Abstract: A method or process for making polycrystalline diamond or polycrystalline CBN cutting tools (Superabrasives), which have integral chip-breaking features is disclosed. This method involves pressing a die or other like rigid component against either the outer can cover or the diamond or CBN region directly. This invention provides economical manufacture of diamond chip-breaker tools, while avoiding unnecessary EDM EDG, grinding, or laser processes. This process forms the chip-breaker on the upper surface of the diamond region, during or prior to sintering. This invention permits a wide variety of chip-breaker or other diamond surface features, while minimizing cost and processing steps. Disclosed embodiments include: pressing through the can assembly; pressing within the assembly by introducing a rigid component in the can; and pressing two cans together with an intervening rigid component imposing the desired diamond surface features.

Abstract: A method for applying cutting elements to a tool for cutting or milling a metal item in a well is disclosed, along with the cutting element used in the method. The tool can include one or more blades extending outwardly or downwardly from the tool for cutting a metal item such as the wall of a casing string, or for removing a predetermined length of a casing string in a cutting action. The blade or blades have cutting elements positioned on the leading faces of the blades to engage the casing string or other metal item in the bore hole. Each cutting element is composed of a plurality of effective cutting faces. Each cutting face can have a substantially triangular shape, or a substantially square shape, or some other geometric shape. The cutting elements can be arranged in a random pattern. Each cutting element can be oriented in a random orientation relative to the blade.

Abstract: A screwing plate or thread cutting bit comprising at least one cutting tip whose contour matches the desired shape of the threading. The cutting tip is configured as a chip forming element which is shaped in the form of a spur located between both sides of the cutting faces. The chip forming element rises above the cutting faces more or less in the form of a table mountain. The flanks of the spur, which are slanted in the form of inclined walls, are spaced at different distances from the adjacent cutting edges so as to form cutting faces with differing widths.

Abstract: An indexable cutting insert for use with a cutting tool includes an insert body having a first surface and a side relief surface defining a cutting edge adjacent the intersection of the first surface and the side relief surface. A chip breaking structure is interposed between the first surface and the cutting edge. The chip breaking structure includes first and second series of wedges. Each series of wedges is disposed inwardly from the cutting edge and the wedge series are disposed in orthogonal or normal relation to one another. In a preferred arrangement, the narrow edges of the first and second series of wedges are aligned with one another.

Abstract: The invention concerns a cutting insert (10) for drilling. Said cutting insert (10) has a substantially rhomboid basic shape and its four cutting edges (20, 30), which each form cutting corners (15, 16), are broken, two first opposite cutting edges (20) each having cutting edge sections (21, 22) which form an obtuse angle (&egr;1) of between 140 and <180°. The two second opposite cutting edges (30) have a constriction, such that two cutting edge sections (31, 32) forming an angle (&egr;2) of >180° and 230° are produced. The invention further concerns a drill, wherein at least two of said cutting inserts are disposed on the front face of the shank, each disposed in a recess. The radially outer cutting insert has a concave active cutting edge and the radially inner cutting insert has a convex active cutting edge.

Abstract: An indexable insert for metal cutting having an upper surface, a bottom surface and side surfaces. At least a portion of the intersecting lines between the side surfaces and the upper surface generates a main cutting edge, a secondary cutting edge and a corner cutting edge. The corner portions of the upper side are provided with recesses. The corner cutting edge including at least two radiused edges having different radii. The first radiused edge, having a larger radius, being located adjacent to the main cutting edge and a second radiused edge, having a smaller radius, being located adjacent to the secondary cutting edge. Furthermore, the secondary cutting edge includes a radiused edge having a larger radius than the two aforementioned corner radiused edges and the recess includes a rear plane being so arranged that the chips hit a rear plane of the upper surface and break against the rear plane.

