GB2550345A

GB2550345A - Component manufacturing

Info

Publication number: GB2550345A
Application number: GB1608438.6A
Authority: GB
Inventors: Skirkowski Krzysztof
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2016-05-13
Filing date: 2016-05-13
Publication date: 2017-11-22
Also published as: GB201608438D0

Abstract

Disclosed is a method of manufacturing a three dimensional component. An outer shell 400 is formed by an additive manufacturing process and the shell is filled with a core material. The method may include forming, by the additive manufacturing process, an internal member 402 extending across at least of portion of an internal space defined by the shell. The filling may include depositing the core material within the shell by a casting process, for example, an injection casting process, a vacuum casting process, and a vacuum pressure casting process. The additive manufacturing process may comprises one or more of: a laser melting process, an electron beam melting process, a direct metal laser sintering process, a blown powder process, and a wire extrusion process. The shell may be made from a metal material, for example titanium, aluminium, and/or steel. The core may be comprise the same or a different material as the shell. A finishing process may be included, for example a machining process, a peening process, a forging process, a drilling process, a filing process, a sanding process, a grinding process, an abrasive polishing process, and/or a hot isostatic pressure process. The component may be a vehicle component, such as an aircraft component.

Description

COMPONENT MANUFACTURING

TECHNICAL FIELD

[0001] The present invention relates to methods of manufacturing a component, and to components manufactured by such methods.

BACKGROUND

[0002] Additive Layer Manufacturing (ALM) is a process by which a structural component can be formed by selectively adding layers of material, rather than removing, for example by machining, material to form the component. For example, in some ALM processes, a layer of powdered material is deposited and particles of the powdered material are selectively fused (for example by melting the powdered particles with a directable energy source). Following fusion of a selected portion of the layer, a further layer of powdered material is deposited and selectively fused. By selectively fusing the powdered material in multiple layers, a three dimensional object or component can be manufactured.

[0003] ALM processes are useful for rapid prototyping of components and for producing bespoke components because the dimensions of components manufactured by ALM can be easily specified using, for example, computer aided design (CAD) tools. Furthermore, ALM enables components with complex geometries to be produced, which would otherwise be difficult to produce using non-additive manufacturing processes.

[0004] In many ALM processes, the time taken to manufacture an individual component can be relatively long. This may be, for example, because, the directable energy source must be scanned over each layer of powdered material to “write” the desired pattern in each layer to form a three dimensional component. For larger components, components comprising large sections sizes, and components that are required to be manufactured in large quantities, the time taken to produce each component using an ALM process may make ALM unsuitable for production.

SUMMARY

[0005] A first aspect of the present invention provides a method of manufacturing a three dimensional component, the method comprising fabricating, by an additive manufacturing process, an outer shell and filling the shell with a core material.

[0006] Optionally, the method comprises forming, by the additive manufacturing process, an internal member extending across at least of portion of an internal space defined by the shell.

[0007] Optionally, the filling comprises depositing the core material within the shell by a casting process.

[0008] Optionally, the casting process comprises one or more of: an injection casting process, a vacuum casting process, and a vacuum pressure casting process.

[0009] Optionally, the method comprises controlling the temperature of the shell during the filling.

[0010] Optionally, the method comprises cooling the shell during the filling.

[0011] Optionally, the method comprises controlling the temperature of the core material during the filling.

[0012] Optionally, the method comprises cooling the core material, after filling the shell with the core material, at a rate lower rate than a rate at which the shell cools.

[0013] Optionally, the method comprises fusing the shell with the core material.

[0014] Optionally, the method comprises melting the shell with the core material.

[0015] Optionally, the additive manufacturing process comprises one or more of: a laser melting process, an electron beam melting process, a direct metal laser sintering process, a blown powder process, and a wire extrusion process.

[0016] Optionally, the shell is formed of substantially the same material as the core material.

[0017] Optionally, the shell is formed of a different material to the core material.

