Abstract:
A cylinder bore including an inner surface including an axial travel area and an axial non-travel area including two discontinuous axial widths of the cylindrical bore and the axial travel area extending therebetween. A nominal diameter of the axial travel area is greater than that of the axial non-travel area. A plurality of annular grooves is formed in the two discontinuous axial widths of the cylindrical bore.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a division of Ser. No. 13/913,865, filed Jun. 10, 2013, issued as U.S. Pat. No. ______ on ______. This application is also related to the application having Ser. No. 13/461,160, filed May 1, 2012, issued as U.S. Pat. No. 8,726,874 on May 20, 2014. This application is also related to the application having Ser. No. 13/913,871, filed Jun. 10, 2013, the disclosures of which are hereby incorporated in their entirety by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to cylindrical surfaces of cylindrical engine bores. 
       BACKGROUND 
       [0003]    Automotive engine blocks include a number of cylindrical engine bores. The inner surface of each engine bore is machined so that the surface is suitable for use in automotive applications, e.g., exhibits suitable wear resistance and strength. The machining process may include roughening the inner surface and subsequently applying a metallic coating to the roughened surface and subsequently honing the metallic coating to obtain a finished inner surface. Various surface roughening techniques are known in the art, but have suffered from one or more drawbacks or disadvantages. 
       SUMMARY 
       [0004]    In a first embodiment, a cylinder bore is disclosed. The cylinder bore includes an inner surface including an axial travel area and an axial non-travel area including two discontinuous axial widths of the cylindrical bore and the axial travel area extending therebetween. A nominal diameter of the axial travel area is greater than that of the axial non-travel area. A plurality of annular grooves is formed in the two discontinuous axial widths of the cylindrical bore. 
         [0005]    In a second embodiment, a cylinder bore is disclosed. The cylinder bore includes first and second axial non-travel inner surface portions and an axial travel inner surface portion extending therebetween. A nominal diameter of the axial travel inner surface portion is greater than that of the first and second axial non-travel inner surface portions. A plurality of the annular grooves is formed in each of the first and second axial non-travel inner surface portions. A plurality of peaks extends between the plurality of annular grooves. 
         [0006]    In a third embodiment, a cylinder bore is disclosed. The cylinder bore includes first and second axial non-travel inner surface portions and an axial travel inner surface portion extending therebetween. A nominal diameter of the axial travel inner surface portion is greater than that of the first and second axial non-travel inner surface portions. A plurality of annular grooves is formed in each of the first and second axial non-travel areas and has a square wave shape of a uniform dimension. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  depicts a top view of a joint or deck face of an exemplary engine block of an internal combustion engine; 
           [0008]      FIG. 2A  depicts a pre-boring step in which an unprocessed cylinder bore inner surface is bored to a diameter; 
           [0009]      FIG. 2B  depicts an interpolating step in which a travel area is machined using a cutting tool to produce a recessed inner surface with a pocket and annular surface grooves; 
           [0010]      FIG. 2C  depicts a deforming step in which flat peaks between adjacent grooves are deformed to obtain deformed peaks; 
           [0011]      FIG. 2D  depicts an interpolating step in which one or more of the non-travel areas are machined using a cutting tool to form annular grooves; 
           [0012]      FIG. 2E  shows a magnified, schematic view of annular grooves formed in the non-travel areas of an engine bore; 
           [0013]      FIG. 3A  depicts a perspective view of a cutting tool according to one embodiment; 
           [0014]      FIG. 3B  depicts a top view of cutting tool showing a top axial row of cutting elements; 
           [0015]      FIGS. 3C, 3D and 3E  depict cross-sectional, schematic views of first and second groove cutting elements and pocket cutting elements taken along lines  3 C- 3 C,  3 D- 3 D and  3 E- 3 E of  FIG. 3A , respectively; 
           [0016]      FIG. 3F  shows a cylindrical shank for mounting a cutting tool in a tool holder according to one embodiment; 
           [0017]      FIG. 4A  is a schematic, top view of a cylinder bore according to one embodiment; 
           [0018]      FIG. 4B  is a schematic, side view of the cylinder bore of  FIG. 4B  according to one embodiment; 
           [0019]      FIG. 5  shows an exploded, fragmented view of the inner surface of the cylinder bore before, during and after an interpolating step; 
           [0020]      FIGS. 6A, 6B and 6C  illustrate a swiper tool according to one embodiment; and 
           [0021]      FIG. 7  illustrates a magnified, cross-sectional view of the inner surface of a cylinder bore. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Reference will now be made in detail to embodiments known to the inventors. However, it should be understood that disclosed embodiments are merely exemplary of the present invention which may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, rather merely as representative bases for teaching one skilled in the art to variously employ the present invention. 
