GB2542124A

GB2542124A - Method and tools for manufacturing a blisk

Info

Publication number: GB2542124A
Application number: GB1515867.8A
Authority: GB
Inventors: Kirby Mark; Devey Mike; Spearings Warwick; Hill Sam
Original assignee: Technicut Ltd
Current assignee: Technicut Ltd
Priority date: 2015-09-08
Filing date: 2015-09-08
Publication date: 2017-03-15
Anticipated expiration: 2035-09-08
Also published as: WO2017042158A1; GB2542124B; GB201515867D0

Abstract

A method of manufacturing a bladed disc (blisk) is disclosed, together with a milling tool 201 for performing the method. The blank is securely mounted, and a milling tool 201 is mounted to a machining device proximate the blank. The milling tool 201 comprises at least one cutting tooth 204 having at least one axial radius of curvature 207, the tool itself being a separate aspect of the invention. The blank is milled into a semi-finished blisk with a succession of passes, for instance following a trochoidal path. The at least one axial radius of curvature 207 of the tool allows milling closer to the tolerances of the finished blisk in fewer passes. The tool may have a ball end or a flat end 301, teeth may be provided on the flat end. The teeth may include sinusoid crenulations for chip breaking.

Description

METHOD AND TOOLS FOR MANUFACTURING A BLISK

Field of the Invention

The present invention relates to a method of manufacturing a blisk from a blank using one or more milling tools comprising at least one axial radius of curvature.

Background of the Invention [0001] A bladed disk 104 (known by the portmanteau of blisk) is an essential component of many modern turbines or compressors, particularly aeronautical jet engines. A blisk 101 comprises a central rotor disk 102 with a series of blades 103 arranged peripherally about the disk. A typical jet engine may comprise four to six blisks 101, each comprising 125 blades 103.

[0002] Typically, a blisk is machined from a single piece of material 104, as opposed to casting the entire article, or welding or mounting individual blades to a separately manufactured rotor. This takes advantage of material properties of the blank, typically made of titanium, and minimises the number of part interfaces where defects or cracks may propagate.

[0003] Due to the number of blades 103, the complex geometries involved and the size of the end product, the timescales required for manufacture are large, with a milling time of typically more than 70 hours for a blisk comprising 125 blades.

[0004] With reference to figure 1 there is depicted a prior art manufacturing process of a blisk by known machining methods, which begins by securely mounting a blank 104 within a CNC milling machine, typically using numerous bolts 105 located through the centre of the material. A series of parallel ripping cuts 106 are then made about a portion of the circumference of the circular blank to produce an initial outline of the blade 107.

[0005] A roughing milling tool is then used to quickly remove large amounts of blank material and produce a semi-finished outline of the blade 108.

Iterative machining with a finishing milling tool is then required to smooth the blade surface to required tolerances, into the final product.

[0006] During milling of the semi-finished blisk, the roughing milling tool typically leaves the surfaces of the blade with high ridges 109 and deep valleys 110 separated by sharp edges, which must be milled down to produce the final smooth product 101. The scale and edges of the machined steps 109, 110 of the part-finished blisk cause substantial, and frequently premature, wear of finishing tools.

[0007] There is therefore a need to improve blisk milling techniques both to reduce blisk milling time as much as possible and increase milling tool life during milling operations.

Summary of the Invention [0008] According to a first aspect there of the present invention, there is provided a method of manufacturing a semi-finished blisk from a blank comprising the steps of mounting the blank securely, mounting a milling tool to a machining device proximate the blank, wherein the milling tool comprises at least one axial radius of curvature, and milling the blank into the semi-finished blisk with a succession of passes. Advantageously, the at least one axial radius of curvature of the tool allows a reduction of the scale of the ridges and valleys between successive milling passes, with offsetting milling passes in a vertical direction transverse to the blank’s main axis such that the tool curvature substantially matches the machined surface geometry required, such that only a thin edge separates two vertically-adjacent portions of a blade surface, which exhibit only minor surface defects.

[0009] Preferably, the cutting end comprises at least one cutting tooth wherein, the at least one tooth comprises at least one axial radius of curvature and the at least one tooth comprises a chipbreaker, wherein the chipbreaker comprises a plurality of substantially sinusoidal crenulations, and milling the blank into a semi-finished blisk with a succession of passes. Advantageously, the use of a chipbreaker geometry for the milling tool allows the removal of large volumes of material quickly. The chipbreaker breaks down large filaments of swarf into small granules which are readily transported away from the cutting face.

