Abstract:
A method for repairing a defect in a component having a first major surface and a second major surface, a thickness defined between the major surfaces, and an edge adjoining both the major surfaces is characterized by forming a slot cut entirely through the thickness of the component between the first and second major surfaces, the slot extending inward from the edge of the component towards an interior of the component to a depth from the edge sufficient to remove at least a substantial part of the defect, the slot defining an open end at the edge of the component, a closed end within the component, a width, a radius formed by the closed end, and opposing chamfered edges at the open end.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. application Ser. No. 11/273,057, entitled “SYSTEM AND METHOD FOR REPAIRING A GAS TURBINE ENGINE COMPONENT,” filed Nov. 14, 2005, which claims priority to U.S. Provisional Patent Application Ser. No. 60/669,444, entitled, “REPAIR SYSTEMS AND METHODS FOR GAS TURBINE ENGINE COMPONENTS,” filed on Jul. 15, 2005. 
     
    
     BACKGROUND 
       [0002]    The present invention relates generally to a method and system for repairing a defect in a component, such as a gas turbine engine component (e.g., blades, vanes, etc.). More particularly, the present invention relates to a repair system and method that includes substantially removing a defect from a component by forming a slot in the component to remove a section that substantially encompasses the defect. 
         [0003]    A gas turbine engine component, such as a blade tip, a blade trailing edge, a blade platform, a vane trailing edge, or a vane platform, may become damaged during use. During operation, the gas turbine engine component is typically exposed to high pressure, foreign objects, or high temperatures. Over time, these operating conditions may cause small cracks or other defects to develop in the gas turbine engine component. Although such defects may be small, they often have a significant impact, and the gas turbine engine component may be rendered unacceptable for use. As such, many repair processes have been developed to salvage these gas turbine engine components. It is important that the repair process or system generally preserve the integrity of the gas turbine engine component, and does not adversely affect functionality of the gas turbine engine component. 
         [0004]    Defects in gas turbine engine components have typically been repaired by hand. In one approach, an operator holds the defective gas turbine engine component in his hand while using a grinding wheel, a carbide cutter, or other tool or cutting surface to route out (i.e., remove) at least a substantial amount of the defect in the part. The operator generally determines a geometry of the section to be removed based upon the type and location of the defect. Thereafter, the gas turbine engine component is built back up, such as by welding a replacement piece to the gas turbine engine component, in order to place the gas turbine engine component in a condition that allows it to be returned to service in an engine. This approach is less than ideal because various operators may utilize different cutting surfaces (e.g., grinding wheels), which may remove different amounts of material from a gas turbine engine component, possibly creating different edge geometries. A diversity in edge geometries may cause the welding process to be more difficult and variable from one operator to another. Further, the inability to reproduce repair procedures may be a drawback in some manufacturing and servicing environments. 
       BRIEF SUMMARY 
       [0005]    The present invention is a method of repairing a defect in a component having a first major surface and a second major surface, a thickness defined between the major surfaces, and an edge adjoining both the major surfaces. The method includes forming a slot cut entirely through the thickness of the component between the first and second major surfaces, the slot extending inward from the edge of the component towards an interior of the component to a depth from the edge sufficient to remove at least a substantial part of the defect, the slot defining an open end at the edge of the component, a closed end within the component, a width, a radius formed by the closed end, and opposing chamfered edges at the open end. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of a gas turbine engine blade, which includes a platform and a main body (including a tip). 
           [0007]      FIG. 2  is a perspective view of a template that may be used to determine whether a component is repairable. 
           [0008]      FIG. 3  is a schematic sectional view of an example of a slot in a component (shown as a partial section), where the slot has a geometry that facilitates the weld repair process. 
           [0009]      FIG. 4  is a perspective view of a universal holding fixture, which may be used to hold a component in a predetermined position while a slot is formed in the component. 
           [0010]      FIG. 5  is a perspective view of a holding fixture that is configured to receive one specific component. 
           [0011]      FIG. 6  is a perspective view of a set-up fixture that may be used to align a blade within a holding fixture. 
           [0012]      FIG. 7  is a perspective view of a device that may be used in accordance with a first embodiment of the present invention, where the device includes a grinding wheel that is capable of forming a slot in a component. 
