Ceramic blade for cutting reinforcing fibre sheet

Abstract

A ceramic blade for cutting one or more reinforcing fibre sheets, the ceramic blade comprising a cutting portion comprising a serrated cutting edge defining a cutting plane; a spine; and a body between the cutting edge and the spine, wherein the thickness of the spine is less than the maximum thickness of the body, said thicknesses being measured in a direction perpendicular to the cutting plane.

Description

[0001] MAC01 -134072PC

[0002] CERAMIC BLADE FOR CUTTING REINFORCING FIBRE SHEET

[0003] TECHNICAL FIELD

[0004] This invention relates to a blade for cutting one or more reinforcing fibre sheets.

[0005] BACKGROUND

[0006] Some textile cutting machines utilise reciprocal motion of a stainless steel blade to cut sheets of textiles. Such machines have been used for cutting multiple reinforcing fibre sheets, such as carbon fibre sheets. However, it has been found that the stainless steel blades used can be easily and quickly blunted and broken when being used to cut multiple reinforcing fibre sheets. Attempting to cut fibre sheets using a blunted blade can cause damage to the fibre sheets due to the material being deflected and / or dragged by the blade. Furthermore, the cost of cutting fibre sheets is increased significantly by the high rate at which broken stainless steel blades must be replaced.

[0007] It would therefore be desirable to develop a blade which is less easily blunted and longer lasting.

[0008] SUMMARY OF THE INVENTION

[0009] According to a first aspect of the present invention there is provided a ceramic blade for cutting one or more reinforcing fibre sheets, the ceramic blade comprising a cutting portion comprising a serrated cutting edge defining a cutting plane; a spine; and a body between the cutting edge and the spine, wherein the thickness of the spine is less than the maximum thickness of the body, said thicknesses being measured in a direction perpendicular to the cutting plane.

[0010] The thickness of the spine may be greater than the thickness of the cutting edge.

[0011] The body may comprise a first narrowing portion between a portion of the body having the maximum thickness and the cutting edge, the narrowing portion comprising first and second edges, the first and second edges being non-parallel to the cutting plane. MAC01 -134072PC

[0012] Each of the first and second edges may be at an angle of between 10 and 80 degrees to the cutting plane.

[0013] The body may comprise a second narrowing portion between the portion of the body having the maximum thickness and the spine, the narrowing portion comprising third and fourth edges, the third and fourth edges being non-parallel to the cutting plane.

[0014] Each of the third and fourth edges may be at an angle of between 5 and 45 degrees to the cutting plane.

[0015] The length of the first narrowing portion parallel to the cutting plane may be longer than the length of the second narrowing portion parallel to the cutting plane.

[0016] The first and second edges may be longer than the third and fourth edges.

[0017] The body may taper to the cutting edge in a first direction coincident with the cutting plane and the body may taper to the spine in a second direction, the second direction being coincident with the cutting plane and opposite to the first direction.

[0018] The body may taper in the second direction to a lesser extent than in the first direction.

[0019] The body may taper to form the cutting edge at an angle of 45 degrees.

[0020] The body may taper to form the spine at an angle of 20 degrees.

[0021] The blade may have a longitudinal axis which is coincident with the cutting plane.

[0022] The cutting portion of the blade may have a length measured parallel to the longitudinal axis.

[0023] The blade may comprise a shank portion, the shank portion having a thickness equal to or greater than the maximum thickness of the body of the cutting portion.

[0024] The length of cutting portion may be less than the length of the shank portion. MAC01 -134072PC

[0025] The blade may comprise a transition portion extending between the cutting portion and the shank portion, the transition portion having a curved region.

[0026] The curved region of the transition portion may have a transition radius of 10mm.

[0027] The ratio of the length of the transition portion to the length of the cutting portion may be greater than 1 to 5.

[0028] The serrated cutting edge may comprise a plurality of cutting teeth and a plurality of depressions, each pair of adjacent cutting teeth of the plurality of cutting teeth being separated by a depression of the plurality of depressions.

[0029] The cutting edge may comprise an edge of each of the plurality of cutting teeth and an edge of each of the plurality of depressions.

[0030] The edge of each of the plurality of depressions may comprise a curved portion.