[0010] Suitably, the milling tool comprises, a cutting end, wherein the cutting end comprises at least one cutting tooth wherein, the at least one tooth comprises at least one axial radius of curvature and the at least one tooth comprises a chipbreaker, wherein the chipbreaker comprises a plurality of substantially sinusoidal crenulations, the method further comprising the steps of mounting a second milling tool to the machining device proximate the blank, wherein, the second milling tool comprises at least one axial radius of curvature, and milling the blank into a substantially semi-finished blisk with a second succession of passes. Advantageously, the disclosed methods may be combined to allow the quick creation, from a blank, of a semi-finished blisk. The milling tool with chipbreaker geometry allows large volumes of material to be removed quickly, and the smooth toothed milling tool (without a chipbreaker geometry) then provides a close approximation of the final complex geometries of the blisk that requires little further finishing.

[0011] Suitably, the succession of passes at least partially overlap. This ensures that the surface is substantially continuous and free from deep valleys, or peaks and sharp edges which would require significant milling. The succession of passes, may at least in part, follow a substantially trochoidal path. Trochoidal milling paths allow for the creation of complex geometries quickly and efficiently.

[0012] The methods described herein are particularly suitable for blanks made from titanium or nickel. Suitably, the blank of the present invention is made from titanium or nickel.

[0013] According to a second aspect of the present invention, there is provided a milling tool comprising, a shank end, and a cutting end, wherein the cutting end comprises at least one cutting tooth wherein, the at least one tooth comprises at least one axial radius of curvature. Advantageously, the axial radius of curvature allows for the creation of complex geometries on the first cut of the blank, because the tool is curved. A straight-edged tool is unable to create a curved profile without large steps left in the material of the blank.

[0014] Preferably, the at least one tooth further comprises a chipbreaker geometry. The chipbreaker geometry comprises a plurality of substantially sinusoidal crenulations. The sinusoidal crenulations upon the teeth of the cutting tool facilitate deep cutting of the blank, allowing large volumes of material to be taken quickly. The serrations also allow the cut material to be broken down into small chips that may be easily transported away from the cutting face.

[0015] Preferably the at least one axial radius of curvature is in the range 2mm - 250mm. The at least one axial radius of curvature allows the milling tool to carve out a semi-finished blisk with geometries which comprise a complementary radius of curvature to the milling tool.

[0016] Advantageously, the milling tool of the second aspect of the present invention may comprise a second two axial radius of curvature. The second axial radius of curvature is axially adjacent the first axial radius of curvature about a long axis of the milling tool. The second axial radius of curvature is located on the adjacent the base of the tool. The second axial radius of curvature is in the range 0mm - 50mm. Advantageously, the inclusion of a second axial radius of curvature allows the milling tool to be profiled. The multi-radius profile eases the transition from the first axial radius of curvature to the base of the milling too. This reduces the likelihood of the tool rubbing against the blisk. This reduces wear and extends the longevity of the milling too.

[0017] Preferably, at least one axial radius of curvature of the second aspect of the present invention extends along the milling tool 100mm or less. This allows the milling tool to provide a cut with a radius of curvature up to 100mm in depth.

[0018] The milling tool of the second aspect of the present invention may suitably comprise a number of teeth in the range 2 - 50. As such, the milling tool may be adapted to comprise a number of teeth to suit the material being shaped.

[0019] The at least one tooth of the second aspect of the present invention is preferably in the form of a helix. The helix of the second aspect of the present invention suitably has a helix angle in the range 0°-80°.

[0020] Alternatively, the at least one tooth of the second aspect of the present invention comprises a serrated edge. A serrated edge allows chips of freshly hewn material to be further broken down into smaller granules. This allows the milling tool to safely make deeper cuts without the risk of the large chips becoming stuck and seizing the cutter. The large chips are crushed or split into smaller chunks which may easily work their way free of the cutting face. Suitably, the serrated edge of the second aspect of the present invention follows a sinusoidal path with a period in the range 0.1mm - 10mm.

[0021] The sinusoidal path of the second aspect of the present invention alternatively comprises truncated peaks. The topology of the crenulations may be tailored to suit the material or optimised to more efficiently break down chips.

