GB2423496A

GB2423496A - A foam body for a master model

Info

Publication number: GB2423496A
Application number: GB0610129A
Authority: GB
Inventors: Thomas Joseph Corden
Original assignee: Advanced Composites Group Ltd
Current assignee: Cytec Industrial Materials Derby Ltd
Priority date: 2003-01-23
Filing date: 2004-01-22
Publication date: 2006-08-30
Also published as: GB2397549B; GB0301498D0; GB0610129D0; GB0401365D0; GB2397549A

Abstract

A master model 10 for use in the production of a mould tool, the master model comprising a main body 12 formed of a foamed material. The foamed body may be a substantially isotropic closed-cell polymeric thermoplastic or a metallic material such as a foamed aluminium alloy. The master model may comprise a mouldable outer layer 14 of a thermosetting syntactic material in the form of a phenolic or epoxy dough or a settable ceramic, cement slurry or a metallic alloy such as lead alloy. The settable material may be mechanically attached to the main body by location of the settable material within the open cells and cavities 18 in the foam structure on the outer surface 16 of the main body or by means of an adhesive. The outer layer may be a plurality of discrete units (214 a,b,c figure 6) such as blocks or slabs in a solid or semi solid state attached to the main body by pins, dowels or threaded fasteners (28 figure 7) or an adhesive (226 figure 6). The main body and outer layer may be placed in a vacuum bag 22 or autoclave to consolidate attachment of the material to the main body as well as removing any unnecessary voids in the material. A method of forming a master model is also included.

Description

1 2423496 Master Models This invention relates to master models and

methods of forming master models, and particularly but not exclusively to master models for use in the production of moulded composite structures.

The production of moulded composite structures, particularly for structures requiring high levels of accuracy in their shape and dimensions, requires a highly precise master model to be formed from which a mould tool can be produced which in turn is used to mould composite structures. There are many important requiremen to be considered when forming a master model, including the materials and their physical and chemical characteristics and properties for the mould tool and the master model itself.

Master models are currently formed from such materials as wood, plaster or syntactic epoxy blocks. These materials however suffer from a variety of disadvantages.

Wood is prone to movement as its moisture content changes, is orthotropic due to the grain structure, needs sealing, and requires considerable skill and expertise to model.

Plaster has limited temperature capability, requires long drying times, is only realistically suitable for shapes that can be lofted between templates, and also requires a high level of skill to form.

The raw materials and the processes used in the manufacture of epoxybased tooling materials are expensive. A high level of skill is also required to build up and bond the blocks of material together to form a model and often this is a multi-stage process rendering the process labour intensive. The material is also heavy and often the joins between the blocks show as witness marks on the final model. Furthermore, particularly for large models, the majority of the expensive material and labour is used to produce the interior of the model where its advantageous characteristics are not particularly required. Fabricating hollow models with such materials is particularly difficult and often considered impracticable despite the expense of solid models.

According to one aspect of the present invention there is provided a master model for use in the production of a mould tool, the master model comprising a main body formed of a foamed material.

Preferably the foamed material is a substantially closed-cell material, and is preferably isotropic.

The foamed material may comprise a foamed metallic material. Preferably the material comprises foamed aluminium or an alloy of or comprising aluminium.

Alternatively, or in addition, the main body may be formed of a foamed polymeric material, which may be a thermoplastic material.

The master model may further comprise an outer layer. The outer layer may comprise a settable material applied to the main body to substantially set thereon. The settable material preferably comprises a thermosetting material.

The settable material may comprise a syntactic material, and may be in the form of a dough. Alternatively or in addition the settable material may comprise ceramic and/or cement-based material desirably in the form of a slurry. The settable material is preferably a phenolic dough although other doughs may be used either as an alternative or in addition, for example epoxy, polyester and/or vinyl ester doughs. Preferably the settable material is substantially void free, other than when syntactic wherein certain voids are intentionally provided with other voids substantially absent.

Preferably the settable material is firmly attached to the main body, and is preferably mechanically fixed to the main body, particularly when the main body is a foamed metallic material, by location of the settable material within open cells and cavities in the foam structure on the outer surface of the main body.

