Patent Publication Number: US-6988858-B2

Title: Oxidation-resistant cutting assembly

Description:
FIELD OF THE INVENTION 
   The invention pertains to a cutting assembly that includes a tool holder that contains a pocket, a shim, and a cutting insert. The invention further pertains to a tool holder assembly that comprises a tool holder that contains a pocket and a shim. The invention also pertains to a shim for use with a tool holder that contains a pocket and a cutting insert. 
   BACKGROUND OF THE INVENTION 
   Certain cutting assemblies used for the removal of material may include a tool holder that contains a pocket, a shim and a cutting insert. Typically, the shim is affixed within the pocket such as, for example, by a shim screw or a threaded pin. The cutting insert typically rests upon the upper surface of the shim and is affixed (or firmly secured) thereto by a clamp member. There may be a mechanical chip breaker between the clamp and the cutting insert. 
   Certain material removal applications, e.g., a turning application, use a coated or an uncoated polycrystalline cubic boron nitride (PCBN) cutting insert. While current PCBN cutting inserts (coated and uncoated) perform adequately, a material removal application that uses such a cutting insert generates a great amount of heat. This heat generally passes into the shim upon which the cutting insert rests so that the shim becomes hot. In some situations, especially when the cutting length is particularly long, for example, one or more hours in a cut such as may be encountered with machining a mill roll such as a steel mill roll, this heat passes into the pocket region of the tool holder and causes the pocket to become hot resulting in oxidation of the toolholder assembly including the shim. 
   In the past, the shim has been made from a carbide-based material (e.g., cemented (cobalt) tungsten carbide). When the shim received the heat from the material removal application and thereby became hot (e.g., a temperature greater than about 400 degrees Centigrade), it oxidized wherein the oxidation was greatest in those portions defined by the surfaces exposed to the air. Because the oxidized portions of the shim (i.e., the oxidized tungsten carbide-cobalt material) had a lower density than the non-oxidized material, those portions of the shim that were exposed to the air increased in size. Such an increase in size caused a raised ridge in the region of the cutting edge in the area of the cut. Upon the indexing of the cutting insert, such a ridge resulted in the misalignment of the cutting insert with respect to the shim. This misalignment caused the cutting insert to chip under certain circumstances. 
   In addition, the oxidized tungsten carbide-cobalt material is itself very brittle. The oxidized tungsten carbide-cobalt material also has poor adhesion to the non-oxidized tungsten carbide-cobalt material. Upon continued use of the cutting assembly, the oxidized tungsten carbide-cobalt material falls away from the shim which leaves large pits along the edge of the shim where the rate of oxidation is the greatest and in areas beneath the PCBN cutting insert that oxidize more slowly. The result is the existence of pits and ridges in the shim that cause unstable seating of the cutting insert. 
   In a situation in which the pocket region of the tool holder would receive heat and reach a temperature in excess of about 400 degrees Centigrade, the region of the tool holder that defines the pocket would experience oxidation. Since the tool holder is typically made from steel, and in some cases it may be made from tungsten carbide, the oxidation would result in an increase in the size of the surfaces that define the pocket since the oxidized material has a lower density than the non-oxidized material. Under certain circumstances, such a change in the dimension of the pocket would result in the misalignment of the cutting insert upon indexing. Such misalignment could result in chipping of the cutting insert. 
   It would thus be desirable to provide a cutting assembly that includes a shim that maintains its dimensional integrity during the material removal operation. As a result, upon indexing of the cutting insert, alignment and support would be maintained between the cutting insert and the shim so as to minimize the potential for the chipping of the cutting insert. Further, alignment and support would be maintained so as to minimize the potential for loss of wear resistance because of an improper attack angle in the material removal operation even when the PCBN cutting insert does not chip. 