           [0013]      FIGS. 8A-8D  are schematic side views of the different steps in forming a slot in accordance with a second embodiment of the present invention, which includes forming an initial cut ( FIG. 8B ), finished cut ( FIG. 8C ), and final slot in the blade ( FIG. 8D ). 
           [0014]      FIG. 9A  is a perspective view of a rough-cut fixture, which may be used to form an initial cut in a component. 
           [0015]      FIG. 9B  is a partial perspective view of the rough-cut fixture shown in  FIG. 9A , where a holding fixture has been attached to the rough-cut fixture by mating ridges in the rough-cut fixture with grooves in the holding fixture. 
           [0016]      FIG. 10A  is a perspective view of a finish router, which may be used to finish the initial cut in a component to a predetermined width and radius, thereby forming a finished cut. 
           [0017]      FIG. 10B  is a perspective view of the finish router of  FIG. 10A , where a router is positioned in contact with an initial cut in a blade. 
           [0018]      FIG. 11A  is a perspective view of a chamfer fixture, which ma be used to chamfer an edge of a finished cut. 
           [0019]      FIG. 11B  is a partial perspective side view of the chamfer fixture of  FIG. 11A , where the holding fixture has been secured to chamfer fixture. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The present invention is both a method and system for repairing a defect in a component, such as a gas turbine engine component (e.g., a turbine blade tip, turbine blade trailing edge, turbine blade platform, vane trailing edge, vane platform, etc.), where the method and system may each be used to prepare a component for a weld repair process. As stated in the Background section, a defect in a component may be in the form of a crack in a body of the component. As used herein, the term “defect” includes any internal or external feature, characteristic, attribute, aspect, or other such quality that is present or existing within a component, and for which removal or repair thereof is desirable. This damage may take the form of physical or structural deformations, malformations, imperfections, anomalies or irregularities including, but not limited to, cracks, dents, fissures, fractures, pits, depressions, voids, cavities, and substandard surfaces or edges. Additionally, the damage may take the form of material-based flaws, weaknesses, or non-uniformities. 
         [0021]    In accordance with the general principles of the invention, at least a substantial amount of a defect is removed from a component by removing a section of the component that substantially encompasses the defect. In the present invention, the defect is removed by forming (or “creating”) a “slot” in the component to remove a section of the component that substantially encompasses the defect. A “slot” is used as a general term describing a void left in a component after a portion thereof is removed, and the use of the term “slot” is not intended to limit the scope of the present invention to specific shapes or geometries disclosed in the embodiments. The slot formed in the component has a predetermined geometry (i.e., a predetermined shape), which is selected based upon various factors that will be discussed below. As the slot is formed, at least a substantial part of the defect is removed, leaving a void in the component. The slot may also encompass regions adjacent the visible defect in order to remove any latent or unexposed damage. The void in the component created by the slot may then be repaired according to methods known in the art, such as by welding (or otherwise integrally joining) a replacement piece to the component in order to fill the void. In this way, a component may be prepared for repair by removing at least a substantial part of the defect in the component. Hereinafter, referring to removal of the “defect” should be understood as meaning “at least a substantial part of the defect”. 
         [0022]    The predetermined slot geometry is selected based upon various factors. One consideration is whether the geometry will aid a subsequent repair process (e.g., a weld repair process). In the embodiments described below, the slot has a radial end portion that provides an area for a weld pool to gather, while a welding may use the chamfered edges as a visual reference point for where a sidewall weld build-up should stop. 
         [0023]    The slot geometry is also selected based upon a study of a structure of the component being repaired, such as a stress analysis of the component in its particular application. When a portion of a component is removed in order to remove a defect, the structural integrity of the component may be adversely affected. For example, if a part of a hollow turbine blade wall is removed to remove a defect, leaving a void, and a replacement piece is welded in the void, the turbine blade wall may not be as structurally sound because the seams from the weld repair may weaken the turbine blade wall. Furthermore, the shape of the void may also affect the stress distribution properties of the turbine blade. The inventors of the present invention believe that the particular slot geometry disclosed in the embodiments helps to minimize adverse affects on the structural integrity of a turbine blade. This is, in part, due to the sound weld resulting from how the geometry of the slot aids the welding process. The slot geometry should be selected with these considerations in mind, in order to prevent failure of the component after repair. 