         [0023]    Except where expressly indicated, all numerical quantities in this description indicating amounts of material are to be understood as modified by the word “about” in describing the broadest scope of the present invention. 
         [0024]    Automotive engine blocks include a number of cylindrical engine bores. The inner surface of each engine bore is machined so that the surface is suitable for use in automotive applications, e.g., exhibits suitable wear resistance and strength. The machining process may include roughening the inner surface and subsequently applying a metallic coating to the roughened surface and subsequently honing the metallic coating to obtain a finished inner surface with requisite strength and wear resistance. Alternatively, a liner material having requisite strength and wear resistance characteristics may be applied to the unfinished inner surface of the engine bore. 
         [0025]    Embodiments disclosed herein provide cutting tools and processes for roughening the inner surface of cylindrical bores, e.g., engine bores, to enhance the adhesion and bonding of a subsequently applied metallic coating, e.g., thermal spray coating, onto the inner surface. Accordingly, the finished inner surface may have enhanced strength and wear resistance. 
         [0026]      FIG. 1  depicts a top view of a joint face of an exemplary engine block  100  of an internal combustion engine. The engine block includes cylinder bores  102 , each of which includes an inner surface portion  104 , which may be formed of a metal material, such as, but not limited to, aluminum, magnesium or iron, or an alloy thereof, or steel. In certain applications, aluminum or magnesium alloy may be utilized because of their relatively light weight compared to steel or iron. The relatively light weight aluminum or magnesium alloy materials may permit a reduction in engine size and weight, which may improve engine power output and fuel economy. 
         [0027]      FIGS. 2A, 2B, 2C, 2D and 2E  depict cross-sectional views of a cylinder bore inner surface relating to steps of a process for applying a profile to the inner surface of the cylinder bore.  FIG. 2A  depicts a pre-boring step in which an unprocessed cylinder bore inner surface  200  is bored to a diameter that is less than the diameter of the finished, e.g., honed, diameter of the inner surface. In some variations, the difference in diameter is 150 to 250 microns (μms). In other variations, the difference in diameter is 175 to 225 microns. In one variation, the difference in diameter is 200 microns. 
         [0028]      FIG. 2B  depicts an interpolating step in which a travel area  202  is machined into the pre-bored inner surface  200  using a cutting tool. Interpolation-based roughening can be accomplished with a cutting tool suitable for cylinder bores of varying diameter. The cutting tool can be used to roughen only a selected area of the bore, such as the ring travel area of the bore. Roughening only the ring travel portion of the bore may reduce coating cycle time, material consumption, honing time and overspray of the crank case. 
         [0029]    The length of the travel area corresponds to the distance in which a piston travels within the engine bore. In some variations, the length of travel area  202  is 90 to 150 millimeters. In one variation, the length of travel area  202  is 117 millimeters. The travel area surface is manufactured to resist wear caused by piston travel. The cutting tool forms annular grooves  204  (as shown in magnified area  208  of  FIG. 2B ) and a pocket  206  into the travel area  202 . It should be understood that the number of grooves shown in magnified area  208  are simply exemplary. Dimension  210  shows the depth of pocket  206 . Dimension  212  shows the depth of annular grooves  204 . In some variations, the groove depth is 100 to 140 microns. In another variation, the groove depth is 120 microns. In some variations, the pocket depth is 200 to 300 microns. In another variation, the pocket depth is 250 microns. 
         [0030]    The pre-bored inner surface  200  also includes non-travel portions  214  and  216 . These areas are outside the axial travel distance of the piston. Dimensions  218  and  220  show the length of non-travel portions  214  and  216 . In some variations, the length of non-travel area  214  is 2 to 7 millimeters. In one variation, the length of non-travel area  214  is 3.5 millimeters. In some variations, the length of non-travel area  216  is 5 to 25 millimeters. In one variation, the length of non-travel area  216  is 17 millimeters. The cutting tool and the interpolating step are described in greater detail below. 
