Abstract:
There is provided an apparatus for machining a workpiece having a plurality of faces. The apparatus comprises a machine frame, a cutting tool mounted to the machine frame, a support member, a first connecting member interconnecting the machine frame to the support member and defining a relative rotation between the support member and the machine frame about first and second transverse axes, and a second connecting member engaged to the support member and configured to retain the workpiece, the second connecting member being rotatable with respect to the first connecting member about a third axis for exposing alternate ones of the plurality of faces of the retained workpiece to the cutting tool, the third axis extending along a direction different than respective directions of the first and second axes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims priority of U.S. provisional Application Ser. No. 61/664,392, filed on Jun. 26, 2012. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to the field of computer-aided machining, in particular to a multi-axis tool for manufacturing prostheses. 
       BACKGROUND OF THE ART 
       [0003]    In order to reduce costs and increase throughput when machining a workpiece for manufacturing an object having a complex geometry, such as a prosthesis, multi-axis milling machines may be used. Such machines support the workpiece on a frame movable about a plurality of axes. In this manner, the position of the workpiece relative to a cutting tool of the milling machine may be adjusted to improve the machining process. However, such multi-axis machines usually occlude at least one face of the workpiece, this face remaining inaccessible throughout the machining process. Once all faces except the occluded face have been machined, the workpiece then needs to be repositioned to expose the remaining face. This in turn reduces the accuracy and efficiency of the machining process. 
         [0004]    There is therefore a need for an improved machining tool for manufacturing objects of complex geometries. 
       SUMMARY 
       [0005]    In accordance with a first broad aspect, there is provided an apparatus for machining a workpiece having a plurality of faces. The apparatus comprises a machine frame, a cutting tool mounted to the machine frame, a support member, a first connecting member interconnecting the machine frame to the support member and defining a relative rotation between the support member and the machine frame about first and second transverse axes, and a second connecting member engaged to the support member and configured to retain the workpiece, the second connecting member being rotatable with respect to the first connecting member about a third axis for exposing alternate ones of the plurality of faces of the retained workpiece to the cutting tool, the third axis extending along a direction different than respective directions of the first and second axes. 
         [0006]    In accordance with a second broad aspect, there is provided a method for machining a workpiece having a plurality of faces using a cutting tool mounted to a machine frame, the method comprising securing the workpiece to a support member interconnected to the machine frame through a first connecting member, the first connecting member defining a relative rotation between the support member and the machine frame about first and second transverse axes, a second connecting member engaged to the support member and retaining the workpiece, the second connecting member rotatable with respect to the first connecting member about a third axis extending along a direction different than respective directions of the first and second axes, exposing alternate ones of the plurality of faces to the cutting tool by at least one of rotating the support member relative to the machine frame about the first axis, rotating the support member relative to the machine frame about the second axis, and rotating the second connecting member relative to the first connecting member about the third axis, and machining the exposed alternate ones of the plurality of faces with the cutting tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
           [0008]      FIG. 1   a  is a flowchart of a computer-aided method for manufacturing a patient-specific prosthesis, in accordance with an illustrative embodiment of the present invention; 
           [0009]      FIG. 1   b  is a flowchart of the step of virtually machining a 3D model of a prosthesis of  FIG. 1   a;    
           [0010]      FIG. 2  is a front perspective view of a six-axis milling machine, in accordance with an illustrative embodiment of the present invention; 
           [0011]      FIG. 3  is a close-up view of the milling machine of  FIG. 2 ; 
           [0012]      FIG. 4  is a schematic view of a workpiece, in accordance with an illustrative embodiment of the present invention; 
           [0013]      FIG. 5  is a front perspective view of a rotated support frame of a six-axis milling machine, in accordance with an illustrative embodiment of the present invention; 
           [0014]      FIG. 6  is a front perspective view of a rotated workpiece support of a six-axis milling machine, in accordance with an illustrative embodiment of the present invention; 
           [0015]      FIG. 7   a  is a front perspective view of a tilted workpiece held in a workpiece support of a six-axis milling machine, in accordance with an illustrative embodiment of the present invention; 