   It would also be desirable to provide a cutting assembly that includes a tool holder wherein the region of the tool holder adjacent to the pocket exhibits oxidation resistance so as to maintain its dimensional integrity. As a result, upon indexing of the cutting insert, alignment and support would be maintained between the cutting insert and the shim so as to minimize the potential for the chipping of the cutting insert. Further, alignment and support would be maintained so as to minimize the potential for loss of wear resistance because of an improper attack angle in the material removal operation even when the PCBN cutting insert does not chip. 
   SUMMARY OF THE INVENTION 
   In one form, the invention is a cutting assembly that comprises a tool holder that includes a pocket. The cutting assembly further includes a shim contained within the pocket. The shim presents an oxidization-resistant surface. The cutting assembly also includes a cutting insert that rests upon the shim. 
   In another form thereof the invention is a cutting assembly that comprises a tool holder that has a pocket that presents an oxidation-resistant surface. The cutting assembly also has a shim contained within the pocket. The cutting assembly further has a cutting insert that rests upon the shim. 
   In still another form thereof, the invention is a tool holder assembly that comprises a tool holder that contains a pocket. The assembly further has a shim contained within the pocket. The shim presents an oxidation-resistant surface. 
   In yet another form thereof, the invention is a shim for use in conjunction with a tool holder that contains a pocket wherein the shim is within the pocket. The shim has a shim body wherein the shim body presents an oxidation-resistant surface. 
   In yet still another form thereof, the invention is a mechanical chipbreaker for use in conjunction with a cutting insert secured within the pocket of a tool holder. The chipbreaker has a chipbreaker body. The chipbreaker body presents an oxidation-resistant surface. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following is a brief description of the drawings that form a part of this patent application: 
       FIG. 1  is an isometric view of a specific embodiment of a cutting assembly with the components (including the tool holder, the shim, the mechanical chipbreaker, and the cutting insert) exploded away from one another; 
       FIG. 2  is an isometric view of another specific embodiment of a cutting assembly with the components (including the tool holder, the shim, the mechanical chipbreaker, and the cutting insert) exploded away from one another, and wherein a portion of the coating on the shim has been removed to expose the underlying substrate; 
       FIG. 3  is an isometric view of a specific embodiment of a tool holder that has a pocket wherein the surface of the head portion of the tool holder (that includes the pocket) is coated with an oxidation-resistant coating; 
       FIG. 4  is an isometric view of another specific embodiment of a tool holder that has a pocket wherein an oxidation-resistant insert is contained within the pocket; 
       FIG. 5  is an isometric view of an alternate embodiment of the pocket insert designed for use with the tool holder of  FIG. 4  wherein a portion of the oxidation-resistant coating on the pocket insert has been removed to expose the underlying substrate; and 
       FIG. 6  is an isometric view of a mechanical chipbreaker that has an oxidation-resistant coating thereon wherein a portion of the oxidation-resistant coating has been removed to expose the underlying substrate. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to the drawings,  FIG. 1  illustrates a specific embodiment of a cutting assembly generally designated as  20 . Cutting assembly  20  includes a tool holder  22  that has one end  24  at which there is a generally circular pocket  26 . The pocket  26  has a pair of generally arcuate side surfaces  28  that intersect with a generally circular bottom surface  30 . In the specific embodiment of  FIG. 1  the side surfaces  28  are spaced apart at the boundary of their closest proximity. The tool holder  22  contains an aperture  32  in the bottom surface  30  of the pocket  26 . 
   The tool holder  22  further includes a head portion  35  that presents a top surface  36 . The tool holder  22  contains a threaded aperture  38  in the top surface  36  thereof. 
   Cutting assembly  20  includes a shim  42  that presents an oxidation-resistant surface as hereinafter described. Shim  42  has a top surface  44 , a bottom surface  46 , and a cylindrical side surface  48  that intersects with the top and bottom surfaces ( 44  and  46 , respectively). Although the geometry may vary depending upon the application, shim  42  has a generally cylindrical geometry. The shim  42  has a chamfer  49  at the bottom circumferential edge thereof. The shim  42  contains an aperture  50  therein. The shim  42  comprises an uncoated ceramic material so that the shim  42  presents an oxidation-resistant surface. As an option, the ceramic shim may have a coating thereon so that the shim would comprise a ceramic substrate having an oxidation-resistant coating. 