[0018] Optionally, the shell is formed of a metal material.

[0019] Optionally, the metal material of the shell comprises one or more of titanium, aluminium, and steel.

[0020] Optionally, the core is formed of a metal material.

[0021] Optionally, the metal material of the core comprises one or more of: titanium, aluminium, and steel.

[0022] Optionally, the core is formed of a plastics material, a resin material or a composite material.

[0023] Optionally, the method comprises performing the additive manufacturing process to form the shell such that a maximum dimension of the component is orientated to be parallel with a build plane of an additive manufacturing apparatus and/or such that a minimum dimension of the component is orientated to be perpendicular with the build plane of the additive manufacturing apparatus.

[0024] Optionally, the fabricating comprises: forming, by the additive manufacturing process, a first shell portion and a second shell portion; and assembling the first shell portion with the second shell portion to form the shell.

[0025] Optionally, the method comprises bonding the first shell portion to the second shell portion via the core material.

[0026] Optionally, at least a portion of the shell is formed with a thickness less than 5 mm.

[0027] Optionally, at least a portion of the shell is formed with a thickness less than 3 mm.

[0028] Optionally, at least a portion of the shell is formed with a thickness less than 2 mm.

[0029] Optionally, the method comprises externally supporting the shell when filling the shell with the core material.

[0030] Optionally, the method comprises externally supporting the shell with foundry sand and/or a ceramic coat.

[0031] Optionally, the method comprises a finishing process.

[0032] Optionally, the finishing process comprises one or more of: a riser removal process, a machining process, a peening process, a forging process, a drilling process, a filing process, a sanding process, a grinding process, an abrasive polishing process, and a hot isostatic pressure process.

[0033] A second aspect of the present invention provides a component manufactured according to a method according to the first aspect of the present invention.

[0034] Optionally, the component comprises an interface layer between the shell and the core material, wherein the interface layer comprises a mixture material from the shell and the core material.

[0035] Optionally, the component comprises a distinct interface between the shell and the core material.

[0036] Optionally, the component is a vehicle component.

[0037] Optionally, the component is an aircraft component.

[0038] A third aspect of the present invention provides a vehicle comprising a component according to the second aspect of the present invention.

[0039] Optionally, the vehicle is an aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [0041] Figure 1 is a schematic diagram illustrating an example of a component manufactured by additive layer manufacturing; [0042] Figure 2 is a flow diagram illustrating a method of manufacturing a component according to an embodiment of the invention; [0043] Figure 3 a is a schematic diagram illustrating an example of a shell manufactured during a method according to an embodiment of the invention; [0044] Figure 3b is a schematic diagram illustrating an example of a component manufactured in accordance with an embodiment of the invention; [0045] Figure 4 is a schematic diagram illustrating an example of a shell manufactured during a method according to an embodiment of the invention; [0046] Figure 5a is a schematic diagram illustrating an example of a shell manufactured during a method according to an embodiment of the invention; [0047] Figure 5b is a schematic diagram illustrating an example of a component manufactured in accordance with an embodiment of the invention; [0048] Figure 6 is a schematic diagram illustrating an example of a component manufactured in accordance with an embodiment of the invention; and [0049] Figure 7 is a schematic diagram illustrating an example of a vehicle of an embodiment of the invention.

DETAILED DESCRIPTION

[0050] Figure 1 is a schematic diagram illustrating a cross section of an example of a component 100 manufactured by an additive layer manufacturing (ALM) process. For example, the component 100 may be manufactured using one or more of: a laser melting process, an electron beam melting process, a direct metal laser sintering process, a blown powder process, and a wire deposition process.

[0051] The component 100 shown in Figure 1, is an I-section component. However, it will be understood that the component 100 could be any shape and/or have any shaped cross-section in other embodiments.

[0052] The component 100 comprises a base flange 102, a top flange 104, and a web 106 connecting the base flange 102 to the top flange 104. In this example, the component 100 also comprises fillets 108 between the base flange 102 and the web 106 and between the web 106 and the top flange 104.