           [0016]      FIG. 7   b  is a front perspective view of a workpiece held in a workpiece support of a six-axis milling machine and rotated at 90 degrees, in accordance with an illustrative embodiment of the present invention; 
           [0017]      FIG. 8   a  is a front perspective view of a cutting tool machining a face of a workpiece held in a six-axis milling machine, in accordance with an illustrative embodiment of the present invention; 
           [0018]      FIG. 8   b  is a front perspective view of the cutting tool machining an alternate face of the workpiece of  FIG. 8   a  with the workpiece held in the rotated support frame of the six-axis milling machine, in accordance with a first illustrative embodiment of the present invention; 
           [0019]      FIG. 9   a  is a front perspective view of a cutting tool machining a face of the workpiece of  FIG. 8   a  with the workpiece held in the rotated support frame of the six-axis milling machine, in accordance with a second illustrative embodiment of the present invention; and 
           [0020]      FIG. 9   b  is a front perspective view of the cutting tool machining an alternate face of the workpiece of  FIG. 9   a.    
       
    
    
       [0021]    It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
       DETAILED DESCRIPTION 
       [0022]    Referring to  FIG. 1   a , a computer-aided method  100  for manufacturing an object of a complex geometry, such as a patient-specific prosthetic implant will now be described. The method comprises acquiring images at step  102 , which refers to acquiring image data related to the object to be manufactured. In the case where a prosthesis is to be manufactured, this comprises capturing images of the patient&#39;s anatomical region where the prosthesis is to be implanted. Such anatomical region may for example comprise the hip, knee, and ankle regions when total knee replacement surgery is concerned. It should be understood that other anatomical regions, such as the mouth, ear, hand, etc., may be imaged in the process of manufacturing other types of prosthetic implants. It should also be understood that objects other than prostheses may be manufactured. 
         [0023]    The images may be obtained from scans generated using Magnetic Resonance Imaging (MRI), Computed Tomography (CT), ultrasound, x-ray technology, optical coherence tomography, or the like. The images may also be obtained using techniques for three-dimensional scanning of objects, especially when manufacturing objects other than prostheses. Such techniques may include, but are not limited to, white light, laser dot or line projection, time-of-flight, and the like. Acquiring images  102  may be done along one or more planes throughout the body part, such as sagittal, coronal, and transverse. In some embodiments, multiple orientations are performed and the data may be combined or merged during the processing phase (step  104 ). For example, a base set of images may be prepared on the basis of data acquired along a sagittal plane, with missing information being provided using data acquired along a coronal plane. Other combinations or techniques to optimize the use of data along more than one orientation will be readily understood by those skilled in the art. The captured images may further be provided in various known formats and using various known protocols, such as Digital Imaging and Communications in Medicine (DICOM), for handling, storing, printing, and transmitting information. Other exemplary formats are GE SIGNA Horizon LX, Siemens Magnatom Vision, SMIS MRD/SUR, and GE MR SIGNA 3/5 formats. 
         [0024]    Referring to  FIG. 1   b  in addition to  FIG. 1   a , the images, once captured, are processed (step  104 ) using a computer software to create a three dimensional (3D) model of the object. In the case of a prosthetic implant, it is desirable for the latter to be adapted to fit the patient&#39;s unique anatomical region, e.g. a damaged knee joint, for which the images have been captured. Using such a 3D model, it can be ensured that the prosthetic implant provides adequate integration with surrounding bone. Once the 3D model has been created, it may be virtually machined using the computer software (step  106 ) prior to manufacturing the object (step  108 ). In step  106 , a user may define machining parameters (step  110 ), such as the raw workpiece material to be used during the machining process, as well as the cutting tools and cutting operations to be effected. The location of the cutting tool as well as the contact areas between the cutting tool and the workpiece and the inclination, if any, of the cutting tool relative to the surface of the workpiece may further be defined. A specific machining trajectory used for producing an object of the desired shape may therefore be generated. An optional machining simulation may further be performed to enable accurate planning of the machining process (step  112 ). For instance, step  112  may comprise ascertaining optimum cutting tool positioning relative to the workpiece for providing the fastest access to individual workpiece locations and ensure uniform machining of the desired features of the object. A computer numerical control (CNC) code specifying the tool paths may then be generated by the computer software (step  114 ). The code may then be sent to the machining tool (step  116 ) over a suitable communication link for manufacturing the object (step  108 ) in an automated manner. 