[0031] The edge of each depression of the plurality of depressions may be semi-circular.

[0032] The spine may comprise a smooth surface.

[0033] The ceramic may be tungsten carbide.

[0034] There may be provided a cutting machine comprising the blade and an actuator, wherein the actuator is configured to cause reciprocal motion of the blade along the cutting plane, wherein the reciprocal motion of the blade is in two opposite directions parallel to the longitudinal axis of the blade.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings: MAC01 -134072PC

[0037] Figure 1 shows an example of a conventional blade.

[0038] Figure 2 shows an improved blade.

[0039] Figure 3 shows a cross section of the improved blade.

[0040] Figure 4 shows a cross section of the improved blade.

[0041] Figure 5 shows a closer view of the transition portion of the improved blade.

[0042] Figure 6 shows a closer view of the serrated cutting edge of the improved blade.

[0043] DETAILED DESCRIPTION OF THE DRAWINGS

[0044] The following description is presented to enable any person skilled in the art to make and use the invention and is provided in the context of a particular application. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art.

[0045] The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0046] Figure 1 illustrates an example of a conventional blade 100. Figure 1 shows (a) a front view of the blade and (b) a cross section of the cutting portion of the blade.

[0047] The blade is made from stainless steel. The blade comprises a shank portion 101 , a cutting portion 102 and a transition portion 103 between the shank portion and the cutting portion. The blade may be connectable to a cutting machine by an attachment 104. The cutting portion 102 includes a serrated cutting edge 105 and a spine 106. The cutting portion 102 has a body 107 between the cutting edge 105 and the spine 106.

[0048] Figure 2 illustrates an example of an improved blade 200. MAC01 -134072PC

[0049] The blade comprises a shank portion 201 , a cutting portion 202 and a transition portion 203 between the shank portion and the cutting portion. The blade may be connected to a cutting machine by an attachment 204. The attachment is configured to engage a component of the cutting machine to connect the blade to the cutting machine. The attachment may comprise a hole which extends through the blade. The hole may engage a bolt of the cutting machine. The bolt of the cutting machine may engage a threaded hole in the cutting machine. The attachment may otherwise comprise a depression or protrusion in the blade configured to engage with an element of the cutting machine. The cutting portion 202 includes a serrated cutting edge 205 and a spine 206. The cutting portion 202 has a body 207 between the cutting edge 205 and the spine 206. While the cutting edge is serrated, the spine comprises a smooth surface free of serrations. In other words, the spine is non-serrated. The shank portion also comprises smooth surfaces and edges which are non-serrated. The cutting portion may be the only portion of the blade comprising an edge which is serrated.

[0050] The blade 200 is made from a ceramic material. In other words, it is a ceramic blade. The ceramic may be tungsten carbide. The ceramic may be zirconium dioxide. The ceramic material allows the blade to be sharper for longer. The use of ceramic material increases the life of the blade before blunting.

[0051] The serrated cutting edge 205 defines a cutting plane 208. The cutting plane 208 bisects the cross section of the cutting portion 202. The longitudinal axis 209 of the blade intersects the cutting plane 208. The longitudinal axis 209 extends generally in the direction A. The cutting portion 202 may terminate in a point P at its end. The point P may be located approximately along the longitudinal axis of the blade.

[0052] Figure 3 shows a cross section of the cutting section 202 of the blade 200.

[0053] As mentioned above, the cutting edge 205 defines a cutting plane 208 which bisects the cross section of the cutting portion 202. The blade has a thickness which is measured in a direction perpendicular to the cutting plane 208. The body 207 of the cutting portion 202 has a body thickness measured in a direction perpendicular to the cutting plane. The body 207 of cutting portion of the blade has a body thickness which runs in a direction perpendicular to the cutting plane. For example, the body 207 of MAC01 -134072PC the cutting portion 202 has a maximum thickness 210 measured across its widest part. The maximum thickness 210 of the body 207 may be referred to herein as the maximum body thickness.

[0054] Figure 3 shows that the body 207 of the cutting portion of the blade tapers to form the cutting edge 205. The body 207 tapers to the cutting edge 205 in a first direction 218 along the cutting plane. The first direction 218 is perpendicular to the longitudinal axis 209 of the blade. The first direction 218 is perpendicular to the direction in which the thickness of the blade is measured.