[0053] The component may be formed, for example, by depositing a first layer of powdered material on a platen in an additive manufacturing apparatus (not shown). The first layer of powdered material may be selectively fused, for example, by directing an energy source to scan over the layer of powdered material to “write” the desired pattern into layer. Once the first layer of powdered material is selectively fused, a second layer of powdered material may be deposited onto the first layer of powdered material and the second layer of powdered material may be selectively fused. Successive iterations of depositing a layer of powdered material and selective fusing of the powdered layers enable a three dimensional component to be constructed layer-by-layer. The portions of the successive layers that are successively fused are depicted in Figure 1 by lines 110 extending across the component 100.

[0054] The thiclmess of each layer may vary depending on the apparatus used to manufacture the component 100 and/or the material from which the component 100 is manufactured. For example, the thickness of each layer may be several tens to several hundreds of micrometres. In a specific example, for the manufacture of a component 100 made of titanium, the thickness of each layer may be 70 micrometres.

[0055] The path over which an energy source is scanned over the portions of powdered material that are to be fused to create the component 100 is illustrated with dashed lines labelled 110. As shown in Figure 1, to form a solid component, the energy source is scanned over all portions of the powdered material that are to be fused. For the production of relatively large components, this process may take several hours. In some examples, the process may take tens of hours.

[0056] Figure 2 is a flow diagram illustrating a method 200 of manufacturing a three dimensional solid component according to an embodiment of the invention. The method 200 provides a hybrid component which may have the advantages of a component fabricated by an ALM process, such as the component 100 described with reference to figure 1, but may be manufactured in a shorter time.

[0057] At block 202, an outer shell of a component is fabricated by an ALM process. For example, the ALM process may comprise one or more of: a laser melting process, an electron beam melting process, a direct metal laser sintering process, a blown powder process, and a wire deposition process. The outer shell may be a substantially hollow shell.

[0058] Portions of the shell that are fabricated by ALM may be designed or arranged to provide desired structural properties of the finished components. Alternatively, or additionally, portions of the shell that are fabricated by ALM may be designed or arranged to provide mechanical strength to the shell during filling of the shell with the core material as described below. Such portions may subsequently form part of the component, or may be removed following filling of the shell with the core material.

[0059] In some embodiments, one or more surface features may be provided on the internal surface of the shell during the ALM process to control the properties of the interface between the shell and material subsequently deposited within the shell. For example, the internal surface of the shell may be provided with a textured finish or with a surface relief to provide increased surface area to improve the mechanical contact between the shell and material deposited within the shell.

[0060] At block 204, the shell is filled with a core material. For example, the material may be cast or injected into the shell.

[0061] In some embodiments, the shell and/or the core may be manufactured from a metal or metal alloy material, such as titanium, aluminium, or steel. In other embodiments, the shell and/or the core material may be, for example, a plastics material, a resin, or a composite material.

[0062] The resulting hybrid structure may have the same external form and/or the same external appearance as the component 100 described with reference to Figure 1, but may have structural and/or mechanical properties that can be tailored by the ALM process. Structural properties of mechanical components are often dictated by the form and/or material quality of material at, or close to the surface of the component. For example, imperfections at, or near to, the surface may act as a point from which fractures propagate through the component whereas flaws within the component (i.e. not at, or near, the surface) that are not subject to same stresses may not initiate a failure of the component. This may, for example, enable a lighter material with lower mechanical strength to be used as the core material. For example, the shell may be fabricated from titanium to provide high mechanical strength, with the core material being made from lighter aluminium, plastic, or resin. Such hybrid constructions are unable to be fabricated using known ALM processes in which it is not possible to selectively deposit different materials.

[0063] Figures 3a and 3b respectively illustrate a shell 302 and a component 300 comprising a shell 302 and a core 304 manufactured as a result of carrying out the method 200 described with reference to Figure 2. The component may be, for example, a structural component in mechanism, a structure, a machine, a vehicle or a building.