         [0025]    Referring now to  FIG. 2 ,  FIG. 3 , and  FIG. 4 , a multi-axis milling machine  200  for free-form machining an object, such as an implant prosthesis, will now be described. The milling machine  200  is illustratively used to implement step  108  of the method  100  described above with reference to  FIG. 1   a  and  FIG. 1   b . The milling machine  200  illustratively comprises a cutting tool  202  mounted on a connecting member, such as a spindle  204 , coupled to a machine frame  205  and having a tip  206  adapted to mate with a surface of a workpiece  208 . The workpiece  208 , which is illustratively shaped as a block, may be made of any material suitable for manufacturing the object. In the case of a prosthesis, such material may include but not be limited to a polymer, a metal, a cross-linked polymer, a ceramic, a composite, and an alloy. 
         [0026]    The cutting tool  202  illustratively has a shape and size adapted to remove material from the workpiece  208  by movement of the tip  206  of the cutting tool  202  within the milling machine  200  and on the surface of the workpiece  208 . For this purpose, the cutting tool  202  may be translated along the X, Y, and Z axes using a manual wheel, quill drive, automatic control dial, automatic control from a controller, or the like, to enable accurate positioning of the cutting tip  206  relative to an exposed surface of the workpiece  208 . As illustrated in hashed lines on  FIG. 2 , the spindle  204  may further be angled relative to the Z axis for inclining the cutting tool  202  relative to the exposed surface of the workpiece  208 . Illustratively, such a surface may be one of the faces  209   a ,  209   b ,  209   c ,  209   d ,  209   e , and  209   f , depending on the orientation of the workpiece  208 . Indeed, as will be described below, components of the milling machine  200  may be rotated in three (3) degrees of freedom about axes A, B, and C for positioning the workpiece  208  at a desired orientation relative to the cutting tool  202 . In one embodiment, axes B and C are transverse while axis A extends along a direction different than axes B and C. In particular, in the illustrated embodiment, axes A and C and axes B and C are substantially perpendicular. Once the workpiece  208  has been fully machined by the cutting tool  202 , a prosthesis  210  having a desired shape may be obtained. Although the workpiece  208  has been illustrated as having the shape of a parallelepiped, it should be understood that any other suitable shape, such as a cylinder, may apply. 
         [0027]    The milling machine  200  further comprises a support frame  211  illustratively comprising a first member, such as a column  212  having a substantially square cross-section, connected to the machine frame  205  and a substantially planar base member  214 . The base member  214  illustratively extends away from the column  212  along a plane substantially perpendicular to the plane of the column  212 , thereby forming an L-shape therewith. The support frame  211  may be connected to the machine frame  205  through a connection allowing the support frame  211  to be rotatable relative to the machine frame  205  in a clockwise or counterclockwise direction about the rotary axis B. The connection may be a rotary shaft  215  received within an aperture (not shown) formed in the column  212  and extending along axis B for enabling rotation of the support frame  211  about axis B. Any other suitable connection (e.g. a spindle) known to those skilled in the art that allows relative rotation between the support frame  211  and the machine frame  205  about the axis B may apply. As used herein, a direction of rotation is said to be clockwise or counterclockwise when the milling machine  200  is viewed from the front, as shown for example in  FIG. 5 . The support frame  211  may be rotated in either direction for presenting alternative faces of the workpiece  208  to the cutting tool  202 , as will be discussed in further detail below. For example, as illustrated in  FIG. 5 , the support frame  211  may be rotated in a clockwise direction B 1  about axis B from the initial position of  FIG. 3 , shown in hashed lines, to a rotated position, shown in solid lines. 
