WO2001038037A1

WO2001038037A1 - Method and apparatus for enhancing the bonding properties of a hard material mounting surface

Info

Publication number: WO2001038037A1
Application number: PCT/CA2000/001384
Authority: WO
Inventors: Laurent Martens
Original assignee: Laurent Martens
Priority date: 1999-11-22
Filing date: 2000-11-22
Publication date: 2001-05-31
Also published as: AU1644601A; CA2311516A1

Abstract

A process for enhancing the mounting surface of a hard surface comprises laser beam (21) cutting a void through the rotating mounting surface (11) and into the material (10), creating an undercut (40) for enhanced mechanical bonding properties. By repositioning the relative positions of the laser beam (21) and rotating suface (11), a plurality of different undercut voids (40) can be formed. Preferably the laser beam (21) can be pulsed and synchronized with the speed of rotation of the surface for cutting a pattern of undercut voids in the surface. Apparatus comprises a rotating plate (14) to which the material is temporarily affixed, a drive (23) for rotating the affixed mounting surface in its plane and a laser (20) which emits a laser beam (21) along an axis which intercepts the mounting surface and which is angled from the plate's axis (r) of rotation. A controller (25) and a two dimensional actuator control (31x31z) the relative coordinates of the intercept ofthe laser beam and mounting surface.

Description

METHOD AND APPARATUS FOR ENHANCING THE BONDING PROPERTIES OF A HARD MATERIAL MOUNTING SURFACE FIELD OF THE INVENTION The present invention relates to means for affixing natural diamond to a substrate such as metal or other materials, particularly for tool supports or holders. More specifically, a process is disclosed for machining a diamond, ceramic or hard metal mounting surface with a laser and the unique product resulting therefrom.

BACKGROUND OF THE INVENTION Non-gem quality diamond has unsurpassed wear resistance and is appropriately used in industrial applications such as machining and earth drilling. Natural diamond has many disadvantages which have resulted in a shift to the use of engineered polycrystalline forms. Some of the disadvantages of using natural diamond include its relatively brittle characteristics, and its size limitation. An alternative to natural diamond is the engineered polycrystalline diamond and man-made thick film diamond. Polycrystalline diamonds are referred to in the industry as