         [0024]    The inventive repair system and method may be used to remove a defect in a component more consistently than with many existing methods because of the predetermined geometry of at least a part of the slot. Rather than an operator determining what the slot geometry will be during the repair process, the geometry is predetermined and is consistent for each repair process using the particular repair process or system, regardless of the operator or irrespective of the extent of the damage. The consistency is attributable to the fixtures and devices of the inventive method and system. The resulting consistency allows for a generally reproducible method and system of repair, which may be advantageous in many manufacturing and servicing environments. Furthermore, the inventive system and method of the present invention are more ergonomic than many current systems and methods because of the use of fixtures to hold the component in a predetermined position. 
         [0025]    In a first embodiment of the present invention, a single device is used to form a slot in a component. In a second embodiment of the present invention, multiple devices are used to form a slot in a component. Each of the multiple devices includes a different cutting surface, which each serve a different function. A first device forms an initial cut in the component. A second device finishes the initial cut to a predetermined width and radius, which results in a finished cut. Finally, a third device chamfers the edges of the finished cut. 
         [0026]      FIG. 1  is a perspective view of blade  10 , for use in a gas turbine engine. Blade  10  is shown as an example of a “component” that may be used in conjunction with the present invention. Blade  10  includes platform  12  and main body  14 , which includes tip  16 . Main body  14  of blade  10  typically includes complicated passages (not shown) for cooling air. These passages aid the cooling of blade  10  during operation of the gas turbine engine, and without such cooling, blade  10  may overheat and main body  14  may warp. While the present invention is described in reference to blade  10 , it should be understood by those skilled in the art that the present invention is applicable to any suitable damaged component that requires repair. Once a damaged component is discovered, it is preferable that an operator determines whether the damage is suitable for repair before delving into the repair process. Various factors influence whether a component may be repaired. In the case of blade  10 , a defect within main body  14  may not be suitable for repair if the removal of the defect would damage the internal cooling passages. A template that identifies a repairable area on the component may be used to determine whether a defect is suitable for repair. 
         [0027]      FIG. 2  is a perspective view of template  20 , which may be used to determine whether a component may be repaired. Template  20  is designed to fit over blade  10  (shown in  FIG. 1 ). Repairable area  22  (which is shown to be a trapezoidal shape) has been identified as the area that may be repaired. Repairable area  22  of template  20  was selected after an internal geometry of blade  10  was analyzed to ensure that repairs would only be made in areas that would not adversely affect the internal structure (e.g., cooling passageways) or integrity of blade  10 . For example, it may be preferred to leave a minimum gap (e.g., 0.035 inches) between any slot and internal structure in order to allow for a sound weld between a replacement piece and blade  10 . In alternate embodiments, repairable area  22  may be also encompass areas of blade  10  (or other component) that are not subject to maximum stress, in order to minimize the possibility of failure of blade  10  after repair. 
         [0028]    The boundaries of repairable area  22  may be formed using any suitable method, such as by scribing lines directly on template  22 , or otherwise marking template  22 . If a defect falls within the area bounded by repairable area  22 , then the defect can be repaired using the present invention. However, if a defect falls outside repairable area  22 , the defect cannot be repaired using this invention without adversely affecting the internal cooling passages of main body  14  of blade  10 . In this way, template  20  provides a visual indicium of whether a defect is suitable for repair. 
         [0029]    Template  20  may be formed of a transparent material, such as Plexiglas. It is preferred that at least a part of template  20  is formed of a transparent material because after template  20  is positioned over blade  10 , it is necessary to compare a location of the defect with the location of repairable area  22 . In alternate embodiments, repairable area  22  is identified using other suitable means. For example, template  20  may be opaque with a transparent window only allowing the repairable area  22  to be viewed by an operator. Template  20  (and repairable area  22 ) may be modified so that it can be used with a component other than blade  10 . 
         [0030]    Once it has been determined that blade  10  can be repaired, a slot is formed in blade in order to remove at least a substantial amount of crack  16  therefrom. Forming the slot in blade  10  prepares blade  10  for weld repair (using processes known in the art), so that blade  10  may be repaired and returned to service. For example, in a subsequent weld repair step, a replacement piece shaped similarly to the slot may be welded into the slot. Thereafter, the replacement piece may be machined down to the desired geometry. 