[0022] The milling tool of the second aspect of the present invention is preferably made from one of the following: high speed steel, tungsten carbide, cubic boron nitride, ceramic. This allows the milling tool to be constructed of a material complementary to the blank being cut in order to extend the longevity of the milling tool.

[0023] The milling tool is preferably treated with one of the following: AITiN, AlCrN, AITiN/SiN, AlCrN/SiN, TiB2, TiSiN. This allows the milling tool to be treated with a coating to improve the material properties of the milling tool or tune those properties to suit a particular blank material. This improves the cut produced by the milling tool and prolongs the milling tool’s useful lifetime.

[0024] The milling tool comprises a base. The base may suitably comprise at least one cutting tooth. Advantageously, providing teeth upon the base of the tool provides a further cutting axis which is aligned along a long axis of the milling tool.

[0025] Alternatively, the milling tool comprises a ball end. The ball end allows the tool to carve out fine detail or be manipulated in tight corners.

[0026] Other aspects are as set out in the claims herein.

Brief Description of the Drawings [0027] For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which:

Figure 1 shows the prior art process of manufacturing a blisk.

Figure 2 shows a perspective view of a first embodiment of a milling tool.

Figure 3 shows an end view of a first embodiment of a milling tool.

Figure 4 shows a side view of a first embodiment of a milling tool.

Figure 5 shows a side view of a second embodiment of a milling tool.

Figure 6 shows a side view of a third embodiment of a milling tool.

Figure 7 shows a process for manufacturing a semi-finished blisk as described herein.

Detailed Description of the Embodiments [0028] There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

[0029] Referring to figures 2-4 there is provided a first embodiment of a milling tool 201 suitable for producing a semi-finished blisk from a blank. Parallel rip cuts create slots in the circumference of the blank.

[0030] The milling tool comprises a substantially cylindrical shank 202. It will be apparent to one skilled in the art that the shank can be a made in range of diameters.

[0031] Depending on the embodiment, outer diameters for the shank 202 are in the range 1mm - 50mm. However, it will be apparent that shank diameters outside this range may also be used.

[0032] The milling tool 201 may be constructed of any suitable material. Blisks are made from a variety of different materials (titanium and nickel by way of non-limitative example). One skilled in the art can select a milling tool 201 made of the most appropriate material for the blank. The milling tool material can be selected to compliment the blank material.

[0033] Suitable milling tool materials include, but are not limited to, high speed steels, tungsten carbide, cubic boron nitride and ceramics.

[0034] The milling tool 201 can be coated or treated to improve its surface properties. Doing so can, for example, tune the hardness of the milling tool 201. Example treatment agents include, but are not limited to, aluminium titanium nitride (AITiN), aluminium chromium nitride (AlCrN), aluminium titanium silicon nitride (AITiN/SiN), aluminium chromium silicon nitride (AlCrN/SiN), titanium diboride (TiB2), or titanium silicon nitride (TiSiN).

[0035] The milling tool 201 comprises two ends. The first end terminates with a mill interfacing end. In the embodiment presented in figures 2-4 this is simply the end of the cylindrical shank 202. However, it will be apparent to one skilled in the art that any suitable means of attaching the milling tool to the milling machining may be used.

[0036] The end of the milling tool 201 opposite the mill interfacing end (the shank end) comprises a cutting end 203 for removing material from the blank. The cutting end 203 comprises a cutting face. The cutting face contacts the blank and removes material from the blank surface. The cutting face comprises at least one tooth 204 which removes material from the surface of the bank. Alternatively, a number of teeth 204 can be arranged upon the cutting end of the milling tool 201. Depending on the embodiment, a milling tool 201 will comprise a number of teeth 204 in the range 2-50. Although the milling tool 201 may be equipped with a number of teeth 204 outside this range for suitable applications.

[0037] Arranged adjacent each tooth 204 is a complimentary flute 205 which allows the freshly cut material to be transported away from the blank in the form of swarf.

[0038] Each tooth 204 and flute 205 are in a complementary helix 206. The helix 206 may, depending on the material to be cut and the direction of rotation of the machine, be left or right handed.

[0039] Depending on the embodiment, the helix angle (i.e. the angle the tooth 204 advances as it progresses along the helix 206) is in the range 0° - 80°. One skilled in the art will select the value of the helix angle as appropriate depending on the material the blank is made from. Certain materials may require a helix angle outside this range.