polycrystalline diamond compact or PDC. PDC diamonds are formed of a matrix of diamond grains, often mixed with powdered binder or silica. While PDC diamonds are more readily mounted to metal, they are not as strong and durable as naturally occurring diamond. Man-made thick film diamond is made using a technique called Chemical Vapour Deposition or CVD wherein chemicals are deposited on the bonding surface in a gas and, under ideal conditions, crystals formed are grown to create a thick film. PDC used for industrial purposes is formed into polycrystalline structures. Single crystal diamonds are problematic as they have structural planes of cleavage which result in fracture when large or sudden force is applied in the direction of one of its planes of cleavage. Consequently, when single crystal diamond is fixedly set into a metal matrix, limitations are imposed upon the angles at which it can be used. This problem is not limited to applications where single crystal diamond is set into a metal matrix. Rather it is a problem in substantially all industrial applications where single crystal diamond is used. PDC diamond, in its polycrystalline form, has an added toughness over single crystal diamond due to the random distribution of the crystals which results in a lack of distinct planes of cleavage. Therefore, polycrystalline diamond is frequently the preferred form of diamond in many drilling, turning, cutting or similar operations and has been directly substituted for single crystal diamond for use in a metal matrix. Thick film diamond, has a controllable toughness compared to single crystal diamond. The random distribution of the crystals, caused by re- nucleation during the process, and the crystal-type of each individual crystal results in a lack of distinct planes of cleavage. Therefore, thick film diamond is of increasing interest for use in drilling, turning, cutting or similar operations. Brazilian natural diamond, called carbonado, is a naturally occurring random diamond structure and, like PDC, does not have cleavage weakness. It is found in large enough diamonds to be useful for tool insert manufacture and is stronger than PDC diamond, however it has all of the mounting problems associated with natural diamond. Natural and polycrystalline forms of diamond are typically affixed to a tool holder or insert made from metal or other appropriate materials to be used for drilling or cutting purposes. The difficulty in affixing the diamond to the insert has been of particular interest and has resulted in the development of several mounting techniques. One system of mounting is to surround the diamond in a supportive matrix. This system is wasteful as it requires a substantial quantity of diamond to be unexposed and useless for cutting or drilling purposes. The impracticality of this system has resulted in a turn of the technology towards PDC. PDC provides greater opportunity for affecting a superior mounting surface than has previously been known or available for natural diamond. For instance, in US patent 4,629,373 to Hall and incorporated herein by reference, a PDC diamond is disclosed which has a mounting surface which has been enhanced for improved mechanical attachment. Various forms of parallel and linear channels or an array of pits are formed in the mounting surface so as to enhance the mechanical connection to the substrate. It is known to manufacture PDC diamond in a press in which grains of diamond and other starting materials are subjected to ultrahigh pressure and temperature conditions. Hall discounts the use of natural diamonds for a variety of reasons and goes on to describe the elimination of several proposed methods of affixing PDC to tools. However, Hall describes further difficulties in mounting even PDC, such as lack of adhesives which bond PDC or natural diamonds to a substrate, residual thermal stresses placed on a cemented tungsten carbide backing with brazing, and the wasteful use of a metal matrix mount. In the face of the described problems, Hall's approach was to enhance the mounting surface of the PDC. Due to the method of manufacture, Hall's PDC is formed under pressure to create the enhanced surface, including one in which diamond grains are placed in a dovetail mold, and pressed to form PDC having a plurality of parallel dovetail grooves. Because of the interlocking nature of the dovetails, the only way to expose the PDC enhanced surface is to acid dissolve the mold out of the grooves. This technique cannot be applied to natural diamond as natural crystalline diamond cannot