         [0031]      FIG. 3  is a schematic side view of an embodiment of slot  30  in component  32  (shown as a partial section). Component  32  is shown as any generic component that includes a defect that requires repair, such as blade  10 . Also shown in  FIG. 3  is a side view of an example of a suitable grinding wheel  34  that may be used to form slot  30  in accordance with the first embodiment of the present invention. Slot  30  has a geometry that facilitates a weld repair process after at least a substantial part of the defect is removed from component  32 . Specifically, end portion  36  of slot  30  provides an area for a weld pool to gather, while chamfered edges  38 A and  38 B of slot  30  provide a visual reference point for determining a stopping point for sidewall weld build-up. 
         [0032]    If component  32  is a gas turbine engine blade including internal cooling passages, such as blade  10 , a depth of chamfered edges  38 A and  38 B depend upon a thickness of a wall (i.e., a dimension between the exterior surface of component  32  and the interior cooling passages) generally at the location of defect in component  32 . By using a chamfer depth generally equal to a thickness of a wall of component  32  generally at the location of the defect in component  32 , a welder is given a visual indicium of a thickness of the wall, which aids the welder in weld-repairing blade  10 . 
         [0033]    Determining a desired depth D of slot  30  is based on various factors, including the internal geometry of component  32  and the geometry of the defect in component  32 . For example, if component  32  is blade  10  of  FIG. 1 , a consideration for determining depth D includes the location of the internal cooling passages in main body  14  of blade  10 . The internal cooling passages typically need to be of a certain minimum size in order to facilitate proper air circulation and cooling of blade  10 . As a result, depth D will depend on the desired size of the cooling air passages. Furthermore, depth D must be large enough to substantially remove the defect from blade  10 . 
         [0034]    Grinding wheel  34  may be any suitable grinding wheel, such as, but not limited to, a cubic boron nitride (CBN) wheel or a diamond plated steel wheel. In the first embodiment of the present invention, grinding wheel  34  is designed to have a geometry that allows slot  30  to be cut, radius  36  of slot  30  to be rounded, and edges  38 A and  38 B slot  30  to be chamfered, with a single device with a single cutting tool, rather than multiple devices each having a separate cutting tool (e.g., the second embodiment described in reference to  FIGS. 8A-11B ). The use of a single device provides the advantage of time efficiency over the second embodiment, which includes the use of multiple devices to form slot  30 . 
         [0035]    Section  40  of grinding wheel  34  forms radius  36 , while sections  42 A and  42 B form chamfers  38 A and  38 B, respectively. A geometry of grinding wheel  34  is complimentary to slot  30 . That is, the dimensions of grinding wheel  34  determine the depth D and width W of slot  30 , and the depth of chamfered edges  38 A and  38 B. In the first embodiment of the present invention, grinding wheel  34  has route depth RD of about 0.060 inches, radius R of about 0.625 inches, inner width IW of about 0.125 inches, and an outer width OW of about 0.25 inches, and a chamfer angle C of about 135 degrees (°). Depth D of slot  30  is generally equal to route depth RD of grinding wheel  34 , while width W of slot  30  is generally equal to inner width IW of grinding wheel  34 , and so forth. In alternate embodiments, grinding wheel  34  may have a route depth RD of about 0.100 inches, about 0.140 inches, or about 0.150 inches. In order to achieve slots of different depths, widths, and/or chamfer depths, grinding wheels having different dimensions are used. 
         [0036]      FIG. 4  is a perspective view of holding fixture  50 , which may be used to hold blade  10  (or other component) in a predetermined position while a slot is formed in blade  10 . Specifically, holding fixture  50  is configured to attach to a device (e.g., device  65  of  FIG. 7  or rough-cut fixture  90  of  FIG. 9A ), and functions to hold blade  10  in a fixed, predetermined position while the device forms a cut in blade  10 . Once it has been determined that blade  10  can be repaired (e.g., by using template  20  shown in  FIG. 2 ), an operator may position blade  10  in holding fixture  50 , or any suitable holding fixture. Holding fixture  50  is designed to hold blade  10  in a predetermined position so that defects therein can be easily and consistently removed by various operators. Holding fixture  50  includes clamps  52  and  54 , which are configured to hold blade  10  in a substantially fixed position. As it will be shown in  FIG. 6 , clamps  52  and  54  each grasp main body  14  of blade  10 . 