An adhesive may be used to secure attachment of the settable material to the main body. This may be particularly useful when the main body comprises high density, relatively low porosity foam such as a polymeric material like polystyrene, extruded polystyrene, polyurethane, polyvinylchloride, polyetheriniide, polypropylene, polyethylene, polymethacryljmjde or blends and co-polymers of such materials. Preferably the settable material is provided on the main body at a thickness in the region of 5 to 50 mm. More preferably, it is substantially 10 to 20 mm in thickness. Suitable adhesives are preferably one or more of an epoxy, cyanate ester, urethane, silicone, polyester, hot melt thermoplastic or other flexible mastic type material.

Alternatively or in addition the outer layer may comprise material applied to the main body in a generally solid or semi-solid state. The outer layer material may be a settable material which is applied to the main body in a set or part-set condition. The settable material may be substantially as described above.

Preferably the outer layer comprises a plurality of discrete units attached to the main body. Adhesive and/or mechanical attachment means such as pins, dowels, threaded fasteners or other means may be used to secure attachment of the outer layer to the main body.

Particularly where the outer layer is applied in a part-set condition material thereof preferably locates within open cells and cavities in the foam structure on the outer surface of the main body.

In accordance with a still further embodiment the outer layer may comprise, in addition or as an alternative to the materials discussed above, a mouldable material, such as a metallic material like lead or a lead alloy which is desirably mouldable on the main body. Such material is preferably attached to the main body by adhesive such as one or more of those indicated above, mechanical attachment or by any other suitable means.

According to another aspect of this invention, there is provided a method of forming a master model for use in the production of a mould tool, the method comprising providing a main body of a foamed material, and shaping said main body to generally the shape and size of a mould tool to be produced therefrom.

Preferably the foamed material used is substantially as described in any one or more of the preceding twelve paragraphs.

The method preferably further includes applying an outer layer of material to said shaped main body.

Preferably the material used is settable material substantially as described above.

Alternatively or in addition the method includes attaching one or more discrete units, such as blocks or slabs, of material in a solid or semisolid state.

The or each unit may be attached by adhesion using one or more adhesives such as those described above and/or mechanical attachment, using for example threaded fasteners, dowels, pins or other suitable means.

Preferably each unit is prepared from settable material, preferably as described above, and preformed into a desired shape and size for attachment to the main body. Each unit is preferably applied to the main body in a set or part- set condition.

In accordance with a still further alternative or addition, a layer of a mouldable material may be applied to the main body. The mouldable material may comprise a metallic material such as lead or an alloy of lead. The mouldable material may be moulded on the main body to generally follow the contours thereof. The mouldable material may be attached to the main body by adhesive such as any one or more of those described above and/or mechanical fixing means such as threaded fasteners, dowels, pins or the like.

Preferably the material according to any of the aforesaid embodiments is applied under conditions to promote mechanical attachment thereof to the main body. Preferably the material is applied to locate within open cells and cavities on the outer surface of the foamed material, whereby to secure attachment thereof to the main body. Pressure may be applied to the material on the main body, which pressure may be provided by a vacuum formed around the main body and the material. A vacuum bag may be located over the main body and said material to enable the formation of vacuum pressure to act to consolidate attachment of said material to the main body and to act to remove or minimise any undesirable voids in the material.

The method may further comprise the step of curing the material in particular the settable material, preferably after but possibly during the application of pressure. Curing may comprise the application of heat, which may be done in an oven or autoclave depending somewhat upon the size of the model and whether the application of both heat and temperature are required or desirable during curing. Preferably curing is done at temperatures of less than 120 C and desirably at less than 80 C, for up to a maximum of five hours.

Preferably, the method includes shaping the material on said main body.

Shaping preferably takes place after pressurisation and, also preferably, after curing.

The shaping step may comprise cutting the material using cutting, router and/or milling apparatus which may be guided by laser. The apparatus may be CNC controlled.

Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Fig. us a diagrammatic cross-section of a master model according to the present invention; Fig. 2 is an enlarged cross-sectional detail of the outer surface of the master model of Fig. 1; Fig. 3 is a diagrammatic crosssection of a master model being formed according to the present invention; Fig. 4 is a diagrammatic cross-section of a master model according to a second embodiment of the present invention; Fig. 5 is an enlarged crosssectional detail of the outer surface of the master model of Fig. 4; Fig. 6 is a diagrammatic cross-section of a master model according to a third embodiment of the present invention; Fig. 7 is an enlarged crosssectional detail of the outer surface of the master model of Fig. 6; Fig. 8 is a diagrammatic cross-section of a master model according to a fourth embodiment of the present invention; and Fig. 9 is an enlarged crosssectional detail of the outer surface of the master model of Fig. 8.