be pressed into a mold. Hall discloses that machining techniques are possible for post-press cycle formation of these surfaces, such techniques including laser or electric discharge machining. However, even if machined rather than pressed, Hall's substantially linear, parallel grooved surfaces highly weaken natural crystal, subject to breakage along cleavage lines. It is also known to use lasers to remove inclusions, bore linear holes through and etch indicia on the surface of gem quality diamonds. If applied to the surface of industrial diamonds these linear alterations have the same problems as those identified with Hall's grooved surfaces. Therefore, there is demonstrated a need for an effective mechanical bonding surface which can be utilized with natural diamonds or thick film diamonds so as to take advantage of the superior strength of diamond without risk of fracture. Such techniques are further advantageous if also applicable to PDC diamond to form a stronger bonding surface. SUMMARY OF THE INVENTION In a preferred form of the invention a laser-machining process is disclosed which is capable of cutting an enhanced mounting surface in the plane surface of a superhard material such as diamond. The term cutting is to be interpreted broadly as resulting in a void being left in the material and can include: melting and blowing molten material out of the void, melting and boiling material away, and vaporizing material away. The enhanced planer mounting surface has superior mechanical interlocking and bonding capability when mounted as cutting elements to tool substrates. In another form of the invention, a tool substrate can be similarly laser-machined for producing a superior mounting surface on a tool insert for the application of PDC or thick film diamond material. Accordingly, in one broad form of the invention, the mounting surface which is to be laser-machined is temporarily mounted for rotation about an axis perpendicular to its surface. A laser beam is directed along an axis which is at an angle to the surface's rotating axis. The laser beam axis intersects the rotating mounting surface for cutting an undercut void in the mounting surface as it rotates. The position, form and size of the undercut varies depending upon how often and where the laser beam is directed onto the rotating surface. By repositioning the laser beam with respect to the rotating surface, a plurality of different undercut voids can be formed. In another aspect of the invention, the laser beam can be pulsed and synchronized with the speed of rotation of the surface for cutting a pattern of undercut voids in the surface. The process is suitable for enhancing cutting elements and tool inserts alike for producing superior cutting tools. One form of apparatus suitable for enhancing the planer mounting surface of a hard material comprises: a rotating plate to which the material is temporarily affixed, the planer surface being arranged perpendicular to the plate's axis of rotation, a drive for rotating the plate and affixed mounting surface, a laser which emits a laser beam along an axis which intercepts the mounting surface and which is angled from the plate's axis of rotation. A two dimensional actuator controls the relative coordinates of the intercept of the laser beam and mounting surface, preferably to enable intercept of substantially the entire mounting surface by the laser beam. A one dimension actuator controls the focus of the laser beam. Preferably the laser beam is pulsed and the drive is variable speed for ensuring the surface speed of the mounting surface intercepted by the laser beam is maintained at or below a predetermined speed.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a cutting material mounted to a tool insert, the mounting surface of the material having been enhanced in accordance with the present invention; Figure 2 is a perspective schematic and somewhat fanciful view of a diamond, ceramic or hard metal disc affixed to a rotary plate movable on a two axis table, and a single axis moving laser used for implementing an embodiment the invention, shown oriented in three-dimensional Cartesian coordinates. Figure 3 is a perspective schematic of one form of a 3-axis system for relative positioning of the surface and the laser; Figures 4a and 4b are a side view and a partial close-up side view of the formation of a void using incremental advancing of the X-Y table; Figures 5a,5b,5c,5d are a plan view of the disc, a cross-sectional side view and a close up partial views of an undercut void, respectively. The