         [0037]    Holding fixture  50  is designed as a universal fixture that is capable of receiving and holding various components in various positions. In an alternate embodiment, a holding fixture is configured to receive one specific component. An example of such a fixture is shown in  FIG. 5 , which shows a perspective view of fixture  60 . Fixture  60  is designed to hold blade  10  in a specific position to ensure all operators orient blade  10  the same when removing a defect from blade  10 . Unlike fixture  50  of  FIG. 4 , fixture  60  is not designed to hold to various components. Rather, fixture  60  is designed to hold only blade  10 . Fixture  60  includes ridges  62 , clamp  63 , and shoulder  64 . Main body  14  of blade  10  rests on shoulder  64 , while platform  12  of blade  10  rests on ridges  62 . Ridges  62  are configured to mate with ridges in platform  12  of blade  10 . Clamp  63  secures blade  10  in place. While the rest of the detailed description discusses the use of fixture  50  of  FIG. 4 , it should be kept in mind that fixture  60  may be a suitable substitution for fixture  50 . 
         [0038]      FIG. 6  is a perspective view of set-up fixture  70 , where holding fixture  50  is attached to set-up fixture  70 , and blade  10  is positioned in holding fixture  50  and secured by clamps  52  and  54 . An operator may utilize set-up fixture  70  to properly position blade  10  within holding fixture  50  so that blade  10  aligns properly with the cutting device. 
         [0039]    Blade  10  is first positioned in holding fixture  50 , and then holding fixture  50  is positioned in set-up fixture  70 . In order to position blade  10  in holding fixture  50 , blade  10  is brought parallel to holding fixture  50  and positioned against indicator stop  72 . Blade tip  16  is aligned with mark  75  on indicator  74 . Once crack  18  on blade tip  16  is aligned with mark  75 , and blade  10  is otherwise aligned with set-up fixture  70 , clamps  52  and  54  are tightened down so blade  10  is held securely in holding fixture  50 . In an alternate embodiment, holding fixture  50  is positioned in set-up fixture  70 , and then blade  10  is positioned in holding fixture  50 . After blade  10  is properly positioned within holding fixture  50 , blade  10  and holding fixture  50  may be removed from set-up fixture  70 . 
         [0040]      FIG. 7  is a perspective view of device  65 , which may be used to form a slot in blade  10 , in accordance with a first embodiment of the present invention. Holding fixture  50  is attached to device  65 . Device  65  includes grinding wheel  34  (also described in reference to  FIG. 3 ), air gun  66 , which drives grinding wheel  34 , screw  68 , and frame  69 . Air gun  66  is mounted to frame  69 , while grinding wheel  34  is coupled to air gun  66 . Frame  69  of device  65  is configured to receive holding fixture  50 . For example, frame  69  may include rails that mate with corresponding grooves in holding fixture  50 . Examples of suitable rails that may be incorporated into frame  69  are shown in  FIG. 9A  with respect to rough-cut fixture  80 . After holding fixture  50  and frame  69  are secured together, screw  68  is aligned with a corresponding threaded hole  96  (shown in  FIG. 9B ) in holding fixture  50  to secure holding fixture  50  to frame  69 . In alternate embodiments, holding fixture  50  and frame  69  may be secured together using any suitable means, such as, but not limited to, a clamping mechanism. 
         [0041]    Once it has been determined that crack  18  in tip  16  of blade  10  is suitable for repair, an operator may position blade  10  in holding fixture  50  in a predetermined position, as described in reference to  FIGS. 5 and 6 . Holding fixture  50  is then attached to device  65 , and because blade  10  was aligned on holding fixture  50  using set-up fixture  70  (shown in  FIG. 5 ), crack  18  has been “pre-aligned” with grinding wheel  34 . Grinding wheel  34  is then rotated with air gun  66  as it is placed in contact with crack  18 , thereby removing material and forming a slot (e.g., slot  30  shown in  FIG. 3 ). Once the slot is formed in tip  16  of blade  10 , blade  10  is ready to be weld repaired (by processes known in the art) and returned to service in a gas turbine engine. In alternate embodiments, holding fixture  60  may be substituted for holding fixture  50 . 