         [0031]      FIG. 2C  depicts a deforming step in which the flat peaks between adjacent grooves  204  are deformed to obtain deformed peaks  222  in which each peak  222  includes a pair of undercuts  224 , as shown in magnified area  226  of  FIG. 2C . It should be understood that the number of deformed peaks shown in magnified area  226  are simply exemplary. The deforming step may be carried out using a swiping tool. The swiping tool and the deforming step are described in greater detail below. 
         [0032]      FIG. 2D  depicts an interpolating step in which one or more of the non-travel areas  214  and  216  are machined using a cutting tool to form annular grooves  228 , as shown in magnified area  230  of  FIG. 2E . Flat peaks  232  extend between annular grooves  228 . It should be understood that the number of grooves shown in magnified area  230  are simply exemplary. In one embodiment, the grooves form a square wave shape of a uniform dimension. In some variations, the dimension is 25 to 100 microns. In one variation, the dimension is 50 microns. As described in more detail below, the cutting tool may form a profile of grooves within one or more of the non-travel areas  214  and  216 . 
         [0033]      FIG. 3A  depicts a perspective view of a cutting tool  300  according to one embodiment. Cutting tool  300  includes a cylindrical body  302  and first, second, third and fourth axial rows  304 ,  306 ,  308  and  310  of cutting elements. Cylindrical body  302  may be formed of steel or cemented tungsten carbide. The cutting elements may be formed of a cutting tool material suitable for machining aluminum or magnesium alloy. The considerations for selecting such materials include without limitation chemical compatibility and/or hardness. Non-limiting examples of such materials include, without limitation, high speed steel, sintered tungsten carbide or polycrystalline diamond. Each axial row  304 ,  306 ,  308  and  310  includes 6 cutting elements. As shown in  FIG. 3A , the 6 cutting elements are equally radially spaced apart from adjacent cutting elements. In other words, the six cutting elements are located at 0, 60, 120, 180, 240, and 300 degrees around the circumference of the cylindrical body  302 . While 6 cutting elements are shown in  FIG. 3A , any number of cutting elements may be used according to one or more embodiments. In certain variations, 2 to 24 cutting elements are utilized. 
         [0034]      FIG. 3B  depicts a top view of cutting tool  300  showing the first axial row  304  of cutting elements. As shown in  FIG. 3B , the 0 degree cutting element includes a cutting surface  312  and a relief surface  314 . The other degree cutting elements include similar cutting and relief surfaces. The relief surface can otherwise be referred to as an end face. In the embodiment shown, each of the cutting elements is one of three types of cutting elements, i.e., a first type of groove cutting element (G 1 ), a second type of groove cutting element (G 2 ) and a pocket cutting element (P). In the embodiment shown in  FIG. 3B , the 60 and 240 degree cutting elements are the first type of groove cutting element; the 120 and 300 degree cutting elements are the second type of groove cutting element; and the 0 and 180 degree cutting elements are the pocket cutting element. Accordingly, the sequence of cutting elements from 0 to 300 degrees is G 1 , G 2 , P, G 1 , G 2  and P, as shown in  FIG. 3B . However, it shall be understood that any sequence of cutting elements is within the scope of one or more embodiments. In some variations, the sequence is G 1 , P, G 2 , G 1 , P and G 2  or P, G 1 , G 1 , P, G 2  and G 2 . In the embodiment shown, two groove cutting elements are necessary due to the width and number of valleys between peaks, which exceed the number and widths which can be cut with one element. For other groove geometries, one or three groove cutting elements may be used. The sequence of cutting is not significant as long as all utilized elements are in the axial row. 
         [0035]    In the embodiment shown, the arrangement of teeth on the G 1  and G 2  cutting elements are dimensioned differently. Regarding G 1  shown in  FIG. 3C , tooth  332 , which is closest to relief surface  322 , has an outermost side wall that is flush with relief surface  322 . Regarding G 2  shown in  FIG. 3D , tooth  350 , which is closest to relief surface  340 , has an outermost side wall that is offset from relief surface  340 . As shown in  FIG. 3D , the offset is 400 microns. In other variations, the offset may be 0 to 500 microns. Accordingly, there is a 400 micron offset between the relief edge tooth of G 1  and relief edge tooth of G 2 . The relief surface facing side of the sixth tooth  354  of G 1  cutting element  318  and the relief surface facing side of the fifth tool  356  of G 2  cutting element  336  are offset from each other by 550 microns. These differing dimensions are utilized so that within each row of cutting elements, the G 1  and G 2  cutting elements can be axially offset from each other. For example, the axial offset may be 550 microns. In this embodiment, this allows the edges to cut two separate rows of grooves, one by each offset element, with acceptable stress on the teeth. 