   Exemplary ceramic materials for the shim include silicon nitrides or SiAlONs or alumina-based materials. Patents that are exemplary of the silicon nitride or SiAlON ceramic materials include U.S. Pat. No. 4,563,433 to Yeckley, U.S. Pat. No. 4,711,644 to Yeckley, U.S. Pat. No. 4,889,755 to Mehrotra et al., U.S. Pat. No. 5,370,716 to Mehrotra et al., and U.S. Pat. No. 4,826,791 to Mehrotra et al. Patents that are exemplary of the alumina-based materials include U.S. Pat. No. 5,059,564 to Mehrotra et al., U.S. Pat. No. 5,024,976 to Mehrotra et al. and U.S. Pat. No. 4,965,231 to Mehrotra et al. An exemplary ceramic material for the shim may also include hafnia or zirconia. 
   In the alternative, the shim  42  may comprise a cermet substrate or a carbide-based substrate with an oxidation-resistant coating applied thereto. Exemplary carbide-based materials for the substrate in the alternative embodiment of the shim include cemented (cobalt) tungsten carbide wherein the cobalt content may range between about 0 weight percent and about 13 weight percent, and more preferably, the cobalt content ranges between 3 weight percent and 13 weight percent, and most preferably between about 6 weight percent and about 11 weight percent. Cemented (cobalt) tungsten carbide material may optionally contain additives such as titanium, tantalum, niobium, chromium and vanadium. 
   Exemplary oxidation-resistant coatings (applied by physical vapor deposition [PVD] or chemical vapor deposition [CVD] depending upon the specific situation) for application to the substrate (e.g., carbide-based material, cermet material or ceramic material) may include alumina, titanium aluminum nitride, titanium nitride, titanium carbonitride, titanium carbide, or titanium diboride in single layer as well as various multi-layer coating schemes. One exemplary single layer coating scheme comprises a layer of titanium aluminum nitride applied by physical vapor deposition. Referring to multi-layer coating schemes, one such coating scheme may comprise a base layer (e.g., titanium carbide) and a coating of alumina on the base layer. Another coating scheme may comprise a base layer (e.g., titanium carbide), an intermediate layer of alumina on the base layer, and a layer of titanium nitride on the alumina layer. Yet another coating scheme may comprise a base layer titanium nitride applied by CVD to the substrate and a layer of titanium aluminum nitride applied by PVD to the base layer. Another coating scheme may comprise a base layer of titanium carbide applied by CVD to the substrate, a first intermediate layer of alumina applied by CVD to the base layer, a second intermediate layer of titanium nitride applied by CVD to the first intermediate layer, and a top layer of titanium nitride or titanium aluminum nitride or titanium diboride applied to the second intermediate layer by PVD. 
   Cutting assembly  20  further has a cylindrical shim pin  54  that has a shank  56  and a top end  58 . The shim pin  54  passes through the aperture  50  in the shim  42  and into engagement with the aperture  32  in the pocket  26 . The shim pin  54  positions the shim  42  within the pocket  26  of the tool holder  22 . The top end  58  of the shim pin  54  is flush with the top surface  44  of the shim  42 . 
   Cutting assembly  20  also includes a cutting insert  62 . While the cutting insert  62  may comprise any one of a number of commonly used materials, one preferred embodiment of the cutting insert  62  is a coated or an uncoated polycrystalline cubic boron nitride (PCBN). Other options for the cutting insert  62  include an uncoated polycrystalline diamond cutting insert or a diamond coated cutting insert. Cutting insert  62  is shown as being of a generally cylindrical shape so that it has a top surface  64 , a bottom surface  66 , and a side surface  68  that intersects with the top and bottom surfaces ( 64  and  66 , respectively) to form opposite cylindrical circumferential edges that typically are chamfered. However, the cutting insert could take on other geometries depending upon the application. The bottom surface  66  of the cutting insert  62  rests upon the top surface  44  of the shim  42 . 