         [0042]    In a second embodiment of the present invention, a slot is formed in a component using multiple devices, where the final slot is formed in three steps: 1) an initial cut is formed in the component, 2) the initial cut is finished to a predetermined width, while a end portion of the initial cut is formed to a predetermined radius, resulting in a finished cut, and 3) edges of the finished cut are chamfered. This embodiment is discussed in reference to  FIGS. 8A-11B .  FIGS. 8A-8D  illustrate each step in forming a slot in a component. Specifically,  FIGS. 8A-8D  are a schematic side views of crack  18  in blade  10  (also shown in  FIG. 1 ), initial cut  76  in blade  10 , finished cut  77  in blade  10 , and slot  78  in blade  10 , respectively, in accordance with the second embodiment of the present invention. 
         [0043]      FIG. 8A  is a schematic side view of blade  10 , in which crack  18  has formed. It is assumed for purposes of description that crack  18  is suitable for repair.  FIG. 8B  is a schematic side view of blade  10 , where initial cut  76  has been formed therein with a first cutting device (e.g., rough-cut fixture  80  shown in  FIG. 9A ). Initial cut  76  in blade  10  substantially removes crack  18  (and possibly some material surrounding crack  18  in order to remove latent defects) from blade  10 , and produces a rough-cut rout in blade  10 . Initial cut  76  does not have the desired geometry of the slot. Rather, this desired geometry is achieved with a second and a third devices, which form the finished cut  77  ( FIG. 8C ) and the finished slot  78  ( FIG. 8D ). Precutting blade  10  by forming initial cut  76  limits the amount of cutting that will be need to be done afterwards with a carbide cutter. 
         [0044]      FIG. 8C  is a schematic side view of blade  10 ,where finished cut  77  has been formed therein. Finished cut  77  is formed by finishing initial cut  76  (shown in  FIG. 8B ) to a predetermined width W and finishing end portion  77 A to radius R with a second device (e.g., finish router  100  shown in  FIG. 10A ). While finished cut  77  has a geometry that is close to the desired geometry of final slot  78  (shown in  FIG. 8D ), edges  77 B and  77 C of finished cut  77  are still unfinished (i.e., unchamfered).  FIG. 8D  is a schematic side view of blade  10 , where slot  78  is formed therein. Width 
         [0045]    W and radius R of end portion  78 A of slot  78  have the same dimensions has width W and radius R of end portion  77 A of finished cut  77 . In order to form slot  78  having the desired geometry, edges of finished cut  77 B and  77 C are chamfered to form edges  78 B and  78 C. Resulting slot  78  has a geometry that facilitates the weld-repair process, as previously discussed. 
         [0046]      FIG. 9A  is a perspective view of rough-cut fixture  80 , which includes frame  82 , grinding wheel  84 , spindle  86 , air gun  88 , which is mounted to frame  82 , and screw  90 . Grinding wheel  84  is mounted on spindle  86 , which is coupled to and driven by air gun  88 . Rough-cut fixture is an embodiment of a device that may be used to form initial cut  76  (shown in  FIG. 8B ) in tip  16  of blade  10  to remove at least a substantial portion of crack  18 . Frame  82  of rough-cut fixture  80  is configured to receive holding fixture  50  (shown in  FIG. 4 ). Frame  82  includes rails  92  and  94 , which mate with corresponding grooves in holding fixture  50 . By aligning holding fixture  50  grooves with rails  92  and  94  and “sliding” holding fixture  50  onto frame, holding fixture  50  is attached to rough-cut fixture  80 . After holding fixture  50  and rough-cut fixture  80  are attached together, screw  90  is aligned with a corresponding threaded hole  96  (shown in  FIG. 9B ) in holding fixture  50  to secure holding fixture  50  to rough-cut fixture  80 . In alternate embodiments, holding fixture  50  and rough-cut fixture  80  may be secured together using any suitable means. 