Abstract: A turning insert, preferably for internal machining, includes a polygonal body of hard wear resistant material, which has an upper surface and a lower surface provided in separate substantially parallel planes and a number of side surfaces each interconnecting the upper and lower surfaces. A first side surface is a leading edge surface, and a second side surface is a trailing edge surface during machining. At least one chip former is provided. At least one rounded cutting corner having cutting edges is formed at an intersection of the two side surfaces. The cutting corner defines a bisector plane. The chip former is asymmetrically arranged relative to the bisector plane. The chip former has a surface that is provided in the plane of the upper surface. The surface is provided at substantially one side of the bisector plane and the convex portion of the chip former has a lower edge intersected by the bisector plane at least twice.

Abstract: A drilling tool including a substantially columnar tool body rotatable about an axis, the tool body having a chip discharge groove formed in the outer periphery thereof opened at a distal end surface of the tool body; and a cutting edge having a rake face and extending from an end adjacent to the axis toward the outer periphery of the tool provided along a crossing ridge between a wall surface of the chip discharge groove facing in a circumferential direction of the tool and the distal end face. In the drilling tool, a concave surface rises in the circumferential direction of the tool with respect to the rake face of the cutting edge, the concave surface forming a concave curve advancing toward the distal end face of the tool in the circumferential direction of the tool, the concave surface being formed between the crossing ridge and the distal end face.

Abstract: A tangential cutting insert has a body with an operative front surface associated with upper and lower main cutting edges, side auxiliary cutting edges and corner cutting edges therebetween. All cutting edged have rake surfaces formed at the front surface and extending from their associated cutting edges in an inward direction of the cutting insert. The cutting insert has an imaginary reference plane passing through extremities of the cutting corner edges thereof. Each of the main cutting edges extends from its associated comer edges in an inward direction of the cutting insert away from the reference plane.

Abstract: An indexable insert having a tip body formed of a polygonal flat plate. An upper surface of the tip body serves as a rake face, and edges are formed along ridges defined by sides of the rake face. Nose portion edges are formed at corners of the rake face at which the edges adjacent to each other intersect. The nose portion edges each have a rake angle varied between both ends of the nose portion edge.

Abstract: The invention relates to a cutting insert (10) with 8 usable cutting edges and with large longitudinal surfaces, each comprising a protruding rib (20) in the center along their longitudinal axes. The cutting edges (13) defining said longitudinal surfaces form an angle of 70°<(90°−&bgr;)<90° with their respective ends and the short rounded edges (14) of the upper and lower surfaces (11, 12). According to the invention, milling tools are fitted with a plurality of such cutting inserts.

Abstract: Disclosed is a cutting insert capable of enhancing the surface roughness of worked materials and lengthening the durability of a cutting tool which has utilized in conjunction with the cutting insert, capable of efficiently removing cut chips from the cutting region by making a chip breaker into a complete free curved surface to discharge the cut chips in the most natural direction and form, which are formed when performing a desired cutting operation of ferrous or nonferrous metals such as aluminum, copper, stainless, etc., to also minimize the resistance to chip flow and the occurrence of the melted-sticking phenomenon. The cutting insert has a specific chip breaker formed on an upper surface thereof with the aid of a pressure molding operation using a mold and in a sintering operation. A lower surface of the cutting insert is formed as a plane. The lower surface is firmly fixed on a holder for cutting tool and supports the cutting insert when mounting the cutting insert in the holder for cutting tool.

Abstract: A rhombic shaped metal cutting insert is adapted for longitudinal turning and copy turning. Opposing nose corners of the insert form equal angles less than 60 degrees. A pair of side cutting edges converge toward each of the nose corners. The side cutting edges of each pair form obtuse angles with respective side cutting edges of the other pair. A longest diagonal extending through the insert intersects both of the nose corners and forms an acute angle relative to a diagonal which bisects both of the obtuse angles. Each nose corner has a corner cutting edge formed by a plurality of curved segments. First and second ones of those segments are disposed on opposite sides of the longest diagonal and together form an angle of about 90°. Situated between the first and second segments is a third segment which is intersected by the longest diagonal. Adjacently disposed ones of the curved segments at each corner have radii that are different from one another.