[0055] The cutting edge 205 has a thickness which runs in a direction perpendicular to the cutting plane. The cutting edge 205 has a cutting edge thickness which runs in a direction perpendicular to the cutting plane. The thickness of the cutting edge 205 (in the direction perpendicular to the cutting plane) is less than the maximum thickness 210 of the body. In fact, the cross section of the blade shows that, in two dimensions, the body may taper to a point to form the cutting edge.

[0056] Figure 3 also shows the thickness 214 of the spine 206. The spine 206 has a spine thickness 214 which runs in a direction perpendicular to the cutting plane. The thickness of the spine 206 is measured in a direction perpendicular to the cutting plane 208. As shown in figure 1 , the thickness of the spine 106 of the blade 100 is equal to the thickness of the body 107. In contrast, in blade 200, the thickness 214 of the spine 206 is less than the maximum thickness of the body 207. The thickness of the spine 206 may be less than any thickness of the body 207. In other words, the body of the blade may be thicker than the spine at all points along the cutting plane.

[0057] The thickness 214 of the spine is greater than the thickness of the cutting edge 205. The body 207 tapers to the spine 206 in a second direction 219. The second direction is along the cutting plane 208 and is opposite to the first direction 218. The second direction 219 is perpendicular to the longitudinal axis 209 of the blade. The second direction 219 is perpendicular to the direction in which the thickness of the blade is measured. MAC01 -134072PC

[0058] The body may taper in the second direction 219 to a lesser extent than in the first direction 218. The body may taper to form the cutting edge an angle of between 10 and 80 degrees. The body may taper to form the cutting edge an angle of between 20 and 70 degrees. The body may taper to form the cutting edge an angle of between 30 and 60 degrees. The body may taper to form the cutting edge an angle of between 31 and 60 degrees. The body may taper to form the cutting edge an angle greater than

[0059] 40 degrees or greater than 45 degrees. For example, the body may taper to form the cutting edge at an angle of 40 degrees or 45 degrees or 50 degrees. The body may taper to form the spine at an angle of between 5 and 45 degrees. The body may taper to form the spine at an angle of between 15 and 35 degrees. The body may taper to form the spine at an angle of between 20 and 30 degrees. The body may taper to form the cutting edge at an angle less than 30 degrees or less than 25 degrees. The body may taper to form the spine at an angle of 15 degrees or 20 degrees or 25 degrees.

[0060] Figure 4 shows the same cross section of the cutting section 202 of the blade, with different parts of the blade labelled. Figure 4 also illustrates the longitudinal axis 209 of the blade, which intersects the cutting plane 208. In other words, the longitudinal axis 209 is coincident with the cutting plane 208.

[0061] Figure 4 illustrates that the body 207 comprises a first narrowing portion 211 (indicated with a dotted line) between a portion of the body having the maximum thickness 210 and the cutting edge 205. The first narrowing portion 211 comprises a first edge 212 and a second edge 213. Figure 3 shows that the first and second edges 212, 213 are non-parallel to the cutting plane. Each of the first and second edges may be at angle of between 10 and 80 degrees to the cutting plane. For example, each of the first and second edges may be at an angle of 45 degrees to the cutting plane.

[0062] The body 207 comprises a second narrowing portion 215 (also indicated with a dotted line) between a portion of the body having the maximum thickness 210 and the spine 206. The narrowing portion 215 comprises a third edge 216 and a fourth edge 217. The third and fourth edges 216, 217 are non-parallel to the cutting plane. Each of the third and fourth edges may be at an angle of between 5 and 45 degrees to the cutting MAC01 -134072PC plane. For example, each of the first and second edges may be at an angle of 20 degrees to the cutting plane.

[0063] In the example blade 200, the length of the first narrowing portion 211 measured parallel to the cutting plane is larger than the length of the second narrowing portion 215 measured parallel to the cutting plane. Each of the first and second edges 212, 213 are longer than each of the third and fourth edges 216, 217.