   The cutting assembly  20  further comprises a discrete mechanical chip breaker  70  that has a bottom surface  72 , an arcuate (or rounded) rear surface  73 , and a top surface  74 . When assembled, the bottom surface  72  of the chip breaker  70  rests upon the top surface  64  of the cutting insert  62 . Although this embodiment shows a discrete chipbreaker, applicants contemplate that the cutting insert may include integral chipbreaker feature(s). The specific embodiment of  FIG. 1  depicts an uncoated chipbreaker; however, applicants contemplate that the chipbreaker may be coated with an oxidation-resistant coating. Referring to FIG.  6 ., there is shown a coated chipbreaker  75  that has a substrate (or chipbreaker body)  76  with an oxidation-resistant coating  77  thereon. A portion of the coating  77  is removed to expose the underlying substrate  76 . The substrate  76  may comprise any one of a ceramic material, a cermet material or a carbide-based material (e.g., cemented (cobalt) tungsten carbide). The oxidation-resistant coating may comprise any one of the coating materials and coating schemes described hereinabove in connection with shim  42 . 
   Cutting assembly  20  also has a clamp  78 . Clamp  78  has a generally cylindrical body  80  with a threaded aperture  82  passing through the length of the body  80 . Clamp  78  further includes an integral arm  84  that has a distal end  85 . A clamp screw  86  has an upper threaded portion  88  and a lower threaded portion  90 . The lower threaded portion  90  of the clamp screw  86  is received within the threaded aperture  38 . The upper threaded portion  88  of the clamp screw  86  is received within the threaded aperture  82  of the clamp  78 . The clamp  78  is tightened down by the rotation of the clamp screw  86  so that the arm presses against the chipbreaker  70  which, in turn, presses against the cutting insert  62  whereby the cutting insert  62  and chipbreaker  70  are firmly secured to the tool holder  22 . 
   Although the specific embodiment shows a tool holder of a particular design, applicants contemplate that the present invention may be used in conjunction with tool holders having geometries and configurations different from that shown herein. These other tool holder designs are well-known to those skilled in the art. 
   Referring to  FIG. 2 , there is illustrated another specific embodiment of the cutting assembly generally designated as  94 . Cutting assembly  94  includes a tool holder  96  that has one end  98  with a pocket  100  therein. The pocket  100  has a pair of side surfaces  102  and a bottom surface  104  that intersects the side surfaces  102 . The tool holder  96  contains an aperture  106  in the bottom surface  104  of the pocket  100 . The tool holder  96  also has a head portion  107  that has a top surface  108 . The top surface  108  of the head portion  107  contains a threaded aperture  110  therein. 
   Cutting assembly  94  further includes a shim  112  that has a top surface  116 , a bottom surface  118 , and four side surfaces  120 . The side surfaces  120  intersect the top and bottom surfaces ( 116  and  118 , respectively). Shim  112  further contains an aperture  121 . In the specific embodiment of  FIG. 2 , the shim  112  comprises a carbide-based substrate  113  having an oxidation-resistant coating  114  applied thereto. In  FIG. 2 , a portion of the oxidation-resistant coating  114  has been removed to expose the underlying substrate  113 . 
   Exemplary carbide-based materials for the substrate in the embodiment of the shim  112  include cemented (cobalt) tungsten carbide wherein the cobalt content may range between about 0 weight percent and about 13 weight percent, and more preferably, the cobalt content ranges between 3 weight percent and 13 weight percent, and most preferably between about 6 weight percent and about 11 weight percent. Cemented (cobalt) tungsten carbide material may optionally contain additives such as titanium, tantalum, niobium, chromium and vanadium. An optional material for the substrate  113  is a cermet wherein the cermet would have an oxidation-resistant coating thereon. 