         [0036]    In some variations, there is at least one of G 1  and G 2  and at least one of P. As shown in  FIG. 3A , the cutting elements in each row are offset or staggered circumferentially from one another between each row, e.g., each cutting element of the 0, 60, 120, 180, 240 and 300 degree cutting elements is staggered by 60 degrees in adjacent rows. The staggering improves the lifetime of the cutting tool by smoothing out the initial cutting of the inner surface profile. If the cutting elements are aligned between adjacent rows, more force would be necessary to initiate the cutting operation, and may cause more wear on the cutting elements or deflection and vibration of the tool. 
         [0037]      FIGS. 3C, 3D and 3E  depict cross-sectional, schematic views of G 1 , G 2  and P cutting elements taken along lines  3 C- 3 C,  3 D- 3 D and  3 E- 3 E of  FIG. 3B , respectively. Referring to  FIG. 3C , a G 1  cutting element  318  is shown having cutting surface  320 , relief surface  322  and locating surface  324 . The cutting surface  320  schematically includes a number of teeth  326 . It should be understood that the number of teeth shown are simply exemplary. In certain variations, the number of teeth is 1 to 2 per millimeter of axial length. In one variation, the number of teeth is 1.25 teeth per axial length. Each tooth is rectangular in shape, although other shapes, e.g., square shapes, are contemplated by one or more embodiments. Each tooth has a top surface  328  and side surfaces  330 . As shown in  FIG. 3C , the length of top surface  328  is 250 microns and the length of side surfaces  330  is 300 microns. In other variations, the length of the top surface is 200 to 400 microns and the length of the side surfaces is 200 to 500 microns. Flat valleys  358  extend between adjacent teeth  326 . As shown in  FIG. 3C , the width of the valley  358  is 550 microns. In other variations, the width of the valley is 450 to 1,000 microns. Cutting element  318  also includes a chamfer  334 . In the embodiment shown, chamfer  334  is at a 15 degree angle. This chamfer provides stress relief and ease of mounting of the cutting elements. In the embodiment shown, the cutting elements are replaceable brazed polycrystalline diamond elements. In other embodiments, replaceable tungsten carbide elements mounted in adjustable cartridges may be used. 
         [0038]    Referring to  FIG. 3D , a G 2  cutting element  336  is shown having a cutting surface  338 , a relief surface  340  and a locating surface  342 . The cutting surface  338  schematically includes a number of teeth  344 . It should be understood that the number of teeth shown are simply exemplary. In certain variations, the number of teeth is 1 to 2 teeth per millimeter of axial length. In one variation, the number of teeth is 1.25 per millimeter of axial length. Each tooth is rectangular in shape, although other shapes, e.g., square shapes, are contemplated by one or more embodiments. Each tooth has a top surface  346  and side surfaces  348 . As shown in  FIG. 3D , the length of top surface  346  is 250 microns and the length of side surfaces  348  is 300 microns. In other variations, the length of the top surface is 200 to 400 microns and the length of the side surfaces is 200 to 500 microns. Tooth  350 , which is closest to relief surface  340 , has an outermost side wall that is offset from relief surface  340 . As shown in  FIG. 3D , the offset is 400 microns. In other variations, the offset may be 0 to 500 microns. Flat valleys  358  extend between adjacent teeth  344 . As shown in  FIG. 3D , the width of the valley  360  is 550 microns. In other variations, the width of the valley is 400 to 1,000 microns. Cutting element  336  also includes a chamfer  352 . In the embodiment shown, chamfer  352  is at a 15 degree angle. This chamfer provides stress relief and ease of mounting of the cutting elements. In the embodiment shown, the cutting elements are replaceable brazed polycrystalline diamond elements. In other embodiments, replaceable tungsten carbide elements mounted in adjustable cartridges may be used. 