views illustrate the results of a plurality of ΔY step translations of the disc, relative

to the laser beam, from the lower portion of the rotating mounting surface to its center; Figures 6a, 6b, 6c, 6d are views according to Figs 5a - 5d illustrating

the results of a plurality of subsequent ΔY step translations of the mounting

surface, relative to the laser beam for the second half of the mounting surface from its center to the upper portion top of the semicircle; Figures 7a,7b,7c,7d are views according to Figs. 6a - 6d illustrating

the results of a plurality of additional ΔX step translations of the mounting surface

across its diameter; Figures 8a,8b,8c,8d are views according to Figs. 7a - 7d illustrating

the results of a plurality of diagonal ΔX, ΔY step translations of the mounting surface across its diameter; Figures 9a,9b,9c,9d are views according to Figs. 5a - 5d illustrating

the results of a plurality of combined ΔX, ΔY step translations of the mounting

surface resulting in an elliptical translation of the laser beam across the mounting surface for forming a plurality of conical undercuts; Figures 10a, 10b, 10c are a plan view of the disc, a cross-sectional side view and a perpendicular face on view of the mounting surface illustrating a

pattern of voids formed by a pulsing of the laser beam at a plurality of ΔX,ΔY step

translations of the mounting surface, relative to the laser beam; Figures 11a and 11 b illustrate a cross-section through the centeriine of a diamond disc illustrating a plurality of the preferred dovetail voids and a fanciful perspective representation of their orientation distributed in a discrete and discontinuous fashion on an inclined disc; Figure 12a illustrates a cutting element laser-machined according to the first embodiment of the invention and bonded to a tool insert; and Figure 12b illustrates a cutting element mounted to a laser- machined tool insert according to the second embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Having reference to Figs. 1 , 12a and 12b, a laser-machining process is applied to a mounting surface 10 of a hard or superhard material 11 for improving mechanical bonding at the interface to a second material. In a first embodiment, the hard material 11 is diamond disc D mounted to a tool substrate, holder or insert 12, such that used for a subterranean drill bit. The surface 10 of the diamond is laser-machined for enhancing its surface. The disc D can then be mechanically bonded to the tool insert 12. In this first embodiment, the invention is described for applications involving the mounting of natural or other diamond to a metal substrate or other tool insert 12 through laser-machining of the diamond's mounting surface 10. However, the invention is equally applicable to laser-machining of the mounting surface of the tool insert 12 for the subsequent mounting of PDC, thick film diamond and ceramics. In a simple form, in the first embodiment and the result of which is shown in Fig. 12a, the diamond material 11 has a cutting surface 13 which may have one of many cutting surfaces, often merely being a planer disc D (as shown in Fig. 1 ). The diamond disc D has a mounting surface 10 for eventual mounting to the tool insert 12. The diamond's mounting surface 10 is machined for forming one or more voids having an undercut feature, thereby enhancing the mechanical interlocking ability of the diamond material 11 to be bonded to the tool insert 12. In the simplest respect, the machining is directed to forming voids (described below) through and into the mounting surface 10 and leaving at least an interface which forms a mechanical, interlocking undercut at the entrance to the void. In a second embodiment and the result of which is shown in Fig. 12b and alternatively, by applying the same laser-machining technique to the hard metal material 11 of a carrier-substrate tool insert 12 such as tungsten carbide, an ideal interlocking bonding surface is formed upon which diamond can be grown using thick film Chemical Vapor Deposition (CVD) techniques or to which pressure-form polycrystalline diamond compact (PDC) or other ceramic material is mounted during its plastic production phase. Having reference to Figs. 2 and 3, apparatus for laser-machining comprises a rotary plate 14 upon which the hard material 11 is temporarily affixed with a suitable compound so that the planer mounting surface 10 is exposed and is perpendicular to the rotational axis R. The rotational axis is set along the R- vector, the angle between the R-vector and the Z-axis determines the angle of the void's undercut 40. For permitting automation of the laser-machining process, the mounting surface 10 must be substantially planer so that it may be rotated in its plane during laser-machining. A 5 Watt, 3500 Hz, Yttrium-Aluminum-Garnet (YAG) laser 20 emits a beam 21 along a Z-axis, shown in Fig. 2 as being vertical. The laser beam 21

has a focal point F which can be focused through incremental translation (Δz) of

the laser 20 along the Z-axis, illustrated fancifully by a movable carriage 22 driven by a microstepper motor 31z. The axis of rotation R of the plate is divergent from the laser's Z-axis (at an non-zero angle) so that the mounting surface 10 is not perpendicular to the laser's Z-axis. The plate's rotational axis R is along an R-vector angled generally upwardly in the Z direction and along the X- axis. The Y-axis is perpendicular to the X and Z-axes. The rotating plate 14 is driven with a variable speed controllable servo motor 23. The rotational speed range of the servo motor 23 and plate 14 is sufficient to achieve surface speeds over the majority of the mounting surface 11 of about twelve mm/second (the critical speed) for natural diamond material 11. A critical speed of twelve mm/s is based on a 5W YAG laser and is both laser and material dependent. The optimal surface speed can be predetermined, empirically or through other means. Other critical speeds can be predetermined and are applicable for different lasers, power settings and substrate materials. At speeds faster than critical, less cutting is achieved and multiple passes are required. At slower speeds, the hard material substrate 10 is at risk of damage due to excessive heat build-up.

In one embodiment, the rotating plate 14 and servo motor 23 are

movable (Δx.Δy) on an X-Y table 30 (Fig. 3) using X-Y actuators or microstepper

motors 31xy for repositioning the rotating plate 14 and mounting surface 11 under the beam 21 of the laser 20. Alternatively, but not shown, the laser 20 could be translated in X and Y over the rotating plate 14. The laser 20 is movable in the Z- axis using another actuator or microstepper motor 31z so that the laser beam

focus F can be adjusted (Δz) as the rotating plate 14 translates and the mounting

surface 10 approaches and falls away from the laser beam focal point F. If the laser 20 is pulsed, then a plurality of circumferentially spaced voids V are formed shown in Fig. 10a - 10c. By translating the X-Y table 30 so that the laser beam 21 is focused at a point F on the lower semicircle portion of the mounting surface 10 (above the rotational axis), a first path is cut forming a radially outward directed voids V in the material's surface 10. By actuating and translating the X-Y table 30 so that the laser beam 21 is focused at a point on the upper semicircle portion of the mounting surface 10 (above the rotational axis), a second path is cut forming a radially inward directed void in the material's surface 10. Again, by having passed the axis of

rotation R, successively translating Δx the table 30 in the X-axis while cutting, the