   Exemplary oxidation-resistant coatings (applied by physical vapor deposition [PVD] or chemical vapor deposition [CVD] depending upon the specific situation) for application to the carbide-based substrate may include alumina, titanium aluminum nitride, titanium nitride, titanium carbonitride, titanium carbide, or titanium diboride in single layer as well as various multi-layer coating schemes. One exemplary single layer coating scheme comprises a layer of titanium aluminum nitride applied by PVD. Referring to multi-layer coating schemes, one coating scheme may comprise a base layer (e.g., titanium carbide) and a coating of alumina on the base layer. Another coating scheme may comprise a base layer (e.g., titanium carbide), an intermediate layer of alumina on the base layer, and a layer of titanium nitride on the alumina layer. Yet another multi-layer coating scheme may comprise a base layer of titanium nitride applied by CVD to the substrate and a layer of titanium aluminum nitride applied by PVD to the base layer. Another coating scheme may comprise a base layer of titanium carbide applied by CVD to the substrate, a first intermediate layer of alumina applied by CVD to the base layer, a second intermediate layer of titanium nitride applied by CVD to the first intermediate layer, and a top layer of titanium nitride or titanium aluminum nitride or titanium diboride applied to the second intermediate layer by PVD. 
   Shim  112  may optionally be made from a ceramic material such as, for example, a silicon nitride or a SiAlON material or an alumina-based material. Patents that are exemplary of silicon nitride or SiAlON ceramic materials include U.S. Pat. No. 4,563,433 to Yeckley, U.S. Pat. No. 4,711,644 to Yeckley, U.S. Pat. No. 4,889,755 to Mehrotra et al., U.S. Pat. No. 5,370,716 to Mehrotra et al., and U.S. Pat. No. 4,826,791 to Mehrotra et al. Patents that are exemplary of the alumina-based materials include U.S. Pat. No. 5,059,564 to Mehrotra et al., U.S. Pat. No. 5,024,976 to Mehrotra et al. and U.S. Pat. No. 4,965,231 to Mehrotra et al. Shim  112  may also be made of zirconia or hafnia. 
   As an option, the ceramic substrate may have an oxidation-resistant coating thereon. Exemplary oxidation-resistant coating materials and coating schemes are like those described in conjunction with the shim  112  that has a carbide-based substrate. 
   Cutting assembly  94  further comprises a pin  122 . The pin  122  has an upper portion  124  and a lower portion  126 . The pin  122  passes through the aperture  121  in the shim  112  whereby the lower portion  126  is received within the aperture  106  in the pocket  100  of the tool holder  96 . The pin  122  positions the shim  112  within the pocket  100  of the tool holder  96 . The upper portion  124  of the pin  122  extends upwardly past the top surface  116  of the shim  112 . 
   The cutting assembly  94  further has a cutting insert  130  that presents a generally rectangular shape so that it has a top surface  132 , a bottom surface  134  and four side surfaces  136 . However, the cutting insert may take on other geometries depending upon the application. The side surfaces  136  join together the top and bottom surfaces ( 132  and  134 , respectively). Cutting insert  130  contains an aperture  138  therein. The cutting insert  130  is positioned so that the upper portion  124  of the pin  122  passes through the aperture  138  and the bottom surface  134  of the cutting insert  130  rests against the top surface  116  of the shim  112 . 
   Cutting assembly  94  further comprises a clamp  142  that has a body  144  and a threaded aperture  146  that passes through the length of the body  144 . Clamp  142  further has an integral arm  148  that has a distal end  149 . A clamp screw  150  has an upper threaded portion  151  and a lower threaded portion  152  wherein the lower threaded portion  152  is received within the threaded aperture  110  in the head portion  107  of the tool holder  96 . The upper threaded portion  151  of the clamp screw  150  is received within the threaded aperture  146  of the clamp  144 . The clamp  144  is tightened down by the rotation of the clamp screw  150  to that the cutting insert  130  and the shim  112  are firmly secured within the pocket  100  of the tool holder  96 . 
