B with a linear shape extending straight in parallel to the axis O. Further, the first peripheral cutting edges 4A are right-handed helical and right hand teeth formed as a helical shape handed in the end mill rotational direction T from the rear side to the top side.

Abstract: An end mill having a gash formed in a top portion of a flute. In a cross-section perpendicular to an intersecting ridgeline between an end cutting edge rake face and a gash bottom face of the gash, the gash bottom face and the end cutting edge rake face, and the gash bottom face and the gash wall face are respectively connected together by first and second connecting faces. The connecting faces have a form which either is a concave curve or a substantially concave curve formed with straight lines. A radius of curvature of the concave curve or the radius of a circle inscribed within straight lines forming the substantially concave curve about the front connecting face is larger than a radius of curvature of the concave curve or the radius of a circle inscribed within the straight lines forming the substantially concave curve about the second connecting face.

Abstract: A cutter includes a cutter body, a first cutting portion and a second cutting portion. The first cutting portion is used for primary machining. The second cutting portion is used for precision machining, and is formed between the cutter body and the first cutting portion.

Abstract: A cutting tool, and a loose top therefore, includes two parts detachably connected to each other via a threaded joint in which co-operating male and female threads are included in the form of helicoidal ridges. The profile shape of each helicoidal ridge is defined by a top and two flanks, which delimit a helicoidal groove having a bottom. The first flank is inclined in relation to a center axis of the tool at a first angle that is smaller than a second angle of the second flank in relation to the center axis. Accordingly, the thread ridge is reinforced in comparison with thread ridges having a symmetrical profile shape, whereby larger tensile forces than compressive forces can be applied to the threaded joint while avoiding damage to the thread ridges.

Abstract: End mills are disclosed which may be made monolithically of ceramic or other materials. The cutting portions of the end mills have lengths of cut that are no more than twice their cutting diameters and cores which are at least 0.7 times their cutting diameters. Their axial blades have cutting edges with negative radial rake and are separated by helical flutes. Their cutting ends have negative axial rake and are gashed ahead of center and have radial cutting edges with negative rake. Such end mills also have radiused corners and gashes transitioning from radial to axial at a flute. Methods of milling materials using such ceramic end mills are also disclosed.

Abstract: A chatter-resistant end mill and a method of making such an end mill, in which the teeth of the end mill are unequally spaced apart to substantially reduce or eliminate vibrations produced during cutting of a work piece.

Abstract: A helical multilevel cutting tool has high heat emission efficiency, great strength and excellent durability, and can be positioned easily during drilling operation. The cutting tool includes a cutter shank and a cutter head which are integrally formed, wherein the cutter head is provided with several helical pieces integrally, each helical piece has a cutting blade thereon, a heat emission platform is formed along the cutting blade, a second cutting blade which faces forwardly as viewed in the direction of the cutting operation is formed in front of the heat emission platform, and a cutting blade outer surface is formed between the heat emission platform front surface and the second cutting blade. An outer front cutting blade is formed on the top surface of the cutter head at a position where the blade meets the heat emission platform front surface, and a front cutting blade is formed between the second cutting blade and the center of the cutter head top surface.

Abstract: In the tip section of an end mill body, a plurality of end cutting edges are formed. In the outer peripheral section of the end mill body, a plurality of peripheral cutting edges are formed. Some of the plurality of end cutting edges are long end cutting edges. The angle which is formed by the straight line that connects the axis to a peripheral cutting edge continuous with a long end cutting edge and by the straight line that connects the axis to a peripheral cutting edge continuous with the end cutting edge positioned in forward of the long end cutting edge in the end mill rotation direction, is larger than the angle which is formed by the tangent lines at the inner ends of the long end cutting edge and the end cutting edge positioned in forward of the long end cutting edge in the end mill rotation direction.

Abstract: An end mill including multiple spiral flutes in a helical shape around an axis that are formed in a periphery of the top portion of an end mill body which rotates on the axis. Cutting edges are formed at peripheral side ridge portions of wall surfaces of the flutes facing a front side in an end mill rotating direction. Honing is applied along each peripheral cutting edge such that the cutting edge has a variable honing width in the direction of the axis.

Abstract: There is provided an exceptionally practical rotary cutting tool allowing the life of the tool to be prolonged. The rotary cutting tool has a plurality of helically shaped swarf discharge flutes (2) formed on a periphery of a tool body (1) from a leading end towards a trailing end, and a peripheral blade (4) formed on an intersecting ridgeline of a rake surface (3) of the swarf discharge flutes (2) and the peripheral surface of the tool body (1). A back taper part (B), on which an outside diameter (D1) of the peripheral blade (4) and an inside diameter (D2) of the tool body (1) gradually decrease from the leading end of the tool towards the trailing end, is provided to the leading end of the tool body (1).