undercut 40 is adjusted to provide a second undercut. For a continuous laser beam 21 , the resulting circumferentially extending void is curved and, while it may cross a cleavage, such as in a natural diamond, it will not weaken it. Further, the void has an undercut formed in one or more planes which, when filled with a bonding material prevents its separation without failure of the bonding materials. More preferably however, during machining, the laser beam 21 is pulsed in synchrony with the material's rotation. The formerly continuous void is now broken up into discrete, discontinuous voids (Fig. 10a-10c). As long as the discrete voids are shifted sufficiently radially and the timing of the pulses is sufficiently long, the voids are separated by continuous substrate material 11 , thereby providing strength to the material 11 and minimizing stress raisers. Referring back again to Fig. 2, to coordinate the machining process, a high speed microcomputer 25, such as that powered by an Intel Pentium 166 MHz or higher processor, is employed to numerically control the servo 23, microstepper motors 31xyz and laser pulsing. Controls are provided for controlling the machining to obtain a pre-determined pattern of voids in the mounting surface 10. The microcomputer 25 directs the X-Y table 30 and microcontrollers 31xy to grossly position the mounting surface 10 under the laser

beam 21 and to finely position (Δx) the laser 20 for forming a void V. The laser beam focus F is dynamically manipulated by changing Δz in response to X-axis

changes in the mounting surface 10 being machined.

The rotational speed ω of the servo motor 23 is computer-controlled

to ensure the critical speed is maintained. Note that for a given rpm, when the laser 20 is cutting a void at the radial periphery of the mounting surface 10, that the surface speed is much higher than at the inside radius. Accordingly, the rpm must be adjusted to ensure that the surface speed is maintained at about 12mm/s where the laser beam intercepts the mounting surface it is currently cutting. Thus the rotation speed and the X and Z-axis positions must be known and compensated for. As shown in Figs. 4a and 4b, with the laser beam 21 focused at coordinates CA in the lower semicircle portion of the mounting surface 10 (below the rotational axis), a first path is laser-machined or cut to form one or more shaped voids V in the material 11. The laser beam 21 ablates a portion of the hard material 11 to form the void V. Due to the divergent axes of the laser beam 21 (Z-axis) and rotational plate 14 (R-vector), the voids V form an undercut 40 in the mounting surface 10.

As shown in Fig. 4b, by successively translating Δx the table in the

X-axis while cutting, the void V can be widened. If the laser 20 is substantially continuous (which is relative depending upon the surface speed and laser pulse cycles) then a continuous void is formed. If the plate 14 is translated fully under the laser beam 21 , and without further machining, a parallelogram void is formed. Sufficient angle must be set between the R-vector and the Z-axis to account for the conical beam of the laser and still form an undercut void. As shown more clearly in Figs. 4a and 4b, the laser beam 21 is directed at desired first coordinates CA, located low on the rotating plate 14 and in the material 11. The laser beam 21 is focused at point F in the material 11 cutting the a first void, the base of which is illustrated as B. The void V is angled outwardly to the periphery of the mounting surface 10. The table 30 can be