[0064] Figure 3a is a schematic diagram illustrating a cross section of an example of a shell 302 fabricated by an ALM process, as described above with reference to block 202 of Figure 2. The shell 302 has substantially the same external form as the component 100 described with reference to Figure 1, but includes an internal cavity 306 defining a substantially hollow space.

[0065] The shell 302 comprises an opening 308. The opening 308 is to facilitate deposition of material within the shell to form the core 304 in accordance with block 204 of the method described with reference to Figure 2. The opening 308 is defined during the ALM process. However, it will be understood that in some embodiments the opening 308 may be formed in a subsequent process. For example, the opening 308 may be formed by drilling a hole in the shell 302.

[0066] The path over which an energy source is scanned over the portions of powdered material that are to be fused to create the shell 302 is illustrated with dashed lines labelled 310. It can be seen from Figure 3a that the amount of powdered material that is exposed to energy to create the shell 302 is less than the amount of material that is exposed to energy to create the component 100 shown in Figure 1. Accordingly, the time taken to create the shell 302 is less than the time taken to create the component 100 shown in Figure 1. In some examples, the time taken to create the shell may be several hours, or tens of hours, less than the time taken to create the component 100 shown in Figure 1.

[0067] Figure 3b is a schematic diagram illustrating a cross section of the component 300 after material is deposited within the shell 302 to form the core 304, as described above with reference to block 204 of Figure 2.

[0068] Material may be deposited within the shell 302 to form the core 304 by any deposition process. In some embodiments, the core 304 may be formed by a casting process with the shell 302 acting as a casting mould. The casting process may comprise one or more of: an injection casting process, a vacuum casting process, and a vacuum pressure casting process. In other embodiments, the core 304 may be formed by an injection process in which material is injected into the shell 302.

[0069] The core 304 may provide support to the shell 302 to increase the load bearing capability of the component 300 while reducing the weight of the component 300 as compared to a component made solely by ALM and having the same external dimensions.

[0070] In some embodiments, the core material may be heated above its melting point before being deposited within the shell 302 and allowed to cool and solidify to form the core 304. In some embodiments, the rate at which the material forming the core 304 cools may be controlled.

[0071] During filling of the shell 302 with the core material, the temperature of the shell 302 may be controlled. For example, the shell 302 may be heated or cooled during deposition of material to form the core 304.

[0072] Deposition of molten material to form the core 304, may cause the temperature of the shell 302 to rise. In some examples, the temperature of the shell 302 may rise to such an extent that the shell 302 partially or completely melts. This may enable the shell 302 to fuse to the core 304 such that interface between the shell 302 and the core 304 is continuous and the component 300 is substantially solid.

[0073] Following deposition of material within the shell 302, the core 304 may cool at a different rate to the shell 302. For example, the cooling of the core 304 at a lower rate than the shell 302 may cause the core 304 to develop a tensile residual stress while the shell 302 develops a compressive residual stress. This may, for example, improve the fatigue life of the component 300. The relative rates of cooling of the shell 302 and the core 304 may be controlled to control the amount of tensile or compressive stress in the shell 302 relative to the core 304.

[0074] The material from which the shell 302 is manufactured may be the same material from which the core 304 is manufactured, or the shell 302 may manufactured from a different material to the core 304.

[0075] The shell 302 and/or the core 304 may be manufactured from a metal material. For example, the shell 302 and/or the core 304 may comprise one or more of titanium, aluminium, and steel. In some embodiments, the shell 302 may be made of a metal and the core 304 may be made of a plastics material or resin.

[0076] The thickness of the shell 302 may be chosen to provide suitable support to the material deposited within the cavity 306 and/or to provide the required structural properties of the component. For example, the thickness of the shell 302 may be chosen to resist the pressure applied to the shell 302 by molten material deposited in the cavity 306 and to provide the component with a desired load bearing ability.