Referring to Figs. I to 3 of the drawings, there is provided a master model for use in the production of a mould tool (not shown). The master model 10 comprises a main body 12 formed of a foamed material. A settable material 141s provided on the surface of the main body 12.

In more detail, the foamed material of this particular embodiment comprises foamed aluminium. This has generally isotropic characteristics. For foamed aluminium with a density in the order of 5% of the density of aluminium the structure is generally open cell. This structure has advantage if the master model 10 is to be subjected to autoclave Conditions and the open cell structure will allow the elevated pressure to act primarily on the settable material 14 and not on the whole master model 10. This will help to reduce deformation of the model under the pressure. For foamed aluminium material of greater densities (10 - 20% the density of aluminium) the structure is Predominantly a closed cell structure. Such structures have particular advantage where the settable material is relatively fluid in that the closed cells would tend to prevent excessive movement of the settable material into the foam structure. In open cell structures more fluid materials would tend to migrate further into the foam structure, particularly under conditions of applied pressure and therefore with such structure less fluid settable material are likely to be more suitable.

The settabje material comprises a thermosetting syntactic phenolic dough which is essentially a phenolic resin containing a plurality of small spherical beads which give the material a substantially uniform, microporous structure.

The dough 14 is attached to the surface 16 of the foamed aluminium body 12 by generally mechanical interaction. With reference to Fig. 2, the dough 14 extends into cavities 18 which are present in the outer surface of the main body 12, often formed following machining of the body 12 as will be explained.

Mechanical attachment of the dough 14 to the foamed aluminium 16 in this way can be facilitated by the application of pressure to the layer 14 to cause the material to enter into the cavities 18. The viscosity of the settable material and the porosity of the foam structure can be engineered to assist in achieving the desired amount of interaction and impregnation and therefore the strength of attachment of the dough 14 to the main body 12.

Fig. 3 is a diagrammaj illustration of a method of forming a master model in accordance with the present invention. The main body 12 of foamed aluminium is cut to the general shape and size for the desired master model. In the present example it is shown in the general shape of a dome, although with conventional cutting equipment such as laser guided CNC apparatus quite intricate shapes can be very accurately produced. The main body 12 is placed on a base 20 of generally conventional design. The outer surface is "pitted" with the cavities formed by cells within the foam structure being exposed by cuffing or otherwise.

The dough 14 is applied on the outer surface 16 of the main body 12 using any suitable tool, such as a spatula, knife, trowel or the like, to a thickness of between 5 mm to 50 mm. For most applications a thickness in the order of 10 to mm would be appropriate. The model 10 is then enclosed within a vacuum bag 22 which is sealingly attached to the base 20. A vacuum is then applied inside the bag as air is drawn out from within as illustrated by the arrow 24.

The pressure applied through this arrangement consolidates and compresses the dough 14, urging the dough 14 into the cavities 18 to secure mechanical attachment. Unwanted voids of air trapped within the dough layer 14 are removed or minimised through the application of pressure, so that the syntactic dough 14 has a generally uniform and isotropic structure with no significant unwanted voidage.

Curing conditions may be applied during the application of pressure, or afterwards, to cure the dough 14.

The phenolic dough 14 is cured at a temperature of less than 120 C. Ideal curing conditions would be less than 80 C for up to approximately five hours.

Once the layer 14 is cured on the body 12 the final shape and dimensions of the master model are achieved using appropriate cutting and shaping means, such as laser guided CNC, milling, routing and/or other cutting apparatus. The lack of any significant voids within the dough enables the layer 14 to be very accurately shaped to give smooth and substantially pit-free surface finishes.

It will be appreciated that the main body 12 is generally of the shape and size required, but is slightly smaller to allow the layer 14 to be applied and then cut to the precise shape and dimensions. The dough 14 is therefore generally applied such that before cutting and shaping, but after curing, the overall size of the master model is slightly larger than required.

The use of foamed aluminium and syntactic dough as described above is believed to have a number of advantages over the known prior art. The syntactic dough material is only required in relatively small amounts. The bulk of the master model is comprised of the aluminium foam. Since the dough is considerably more expensive than foamed aluminium, this provides a considerable cost saving and avoids the use of expensive materials inside the model where they are not required.