[0064] According to one example, the blade 200 is connected to a cutting machine by an attachment 204. The cutting machine may be used to cut one or more reinforced fibre sheets, the fibre sheets being in a plane perpendicular to the cutting plane and parallel to the cross section of the blade. The cutting machine may comprise an actuator configured to cause reciprocal motion of the blade along the cutting plane to move the blade through the one or more reinforced fibre sheets. The cutting machine may cause the blade to move in two opposite directions parallel to the longitudinal axis 209 of the blade. The reciprocal motion of the blade may be in the direction A and the direction opposite to the direction A. The blade may be actuated by the cutting machine to repeatedly move a first distance in the direction A and then the same distance in the direction opposite to the direction A.

[0065] The thickness of the spine 206 being less than the maximum thickness 210 of the body 207 of the blade means that the blade is able to move more freely through the reinforced fibre sheets being cut. For example, when the blade is turned by the cutting machine, the reduction in thickness at the spine means that the blade can turn with less deflection / pushing of the fibre sheets caused by the spine, thereby causing less damage to the sheets.

[0066] In the example seen in figures 3 and 4, the third and fourth edges 216, 217 are straight edges. In other words, the body has two chamfers at the spine. It will be appreciated that according to other examples, each edge may not be straight. For example, one or both of the third and fourth edges may comprise a curved portion.

[0067] Furthermore, these figures show vertices between the portion of the body having a maximum thickness and the two narrowing portions 211 and 215. According to an MAC01 -134072PC example in which at least one edge of the blade is not completely straight, one or more of the vertices may be replaced with a curved edge. In other words, there may be a more gradual transition between the portion of the body having the maximum thickness and one or both of the two narrowing portions 211 , 215.

[0068] Figure 5 also shows blade 200. In particular, figure 5 shows (a) a closer front view of the transition portion 203 and (b) a side view of the transition portion 203.

[0069] The transition portion 203 extends between the shank portion 201 and the cutting portion 202. The blade 200 has a length which is measured along the longitudinal axis 209 (parallel to direction A). The transition portion 203 also has a length measured along the longitudinal axis.

[0070] The shank portion may have a thickness equal to or greater than the maximum thickness of the body of the cutting portion, the thickness being measured in a direction perpendicular to the cutting plane 208. In other words, the shank portion has a shank portion thickness running in a direction perpendicular to the cutting plane. The shank portion 201 of blade 200 has a thickness equal to the maximum thickness 210 of the body of the cutting portion 202. As explained above, the thickness of the cutting portion 202 tapers to form the cutting edge 205. The transition portion 203 comprises a curved region 501. The curved region 501 has a thickness (measured in a direction perpendicular to the cutting plane 209) which decreases between the shank portion 102 and the cutting portion 202. In other words, the transition portion 203 acts to reduce the thickness of the blade between the shank portion and the cutting portion. It is desirable for the reduction in thickness between the shank portion and the cutting edge of the cutting portion to be as gradual as possible so as to minimise high stress areas within the transition portion of the blade.

[0071] The side view of the transition portion 203 seen in (b) of figure 5 is viewed at the cutting edge 205 i.e. where the cutting plane 208 intersects with the cutting edge. This figure shows the curved portion 501 between the shank portion 201 and the cutting portion 202 at the cutting edge 205. The curved portion 501 has a radius of curvature, known as the transition radius. The transition radius in this example may be 10 mm. According to other examples, the transition radius may be greater than 8mm or greater than 9mm MAC01 -134072PC or greater than 10 mm. For example, the transition radius may be 9mm or 11 mm or 12mm.

[0072] Figures 1 and 2 show that the length of the transition portion 203 of the blade 200 is greater than the length of the transition portion 103 of the conventional blade 100. Increasing the length of the transition portion 203 (including the length of its curved region 501 ) as described herein means that this transition of blade thickness can be made more gradual. The transition radius of the curved portion can be made larger, thereby reducing high stress areas within the transition portion, further reducing the chance of blade breakage.

[0073] The ratio of the length of the transition portion (in particular the length of the curved region of the transition portion) and the length of the cutting portion of the blade 200 may be greater than the same ratio of the conventional blade 100. The ratio of the length of the transition portion to the length of the cutting portion of the blade may be greater than 1 to 3, or greater than 1 to 4 or greater than 1 to 5. According to one example of the blade 200, the shank portion 201 has a length of 55mm, the cutting portion 202 has a length of 32mm and the transition portion 203 has a length of 8mm, where each length is measured along the blade’s longitudinal axis 209.