Abstract: A face-milling tool includes a milling body forming seats arranged around an axis of rotation of the body. The seats carry identical inserts, each insert being of tetragonal or pentagonal, or hexagonal shape. Each insert includes first and second side faces. Each side face includes a pair of minor cutting edges at each corner of the insert. Two major cutting edges intersect respective ones of the minor cutting edges whereby each major cutting edge and its associated minor cutting edge together form a cooperating pair of cutting edges. There are two of those cooperating pairs at each corner of each side face, whereby there are at least sixteen cooperating pairs on the insert. The minor cutting edges, which function to generate a surface on a workpiece, are sharper than the major cutting edges. During a milling operation the insert is oriented so that only one cutting corner engages a workpiece, and only one of the cooperating pairs of cutting edges of that cutting corner is active.

Abstract: A cutting insert includes an upper chip surface, a bottom surface and side faces therebetween. At each of the end faces the cutting insert has axially protruding portions, each of which appears with a bevel face. Main cutting edges are provided in the intersection between the chip surface and the side surfaces. On each side surface is provided a clearance surface formed on a protruding portion which via a step clearance extends into a secondary helically twisted clearance surface, the chip angle of which increases with increasing cutting depth. The upper face includes along the main cutting edges a planar inclined surface with constant width that extends inwards and intersects with an upwardly inclined secondary chip breaking surface.

Abstract: The cutting insert disclosed is a block of hard metal configured on at least one of its major faces to provide peripheral cutting edges successively index able about a central fastener location to position each edge serial for cutting. The major face slopes downwardly and inwardly from the cutting edges to provide rake surfaces of positive rake behind the cutting edges, and then rises as a sloping ledge to a central boss. A series of depressions disposed along the rake surface produce a ribbed chip which breaks more readily, and into smaller chips, easier to flush or otherwise remove from the cutting site.

Abstract: A method of altering an insert blank by disposing one or more of four shapes at a predetermined location on the blank to provide at least one sharpened edge. The blank can be either a new insert or one that has been dulled and is due to be discarded. The four shapes are a compound shape, a radius and flank shape, a bias helical shape and a helical rake shape. The bias helical shape and the helical rake shape can be either positive or negative. The radius and flank shape can be either concave or convex. The shapes can be ground on a blank using standard grinding machinery.

Abstract: A method for applying cutting elements to a tool for cutting or milling a metal item in a well, along with the cutting element used in the method. The tool can include one or more blades extending outwardly or downwardly from the tool for cutting a metal item such as the wall of a casing string, or for removing a predetermined length of a casing string in a cutting action. The blade or blades have cutting elements positioned on the leading faces of the blades to engage the casing string or other metal item in the bore hole. Each cutting element is composed of a plurality of effective cutting faces. Each cutting face can have a substantially triangular shape, or a substantially square shape, or some other geometric shape. The cutting elements can be arranged in a random pattern. Each cutting element can be oriented in a random orientation relative to the blade.

Abstract: The cutting insert 10 for removing metal from a workpiece includes an insert body 12 having a left-side wall 24, right-side wall 26, a top surface 28 defining a notch 16, a bottom surface 30 and an end region 20 defining a front cutting edge 60. A land region 42 includes a front land portion 44, a left-side land portion 45, and a right-side land portion 46 which together define a periphery of a chip control pocket 40. The chip control pocket 40 includes a front descending wall 47 and a rear ascending wall 48, a left-side descending wall 50 and a right-side descending wall 52. Each of the walls of the chip control pocket preferably has a curvilinear configuration. A protuberance 54 is spaced between the left-side descending wall and the right-side descending wall, and has an elongate top surface 56 spaced along a protuberance axis 66 preferably perpendicular to the front cutting edge 60.