         [0028]    In order to provide the cutting tool  202  access to the faces (references  209   a ,  209   b ,  209   c ,  209   d ,  209   e , and  209   f  in  FIG. 4 ) of the workpiece  208 , the cutting tool  202  being illustratively positioned above the support frame  211  (see  FIG. 2 ), the support frame  211  may be rotated clockwise or counterclockwise about axis B up to 140 degrees. Given the configuration of the milling machine (reference  200  of  FIG. 2 ), rotation about the axis B beyond 140 degrees may not prove suitable as the presence of the base member  214  would most likely prevent the cutting tool  202  from having access to the workpiece  208 . In the example illustrated in  FIG. 5 , the support frame  211  is rotated clockwise in the direction of arrow B 1  by ninety (90) degrees such that the column  212 , is rotated from the initial position shown in hashed lines, where the column  212  extends along a substantially vertical plane (not shown), to the rotated position shown in solid lines, where the column  212  extends along a substantially horizontal plane (not shown). It should be understood that the support frame  211  may be rotated by any other suitable angle about the axis B. 
         [0029]    Referring to  FIG. 6 , a connection, such as a swiveling spindle  216  or the like, is further illustratively mounted to the base member  214  and extends away therefrom along the Z axis. The spindle  216  is adapted to receive and have secured thereto using suitable attachment means, such as fasteners, screw, bolts, and the like, a support member  218  for retaining the workpiece  208 . The spindle  216  enables rotation of the support member  218  relative to the machine frame  205  about the rotary axis C with the support frame  211  serving as a connection member interconnecting the machine frame  205  to the support member  218 . In this manner, the support member  218  may be rotated clockwise or counterclockwise up to 360 degrees about the rotary axis C. The cutting tool  202  may therefore be provided better access to a surface, as in  209   a , of the workpiece  208  held on the workpiece support member  218  and presented to the cutting tool  202  at a suitable orientation. As a result, the cutting tool  202  can more efficiently machine the surface as in  209   a . It should be understood that, in other embodiments, angles beyond 360 degrees may apply. Indeed, the support member  218  may be caused to rotate (either clockwise or counterclockwise) by more than one turn, for instance by one full turn (360 degrees) and an additional angle, e.g. forty (40) degrees for a total of 400 degrees. Other angles may apply. 
         [0030]    For example, the workpiece support member  218 , and accordingly the workpiece  208  held thereon, may be rotated in a counterclockwise direction C 1  about the axis C. As a result, the workpiece support member  218  is moved from the initial position shown in hashed lines, to a rotated position, shown in solid lines. In the rotated position, a longitudinal axis (not shown) of the workpiece support member  218  is at a more acute angle relative to the axis B than was the case in the initial position. By rotating the workpiece support member  218  further counterclockwise in the direction of arrow C 1 , the side face  209   b  of the workpiece  208  may be made more accessible to the cutting tool  202 . The cutting tool  202  may then access the side face  209   b  by angling the spindle (reference  204  in  FIG. 2 ) relative to the Z axis, thereby inclining the cutting tool  202  so that the latter is positioned in proximity to the side face  209   b . Alternatively, the side face  209   b  may be made even more accessible to the cutting tool  202  by rotating the support frame  211  clockwise about axis B. 