[0074] Figure 2 shows that the length of the cutting portion 202 is less than the length of the shank portion 201 . Figures 1 and 2 show that the length of the cutting portion 202 of the blade 200 is less than the length of the cutting portion 102 of the conventional blade 100.

[0075] Reducing the length of the cutting portion of the blade to be less than the length of the shank portion means a higher proportion of the blade is made up of the shank portion. In other words, the shank portion is lengthened. As described above, the shank portion has a greater average thickness than the cutting portion and is therefore less prone to breakage that the cutting portion. Thus, utilising a cutting portion of a reduced length means that the strength of the blade can be increased.

[0076] According to one example, the blade 200 is connected to a cutting machine by an attachment 204. The cutting machine may be used to cut one or more reinforced fibre MAC01 -134072PC sheets, the fibre sheets being in a plane parallel to the cross section of the blade and perpendicular to the cutting plane of the blade. The cutting machine may comprise an actuator configured to cause reciprocal motion of the blade along the cutting plane. The cutting machine may cause the blade to move in two opposite directions parallel to the longitudinal axis 209 of the blade to cut the one or more fibre sheets. The reciprocal motion of the blade may be in the direction A and a direction opposite to the direction A. The blade may be actuated by the cutting machine to repeatedly move a first distance in the direction A and then the same distance in the direction opposite to the direction A.

[0077] The length of the cutting portion may be reduced to a minimum length required for a particular application. The length of the cutting portion may be reduced to a minimum length such that the entire length of the cutting portion is utilised in cutting one or more reinforced fibre sheets of a particular thickness. The minimum length of the cutting portion may be equal to the sum of the thickness of the reinforcing fibre sheet(s) being cut and the first distance moved by the reciprocating blade. The minimum length of the cutting portion may be equal to the sum of the thickness of the reinforcing fibre sheet being cut, the first distance moved by the reciprocating blade and a tolerance. The cutting portion 202 may have a length equal to the minimum length. In other words, the length of the cutting portion may be minimised. The length of the cutting portion may be less than 40mm, or less than 35mm or less than 30mm or less than 25mm. According to one example of the blade 200, the shank portion 201 has a length of 55mm, the cutting portion 202 has a length of 32mm and the transition portion 203 has a length of 8mm.

[0078] Figure 6 shows a closer view of a section of the serrated cutting edge 205 of the cutting portion 202. The cutting edge comprises a plurality of serrations defining the cutting plane 28. In the example seen in figure 6, the plurality of serrations comprise a plurality of cutting teeth 601 and a plurality of depressions 602. The serrated edge comprises a plurality of cutting teeth 601 and a plurality of depressions 602. Each pair of adjacent cutting teeth are separated by a depression. In other words, the cutting teeth are interspersed alternately with the depressions. MAC01 -134072PC

[0079] The cutting edge is made up of an edge of each of the plurality of cutting teeth 601 and an edge of each of the plurality of depressions 602. The thickness of the cutting edge is defined by the thickness of the edge of each cutting tooth in the plurality of cutting teeth. The edge of each of the plurality of depressions 602 comprises a curved portion. In this example, the edge of each depression is semi-circular. Each of the cutting teeth 601 has a straight edge. Utilising curved depressions between cutting teeth can reduce pushing forces on the cutting teeth during cutting. For example, the design of the serrated cutting edge 205 may reduce sideways force deflecting the blade during cutting. Shaping the cutting edge so that the cutting teeth are separated by curved depressions may reduce high stress areas on the cutting teeth during cutting. The blade geometry described may thus improve the accuracy of cutting performed by the blade 200. The design of cutting edge 205 may also further reduce the chance of blade breakage. The cutting edge 205 may therefore increase the number of layers of reinforcing fibres that the blade can cut at once.

[0080] The design of the cutting edge 205 may increase the blade life before breaking failure by approximately 10 times with respect to the cutting edge 105 of the conventional blade 100. It will be appreciated that the serrations on the cutting edge 205 differ in shape from those on the cutting edge 105 of the conventional blade as figure 1 shows that cutting edge 105 incorporates trapezoidal cutting teeth. As well as having a different shape, the size of the cutting teeth 601 may also be greater than the trapezoidal cutting teeth used in the conventional blade.