Abstract: A cutting insert for milling comprises two major sides, two minor sides, and upper and lower sides. At least one pair of cutting edges is formed at the transition of the upper side with a major side and a minor side of the cutting insert. The upper side constitutes a chip surface, and the major and minor sides constitute clearance surfaces. Each pair of cutting edges comprises a major cutting edge extending along the major side, and a minor cutting edge extending along the minor side. The major and minor cutting edges intersect in the area of a cutting corner. The cutting corner is provided inside an imaginary extension line of a major part of the minor side. The major cutting edge slopes such that it forms an acute angle with the lower side. Each pair of cutting edges joins a first clearance surface protruding relative to a plane containing a major portion of the minor and major sides. Recesses are formed in the major sides.

Abstract: A boring tool includes a concave groove formed on the outer peripheral surface of a tool body on the side opposite from a cutting blade with respect to an axis of the tool body. The concave, groove 10 is formed so as to extend from a position x, which is separated rearwardly from a front end face of a head portion, toward the rear side, and to be open downward from above a rake face. Furthermore, a sub-groove is formed between the concave groove and a chip pocket. Accordingly, the natural frequency is increased by reducing the weight of the head portion while limiting rigidity reduction, thereby restricting chattering.

Abstract: A cutting insert is disclosed with triangular shapes imprinted on the top surface of the insert whereby the number of triangular shapes is representative of the cutting range for which the insert will function best. A method for imparting such shapes to the cutting insert is also disclosed.

Abstract: An exchangeable cutting insert comprises a front cutting portion having an operative front surface with two lower corners and at least one upper corner, and a trailing mounting portion extending rearwardly therefrom. The front cutting portion is formed with a major cutting edge extending between the two lower corners and a minor side edge extending between one of the lower corners and said upper corner. The minor side edge is substantially perpendicular to the major cutting edge. The major cutting edge has two trailing extremities associated with the lower corners, and having a leading extremity which protrudes outwardly and is raised upwardly relative to the trailing extremities.

Abstract: A cutting tool comprising a cutter body member having a generally circular shape, a front surface, a back surface and an axis of rotation, the cutter body member includes an outer portion comprising a plurality of individual projections arranged spaced from one another about the cutter body with the space between successive projections defining receiving slots for cutting blades. The individual projections each further comprise an outer surface with at least one of the outer surfaces including a protrusion. Each of the blade receiving slots comprises opposing first and second side surfaces and an inner end portion with the inner end portion having a pair of angled mounting surfaces, one of the mounting surfaces extends from the first side surface and the other mounting surface extends from the second side surface with the angled mounting surfaces extending toward one another. Each of the angled mounting surfaces is oriented at an angle of less than 90 degrees with respect to its respective side surface.

Abstract: A high pressure/high temperature process is disclosed for making polycrystalline diamond or CBN compacts having chip control surfaces formed thereon. Making these chip control surfaces is accomplished by pre-forming the indentations or raised dimples within the can used in the HP/HT process.

Abstract: An indexable cutting insert is disclosed capable of cutting operations over a wide range of depth of cuts. The insert has different geometries at different locations on the cutting surface such that, under differing cutting parameters, a desirable cutting surface will be in contact with the workpiece.

Abstract: The present invention relates to a cutting insert for enhanced chip control. The insert includes a rake surface extending partially along a side cutting edge of the insert to a transition location and extending inwardly toward the center of the insert. A deflecting surface extends upwardly and inwardly toward the center of the insert from the rake surface and beyond the transition location extends upwardly and inwardly from the side cutting edge.

Abstract: A tool bit for a tube end squaring tool includes a cutting edge produced by machining or grinding a hook radius in the tool bit stock on the entrance angle side of the cutting edge and an undercut portion within the hook radius just rearwardly of the cutting edge on the work entrance side thereof to cause separation from the hook radius area of metal chips parted from a metal workpiece by the cutting edge to reduce friction and workpiece metal buildup on or adjacent the cutting edge. The undercut configuration reduces manufacturing costs of the tool bit which otherwise would require additional finishing operations to obtain the same reduction of friction at the cutting edge area.