[0040] The helix 206 of teeth 204 and flutes 205 may be long or short depending on the application. Depending on the embodiment, the helix 206 length will be 100mm or less. As a result, the teeth 204 and flutes 205 of the milling tool 201, extend along the shank a distance of 100mm or less.

[0041] The cutting end 203 of the milling tool 201 terminates with a flat base 301. The base has a diameter in the range 0.25-48mm. However, as shown in Figures 2B and 3B the milling tool 201 may suitably comprise teeth 304 on the base 301. These teeth may be a continuation of the same teeth as earlier described or separate. In the further alternative, the cutting end of the milling tool may terminate with a ball end 305 (Figures 2C and 3C). The cutting end may terminate in any suitable configuration, by way of non limitative example, a dome or concave cavity.

[0042] Each tooth 204 respectively comprises a leading edge 302 and a trailing edge 303. As the milling tool 201 rotates, the leading edge 302 contacts the blank first. Upon contact the leading edge 302 digs into the blank and removes a sliver of material (a chip). As the milling tool 201 continues to rotate the trailing edge 303 passes over the surface of the blank.

[0043] The leading edge 302 and trailing edge 303 comprise two axial radii of curvature 207, 208 respectively. The axial radii sweep out a curve parallel to a long axis 209 of the milling tool 201. As such, the radii of curvature 207, 208 are axial about the milling tool 201.

[0044] The leading edge 302 and trailing edge 303 of the milling tool 201, follow the path of the radii of curvature 207, 208. Subsequently, the teeth 204 decrease in distance from a central axis 209 of the milling tool 201.

[0045] Due to the radii of curvature 207, 208, the helix 206 essentially becomes a spiral as the helix radius decays towards the long axis 209 of the milling tool as the helix 206 progresses towards the cutting end 203.

[0046] The first radius of curvature 207 of the tooth 204 is located toward the shank 202 end of the milling tool 201. The second radius of curvature 208 is located immediately adjacent the first radius of curvature 207, but towards the base 301 of the milling tool 201. The second radius of curvature 208 of the teeth 204 is therefore located between the base 301 and the first radius of curvature 207 on the milling tool 201.

[0047] The purpose of the second radius of curvature 208 is to provide a continuous profile between the leading and trailing edges 302, 303, and the base 301 of the tool. This reduces wear on the tool from rubbing against the blank. The transition from the first radius 207, to the second radius 208 through to the base 301 of the milling tool 201 is substantially continuous.

[0048] As depicted in Figure 2C and 3C, the second radius of curvature 208 may be used to provide the milling tool 201 with a ball end 305. By way of non-limitative example, when the second radius 208 is equal to the radius of the base 301, the second radius of curvature 208 may sweep out a curve from a position perpendicular to the long axis 209 to a point parallel to the long axis 209 of the milling tool 201. This curved profile provides a substantially hemi-spherical end (referred to as a “ball end”) 305 to the milling tool 201.

[0049] The first radius of curvature 207 is in the range of 2mm-250mm. As such the curvature of the leading and trailing edges 302, 303 may be a sharp, pronounced curves or shallow, gentle curves.

[0050] The second radius of curvature 208 is less than the first radius of curvature 207. Depending on the embodiment, the second radius of curvature 208 is in the range of 0mm - 50mm.

[0051] However, given the suitable ranges for the radii of curvature, that the second radius of curvature 208 can be equal to the first radius of curvature 207.

[0052] When the second radius of curvature 208 is equal to the first radius of curvature 207, the trailing edge 303 will not contact the blank surface. As the trailing edge 303 passes over the blank surface, any material in the path of the trailing edge 303 will be removed by the leading edge 302 prior to the trailing edge 303 passing over the blank surface.

[0053] With reference to figure 5 there is presented a second embodiment of the present invention 501 incorporating all the above features and potential dimensions or material choice of the first embodiment 201.

[0054] The second embodiment further comprises a chipbreaker 502. As the milling tool rotates, the teeth 503 remove a “chip” of material from the surface of the blank.

[0055] When performing a rough cut, a large volume of material is removed quickly. As such the “chips” produced are large and are not readily whisked away in the flutes 504 of the tool. A chipbreaker 502 grinds the large chips into smaller pieces of swarf which may readily be transferred by the flutes 504 of the milling tool 501 away from the cutting end.