actuated to shift along the X-axis an increment ΔX. The laser beam 21 is

refocused (ΔZ) higher on the rotating plate 14 and material 10 for cutting an

additional void V having a new base at B'. If the ΔX is small, the voids overlap

forming an even larger void. Similarly as shown later in Figs. 7a-7d, shifting the table in the Y-axis permits alternate positioning of the laser beam on the uprotation edge and down rotation edges of the substrate 10 forming the radially angled voids and respectively. Figs 4a and 4b further illustrate how successive steps of the X-axis microstepper 31x motor from A to A' to A" to A'" result in successive voids having bases at B, B', B", and B'" respectively. The voids V are formed through the surface 10 and into the materials 11. Best seen in Fig. 4b, the voids V have their base B,B' ... located within the material 11 and an entrance E formed at the surface 10. Each base B has a peripheral extent which is at a different position than the peripheral extent of the entrance E, thereby creating a lip or undercut 40. This means that at least one edge of the peripheral extent of the base is shifted radially from the peripheral extent of the entrance E (as in the case of Figs. 4b,5a-5d) or circumferentially from the peripheral extent of the entrance E (as in the case of Figs. 6a-6d). In recognition of the aforementioned cleavage issue with natural diamonds, it is important to avoid a lining up of the voids. Accordingly, for voids V formed in natural diamonds with cleavage, the preferred voids would be small and discontinuous, or continuous but curved. If the laser beam 21 were continuous, then a continuous circular and annular void V would result (Fig. 2). Preferably, a plurality of concentric annular voids are provided for maximal mechanical bonding. Another pattern of void V is a sector appearance of radially and circumferentially bounded and spaced voids, each of which is discontinuous from their radial and circumferential neighboring voids (Fig. 11b). This requires a pulsing of the laser beam 21 at a rate synchronous with the speed of rotation of the surface 10 so that each cut is performed substantially coincident with the desired pattern. Various forms of voids V can be formed by manipulating the coordinates of the laser beam 21 with respect to the mounting surface 10. As

shown in Figs. 5a - 5d, incremental ΔX translation of the surface 10 from

coordinates CA low on the rotating disc to its midpoint CO produces outwardly

angled voids Va. As shown in Figs. 6a - 6d, continuing the incremental ΔX

translation of the surface 10 from the center CO to coordinates CB high on the rotating mounting surface 10 produces inwardly angled voids Vb, the ultimate cross-section of which resembles a parallelogram or dovetail. Note that due to the rotation of the mounting surface 10, the void cross-section becomes mirrored on the diametrically opposing side of the material 11. The form of the parallelogram is not precise. Due to the actual conical shape of the focused laser beam 21 , one cut of the laser beam 21 produces a more conical void V as shown in Fig. 4b. More elaborate voids V can be formed by translating the rotating plate 14 and surface 10 in both X and Y axes. As shown Figs. 7a - 7d, a knotted pyramidal void is formed by addition of ΔY translations of the surface 10 across

the diameter of the surface 10 from coordinates CC - CD which have been

previously already machined with a plurality of ΔX translations (Figs. 6a-6d). As

shown in Figs. 8a - 8d, the addition of diagonal translations CE'-CE" and

CF'=CF", in both ΔX and ΔY, will form larger voids.

Using a 5W, 3500 Hz YAG laser, voids having a base dimension of 0.06 mm and a smaller surface entrance opening of 0.01 mm at the surface 10 are possible, machined for instance into 4mm to 25mm diameter discs of diamond. In summary, as shown in Figs. 1 , 12a and 12b, a diamond disc cutting element D can be produced for use on an earth boring drill bit or other tool, such as a rotary drag bit. The cutters are predominately comprised of a diamond cutting structure attached to either a reduced-volume substrate or directly to a bit body, optionally using a carrier structure mounted to the bit body. In the case of the first embodiment (Fig. 12a), the method consists of preparing and enhancing the bonding surface of the diamond with a laser to obtain an improved bond between the a substrate material and diamond. In the second embodiment (Fig. 12b), one can prepare the bonding surface of the tool insert metal with a laser and then grow a sufficiently thick diamond film on top of it. As described above, the laser 20 is operated to generate voids in the particular hard surface 10 permitting allowing bonding materials under high pressure or temperature to penetrate the mounting surface or in the case of growing a diamond film, starting the crystal nucleation in the voids and extending these crystals on top of the surface, resulting in a permanent mechanical anchoring between the material and the surface. The design or the shape of these voids, as well as the preparation of these voids by metal powder impregnating or metal containing compounds, are critical to achieve the proper anchoring. The undercut design of these voids is such that the cross sectional dimension inside the void exceeds the average cross section of the entrance to these voids. When bonding a PDC or other formable material, a mechanical anchoring or bonding results when material penetrates the voids under plastic conditions and returns or sets to non-plastic conditions. To achieve this, high mechanical pressure and increased temperature, under near vacuum conditions, are crucial to improve the contact affinity between the intruding metal (such as braze of tungsten, copper and nickel or tungsten, copper and silicon) and the diamond and certain organo-metallic agents can be applied, containing Silver, Nickel, Lead, Silicon or Titanium. When growing a diamond film on a laser-prepared bonding surface, a mechanical anchoring results when a gas such as methane, under crystal generating chemical vapour deposition conditions, enters the voids. The nucleating crystals grow to fill the void and extend to the surface resulting in a continuous diamond face of sufficient thickness to allow its use as a tool or drill bit insert.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for enhancing a planer mounting surface of a material comprising:

• rotating the mounting surface about an axis perpendicular to its surface; and

• directing a laser beam along an axis which is at an angle to the rotating axis, the laser beam axis intersecting the rotating mounting surface for cutting an undercut void through the mounting surface and into the material as the mounting surface rotates.

2. The process of claim 1 further comprising:

• pulsing the laser beam so as to cut a plurality of discontinuous undercut voids in the material as it rotates.

3. The process of claim 2 further comprising:

• directing the laser beam to intersect the mounting surface at first coordinates to cut a first undercut void or first set of voids in the material; and

• translating the relative positions of the rotating mounting surface and the laser beam; and

• directing the laser beam to intersect the mounting surface at second coordinates to cut a second undercut void or second set of voids in the material which are angled differently from the mounting surface than are the first set of undercut voids.

4. The process of claim 3 further wherein the mounting surface has a speed of rotation and pulsing of the laser beam has a rate, the process further comprising the step of:

• controlling the speed of rotation of the mounting surface and the rate of pulsing of the laser beam so as to create a pattern of undercut voids through the mounting surface and in the material.

5. The process of claim 4 further wherein the speed of rotation and the rate of pulsing are synchronized so that each undercut void is cut in a predetermined pattern.

6. The process of claim 3 further comprising repeatedly translating the relative positions of the rotating mounting surface and the laser beam and directing the laser beam to intersect the mounting surface at second and subsequent coordinates to cut a plurality of undercut voids, each of which are angled differently from the mounting surface than are the preceding first and

subsequent preceding undercut voids.

7. The process of claim 3 wherein the laser beam is refocused after the rotating mounting surface is translated.

8. The process of claim 3 wherein the mounting surface's material is diamond.

9. Apparatus for enhancing the planer mounting surface of a hard material comprising: a rotating plate to which the material is temporarily affixed with the planer surface arranged perpendicular to the plate's axis of rotation; a drive for rotating the plate; a laser which emits a laser beam along an axis which intercepts the rotating mounting surface and which is arranged at an angle to the plate's axis of rotation for cutting undercut voids in the mounting surface.

10. The apparatus of claim 10 further comprising two dimensional actuator controls for translating the relative coordinates of the intercept of the laser beam and rotating mounting surface

11. The apparatus of claim 11 further comprising means for adjusting the focus of the laser beam intercepting the rotating mounting surface.

12. The apparatus of claim 12 wherein the laser emits a laser beam which pulses at a known rate.

13. The apparatus of claim 13 wherein the rotational speed of the drive is variable.

14. The apparatus of claim 14 further comprising a controller for adjusting the drive's rotational speed so as to ensure the surface speed of the rotating mounting surface is below a predetermined maximum speed.

15. The apparatus of claim 15 wherein controller further synchronizes the laser's rate of pulses and the speed of the drive for forming a pattern of undercut voids in the mounting surface.

16. A cutting element produced according to the process of claim 1 wherein the enhanced planer mounting surface is cut in the planer mounting surface of diamond material.

17. The cutting element of claim 16 wherein the diamond material is carbonado.

18. A cutting tool comprising: a tool substrate having an enhanced planer mounting surface produced according to the process of claim 1 ; and a superhard material mounted onto the mounting surface.