The foamed aluminium is considerably lighter than other known master model material, thus rendering it relatively easy to handle. Also the shaping of the aluminium requires less craftsman skill than materials such as wood, and for many applications can be cut by an automated procedure.

The application of the dough can be done as a single stage, generally regardless of the size of the master model. There would therefore be no, or relatively few seam lines in the surface of the master model.

The relatively thin layer of dough required reduces the likelihood of cracking due to thermal shock as the materials heat up and cool down during the production of mould tool. Also, the dough and aluminium foam have much lower coefficients of thermal expansion than known modelling materials which also helps to reduce thermal expansion effects when manufacturing mould tools.

Further advantages of the use of foamed aluminium is that it is stable up to at least 1800 and therefore remains stable during curing of the dough and subsequent production procedures for mould tools. Aluminium foam also has a low coefficient of thermal expansion (around 20 x E-06) which is very close to the coefficient of thermal expansion of the dough, such that during processing the materials expand and contract together minimising thermally induced stresses.

As mentioned above, the dough will mechanically interlock with the open cells on the surface of the aluminium foam particularly when consolidated under pressure. This helps to maintain the integrity of the master model. Aluminium foam is also an excellent conductor of heat which again helps to minimise thermal stresses and temperature gradients.

The master model 10 produced according to the present invention can be used to produce mould tools for a wide range of industries, including but not limited to the automotive, marine, aeronautical, engineering and power generating industries. In particular an application where the advantages of the present invention may be of considerable use is in the production of very large composite bodies such as wind turbine blades and the like which can be up to 75 metres in length and preferably formed as a unitary body.

Figs. 4 and 5 illustrate a master model 110 according to a second embodiment of the present invention. In this embodiment, a layer of adhesive is applied over the outer surface 116 of the main body 112 to facilitate adhesion of the layer of dough 114 to the outer surface 116 of the body 112. The adhesive may comprise one or more of an epoxy, cyanate ester, urethane, silicone, polyester, hot melt thermoplastic material or other flexible mastic-type material.

An adhesive layer 26 may be used where the foamed material of the main body 112 is of relatively high density and comprises relatively small and/or few open cells or cavities on the outer surface thereof, which would generally provide less favourable mechanical attachment than for less dense, more porous and open celled foam material.

An adhesive layer 26 may also be provided to overcome any chemical resistance to attachment which may arise between the dough 114 and the foamed material of the body 112.

II

It is envisaged that adhesive would be primarily used when the foamed body 112 is of a polymeric material, such as a thermoplastic like polystyrene, polyurethane, polyvinyl chloride, polyetherimjcje, polypropylene, polyethylene, polymethacrylimide or blends and co-polymers thereof, although it may also be useful when using higher density, foamed aluminium and other metallic materials to facilitate attachment.

The master model 112 is otherwise produced according to the method described above, with the additional step of the application of a layer of adhesive prior to application of the layer 114 of dough material.

Fig. 6 and 7 show a master model 210 according to a third embodiment of the present invention. In this embodiment, the main body 212 has a plurality of preformed units such as blocks or slabs 214a, b, c, etc. attached thereto to form the outer layer 214.

Each unit 214a, b etc. is in the form of a block or slab of pre-set or partially set material formed from the settable material 14, 114 discussed above.

To facilitate application of the units to the main body 212, the main body 212 is appropriately shaped, in the example by way of an arrangement of steps.

These steps enable the sequential location of the units 214 on the body 212 by building in a generally upward direction.

A layer of adhesive 226 such as that discussed above may be used between the units 214 and the main body 212 to facilitate attachment. Adhesive may be used between the units 214 to facilitate attachment therebetween.

As an alternative to adhesive or in addition thereto, mechanical fixing means 28 may be provided to secure attachment of the units 214 to the main body 212 and/or to each other.

A simple mechanical fixing means is shown in Fig. 7 as a tie or dowel 28, although any suitable form of fixing means may be used such as threaded fasteners, provided said means 28 do not detrimentally affect the ability to cut the blocks 216 to the desired shape.

As mentioned above, the units 214 are preformed away from the body 212 into a desired shape and then attached to the body 216, either in a set or part-set condition. Once attached, the units 214 may be subjected to further setting or curing and other suitable conditions including elevated pressure. Partial impregnation of the units 214 into the surface 216 of the main body 212 is preferably achieved to secure attachment, particularly for the part-set units 214 but also possibly of the set units 214 to secure attachment. The units 214 may then be shaped in situ on the main body 212 in similar fashion as discussed above, for example by way of CNC machining.