Abstract: A method of breaking chips is disclosed in which the chip generated during cutting is broken into small pieces by increasing the shear strain at the shear plane, which is the joint between the chip and the workpiece, until fracture occurs at the shear plane. This is achieved by forming the chip (1) generated during cutting into a lever, in which the head (11) of the chip is the load-lifting point receiving a force from a first plane (9), the contact between the chip (1) and a second plane (12) of the chip breaker is the fulcrum, and the root (8) of the chip, which joins the chip to the shear plane, is the force-exerting point exerting a force additional to the shear force acting along the shear plane to strain the material until fracture occurs at the shear plane.

Abstract: An indexable cutting insert for metal machining comprises an upper rake surface, a bottom surface and side surfaces that extend between the upper and bottom surfaces. Cutting edges are formed at the transitions between the side surfaces and the upper surface. Disposed along the cutting edges on the upper surface are elongated primary lands. Disposed inside of the lands is a chip-breaking depression. A raised land area to be ground is situated in the chip-breaker, so that the total grinding area of the upper surface becomes about as large as the total grinding area of the bottom surface. The insert can thus be ground by upper and lower grinding wheels which rotate simultaneously in opposite directions.

Abstract: A cutting insert for mounting on edge in the insert pocket of a toolholder. The cutting insert has a mounting surface parallel to the top surface of the insert and a second mounting surface angled relative to the top surface of the insert so that the insert may be mounted in a toolholder having either of these two surfaces. An insert mounted in a toolholder having an angled bottom surface is secured within the insert pocket with a greater lateral force.

Abstract: A cutting insert (1) has an insert body (2) with an upper central clamping surface (3) and a lower clamping surface (4) through which passes an axis of symmetry (A) about which the cutting insert is indexable. The insert body (2) has a pair of opposite and identical cutting end portions (8A,8B) disposed laterally with respect to the upper clamping surface. The cutting end portions (8A,8B) each have a rake surface (9A,9B), a front cutting edge (11A,11B) and side cutting edges (15A,16A,15B,16B). Planes (20A,20B) passing through the midpoints (21A,21B) of the front cutting edges (11A,11B) and being normal thereto are inclined in opposite senses with respect to the axis of symmetry (A) in an end view of the cutting insert.

Abstract: A milling cutting insert including a substantially prismatic body portion having an upper surface, a lower surface, side surfaces and at least one protruding nose-like cutting corner, having a rake surface merging with the upper surface and a wraparound relief flank surface having portions merging respectively with adjacent side surface meeting at the cutting corner, front and side cutting edges formed by the intersection between the rake surface and the wraparound relief flank surface, the cutting edges protruding outwardly relative to their respective side surface surfaces and being elevated relative to the upper surface with at least the side cutting edge sloping towards the lower surface.

Abstract: An indexable insert with a chip breaker configured such that chips produced under various cutting conditions from rough cutting to finish cutting can be disposed of in an optimum way. Protrusions are provided in a chip breaker groove to extend from a central land toward the respective corners of the insert. Each protrusion has a breaker wall which is concave and curved such that chips produced always collide against the breaker wall at an angle of 10.degree.-40.degree. so that the chips are curled helically with a helix angle of 10.degree.-40.degree. and broken into small pieces reliably.

Abstract: A round cutting insert, normally made of cemented carbide, for turning operations is provided. It comprises a top surface, a round clearance surface, and a bottom surface. The top surface comprises a number of main, circumferentially spaced chip-breaking grooves. Essential for the invention is that each of the main grooves comprises a further chip-breaking groove which is encircled by the main groove. Thanks to the superposed grooves, the insert becomes very versatile, with good chip control both at low and high feeds, as well as at small and large cutting depths.

Abstract: A cutting insert has upper, lower and side surfaces and at least one cutting edge formed adjacent the insert lower surface and extending between two adjacent insert corners so as to, at least partially, protrude outwardly therefrom. The cutting edge lies in a plane which slopes upwardly from the insert lower surface at an exterior acute angle .alpha. and which intersects the insert lower surface at an intersection line passing through end points of the cutting edge associated with the insert corners.