         [0031]    Although the base member  214  has been illustrated as substantially planar and a column  212  is shown for illustrative purposes, thus resulting in a support frame  211  having an L-shape, it should be understood that the base member  214  and column  212  may have any other shape suitable for supporting the swiveling spindle  216  and accordingly the workpiece support member  218  thereon. For example, the support frame  211  may only comprise the base member  214 , and accordingly need not have an L-shape. Also, the base member  214  may have a curved surface. A pair of columns as in  212  may also be provided on opposite edges (not shown) of the base member  214 , thus forming a U-shaped support frame  211 . In addition, instead of the spindle  216 , shaft  215 , and support frame  211 , a rotating swivel head (not shown) may couple the workpiece support member  218  to the machine frame (reference  205  in  FIG. 2 ) for enabling rotation thereof about the B and C axes of  FIG. 3 . Other configurations will be readily understood by those skilled in the art. 
         [0032]    Referring to  FIG. 7   a , the workpiece support member  218  illustratively comprises a first substantially planar base member  220  extending along a plane substantially parallel to the plane of the base member  214 . A pair of arms  222   a  and  222   b  project upwardly from opposite edges (not shown) of the base member  220 . Each arm  222   a ,  222   b  extends along a plane substantially perpendicular to the plane of the base member  220 , thereby resulting in a U-shaped workpiece support member  218 . A pair of support plates  224   a  and  224   b  may further be positioned adjacent the arms  222   a  and  222   b  and secured thereto using a suitable connection or attachment means, as will be discussed below. The support plates  224   a ,  224   b  are illustratively adapted to engage opposite faces, as in  209   e  and  209   f  (see  FIG. 4 ), of the workpiece  208  for securely retaining the workpiece  208  between the support plates  224   a  and  224   b . The support plates  224   a  and  224   b  are illustratively shaped and sized so as to contact a reduced area of the opposite faces  209   e  and  209   f  of the workpiece  208 . In this manner, the cutting tool  202  may still be provided access to a portion of the faces  209   e  and  209   f  for machining thereof while the faces  209   a ,  209   f  remain in contact with the support plates  224   a ,  224   b . In particular, it is desirable for the support plates  224   a ,  224   b  to contact as little of the faces  209   e ,  209   f  as possible so that only a reduced portion thereof may still remain once the machined workpiece  208  is produced by the machining tool  200 . The machined workpiece  208  would then be reworked in a subsequent machining process to remove any unwanted remaining material. For analogous reasons, it is desirable for the arms  222   a  and  222   b  to have as small a width as possible, thereby occluding as little as possible of the faces of the workpiece  208 , e.g. faces  209   e ,  209   f , they are adjacent to. 
         [0033]    In one embodiment, an attachment means comprising a first and a second rotary shaft  226   a ,  226   b  is used to secure each support plate  224   a ,  224   b  to a corresponding arm  22   a ,  222   b . In particular, the first rotary shaft  226   a  may be received in apertures (not shown) formed in the arm  222   a  and the support plate  224   a  for rotatably coupling the arm  222   a  to the support plate  224   a . Similarly, the second rotary shaft  226   b  may be received in apertures (not shown) formed in the arm  222   b  and the support plate  224   b  for rotatably coupling the arm  222   b  to the support plate  224   b . When in place, the shafts  226   a  and  226   b  illustratively extend along the X axis and may be rotated up to 360 degrees about the rotary axis A in either a clockwise or a counterclockwise direction. In this manner, respective rotation of the support plates  224   a  and  224   b  about the axis A relative to the arms  222   a  and  222   b  can be achieved. It should be understood that it is desirable for shafts  226   a ,  226   b  to be rotated simultaneously in the same direction and by the same angle in order to achieve suitable rotation of the workpiece  208  retained within the support plates  224   a ,  224   b . It should also be understood that the workpiece  208  may be support by the support member  218  and allowed to rotate relative thereto about axis A using any suitable means other than the support plates  224   a ,  224   b . Moreover, it should be understood that the shafts  226   a  and  226   b  may be rotated beyond 360 degrees so as to rotate by more than one full turn. For example, as discussed above, the shafts  226   a  and  226   b  may be rotated by 400 degrees. Any other angle may apply. In particular, the angles of rotation of the shafts  226   a  and  226   b  may be unlimited. In this case, the shafts  226   a ,  226   b  may be provided with infinite rotation angles (in either the clockwise or counterclockwise directions) so as to continuously rotate while the workpiece  208  is being machined. 