Figs. 8 and 9 illustrate a master model 310 according to a fourth embodiment of the present invention. In this embodiment, an outer layer of mouldable material 30 is applied to the outside of the main body 312. A layer of adhesive 326 may be used to attach the mouldable material 30 to the body 312.

A suitable adhesive 326 may be as described above.

The mouldable material 30 may comprise a sheet or sheets of metallic material such as lead or a lead alloy. The adhesive 326 bonds to the material 30 and mechanically locked and bonds with the outer surface 316 of the main body 312. The mouldable material 30 can then be machined to the desired shape and dimensions using CNC machines and such like.

Various modifications may be made without departing from the spirit or scope of the present invention. For example the foamed aluminium material may comprise an alloy of or comprise aluminium. Other foamed metallic materials may be employed, such as foamed steel or steel alloys. The body 12, 112, 212, 312 may comprise a composite of metallic and non-metallic foamed material, such as a combination of foamed aluminium and foamed thermoplastic material.

The settable material may comprise a thermoplastic material and may comprise one or more of an epoxy, polyester and polyvinyl material either with or without a phenolic material. Alternatively or in addition, the settable material can comprise a ceramic-based and/or cement-based material. The settable material may not be syntactic.

The outer layer 14, 114, 214, 314 may comprise a plurality of layers of the same material or alternatively, or in addition, layers of the different materials discussed above according to the various embodiments. For example a first layer of settabte material may be applied to the main body and then an outer layer of mouldable material may be applied thereto. Any combination of such materials may be used in accordance with the present invention.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims 1. A master model for use in the production of a mould tool, the

master model comprising a main body formed of a foamed material.
2. A master model according to claim 1, in which the foamed material is a substantially closed-cell material.
3. A master model according to claim I or claim 2, in which the foamed 1 0 material is isotropic.
4. A master model according to any preceding claim, in which the foamed material comprises a foamed metallic material.
5. A master model according to claim 4, in which the material comprises foamed aluminium or an alloy of or comprising aluminium.
6. A master model according to any preceding claim, in which the main body comprises a foamed polymeric material.
7. A master model according to claim 6, in which the body is formed of a thermoplastic material.
8. A master model according to any preceding claim, in which the master model comprises an outer layer.
9. A master model according to claim 8, in which the outer layer comprises a settable material applied to the main body to substantially set thereon.
10. A master model according to claim 9, in which the settable material comprises a thermosetting material.
11. A master model according to claim 9 or claim 10, in which the settable material comprises a syntactic material.
12. A master model according to any of claims 9 to 11, in which the settable material is in the form of a dough.
13. A master model according to any of claims 9 to 12, in which the settable material comprises ceramic based material.
14. A master model according to any of claims 9 to 13, in which the settable material comprises cement-based material.
15. A master model according to any of claims 13 or 14, in which the settable material is in the form of a slurry.
16. A master model according to any of claims 9 to 12, in which the settable material comprises a phenolic dough and/or an epoxy dough.
17. A master model according to any of claims 9 to 16, in which the settable material is substantially void free, other than when syntactic wherein certain voids are intentionally provided with other voids substantially absent.
18. A master model comprising any of claims 9 to 17, in which the settable material is firmly attached to the main body.
19. A master model according to claim 18, in which the settable material is mechanically fixed to the main body by location of the settable material within open cells and cavities in the foam structure on the outer surface of the main body.
20. A master model according to any of claims 9 to 19, in which an adhesive is used to secure attachment of the settable material to the main body.
21. A master model according to any of claims 9 to 20, in which the settable material is provided on the main body at a thickness in the region of 5 to 50 mm.
22. A master model according to claim 21, in which the seftable material is provided at substantially 10 to 20 mm in thickness.
23. A master model according to any of claims 20 to 22, in which suitable adhesives are one or more of an epoxy, cyanate ester, urethane, silicone, polyester, hot melt thermoplastic or other flexible mastic type material.
24. A master model according to any of claims 8 to 23, in which the outer layer comprises material applied to the main body in a generally solid or semi-solid state.
25. A master model according to claim 24, in which the outer layer material is a settable material which is applied to the main body in a set or part-set condition.
26. A master model according to any of claims 8 to 25, in which the outer layer comprises a plurality of discrete units attached to the main body.
27. A master model according to any of claims 8 to 26, in which mechanical attachment means such as pins, dowels, threaded fasteners or other means are used to secure attachment of the outer layer to the main body.
28. A master model according to any of claims 8 to 27, in which the outer layer comprises a mouldable material which is mouldable on the main body.
29. A master model according to claim 28, in which the mouldable material is attached to the main body by adhesive, mechanical attachment or by any other