[0056] In the second embodiment 501 depicted in figure 5 the chipbreaker geometry 502 takes the form of sinusoidal crenulations 505 located on the surface of the teeth 503. The sinusoidal crenulations 505 provide the milling tool teeth 503 with serrated edges 506.

[0057] Depending on application (such as material to be cut and finish to be achieved) there may be more or less crenulations 505 on the teeth 503. The sinusoidal pattern has a period in the range 0.1mm - 10mm wherein a small period results in many, narrow, crenulations 505 upon the tooth 503 and the larger period resulting in fewer, broad, crenulations 506 upon the tooth 503.

[0058] The amplitude of the sinusoidal crenulations 505 is suitably varied depending on the blank material (allowing material properties to be matched with, and be complimentary to, the tool) and the finish to be achieved (relatively more rough or smooth).

[0059] The range of amplitudes is suitably in the range 0.1mm - 10mm. Selecting an amplitude toward the lower end of the range results in shallow crenulations 505. Selecting an amplitude toward the high end of the range results in deep crenulations 505.

[0060] Referring to figure 6 there is presented a further embodiment 601 of the milling tool as hereinbefore described with an alternative chipbreaker geometry 602. The sinusoidal crenulations 603 may be truncated 604 to provide a substantially saw tooth chipbreaker with flat peaks 604 as opposed to sine wave-like undulations. Suitably the truncated crenulations 603 may have a period and amplitude in the same ranges are hereinbefore described.

[0061] The chipbreaker milling tools 501, 601 depicted in figures 5 and 6 may be constructed from the range of materials as hereinbefore described to match the tool material to the blank material.

[0062] The chipbreaker milling tools depicted in figures 5 and 6 may be treated as hereinbefore described to improve the cutting or durability properties of the tool.

[0063] With reference to figure 7 there is depicted a method of using the milling tools as hereinbefore described.

[0064] A blank 701 is securely mounted on a CNC milling machine, using numerous bolts 702 located through the centre of the material. The secure mounting allows an articulate milling machine to hold and correctly position the blank ready for milling.

[0065] A series of parallel ripping cuts 703 are made about the circumference of the circular blank 701 to produce outlines of blades 704 on the blisk being manufactured. These ripping cuts 703 are parallel with respect to each other, but are suitably at an angle to the rim of the blank.

[0066] The parallel cuts are angled with respect to the rim (i.e. not perpendicular or parallel to the rim, but arranged at an intermediate angle). This arrangement increases the surface area of the final blade.

[0067] The mill is then fitted with the milling tool equipped with a chipbreaker geometry as herein before described, and via a succession of passes quickly removes a large amount of material from the blade inmanufacture and produces a semi-finished blisk complete with curved geometry 705.

[0068] Each pass may be at a depth of 10mm compared to 0.5mm in the prior art, therefore effecting a 20x increase in the volume of material removed per pass.

[0069] Compared to the high ridges and deep valleys produced by the prior art methods, the chipbreaker milling tool provides a relatively continuous surface with only shallow undulations 706 remaining. As such each pass of the chipbreaker milling tool partially overlaps the previous pass to provide surface continuity.

[0070] The mill is then fitted with the smooth-toothed milling tool (the milling tool does not comprise a chipbreaker geometry) as hereinbefore described (as depicted in figures 2-4), and via a succession of passes about the semi-finished blisk, the smooth-tooth milling tool removes a smaller amount of material from the semi-finished blisk than the chipbreaker milling tool. This produces a relatively more finished outline of the semi-finished blisk than produced by the chipbreaker milling tool, and maintains or improves the curved geometry 707. The smooth tooth milling tool provides a cleaner cut than the chipbreaker milling tool and yeilds an improved finish.

[0071] The semi-finished blisk 708 produced as a result of this method requires relatively little clean up. This significantly reduces the production time from around 75 hours to around 35 hours for a titanium blisk comprising 125 blades.

[0072] As a typical jet engine comprises 4-6 blisks (500-750 blades of complex geometry) the use of the milling tools described herein represents a significant time saving overall.

[0073] The use of the smooth-toothed milling tool and/or the chipbreaker milling tool produces a curved profile in the article immediately. The scalloped profile of the cut allows close overlap of each tool pass, creating a near uniform surface with only minor scallop-like (very shallow furrows or dish-like) artifacts.