         [0039]    In the embodiment shown, the arrangement of teeth on the G 1  and G 2  cutting elements are dimensioned differently. Regarding G 1  shown in  FIG. 3C , tooth  332 , which is closest to relief surface  322 , has an outermost side wall that is flush with relief surface  322 . Regarding G 2  shown in  FIG. 3D , tooth  350 , which is closest to relief surface  340 , has an outermost side wall that is offset from relief surface  340 . As shown in  FIG. 3D , the offset is 400 microns. In other variations, the offset may be 0 to 500 microns. Accordingly, there is a 400 micron offset between the relief edge tooth of G 1  and relief edge tooth of G 2 . The relief surface facing side of the sixth tooth  354  of G 1  cutting element  318  and the relief surface facing side of the fifth tool  356  of G 2  cutting element  336  are offset from each other by 550 microns. These differing dimensions are utilized so that within each row of cutting elements, the G 1  and G 2  cutting elements can be axially offset from each other. For example, the axial offset may be 550 microns. In this embodiment, this allows the edges to cut two separate rows of grooves, one by each offset element, with acceptable stress on the teeth. 
         [0040]    Referring to  FIG. 3E , a P cutting element  362  is shown having a cutting surface  364 , relief surface  366  and a locating surface  368 . Cutting surface  364  is flat or generally flat, and has no teeth, in contrast to the cutting surfaces of the G 1  and G 2  cutting elements, which are shown in phantom. The teeth shown in phantom line in  FIG. 3E  indicates the tooth geometry of the G 1  and/or G 2  cutting elements and how and the cutting surface  364  is radially offset away from the tooth top surfaces  328  and  346 . The P cutting element  362  removes a portion of the peaks between the grooves and creates the pocket. The amount of radial offset controls the depth of the grooves cut in the bottom of the pocket depicted in  FIG. 2B . In the illustrated embodiment, the dimension 120 microns in  FIG. 3E  is the depth of the grooves that are cut when the G 1 , G 2  and P elements are used in combination. The dimension of 50.06 millimeters is the diameter of the cutting tool measured to the top surfaces (minimum diameter) of the teeth that are formed. 
         [0041]      FIG. 3F  shows a cylindrical shank  380  for mounting cutting tool  300  into a tool holder for mounting in a machine spindle. In other embodiments, the shank may be replaced by a direct spindle connection, such as a CAT-V or HSK taper connection. 
         [0042]    Having described the structure of cutting tool  300  according to one embodiment, the following describes the use of cutting tool  300  to machine a profile into an inner surface of a cylinder bore.  FIG. 4A  is a schematic, top view of a cylinder bore  400  according to one embodiment.  FIG. 4B  is a schematic, side view of cylinder bore  400  according to one embodiment. As shown in  FIG. 4A , cutting tool  300  is mounted in a machine tool spindle with an axis of rotation AT parallel to the cylinder bore axis AB. The tool axis AT is offset from the bore axis AB. The spindle may be either a box or motorized spindle. The tool rotates in the spindle about its own axis AT at an angular speed Ω 1  and precesses around the bore axis AB at angular speed Ω 2 . This precession is referred to as circular interpolation. The interpolating movement permits the formation of a pocket and annular, parallel grooves within the inner surface of a cylinder bore. 
         [0043]    In one embodiment, the aspect ratio of the diameter of the cutting tool DT to the inner diameter of the bore DB is considered. In certain variations, the inner diameter is substantially greater than the cutting tool diameter. In certain variations, the cutting tool diameter is 40 to 60 millimeters. In certain variations, the inner diameter of the cylinder bore is 70 to 150 millimeters. Given this dimensional difference, this cutting tool may be utilized with a significant variation in bore diameter. In other words, use of the cutting tools of one or more embodiments does not require separate tooling for each bore diameter. 
         [0044]    Regarding the pre-boring step of  FIG. 2A  identified above, a boring bar (not shown) can be attached to a machine spindle to bore a diameter that is less than the diameter of the finished diameter of the inner surface. In certain variations, the feed rate, i.e., the rate in which the boring bar is fed radially outward into the inner surface, of the spindle is 0.1 to 0.3 mm/rev. In one or more embodiments, the spindle is telescoping. In other embodiments, the spindle may be fixed and the bore may move. In another variation, the feed rate is 0.2 mm/rev. In certain variations, the rotational speed of the boring bar is 1,000 to 3,000 rpms. In another variation, the rotational speed of the boring bar is 2,000 rpms. 