         [0047]    Grinding wheel  84  may be carbide cutter or an impregnated fiber cutoff wheel. A 0.065″ or 0.125″ wide grinding wheel  84  may be used. Grinding wheel  84  has a different geometry than grinding wheel  34  from the first embodiment. Grinding wheel  84  is shaped to form initial cut  76  in blade  10 , rather than a slot having the final geometry. Air gun  88  drives shaft  86 , and thereby drives grinding wheel  84 , which is attached to shaft  86 . Air gun  88  may be any suitable high power air gun, such as, but not limited to, a Dotco, model 1212500-01rt, 23000 rpm, 90 psi/6.1 Bar, which is made commercially available by CooperTools, Houston, Tex. In alternate embodiments, any suitable mechanical motor or other driving device may be substituted for air gun  88 . 
         [0048]      FIG. 9B  is a partial perspective view of rough-cut fixture  80 , where holding fixture  50  has been attached to rough-cut fixture  80  by mating ridges  92  and  94  (shown in  FIG. 9A ) with corresponding grooves in holding fixture  50 . As  FIG. 9B  shows, screw  90  is aligned to fit within a corresponding threaded hole  96  in holding fixture  50 . Blade  10  is securely clamped to holding fixture  50 , and grinding wheel  84  is positioned to form an initial cut in blade  10 . Specifically, crack  18  in tip  16  of blade  10  is aligned with grinding wheel  84  so that initial cut  76  is substantially superimposed over crack  18 , thereby removing at least a substantial section of crack  18  from tip  16  of blade  10 . 
         [0049]    Once initial cut  76  is formed, holding fixture  50  (with blade  10  securely fastened therein) is removed from rough-cut fixture  80 . Initial cut  76  is then finished to a predetermined width and radius with a second cutting device, resulting in finished cut  77  (shown in  FIG. 8C ). In the second embodiment, the second cutting device is finish router  100 , which is shown in  FIGS. 10A and 10B . In alternate embodiments, any suitable cutting device with a cutting surface configured to finish the initial cut to a predetermined width and radius may be used. 
         [0050]      FIG. 10A  is a perspective view of finish router  100 , which includes router  102 , air gun  104 , and frame  106 . Air gun  104  is mounted to frame  106 , while router  102  is coupled to and driven by air gun  104 . As with frame  82  of rough-cut fixture  80 , frame  106  includes rails  108  and  110 , which mate with corresponding grooves in holding fixture  50 . Holding fixture  50  and finish router  100  are further secured together using screw  112 , which is configured to fit within a corresponding threaded hole  96  (shown in  FIG. 10B ) in holding fixture  50 . In alternate embodiments, holding fixture  50  and finish router  100  may be secured together using any suitable means. 
         [0051]    Router  102  may be a 0.125 inch carbide cutter. In alternate embodiments, carbide cutters of any suitable size, or any suitable cutting surface may be used to finish initial cut  76  (shown in  FIG. 8B ). Router  102  establishes a consistent routing width and radius at the end of initial cut  76 . As with air gun  88  of rough-cut fixture  80 , air gun  104  may be any suitable high power air gun, such as, but not limited to, a Dotco, model 1212500-01rt, 23000 rpm, 90 psi/6.1 Bar, which is made commercially available by CooperTools, Houston, Tex. In alternate embodiments, any suitable mechanical motor or other driving device may be substituted for air gun  104 . 
         [0052]      FIG. 10B  is a partial perspective side view of finish router  100 , where holding fixture  50  has been attached to finish router  100  by mating ridges  108  and  110  (shown in  FIG. 10A ) with corresponding grooves in holding fixture  50 . Screw  112  is threaded through threaded hole  96  in holding fixture  50 , thereby further securing holding fixture  50  to finish router  100 . Blade  10  is securely clamped to holding fixture  50 . 
         [0053]      FIG. 10B  illustrates how router  84  aligns with initial cut  76  to finish initial cut  76  to a predetermined width and radius to form finished cut  77 . Because blade  10  was aligned on holding fixture  50  with set-up fixture  70 , positioning holding fixture  50  on finish router  100  aligns initial cut  76  with router  102 , such that router  102  is centered with initial cut  76 . Router  102  is then rotated with air gun  104  as it is placed in contact with initial cut  76 , thereby removing material and finishing a width and radius of initial cut  76  to the predetermined dimensions. As those skilled in the art recognize, the width and radius of initial cut  76  are determined by the size of router  102 . 