[0081] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

MAC01 -134072PCCLAIMS1 . A ceramic blade for cutting one or more reinforcing fibre sheets, the ceramic blade comprising: a cutting portion comprising: a serrated cutting edge defining a cutting plane; a spine; and a body between the cutting edge and the spine, wherein the thickness of the spine is less than the maximum thickness of the body, said thicknesses being measured in a direction perpendicular to the cutting plane.

2. The ceramic blade according to claim 1 , wherein the thickness of the spine is greater than the thickness of the cutting edge.

3. The ceramic blade according to claims 1 or 2, wherein the body comprises a first narrowing portion between a portion of the body having the maximum thickness and the cutting edge, the narrowing portion comprising first and second edges, the first and second edges being non-parallel to the cutting plane.

4. The ceramic blade according to claim 3, wherein each of the first and second edges are at an angle of between 10 and 80 degrees to the cutting plane.

5. The ceramic blade according to claims 3 or 4, wherein the body comprises a second narrowing portion between the portion of the body having the maximum thickness and the spine, the narrowing portion comprising third and fourth edges, the third and fourth edges being non-parallel to the cutting plane.

6. The ceramic blade according to claim 5, wherein each of the third and fourth edges are at an angle of between 5 and 45 degrees to the cutting plane.

7. The ceramic blade according to claims 5 or 6, wherein the length of the first narrowing portion parallel to the cutting plane is longer than the length of the second narrowing portion parallel to the cutting plane.MAC01 -134072PC8. The ceramic blade according to any of claims 5 to 7, wherein the first and second edges are longer than the third and fourth edges.

9. The ceramic blade according to any preceding claim, wherein the body tapers to the cutting edge in a first direction coincident with the cutting plane and the body tapers to the spine in a second direction, the second direction being coincident with the cutting plane and opposite to the first direction.

10. The ceramic blade according to claim 9, wherein the body tapers in the second direction to a lesser extent than in the first direction.11 . The ceramic blade according to claims 9 or 10, wherein the body tapers to form the cutting edge at an angle of 45 degrees.

12. The ceramic blade according to any of claims 9 to 11 , wherein the body tapers to form the spine at an angle of 20 degrees.

13. The ceramic blade according to any preceding claim, wherein the blade has a longitudinal axis which is coincident with the cutting plane, the cutting portion of the blade having a length measured parallel to the longitudinal axis.

14. The ceramic blade according to any preceding claim, wherein the blade comprises a shank portion, the shank portion having a thickness equal to or greater than the maximum thickness of the body of the cutting portion.

15. The ceramic blade according to claim 14, wherein the length of cutting portion is less than the length of the shank portion.

16. The ceramic blade according to claims 14 or 15, wherein the blade comprises a transition portion extending between the cutting portion and the shank portion, the transition portion having a curved region.

17. The ceramic blade according to claim 16, wherein the curved region of the transition portion has a transition radius of 10mm.MAC01 -134072PC18. The ceramic blade according to claims 16 or 17, wherein the ratio of the length of the transition portion to the length of the cutting portion is greater than 1 to 5.

19. The ceramic blade according to any preceding claim, wherein the serrated cutting edge comprises a plurality of cutting teeth and a plurality of depressions, each pair of adjacent cutting teeth of the plurality of cutting teeth being separated by a depression of the plurality of depressions.

20. The ceramic blade according to claim 19, wherein the cutting edge comprises an edge of each of the plurality of cutting teeth and an edge of each of the plurality of depressions.21 . The ceramic blade according to claim 20, wherein the edge of each of the plurality of depressions comprises a curved portion.

22. The ceramic blade according to claim 20 or 21 , wherein the edge of each depression of the plurality of depressions is semi-circular.

23. The ceramic blade according to any preceding claim, wherein the spine comprises a smooth surface.

24. The ceramic blade according to any preceding claim, wherein the ceramic is tungsten carbide.

25. A cutting machine comprising the blade according to claim 13 and an actuator, wherein the actuator is configured to cause reciprocal motion of the blade along the cutting plane, wherein the reciprocal motion of the blade is in two opposite directions parallel to the longitudinal axis of the blade.

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