         [0045]    Regarding the interpolating step of  FIG. 2B  identified above, the cutting tool  300  is used to machine a profile into the inner surface of cylinder bore  400 . In certain variations, the interpolating feed rate (radially outward) of the spindle during this step is 0.1 to 0.3 mm/rev. In another variation, the feed rate is 0.2 mm/rev. In certain variations, the rotational speed of cutting tool  300  is 3,000 to 10,000 rpms. In another variation, the rotational speed of cutting tool  300  is 6,000 rpms. 
         [0046]    As described above, cutting tool  300  includes cylindrical body  302  that includes four rows of cutting elements. According to this embodiment, the axial length of the cut is 35 mm. Therefore, if the length of the travel area is 105 mm, three axial steps are used to complete the interpolating of the travel area. In other words, the axial position of the spindle is set at an upper, middle and lower position before rotating the cutting tool at each of the positions. While 4 cutting element rows are shown in one embodiment, it is understood that additional rows may be utilized. For example, 6 rows may be used to cut a similar travel area in 2 axial steps instead of 3. Further, 12 rows may be used to cut a similar travel area in 1 axial step. 
         [0047]    Moving to  FIG. 4B , a fragmented portion of cylindrical body  302  of cutting tool  300  and cutting elements from axial rows  304 ,  306 ,  308  and  310  are schematically shown in overlapping relationship. As described above and shown in this  FIG. 4B , there are overlaps  406 ,  408  and  410  between adjacent cutting element rows. This overlap helps provide uniform and consistent profile cutting in boundary regions. 
         [0048]      FIG. 5  shows an exploded, fragmented view of the inner surface  500  of the cylinder bore before, during and after the interpolating step. The cutting tool  300  is fed radially outward into the surface of the cylinder bore at a rate of 0.2 mm per revolution. While the cutting tool  300  is being fed into the inner surface, it is rotating at a speed of 6,000 rpms. The P pocket cutting elements cut pocket  502  into the inner surface  500 . The height of the pocket is H and the width is wv. The H value corresponds to the axial offset between the valleys  358  of G 1  and G 2  cutting elements  318  and  336  and the cutting surface  364  of P cutting element  362 . In a non-limiting, specific example, the offset is 250 microns. Therefore, H is 250 microns. The wv value corresponds to the length of the tooth upper surfaces  328  and  356  of the G 1  and G 2  cutting elements  318  and  336 . In the non-limiting, specific example set forth above, the tooth upper surfaces have a length of 250 microns. Accordingly, wv is 250 microns. 
         [0049]    The groove cutting elements G 1  and G 2  remove material  504  to create peaks  506 . The height of these peaks is h and the width is wp. In the non-limiting, specific example shown, wp is 150 microns. The h value is determined by the radial offset between the top of groove cutting elements G 1  and G 2  and the pocket cutting element P. In the non-limiting, specific example set forth above, this offset is 120 microns. Therefore, h is 120 microns. The wv value corresponds to the length of the flat valleys between groove-cutting teeth top surfaces. In the non-limiting, specific example set forth above, the valley length is 250 microns. Accordingly, wv is 250 microns. Given the rotational speed of cutting tool  300 , the cutting of the pocket and annular grooves described above occurs simultaneously or essentially simultaneously, e.g., for a period of time equal to a ⅙ revolution of the cutting tool  300 , if the cutting tool includes six cutting elements and adjacent elements are groove and pocket cutting elements. 
         [0050]    Regarding the deforming step of  FIG. 2C  above, a swiper tool is used to swipe selective area flat peaks between grooves. As used herein in certain embodiments, “swipe” is one form of deforming the selective areas. In one embodiment, deforming does not include cutting or grinding the selective area. These types of processes typically include complete or at least partial material removal. It should be understood that other deforming processes may be utilized in this step. Non-limiting examples of other secondary processes include roller burnishing, diamond knurling or a smearing process in which the flank of the pocket cutting tool is used as a wiper insert. In certain variations, the feed rate of the spindle during this step is 0.1 to 0.3 mm/rev. In another variation, the feed rate is 0.2 mm/rev. In certain variations, the rotational speed of swiper tool  300  is 5,000 to 7,000 rpms. In another variation, the rotational speed of a swiper tool is 6,000 rpms. 