         [0034]    It should further be understood that, although illustrated and described as having a U-shape, the workpiece support member  218  may have any other shape suitable for rotatably supporting the workpiece  208 . For example, although the arms  222   a  and  222   b  are illustrated as being substantially perpendicular to the base member  220 , the arms  222   a ,  222   b  may be projecting upwards therefrom at an angle other than ninety (90) degrees so long as rotary movement of the workpiece  208  relative to the axis A as well as rotary movement of the workpiece support member  218  about the axis C are enabled. Other configurations known to those skilled in the art may apply. 
         [0035]    Provision of the rotary shafts  226   a ,  226   b  allows for the workpiece  208  retained between the support plates  224   a  and  224   b  to be rotated about the axis A for exposing alternate adjacent faces  209   a ,  209   b ,  209   c , and  209   d  of the workpiece  208 . The workpiece  208  may further be tilted about the axis A, to adjust the inclination of an exposed surface, as in  209   a , relative to the Z axis. In this manner, the exposed surface as in  209   a  may be inclined to facilitate the machining process. It should be understood that the cutting tool  202  may also be angled relative the Z axis and accordingly relative to an exposed surface, as in  209   a , of the workpiece  208  by inclining the spindle  204 , as discussed above. 
         [0036]    For example, as illustrated in  FIG. 7   a , the workpiece  208  may be rotated in a counterclockwise direction A 1  about the axis A from an initial position, shown in hashed lines, to a tilted position, shown in solid lines. In the illustrated position, a plane of the upper face  209   a  of the workpiece  208  is at a more acute angle relative to the Z axis than was the case in the initial position. This may ease the machining process. As illustrated in  FIG. 7   b , by rotating the workpiece  208  further in the counterclockwise direction A 1 , e.g. at ninety (90) degrees relative to the initial position shown in hashed lines, the side face  209   d  of the workpiece  208  may be made more accessible to the cutting tool  202 . Rotating the workpiece  208  further in the counterclockwise direction A 1 , e.g. by 180 degrees relative to the initial position, enables exposure of the bottom face  209   c  of the workpiece  208  (shown in hashed lines), which would otherwise not be accessible to the cutting tool  202  even if the latter was to be angled about the Z axis. 
         [0037]    A robot (not shown), such as a CNC-type machine or a multi-axis robot with articulated arms, may be used to induce rotation of the milling machine  200  about at least one of the axes A, B, and C, and thereby induce rotation of the workpiece  208  relative to the cutting tool  202 . In this manner, access to all six faces  209   a ,  209   b ,  209   c ,  209   d ,  209   e , and  209   f  of the workpiece  208  may be provided for machining thereof. As a result, more uniform machining accuracy may be achieved, as desired for producing high precision objects with complex geometries, such as the prosthesis  210  shown in  FIG. 2 . As discussed above, it will be apparent that objects other than the prosthesis  210  may be machined using the milling machine  200 . As also discussed, it should also be understood that the A, B, and C axes may be rotated clockwise, counterclockwise, or both. 