suitable means.
30. A master model according to claim 28 or claim 29, in which the mouldable material comprises a metallic material.
31. A master model according to claim 30, in which the mouldable material comprises lead or a lead alloy.
32. A method of forming a master model for use in the production of a mould tool, the method comprising providing a main body of a foamed material and shaping said main body to generally the shape and size of a mould tool to be produced therefrom.
33. A method according to claim 32, in which the foamed material is as defined in any of claims 1 to 6.
34. A method according to claim 32 or claim33, in which the method further includes applying an outer layer of material to said shaped main body.
35. A method according to claim 34, in which the material used is settable material as defined in any of claims 9 to 31.
36. A method according to any of claims 32 to 35, in which the method includes attaching one or more discrete units, such as blocks or slabs, of material in a solid or semi-solid state.
37. A method according to claim 36, in which the or each unit(s) are attached by adhesion using one or more adhesives and/or mechanical attachment, using for example threaded fasteners, dowels, pins or other suitable means.
38. A method according to claim 36 or claim 37, in which each unit is prepared from settable material.
39. A method according to any of claims 36 to 38, in which each unit is preformed into a desired shape and size for attachment to the main body.
40. A method according to any of claims 36 to 39, in which each unit is applied to the main body in a set or part-set condition.
41. A method according to any of claims 32 to 40, in which a layer of a mouldable material is applied to the main body.
42. A method according to claim 41, in which the mouldable material used comprises a metallic material such as lead or an alloy of lead.
43. A method according to claim 41 or claim 42, in which the mouldable material is moulded on the main body to generally follow the contours thereof.
44. A method according to any of claims 41 to 43, in which the mouldable material is attached to the main body by adhesive and/or mechanical fixing means.
45. A method according to any of claims 34 to 44, in which the material according to any of the aforesaid embodiments is applied under conditions to promote mechanical attachment thereof to the main body.
46. A method according to any of claims 34 to 45, in which the material is applied to locate within open cells and cavities on the outer surface of the foamed material, whereby to secure attachment thereof to the main body.
47. A method according to any of claims 34 to 46, in which pressure is applied to the material on the main body.
48. A method according to claim 47, in which pressure is provided by a vacuum formed around the main body and the material.
49. A method according to claim 48, in which a vacuum bag is located over the main body and said material to enable the formation of vacuum pressure to act to consolidate attachment of said material to the main body and to act to remove or minimise any undesirable voids in the material.
50. A method according to any of claims 34 to 49, in which the method further comprises the step of curing the material.
51. A method according to claim 50, in which the material is cured during the application of pressure.
52. A method according to claim 50 or claim 51, in which the material is cured after the application of pressure.
53. A method according to any of claims 50 to 52, in which curing comprises the application of heat.
54. A method according to any of claims 50 to 53, in which curing is done in an oven or autoclave.
55. A method according to any of claims 50 to 54, in which curing is done at temperatures of less than 120 C.
56. A method according to claim 55, in which curing is conducted at less than 80 C.
57. A method according to any of claims 50 to 56, in which the material is cured for up to five hours.
58. A method according to any of claims 34 to 57, in which the method includes shaping the material on said main body.
59. A method according to any of claims 47 to 58, in which shaping takes place after pressurisation.
60. A method according to any of claims 58 to 59, in which shaping takes place after curing.
61. A method according to any of claim 58 to 60, in which shaping comprises cutting the material using cutting, router and/or milling apparatus.
62. A method according to any of claims 58 to 61, in which shaping is CNC controlled.
63. A master model substantially as hereinbefore described with reference to Figs. 1 and 2.
64. A master model substantially as hereinbefore described with reference to Figs. 4 and 5.
65. A master model substantially as hereinbefore described with reference to Figs. 6 and 7.
66. A master model substantially as hereinbefore described with reference to Figs. 8 and 9.
67. A method substantially as hereinbefore described with reference to the accompanying drawing.
68. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.