         [0051]      FIGS. 6A, 6B and 6C  illustrate a swiper tool  600  according to one embodiment.  FIG. 6A  shows a top view of swiper tool  600 .  FIG. 6B  shows a magnified view of region  602  of swiper tool  600 .  FIG. 6C  shows a side view of swiper tool  600 , including cylindrical shank  604 . Swiper tool  600  includes 4 swiping projections  606 ,  608 ,  610  and  612 . Each swiping projection  606 ,  608 ,  610  and  612  project outward from the center  614  of swiper tool  600 . In one embodiment, the swiper tool has the same diameter as the cutting tool, and the swiper elements have the same axial length as the cutting elements, so that the swiping tool and the cutting tool may be run over the same tool path to simplify programming and reduce motion errors. Each swiping projection includes relief surface  616 , a back surface  618 , and a rake surface  620 . A chamfer  622  extends between rake surface  620  and relief surface  616 . The chamfer or like edge preparation, such as a hone, is used to ensure that the tool deforms the peaks instead of cutting them. In one variation, the angle of the chamfer  622  relative to the landing surface  616  is 15 degrees. In other variations, the angle is 10 to 20 degrees, or a hone with a radius of 25 to 100 microns. In one embodiment, the angle between the rake surface and the relief surface of adjacent swiping projections is 110 degrees. 
         [0052]    The swiping tool  602  is dull enough that it does not cut into the inner surface of the cylinder bore. Instead, the swiping tool  602  mechanically deforms grooves formed in the inner surface of the cylinder bore. Moving back to  FIG. 5 , the swiping tool  600 , used according to the methods identified above, created undercuts  508  and elongates upper surface  510 . As shown in  FIG. 5 , the difference between h (the height of the non-deformed peak) and the height of the deformed peak is Δh. In one variation, Δh is 10 microns, while in other variations, Δh may be 5 to 60 microns. The undercuts increase the adhesion of a subsequent thermal spray coating onto the roughened inner surface of the cylinder bore. 
         [0053]    The machined surface after the pocket grooving step and the swiping step has one or more advantages over other roughening processes. First, adhesion strength of the metal spray may be improved by using the swiping step instead of other secondary processes, such as diamond knurling, roller burnishing. The adhesion strength was tested using a pull test. The adhesion strength may be in the range of 40 to 70 MPa. In other variations, the adhesion strength may be 50 to 60 MPa. Compared to the adhesion strength of a diamond knurling process, the adhesion strength of swiping is at least 20% higher. Further, the Applicants have recognized that adhesion is independent of profile depth of the grooves after the first processing step. This may be advantageous for at least two reasons. The swiping tool cuts relatively lower profile depths compared to conventional processes, such as diamond knurling, roller burnishing. In certain variations, the reduction in profile depth is 30 to 40%. Accordingly, less metal spray material is necessary to fill the profile while not compromising adhesion strength. Also, any variation in the depth of the grooves does not affect the adhesion strength, which makes the swiping step more robust than conventional processes. As another benefit of one or more embodiments, the swiping tool can be operated at much higher operational speeds than other processes, such as roller burnishing. 
         [0054]    Regarding the interpolating step of  FIG. 2D  above, the cutting tool  300  is used to machine non-travel areas  214  and  216  to form annular grooves. In certain variations, the feed rate of the spindle during this step is 0.1 to 0.3 mm/rev. In another variation, the feed rate is 0.2 mm/rev. In certain variations, the rotational speed of cutting tool  300  is 3,000 to 10,000 rpms. In another variation, the rotational speed of a cutting tool is 6,000 rpms. 
         [0055]    These non-travel areas do not require a subsequent metal spray. However, a torch for metal spraying typically stays on throughout the spray process. If these non-ring travel areas are not roughened, then spray metal that is inadvertently sprayed on these areas do not adhere, causing delamination. This delamination may fall into the bore during honing and become entrapped between the honing stones and bore walls, causing unacceptable scratching. The delamination may also fall into the crank case, which would then require removal. As such, by applying the annual grooves identified herein to the non-ring travel areas, thermal spray material adheres during the spray process and mitigates contamination of the intended spray surface and the crank case. The lightly sprayed non-ring travel areas may be easily removed during subsequent honing operation. 
         [0056]      FIG. 7  illustrates a magnified, cross-sectional view of the inner surface of cylinder bore  200 . Non-travel surface  214  includes annular, square grooves  230 . Travel surface  202  includes annular grooves  206  and pocket  208 . 
         [0057]    While the best mode for carrying out the invention has been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.