Abstract: A polygonal cutting insert with at least one rib-shaped raised elongated cutting component of the face arranged at a distance from the cutting edge and extending generally in the chip removal direction. The rib has a front end spaced inwardly of the cutting edge and a cross section increasing from the front end to a region at which the cross section is a maximum and then decreasing from that maximum to a rear end of the rib.

Abstract: A polygon shaped cutting tip for a metal workpiece boring tool, the cutting tip having linear side edges lying in a common plane and adjacent side edges which pass tangentially into rounded corner regions. Parts of the corner regions and of the side edges serve as the primary and secondary cutting edges of the tip. A chip breaker edge is arranged at a distance in from the side edges. A chip breaker surface extends from the side edge to the chip breaker edge. The chip breaker edge includes linear sections corresponding to the linear side edges of the tip and has curved sections which correspond to the curved regions of the side edges. The arc of curvature of both the curved regions and the curved sections is the same although the arcuate length of the curved sections is greater. The chip breaker surface extends from the side edges of the corner regions inward toward and downward into the tip at an acute angle where it intersects the chip breaker edges.

Abstract: A cutting insert includes a cemented carbide body having two main cutting edges joined by a corner cutting edge. A primary land extends behind the corner and main cutting edges. A chip breaker in the form of a micro ridge projects upwardly from a section of the primary land located in the vicinity of the cutting corner. The primary land has a width in the range of 0.1 to 0.8 mm, and the micro ridge has a width which is between 25 and 80 percent of the width of the primary land.

Abstract: A cutting insert for machining workpieces (preferably of metal) while removing the cuttings including at least one cutting edge (10) in the transition region between a rake (16) and a flank (18); the rake (16) comprises a flat face section (20) which is substantially parallel to the cutting edge (10) and several dome-shaped recesses aligned in a row and separated by gaps, the recesses being parallel to the cutting edge (10), and moulded into the face section (20) and partially penetrating the cutting edge (10). To ensure the uninterrupted removal of cuttings when short cuttings are produced, the invention proposes that a cutting form step (24) is provided on the face of the recesses opposite to the cutting edge (10). The cutting form step rises above the face section and is bounded by a bottom boundary line (26) on the cutting edge side and by a top boundary line (28) on the side away from the cutting edge.

Abstract: A milling tool 8 includes a tool holder 10 for housing multiple thread cutting inserts 24 for precise milling of threads on a workpiece. The tool holder 10 is rotatable in an orbitable path spaced radially from a milling axis and is simultaneously rotatable about its own axis for repeatedly bringing each of the cutting inserts into engagement with the workpiece. Each cutting insert is precisely positioned within the tool holder by a stop surface 62 located at an axially rearward end of an insert cavity 28 in the tool holder. An axially elongate tool holder groove 32 is provided in communication with a side face of the generally rectilinear insert cavity. Each cutting insert defines a substantially rectangular plate, an end face for mating engagement with the stop surface 62 and an axially elongate insert groove 26 extending from a corresponding side face on the rectangular plate.

Abstract: A tool bit for a tube end squaring tool includes a cutting edge produced by machining or grinding a hook radius in the tool bit stock on the entrance angle side of the cutting edge and an undercut portion within the hook radius just rearwardly of the cutting edge on the work entrance side thereof to cause separation from the hook radius area of metal chips parted from a metal workpiece by the cutting edge to reduce friction and workpiece metal buildup on or adjacent the cutting edge. The undercut configuration reduces manufacturing costs of the tool bit which otherwise would require additional finishing operations to obtain the same reduction of friction at the cutting edge area.

Abstract: A cutting insert for material removal machining includes a cutting face formed with a longitudinal cutting edge and with a succession of spaced apart rearwardly widening recesses extending along the cutting edge and at least one of the recesses having a respective rib extending along a longitudinal axis transversely to the cutting edge.