[0074] The partially overlapping, scalloped cuts reduce wear upon the milling tools as described herein, thereby reducing replacement milling tool costs and reducing the chance of the milling tool breaking. This further improves time and cost savings, whether by reduced downtime from changing milling tools or by increasing the longevity of the milling tools themselves.

[0075] It will be apparent to one skilled in the art that the above outline method is a best practice method to achieve a semi-finished blisk.

[0076] Suitably, the person skilled in the art may, as the circumstances require, select only sections from the above method.

[0077] For example, if the blank 701, is small with relatively little material to be removed, the mill may be fitted with only the smooth-toothed milling tool as hereinbefore described (as depicted in figures 2-4).

[0078] Then the blank 701 may be milled via a succession of passes about the blank. The smooth-tooth milling tool removes a smaller amount of material from the blank than the chipbreaker milling tool and produces a finer finish 708. This produces an outline of the article being constructed and maintains or improves curved geometry 707. This reduces the amount of time required for tool changing and finishing the article, thereby providing significant time savings.

[0079] Likewise, if a very fine finish is not required on the finished article, or subsequent intermediary stages are required prior to finishing, the mill can be fitted with the chipbreaker milling tool as herein before described. The chipbreaker milling tool may be the only milling tool used. Via a succession of passes about the blank, the chipbreaker milling tool quickly removes a large amount of material from the blank and produces a close approximation 705 to the desired article complete with a curved geometry.

[0080] This method allows semi-finished blisks to be created quickly. The fact that only the chipbreaker milling tool is used further reduces machine down time as no tool change is required.

[0081] One set of mill tooling may be used to mill different materials such as nickel or titanium. However, it is preferable, due to differing material properties, that different milling tools are used. Such sets of milling tools are constructed as above, but in materials suited to the cutting of titanium or nickel respectively.

[0082] The milling tools as hereinbefore described are suitable for use in trochoidal milling. In trochoidal milling the milling tool sweeps out a substantially D-shaped path.

Claims

1. A method of part-manufacturing a blisk from a blank comprising the steps of mounting the blank securely; mounting a milling tool to a machining device proximate the blank, wherein the milling tool comprises at least one cutting tooth having at least one axial radius of curvature; and milling the blank into a semi-finished blisk with a succession of passes.

2. A method according to claim 1, wherein the milling tool comprises a second axial radius of curvature.

3. A method according to claims 1 or 2, wherein the at least one tooth comprises a chipbreaker geometry consisting of a plurality of substantially sinusoidal crenulations.

4. A method according to any of claims 1-3, wherein the milling tool comprises a ball end.

5. A method according to any of claims 1-3, wherein the milling tool comprises a base, wherein the base comprises at least one cutting tooth.

6. A method according to any of claims 1 -5, comprising the further step of mounting a second milling tool to the machining device proximate the semi-finished blisk, wherein the second milling tool comprises at least one cutting tooth having at least one axial radius of curvature; and milling the semi-finished blisk into a substantially finished blisk with a second succession of passes.

7. The method according to any of claims 1 to 6, wherein the succession of passes overlap at least partially in a vertical orientation transverse to a main axis of the blisk.

8. The method according to any of claims 1 to 7, wherein at least some of the passes in the succession of passes follow a substantially trochoidal path.

9. The method of claims 1 to 8, wherein the blisk is made from titanium.

10. The method of claims 1 to 8, wherein the blisk is made from nickel.

11. A blisk manufactured according to the method of any of claims 1 to 10.

12. A milling tool comprising; a shank end; and a cutting end comprising at least one cutting tooth having at least one axial radius of curvature.

13. A method according to claim 12, wherein, the milling tool comprises a second axial radius of curvature.

14. A milling tool according to claim 12 or 13, wherein the at least one axial radius of curvature is in the range of 2mm - 250mm.

15. A milling tool according to claims 13, wherein the second axial radius of curvature is in the range 0mm - 50mm.

16. A milling tool according to any of claims 12 -15, wherein the at least one tooth further comprises a chipbreaker geometry.

17. A milling tool according to claim 16, wherein the chipbreaker geometry comprises a plurality of substantially sinusoidal crenulations.

18. A milling tool according to claim 16 or 17, wherein the chipbreaker geometry comprises a serrated edge.

19. A milling tool according to claim 18, wherein the serrated edge follows a sinusoidal path with a period in the range 0.1mm - 10mm.