         [0038]    For example, referring to  FIG. 8   a , during the machining process, the cutting tool  202  may be translated about the Z axis in the direction of arrow D towards the workpiece  208  for machining the top face  209   a . The workpiece  208  may then be rotated up to 180 degrees about the axis A for alternatively exposing the side face  209   b , the bottom face  209   c , and the side face  209   d  of the workpiece  208  to the cutting tip  206 . As shown in  FIG. 8   b , the support frame  211  may then be rotated clockwise by ninety (90) degrees about the axis B in the direction of arrow B 2  so as to be displaced from the initial position shown in hashed lines toward the rotated position shown in solid lines. In this manner, the side face  209   f  of the workpiece  208  can be exposed to the cutting tool  202 . Rotation about axis B by more than ninety (90) degrees is also possible, such as 140 degrees. Rotation by less than ninety (90) degrees is also possible. Using the spindle  216 , the workpiece support member  218  may then be rotated counterclockwise by 180 degrees about the axis C in the direction of arrow C 2 . In this manner, the side face  209   e  of the workpiece  208  can be presented to the cutting tip  206  for machining thereof and all six faces  209   a ,  209   b ,  209   c ,  209   d ,  209   e , and  209   f  of the workpiece  208  may be machined. As discussed above, in order to access the faces  209   e  and  209   f  once the faces  209   a ,  209   b ,  209   c , and  209   d  have been machined, rather than rotating the support frame  211  in the direction of arrow B 2  and the workpiece support member  218  in the direction of arrow C 2  to achieve the position illustrated in  FIG. 8   b , the cutting tool  202  may be translated about the X and Y axes as well as angled relative the Z axis to gain proper access to the faces  209   e  and  209   f  while the support frame  211  and workpiece support member  218  remain in the position illustrated in  FIG. 8   a.    
         [0039]    Referring now to  FIG. 9   a  and  FIG. 9   b , the faces  209   a ,  209   b ,  209   c ,  209   d ,  209   e , and  209   f  of the workpiece  208  may also be machined using a set of positions of the support frame  211  and workpiece support member  218  alternate to the positions described above with reference to  FIG. 8   a  and  FIG. 8   b . As shown in  FIG. 9   a , the support frame  211  may first be rotated counterclockwise by ninety (90) degrees about the axis B in the direction of arrow B 3  so as to be displaced from the initial position shown in hashed lines toward the rotated position shown in solid lines. In this manner, side face  209   e  can be exposed to the cutting tool  202 . Using the spindle  216 , the workpiece support member  218  may then be rotated counterclockwise by ninety (90) degrees about the axis C in the direction of arrow C 3  (see  FIG. 9   b ) for exposing face  209   b  to the cutting tool  202 . It should be understood that angles other than ninety (90) degrees may apply. Further rotation of the workpiece support member  218  counterclockwise in the direction of arrow C 3  may enable alternate exposure of faces  209   f  and  209   d  to the cutting tool  202 . Upon rotation of the workpiece  208  about the axis A, faces  209   a  and  209   c  may then be suitably positioned relative to the cutting tool  202  so as to be accessed thereby. 
         [0040]    Rotation of the workpiece  208  along at least one of the A, B, and C axes therefore enables positioning of the tip (reference  206  in  FIG. 2 ) of the cutting tool  202  at specific angles and/or locations relative to exposed surfaces of the workpiece  208 . In one embodiment, rotation about axis A may be performed over 360 degrees, rotation about axis B may be performed between +/−140 degrees, and rotation about axis C may be performed over 360 degrees. Variants of the range of rotation will be readily understood by those skilled in the art. It will also be understood that various sets of positions of the support frame  211  and workpiece support member  218  may be used to enable machining of all faces (references  209   a ,  209   b ,  209   c ,  209   d ,  209   e , and  209   f  in  FIG. 4 ) of the workpiece  208 . 
         [0041]    In addition, as discussed above, translation of the cutting tool  202  about the X, Y, and Z axes illustratively enables the cutting tool  202  to more accurately remove material from the workpiece  208 . Use of the six-axis milling machine  200  may further reduce the total machining cost by reducing the volumes of machines, tooling, and fixturing that would be needed to achieve the same result. This in turn eliminates separate setups and reduces queue times, leading to an increased throughput and time savings. Completion of the machining process in a single setup also reduces scrap, rework, and part handling. 
         [0042]    It should be noted that the embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.