   The clamping arrangement for the embodiment of  FIG. 2  is along the lines of that shown and disclosed in U.S. Pat. No. 4,244,666 to Erickson et al. Other possible clamping arrangements for holding the cutting insert and the shim in the pocket of a tool holder include U.S. Pat. No. 3,996,651 to Heaton, U.S. Pat. No. 4,011,049 to McCreery, and U.S. Pat. No. 4,245,937 to Erickson. 
   Referring to  FIG. 3 , there is shown another specific embodiment of a tool holder generally designated as  154 . Tool holder  154  comprises a body  156  that has a head portion  159  (shown by brackets)at one end  157  and which contains a pocket  158 . The entire head portion  159  (including the pocket  158 ) presents an oxidation-resistant surface due to an oxidation-resistant coating as described hereinafter. The pocket  158  in the tool holder body  156  has a pair of coated side surfaces  160  and a coated bottom surface  162  that intersects the coated side surfaces  160 . The tool holder body  156  contains an aperture  164  (which may be threaded) in the coated bottom surface  162  of the pocket  158 . 
   The coating on the head portion  159  is an oxidation-resistant material. Exemplary oxidation-resistant coatings (applied by physical vapor deposition [PVD] or chemical vapor deposition [CVD] depending upon the specific situation) for application to the head portion  159  may include alumina, titanium aluminum nitride, titanium nitride, titanium carbonitride, titanium carbide, or titanium diboride in single layer as well as various multi-layer coating schemes. One exemplary single layer coating scheme comprises a layer of titanium aluminum nitride applied by PVD. One example of a multi-layer coating scheme comprises a base layer (e.g., titanium carbide) and a coating of alumina on the base layer. Another coating scheme may comprise a base layer (e.g., titanium carbide), an intermediate layer of alumina on the base layer, and a layer of titanium nitride on the alumina layer. Yet another multi-layer coating scheme may comprise a base layer of titanium nitride applied by CVD to the substrate and a layer of titanium aluminum nitride applied by PVD to the base layer. Another coating scheme may comprise a base layer of titanium carbide applied by CVD to the substrate, a first intermediate layer of alumina applied by CVD to the base layer, a second intermediate layer of titanium nitride applied by CVD to the first intermediate layer, and a top layer of titanium nitride or titanium aluminum nitride or titanium diboride applied to the second intermediate layer by PVD. 
   Referring to  FIG. 4 , there is shown still another embodiment of a tool holder generally designated as  176 . The tool holder  176  has a tool holder body  178  that contains a pocket  182  at the one end  180  thereof. The pocket  182  in the tool holder body  178  has a pair of side surfaces  184  and a bottom surface  186 . The bottom surface  186  intersects the side surfaces  184 . Although not shown the tool holder body  178  has an aperture (which may be threaded) contained in the bottom surface  186  of the pocket  182 . 
   The tool holder  176  further includes an oxidation-resistant pocket insert  190  that is affixed within the pocket  182  of the tool holder body  178 . The pocket insert  190  has a pair of external side surfaces  192  and an external bottom surface  194 . The external side surfaces  192  of the pocket insert  190  are against the side surfaces  184  of the pocket  182  of the tool holder body  178 . The external bottom surface  194  of the pocket insert  190  is against the bottom surface  186  of the pocket  182  in the tool holder body  178 . 
   The pocket insert  190  has a pair of exposed side surfaces  196  and an exposed bottom surface  198 . The exposed bottom surface  198  intersects the side surfaces  196 . The exposed side surfaces  196  and the exposed bottom surface  198  each presents an oxidation-resistant surface as described hereinafter. The pocket insert  190  contains an aperture  200  therein wherein the aperture  200  is in alignment with the aperture in the pocket  182  of the tool holder body  178 . 