20. A milling tool according to claim 19, wherein the sinusoidal path comprises truncated peaks.

21. A milling tool according to any of claims 12 to 20, wherein at least one radius of curvature extends along the milling tool 100mm or less.

22. A method substantially as described herein, with reference to, and as shown in, the appended drawings 2 to 7.

22. A milling tool according to any of claims 12 to 20, wherein the milling tool comprises a number of teeth in the range 2 to 50.

23. A milling tool according to any of claims 12 to 20, wherein the at least one tooth is in the form of a helix.

24. A milling tool according to claim 23, wherein the helix has a helix angle in the range 0°to 80°.

25. A milling tool according to any of claims 12 to 24, wherein the milling tool is made from one selected from high speed steel, tungsten carbide, cubic boron nitride and ceramic.

26. A milling tool according to any of claims 12 to 25, wherein at least a portion of the cutting end is coated with one selected from AITiN, AlCrN, AITiN/SiN, AlCrN/SiN, TiB2and TiSiN.

27. A milling tool according to any of claims 12 to 25, wherein the milling tool comprises a ball end.

28. A milling tool according to any of claims 12 to 25, wherein the milling tool comprises a base, wherein the base comprises at least one cutting tooth.

29. A milling tool substantially as described herein, with reference to, and as shown in, the appended drawings 2 to 7. Claims

1. A milling tool comprising; at least one cutting tooth; the at least one tooth comprising; a chipbreaker geometry; a first axial radius of curvature arranged toward a shank end of the milling tool; and a second axial radius of curvature arranged between the first radius of curvature and a base of the milling tool wherein; the transition from the first axial radius of curvature to the second axial radius of curvature through to the base is substantially continuous; and the at least one cutting tooth extends up to 100mm along a shank of the milling tool.

2. A milling tool according to claim 1, wherein the first axial radius of curvature is in the range of 2mm - 250mm.

3. A milling tool according to claim 1 or 2, wherein the second axial radius of curvature is in the range 0mm - 50mm.

4. A milling tool according to any of claims 1-3, wherein the chipbreaker geometry comprises of a plurality of substantially sinusoidal crenulations.

5. A milling tool according to any of claims 1 to 4, wherein the chipbreaker geometry comprises a serrated edge.

6. A milling tool according to claim 5 wherein the serrated edge follows a sinusoidal path with a period in the range 0.1mm - 10mm.

7. A milling tool according to claim 6, wherein the substantially sinusoidal path comprises truncated peaks.

8. A milling tool according to any preceding claim wherein the at least one tooth is in the form of a helix.

9. A milling tool according to claim 8 wherein the helix has a helix angle in the range 0° to 80°.

10. A milling tool according to any preceding claim wherein the milling tool comprises a number of teeth in the range 2 to 50.

11. A milling tool according to any preceding claim wherein the milling tool is made from one selected from high speed steel, tungsten carbide, cubic boron nitride and ceramic.

12. A milling tool according to any preceding claim whereinthe milling tool is treated with one treatment selected from AITiN, AlCrN, AITiN/SiN, AlCrN/SiN, ΊΊΒ2 and TiSiN.

13. A milling tool according to any preceding claim, wherein the base comprises at least one cutting tooth.

14. A milling tool according to any of claims 1-13, wherein the milling tool further comprises a ball end.

15. A method of part-manufacturing a blisk using the milling tool as claimed in any of claims 1 to 15, from a blank wherein the method comprises the steps of mounting the blank securely; making a series of parallel ripping cuts about a circumference of the circular blank; mounting the milling tool to a machining device proximate the blank; and milling the blank into a semi-finished blisk with a succession of passes, wherein said passes are 10mm in depth.

16. The method according to claim 15, wherein the succession of passes overlap at least partially in a vertical orientation transverse to a main axis of the blisk.

17. The method according to either of claims 15 or 16, wherein at least some of the passes in the succession of passes follow a substantially trochoidal path.

18. The method according to any of claims 15 to 17, wherein the blisk is made from titanium.

19. The method according to any of claims 15 to 17, wherein the blisk is made from nickel.

20. A blisk manufactured according to the method of any of claims 15 to 19.

21. A milling tool substantially as described herein, with reference to, and as shown in, the appended drawings 2 to 7.