Abstract: A cutting insert is formed with a cutting surface, a side surface joining the cutting surface at a cutting edge, and a wedge-shaped chip-shaping element formed on and raised above the cutting surface. The chip-shaping element has a width that increases uniformly away from the cutting edge, a pair of generally planar side flanks extending at an acute angle to each other, ascending away from the cutting surface away from the cutting edge, and defining a rounded upper edge extending toward the cutting edge, and a rear flank descending from the side flanks toward the cutting surface away from the cutting edge.

Abstract: A rotary boring tool has a body formed relative to a normal forward cutting direction with a main cutting edge extending transversely of the direction, a pair of side cutting edges extending backward in the direction from ends of the main cutting edge, a substantially planar front face extending substantially perpendicular to the direction from the main cutting edge, and a curved cutting face extending backward in the direction from the main cutting edge between the side edges.

Abstract: A cutting tool, for milling, comprises a holder and a cutting insert. The cutting insert has a generally octagonal basic shape and has at least two cutting edges created by a transition between an upper face and an edge face of the cutting insert. The upper face constitutes a rake face and the edge face constitutes a clearance face, created at the transition of two adjacent cutting edges. The edge face forms a clearance angle of at least 20 degrees with a plane extending parallel to a center axis of the insert. The edge face is provided with a step which defines a fracture zone. The step forms an angle with a line extending perpendicular to the center axis. Cutting corners of the insert are beveled to form an angle greater than an angle formed by adjacent cutting edges.

Abstract: Disclosed is a lathe cutting tool assembly found of a tool holder which has a seat to accommondate a cutter insert, the cutter insert being provided with a clamping groove or bore. The insert is held in the tool holder by a clamping shoe. The clamping shoe is tightly secured to on the tool holder. To protect the clamping shoe and improve the seating of the cutter insert in the tool holder, a clamping plate is secured to the clamping shoe and lies upon the cutter insert. A projection is provided on the bottom of the clamping plate facing the cutter insert and is in clamping contact with the groove or bore. The tool assembly is especially adapted for a turning chisel.

Abstract: An indexable cutting insert comprises an upper surface, a bottom surface and side surface extending between said two surfaces. Between two adjacent cutting corners, a rake surfaces is formed such that the rake angle decreases with increasing cutting depth. In this way the cutting edge is reinforced towards a maximal cutting depth. This configuration is favorable, for example, at the machining of materials with a tendency of surface hardening.

Abstract: The invention is designed to improve a cutting performance and a spiral chip discharging ability. Main cutting edges 16 and auxiliary cutting edges 18 are formed along the respective sides of an upper surface 14 of a negative throw-away tip 12 and along side of bevelled corners, respectively. A rake face 22 of each main cutting edge 16 is gradually inclined toward a lower surface of the tip 12 by an angle of inclination .beta. along the extension of the main cutting edge 16 away from its adjacent auxiliary cutting edge 18 and by a rake angle .alpha. (>.beta.) along a direction perpendicular to the main cutting edge 16. The tip 12 is mounted on a cutter 9 as a rotatable cutting tool so as to discharge spiral chips during cutting. To this end, the tip 12 is mounted such that an axial rake angle, a corner angle, an angle of inclination, and a true rake angle are set in a range of -4.degree. to -10.degree., a range of 25.degree. to 60.degree., a range of 0.degree. or larger, and a range of -20.degree. to -5.

Abstract: The indexable insert possesses two parallel cutting edges on opposite sides of an indexable insert body in the form of a rectangular block. In the intermediately placed top surface descending toward the center line (M) there is a chipbreaking structure comprising alternating projections and recesses. These projections and recesses constitute a row, centered on the center line (M), of spherical-like chipbreaking bodies, between which concave chip guiding surfaces are formed. During metalcutting operations, this provides an even flow of chips with the formation of short chips which are free of grooves and tears along the edges.