[0077] It will be understood that the thickness of the shell 302 may vary depending on the geometry of the component 300, the loads which the component is to bear, and the materials from which the shell 302 and the core 304 are manufactured.

[0078] In some examples, during deposition of material within the cavity 306, the shell 302 may be externally supported. For example, the shell 302 may he supported by encasing the shell 302 in a granular material such as foundry sand, and/or a ceramic coat. In some embodiments, the shell 302 may be provided with sacrificial external support members to provide support to overhanging features. Such supports may then be removed after formation of the core 304. Supporting the shell in this way may enable the shell 302 to be formed with a reduced thickness.

[0079] Figure 4 is a schematic diagram illustrating a cross section of a further example of a shell 400 fabricated by an ALM process, as described above with reference to block 202 of Figure 2, in which one or more internal bracing members, extending across at least of portion of an internal space defined by the shell 302, is formed during the ALM process.

[0080] In the embodiment shown in Figure 4, the shell 400 is formed with eight internal bracing members 402, but in other embodiments more or fewer bracing members may be provided. The bracing members 402 provide internal support to the shell 400 when material is deposited within the shell 400 to form the core 304. Supporting the shell 400 in this way may enable the shell 400 to be formed with a reduced thickness.

[0081] The inset to Figure 4 is a pictorial view of a portion of the shell 400 with one of the bracing members 402. As shown in the inset, the bracing member 402 extends between internal surfaces of the shell 400 without enclosing a space, thereby allowing core material deposited within the shell 400 to flow around the bracing member 402. The core material may thereby support the bracing members 402 to increase their load bearing capacity. Prior to introduction of the core material the bracing members 402 may be used to strengthen an otherwise unstable shell 400.

[0082] In some embodiments, the shell 400 may also comprise external bracing structures to support overhanging portions of the shell 400, which may be removed after the core material has been deposited within the shell 400. In other embodiments, the shell 400 may also be externally supported by foundry sand and/or a ceramic coat, as described above, which may enable the thickness of the shell 400 to be further reduced.

[0083] The ALM process to form the shell 400 may be performed such that a maximum dimension of the component is orientated to be parallel with a build plane of an ALM apparatus and/or such that a minimum dimension of the component is orientated to be perpendicular with the build plane of the ALM apparatus. This reduces the number of layers of material that are deposited thus reducing the time taken to manufacture the shell.

[0084] Figures 5a and 5b respectively illustrate a shell 502 and a component 500 comprising a shell 502 and a core 504. As shown in Figure 5a, the shell 502 comprises a first shell portion 502a and a second shell portion 502b. The first and second shell portions 502a, 502b are formed such that they can be assembled together to form the shell 502 prior to the deposition of material to form the core 504, as shown in Figure 5b.

[0085] By forming the shell 502 in two or more shell portions such as the first and second shell portions 502a, 502b, multiple sections of the shell may be manufactured simultaneously thus reducing the number of layers of material used in the ALM process and therefore the time taken to manufacture the shell 502.

[0086] The first shell portion 502a may be fitted to the second shell portion 502b at a shell joint 506. For example, a shell joint 506 may be provided in which the first shell portion 502a is inserted into the second shell portion 502b. In some embodiments, the first and/or second shell portion 502a, 502b may be provided with alignment features which may be removed following deposition of the core. Alternatively, prior to depositing the material to form the core 504, the first shell portion 502 may be bonded to the second shell portion 502b with an adhesive or weld joint. In some embodiments, the first shell portion 502a may be fixed to the second shell portion 502b by the material deposited to form the core 504, or the temperature of the material deposited to form the core 504 may cause the first and/or second shell portions 502a, 502b to melt to fuse the first and second shell portions 502a, 502b together.