   The pocket insert  190  is made from an oxidation-resistant material (e.g., a ceramic material). Exemplary materials for the pocket insert  192  include silicon nitrides, SiAlONs or alumina-based materials. Patents that are exemplary of silicon nitride and SiAlON ceramic materials include U.S. Pat. No. 4,563,433 to Yeckley, U.S. Pat. No. 4,711,644 to Yeckley, U.S. Pat. No. 4,889,755 to Mehrotra et al., U.S. Pat. No. 5,370,716 to Mehrotra et al., and U.S. Pat. No. 4,826,791 to Mehrotra et al. Patents that are exemplary of the alumina-based materials include U.S. Pat. No. 5,059,564 to Mehrotra et al., U.S. Pat. No. 5,024,976 to Mehrotra et al. and U.S. Pat. No. 4,965,231 to Mehrotra et al. The pocket insert  190  may also be made from either zirconia or hafnia. 
   As an option, the ceramic substrate may have an oxidation-resistant coating thereon. Exemplary oxidation-resistant coatings (applied by physical vapor deposition [PVD] or chemical vapor deposition [CVD]) for application to the ceramic substrate of the pocket insert may be the same as the coating materials and coating schemes used in conjunction with the head portion  159  of the tool holder  154 . 
   Referring to  FIG. 5 , there is shown an embodiment of the pocket insert  204  that can be used in conjunction with the tool holder of  FIG. 4 . Pocket insert  204  comprises a carbide-based substrate  206  and an oxidation-resistant coating  208  thereon. Optionally, the pocket insert may comprise a cermet with an oxidation-resistant coating thereon. 
   Exemplary carbide-based materials for the substrate  206  of the pocket insert  204  include cemented (cobalt) tungsten carbide wherein the cobalt content may range between about 0 weight percent and about 13 weight percent, and more preferably, the cobalt content ranges between 3 weight percent and 13 weight percent, and most preferably between about 6 weight percent and about 11 weight percent. Cemented (cobalt) tungsten carbide material may optionally contain additives such as titanium, tantalum, niobium, chromium and vanadium. 
   Exemplary oxidation-resistant coatings (applied by physical vapor deposition [PVD] or chemical vapor deposition [CVD]) for application to the substrate of the pocket insert  204  may be the same as the coating materials and coatings schemes described in connection with shim  42 . 
   The substrate for the coated pocket insert may comprise a cermet material. The oxidation-resistant coatings and coating schemes for application to the cermet substrate may be the same as those described in connection with shim  42 . 
   It is apparent that applicants have provided an improved cutting assembly. By providing a shim with an oxidation-resistant surface, the cutting assembly reduces the potential for chipping of the cutting insert due to post-indexing misalignment between the shim and the cutting insert, as well as reduces the accelerated wear rates of cutting inserts due to such misalignment. The shim may be made from a ceramic (uncoated or coated with an oxidation-resistant material) or a carbide-based substrate having an oxidation-resistant coating thereon or a cermet substrate having an oxidation-resistant coating thereon. 
   It is also apparent that applicants have provided an improved cutting insert by providing a tool holder that has a pocket with an oxidation-resistant surface. The pocket may be coated with an oxidation-resistant material or the pocket may contain a pocket insert wherein the pocket insert has an oxidation-resistant surface. The pocket insert may be made from a ceramic (uncoated or coated with an oxidation-resistant material) or a carbide-based substrate having an oxidation-resistant coating thereon or a cermet substrate with an oxidation-resistant coating thereon. By providing a pocket with an oxidation-resistant surface, the cutting assembly reduces the potential for chipping of the cutting insert due to post-indexing misalignment between the shim and the cutting insert, as well as reduces the accelerated wear rates of cutting inserts due to such misalignment. 
   The patents and other documents identified herein are hereby incorporated by reference herein. 
   Other embodiments of the invention will be apparent to those skilled in the art from a consideration of the specification or a practice of the invention disclosed herein. It is intended that the specification and examples are illustrative only and are not intended to be limiting on the scope of the invention. The true scope and spirit of the invention is indicated by the following claims.