         [0054]    Once finished cut  77  is formed in blade  10 , holding fixture  50  (with blade  10  securely fastened therein) is removed from finish router fixture  100 . Edges  118  of finished cut  77  are then chamfered with a third cutting device. In the second embodiment, the third cutting device is chamfer fixture  120 , which is shown in  FIGS. 11A and 11B . In alternate embodiments, any suitable cutting surface configured to chamfer edge  118  of finished cut  77 . 
         [0055]      FIG. 11A  is a perspective view of chamfer fixture  120 , which includes frame  122 , carbide cutter  124 , air gun  126 , and screw  128 . As with frame  82  of rough-cut fixture  80 , frame  122  includes rails  130  and  132 , which mate with corresponding grooves in holding fixture  50  to attach holding fixture  50  to chamfer fixture  120 . Holding fixture  50  and chamfer fixture  120  are further secured together using screw  128 , which is configured to fit within a corresponding threaded hole  96  (shown in  FIG. 11B ) in holding fixture  50 . In alternate embodiments, holding fixture  50  and chamfer fixture  120  may be secured together using any suitable means. 
         [0056]    Carbide cutter  124  is a 0.250″ carbide cutter. In alternate embodiments, carbide cutters of any suitable size, or any suitable cutting surface may be used to chamfer edge  118  of finished cut  77  near blade tip  16 . Air gun  126  is coupled to carbide cutter  124 , and rotates carbide cutter  124  at a high speed. As with air gun  88  of rough-cut fixture  80 , air gun  126  may be any suitable high power air gun, such as, but not limited to, a Dotco, model 1212500-01rt, 23000 rpm, 90 psi/6.1 Bar, which is made commercially available by CooperTools, Houston, Tex. In alternate embodiments, any suitable mechanical motor or other driving device may be substituted for air gun  104 . 
         [0057]      FIG. 11B  is a partial perspective side view of chamfer fixture  120 , where holding fixture  50  has been attached to chamfer fixture  120  by mating ridges  130  and  132  with corresponding grooves in holding fixture  50 . Screw  128  is threaded through threaded hole  96  in holding fixture  50 , thereby further securing holding fixture  50  to chamfer fixture  120 . Blade  10  is securely clamped to holding fixture  50  and finished cut  77  in tip  16  of blade  10  is aligned with carbide cutter  124 . Once again, because blade  10  was previously aligned on holding fixture  50  with set-up fixture  70 , positioning holding fixture  50  on chamfer fixture  120  aligns finished cut  77  with carbide cutter  124 , such that carbide cutter  124  is centered with finished cut  77 . 
         [0058]    After attaching holding fixture  50  to chamfer fixture  120 , carbide cutter  124  is rotated with air gun  126  as it is placed in contact with finished cut  77 , thereby chamfering edge  118  of finished cut  77 . As those skilled in the art recognize, a configuration of carbide cutter  124  determines a geometry of a chamfer of edges  77 B and  77 C of finished cut  77 , and a depth of the chamfer may be determined by a thickness of blade  10  wall at tip  16 . 
         [0059]    Once edge  77 B and  77 C of finished cut  77  is chamfered, holding fixture  50  (with blade  10  securely fastened therein) is removed from chamfer fixture  120 , and blade  10  is removed from holding fixture  50 . However, in alternate embodiments, blade  10  may be removed from holding fixture  50  prior to removing holding fixture  50  from chamfer fixture  120 . Blade  10  is now prepared for weld repair, and may be weld repaired according to processes known in the art in order to place blade  10  is condition for returning to service in a gas turbine engine. 
         [0060]    While blade  10  tip  16  repair was described and depicted in reference to  FIGS. 1-11B , other portions of blade  10  may also be repaired in accordance with the principals of the present invention. For example, a trailing edge of the blade could be rough-cut, finish routed and chamfered in a similar manner as just described, as could a blade platform, a vane platform, and/or a vane trailing edge, etc. Further, the present invention is not limited to turbine blades or turbine components. The principals of the present invention, where a slot having a predetermined geometry is formed in a component in order to remove at least a substantial amount of a defect from the component, may be applied to any suitable component. 
         [0061]    The terminology used herein is for the purpose of description, not limitation. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as bases for teaching one skilled in the art to variously employ the present invention. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.