[0087] Figure 6 is a schematic diagram illustrating, by way of an example, the effect of some embodiments of the invention. Figure 6 illustrates a component manufactured using ALM, such as the component 100 described with reference to Figure 1, and a shell manufactured using ALM that may be used to create a component such as the component 300 described with reference to Figure 3. Figure 6 includes dimensions in millimetres (mm) representing the dimensions of a typical component. However, it will be understood that the effect of the invention may obtained for components of other dimensions. The thickness of the shell is denoted by “f’ in Figure 6.

[0088] In this example, the thickness of each layer formed in the ALM process is 70 micrometres. Therefore, to manufacture the component 100 and the shell 302, which each have a height of 68 mm as shown requires 972 layers to be deposited and exposed to a source of energy to selectively fuse the layers.

[0089] To manufacture the component 100, the total volume of material that is to be fused is approximated by the area of the cross section multiplied by the length of the component 100. In an example, the component 100 may take 20 hours to be manufactured by a conventional ALM process. For example, the process may include 10 hours of layer deposition and 10 hours of exposing the layers to energy to selectively fuse the layers.

[0090] To manufacture the shell 302, the same number of layers is required (972), and so the same amount of time is required to deposit the layers (10 hours). However, the volume that is required to be fused is reduced by the volume of the cavity 306 defined by the shell 302, and the volume defined by the opening 308.

[0091] As explained above, the thickness, t, of the shell 302 may depend on the geometry of the component to be manufactured, the material from which the component is to be made, and any external support or internal support provided by bracing members. In some embodiments, the thickness, t, may be less than 5 mm. In some embodiments, the thickness, t, may be less than 3 mm. In some embodiments, the thickness, t, may be less than 2 mm.

[0092] In the example shown in Figure 6, when the thickness, t, of the shell 302 is 2 mm, the volume that is to be fused is reduced to 37.2% of the volume of the component 100; when the thickness, t, of the shell 302 is 1.5 mm, the volume that is to be fused is reduced to 28.1% of the volume of the component 100; and when the thickness, t, of the shell 302 is 1 mm, the volume that is to be fused is reduced to 18.39% of the volume of the component 100. Hence, in this example, when the thickness, t, of the shell 302 is 2 mm, the time to manufacture the shell is 13.72 hours; when the thickness, t, of the shell 302 is 1.5 mm, the time to manufacture the shell is 12.81 hours; and when the thickness, t, of the shell 302 is 1 mm, the time to manufacture the shell is 11.89 hours.

[0093] Although in the embodiments described above, the shell defines a single cavity into which the core is deposited, in some embodiments the shell may be defined by the ALM process to define two or more smaller cavities. This may enable larger components to be manufactured in examples where the deposition process limits the amount of material that may be cast in any one process run; for example, where the amount of material in a casting charge is limited.

[0094] Upon completion of the fabricating and filling processes according to the methods described above, in some examples, one or more finishing processes may be performed. For example, the component may be machined, peened, forged, drilled, filed, and/or ground to prepare the component for use. In some examples, a surface treatment may be performed. For example, the component may be anodized, coated or undergo a corrosion protection. In some examples, a riser removal process may be performed to remove risers introduced in the design of the shell. In examples, where external support pillars are added to the design of the shell, these may be removed from the component after the core has been deposited. In some examples, an abrasive polishing process may be applied to the component to remove burrs, sharp edges, and/or other surface imperfections or irregularities resulting from the manufacturing process.

In some examples the component may be subjected to a hot isostatic pressure process to improve material performance.

[0095] Referring to Figure 7, there is shown a schematic side view of an example of a vehicle according to an embodiment of the invention. In the example of Figure 7, the vehicle is an aircraft 700. The aircraft 700 may comprise one or components, such as the components 300, 500 described above with reference to Figures 3 and 5. In other embodiments, the vehicle may be other than an aircraft, such as a road vehicle, a rail vehicle, a watercraft or a spacecraft.

[0096] The above embodiments are to be understood as illustrative examples of the invention. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

CLAIMS:

1. A method of manufacturing a three dimensional component, the method comprising fabricating, by an additive manufacturing process, an outer shell and filling the shell with a core material.