19. The cutting tool of claim 18 wherein the superhard material is a thick film diamond.

20. The cutting tool of claim 19 wherein the superhard material is PDC.

21. A method for manufacturing a diamond cutting element suitable for bonding to a cutting tool substrate comprising:

• forming a planer mounting surface on a diamond material; and

• enhancing the diamond's mounting surface by ^■ rotating the mounting surface about an axis perpendicular to its planer surface while ^■ directing a laser beam along an axis which is at an angle to the rotating axis, the laser beam axis intersecting the rotating mounting surface for cutting one or more undercut voids in the mounting surface as the mounting surface rotates.

AMENDED CLAIMS

[received by the International Bureau on 10 May 2001 ( 10 05 01 ), original claims 1-21 replaced by new claims 1 -21 (5 pages)]

1 A process for enhancing a planer mounting surface of a matenal comprising:

• rotating the mounting surface aoout an axis perpendicular to its surface. • directing a laser beam along an axis which is at an angle to the rotating axis, the laser beam axis intersecting the rotating mounting surface for cutting an undercut void through the mounting surface and into the mateπal as the mounting surface rotates; and

2. The process of claim 1 further composing:

• directing the laser beam to intersect the mounting surface at first coordinates to cut a first set of voids in the mateπal, and

• translating the relative positions of the rotating mounting surface and the laser beam; and • directing tne laser oeam to intersect the mounting surface at second coordinates to cut a second set of voids in the material which are angled differently from the mounting surface than are the first set of undercut

voids.

3. The process of claim 2 wherein one or more of the voids of the second set of undercut voids intersects the mounting surface at the same coordinates as one or more voids of the first set of undercut voids.

4 The process of claim 3 further wherein the mounting surface has a speed of rotation and the pulsing of the laser beam has a rate, the process further comprising the step of

6. The process of claim 2 further compnsing repeatedly translating the relative positions of the rotating mounting surface and the laser beam and directing the laser beam to intersect the mounting surface at second and subsequent coordinates to cut a plurality of undercut voids, each of which are angled differently from the mounting surface than are the preceding first and subsequent preceding undercut voids

7. The process of claim 2 wherein the laser beam is refocused after the rotating mounting surface is translated. 8 The process of claim 2 wherein the mounting surface's mateπal is diamond.

9. Apparatus for enhancing the planer mounting surface of a harα material comprising a rotating plate to which the material is temporaπly affixed with the planer surface arranged perpendicular to the plate's axis of rotation, a drive for rotating the plate; a laser which emits a pulsed laser beam along an axis which intercepts the rotating mounting surface and which is arranged at an angle to the plate s axis of rotation for cutting a plurality of discontinuous undercut voids in the mounting surface.

10. The apparatus of claim 9 further comprising two dimensional actuator controls for translating the relative coordinates of the intercept of the laser beam and rotating mounting surface

11 The apparatus of claim 10 further composing means for adjusting the focus of the laser beam intercepting the rotating mounting surface

12. The apparatus of claim 11 wherein the laser emits a laser beam which pulses at a known rate

13. The apparatus of claim 12 wherein the rotational speed of the drive is variable.

14. The apparatus of claim 13 further comprising a controller for adjusting the drive's rotational speed so as to ensure the surface speed of the rotating mounting surface is below a predetermined maximum speed.

15 The apparatus of claim 14 wnerein controller further synchronizes the laser's rate of pulses and the speed of the drive for forming a pattern of undercut voids in the mounting surface.

17. The cutting element of claim 16 wherein the diamond mateπai is carbonado.

18. A cutting tool comDπsing- a tool su strate having an enhanced planer mounting surface produced according to the process of claim 1 , and a superhard material mounted onto the mounting surface.

19. The cutting tool of claim 18 wherein the superhard mateπal is a thick film diamond.

20. The cutting tool of claim 18 wherein the superhard material is PDC.

• forming a planer mounting surface on a diamond material; and • enhancing the diamond's mounting surface by ■ rotating the mounting surface about an axis perpendicular to its planer surface while ^■ directing a laser beam along an axis which is at an angle to the rotating axis, the laser beam axis intersecting the rotating mounting surface for cutting one or more undercut voids in the mounting surface as the mounting surface rotates.