2. A method according to claim 1, comprising forming, by the additive manufacturing process, an internal member extending across at least of portion of an internal space defined by the shell.

3. A method according to any one of the preceding claims, wherein the filling comprises depositing the core material within the shell by a casting process.

4. A method according to claim 3, wherein the casting process comprises one or more of an injection casting process, a vacuum casting process, and a vacuum pressure casting process.

5. A method according to any one of the preceding claims, comprising controlling the temperature of the shell during the filling.

6. A method according to any one of the preceding claims, comprising cooling the shell during the filling.

7. A method according to any one of the preceding claims, comprising controlling the temperature of the core material during the filling.

8. A method according to any one of the preceding claims, comprising cooling the core material, after filling the shell with the core material, at a rate lower rate than a rate at which the shell cools.

9. A method according to any one of the preceding claims, comprising fusing the shell with the core material.

10. A method according to any one of the preceding claims, comprising melting the shell with the core material.

11. A method according to any one of the preceding claims, wherein the additive manufacturing process comprises one or more of: a laser melting process, an electron beam melting process, a direct metal laser sintering process, a blown powder process, and a wire extrusion process.

12. A method according to any one of the preceding claims, wherein the shell is formed of substantially the same material as the core material.

13. A method according to any one of claim 1 to claim 11, wherein the shell is formed of a different material to the core material.

14. A method according to any one of the preceding claims, wherein the shell is formed of a metal material.

15. A method according to claim 14, wherein the metal material of the shell comprises one or more of: titanium, aluminium, and steel.

16. A method according to any one of the preceding claims, wherein the core is formed of a metal material.

17. A method according to claim 16, wherein the metal material of the core comprises one or more of: titanium, aluminium, and steel.

18. A method according to any one of claim 1 to claim 16, wherein the core is formed of a plastics material, a resin material or a composite material.

19. A method according to any one of the preceding claims, comprising performing the additive manufacturing process to form the shell such that a maximum dimension of the component is orientated to be parallel with a build plane of an additive manufacturing apparatus and/or such that a minimum dimension of the component is orientated to be perpendicular with the build plane of the additive manufacturing apparatus.

20. A method according to any one of the preceding claims, wherein the fabricating comprises: forming, by the additive manufacturing process, a first shell portion and a second shell portion; and assembling the first shell portion with the second shell portion to form the shell.

21. A method according to claim 20, comprising bonding the first shell portion to the second shell portion via the core material.

22. A method according to any one of the preceding claims, wherein at least a portion of the shell is formed with a thickness less than 5 mm.

23. A method according to any one of the preceding claims, wherein at least a portion of the shell is formed with a thickness less than 3 mm.

24. A method according to any one of the preceding claims, wherein at least a portion of the shell is formed with a thickness less than 2 mm.

25. A method according to any one of the preceding claims, comprising externally supporting the shell when depositing the core material within the shell.

26. A method according to claim 25, comprising externally supporting the shell with foundry sand and/or a ceramic coat.

27. A method according to any one of the preceding claims, comprising a finishing process.

28. A method according to claim 27, in which the finishing process comprises one or more of: a riser removal process, a machining process, a peening process, a forging process, a drilling process, a filing process, a sanding process, a grinding process, an abrasive polishing process, and a hot isostatic pressure process.

29. A component manufactured according to a method according to any one of the preceding claims.

30. A component according to claim 29, comprising an interface layer between the shell and the core material, wherein the interface layer comprises a mixture of material from the shell and the core material.

31. A component according to claim 29, comprising a distinct interface between the shell and the core material.

32. A component according to any one of claim 29 to claim 31, wherein the component is a vehicle component.

33. A component according to any one of claim 29 to claim 32, wherein the component is an aircraft component.

34. A vehicle comprising a component according to any one of claim 29 to claim 33.

35. A vehicle according to claim 34, wherein the vehicle is an aircraft.

36. A method, component or vehicle as described herein with reference to Figures 2 to 7.