Fabrication methods for aerosol provision system parts

Abstract

A method of fabricating a part for an aerosol provision system comprises making a mould for the part from a metal, the making including using one or more beams of laser beam to define an inverse textured surface on at least part of the mould, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part, and the surface shape comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 µm to 10 µm; injecting a liquid plastics material from which the part is to be formed into the mould; hardening the liquid plastics material; and releasing the hardened plastics material from the mould to obtain the part having the textured surface.

Description

[0001] FABRICATION METHODS FOR AEROSOL PROVISION SYSTEM PARTS Technical Field

[0002] The present disclosure relates to fabrication methods for fabricating parts for aerosol provision systems, fabrication methods for fabricating machining components for fabricating parts for aerosol provision systems, and machining components for fabricating parts for aerosol provision systems.

[0003] Background

[0004] Aerosol provision systems, such as e-cigarettes and other electronic nicotine delivery systems that deliver nicotine via vaporised liquids, include a reservoir or other liquid storage portion for holding liquid aerosolisable substrate material. Such systems are designed to deliver liquid from the reservoir to an atomiser that generates vapour from the liquid, the vapour being entrained in air flowing through the system when the user inhales to form an aerosol for inhalation. The liquid delivery is commonly achieved by a porous wick that absorbs liquid from the reservoir and transports it by capillary action to the atomiser, which may be an electrical heating element. Liquid may escape from the reservoir without being vaporised by the atomiser (such as via an outlet of the reservoir through which the porous wick extends, or by dripping from a saturated wick), or vaporised liquid may recondense from the inhalable aerosol. This occurrences can produce free liquid within the aerosol provision system. Another source of free liquid is condensation of water vapour from air drawn through the aerosol provision system by the user inhaling through the system in order to obtain the aerosol. This latter circumstance can also occur in heated tobacco aerosol provision systems, in which a portion of tobacco is heated to drive off nicotine and other components to be entrained in an air flow to provide an inhalable aerosol. Liquid from these or other events may be able to move within the aerosol provision system and find its way to locations where its presence is detrimental. Such unwanted liquid may leak out from the system to soil the user and the user’s belongings, or may undesirably interact with components within the system to cause corrosion and malfunctions such as electrical short circuits or poor performance.

[0005] Textured surfaces on faces within an aerosol provision system have been proposed as a technique for addressing unwanted free liquid. A suitably configured textured surface can interact with surface tension forces in small volumes of liquid to inhibit or interrupt movement of liquid over the face, so that the liquid can be kept away from locations where it may cause problems.

[0006] Techniques for forming textured surfaces on parts for liquid aerosol provision systems are therefore of interest. Summary

[0007] According to a first aspect of some embodiments described herein, there is provided a method of fabricating a part for an aerosol provision system, comprising: making a mould for the part from a metal, the making including using one or more beams of laser beam to define an inverse textured surface on at least part of the mould, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part, and the surface shape comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm; injecting a liquid plastics material from which the part is to be formed into the mould; hardening the liquid plastics material; and releasing the hardened plastics material from the mould to obtain the part having the textured surface.

[0008] According to a second aspect of some embodiments described herein, there is provided a method of fabricating a part for an aerosol provision system, comprising: injecting a liquid plastics material from which the part is to be formed into a mould, wherein the mould is formed from a metal and comprises an inverse textured surface on at least a part of the mould, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part, and the surface shape comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm made by etching the metal with one or more beams of laser light; hardening the liquid plastics material; and releasing the hardening plastics material from the mould to obtain the part having the textured surface.

[0009] According to a third aspect of some embodiments described herein, there is provided a method of fabricating a machining component, comprising: making from a metal a machining component for use in fabricating a part for an aerosol provision system, the making including using one or more beams of laser light to define an inverse textured surface on at least part of the machining component, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part for an aerosol provision system, and the surface shape comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm.

[0010] According to a fourth aspect of some embodiments described herein, there is provided a machining component for use in fabricating a part for an aerosol provision system, the machining component being formed from a metal, and comprising an inverse textured surface on at least a part of the machining component, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part for an aerosol provision system, and the surface shape comprising a plurality of laser-etched texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm.

[0011] According to a fifth aspect of some embodiments described herein, there is provided a method of fabricating a part for an aerosol provision system, comprising: using one or more laser beams to etch a textured surface directly onto some or all of a part of an aerosol provision system, the textured surface comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm.

[0012] These and further aspects of the certain embodiments are set out in the appended independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with each other and features of the independent claims in combinations other than those explicitly set out in the claims. Furthermore, the approach described herein is not restricted to specific embodiments such as set out below, but includes and contemplates any appropriate combinations of features presented herein. For example, a method or a machining component may be provided in accordance with approaches described herein which includes any one or more of the various features described below as appropriate.

[0013] Brief Description of the Drawings

[0014] Various embodiments of the invention will now be described in detail by way of example only with reference to the following drawings in which:

[0015] Figures 1A-1 E show highly schematic and not-to-scale plan view representations of parts of various examples of textured surfaces;

[0016] Figures 2 and 3 show highly schematic and not-to scale cross-sectional views through parts of two example textured surfaces;

[0017] Figures 4 and 5 show photographic images of parts of two example textured surfaces;

[0018] Figures 6A-6F shows simplified schematic pictorial representations of steps in an example method of fabricating a part for an aerosol provision system according to the present disclosure; and

[0019] Figure 7 shows a flow chart of steps in an example method of fabricating a part for an aerosol provision system according to the present disclosure.

[0020] Detailed Description

[0021] Aspects and features of certain examples and embodiments are discussed I described herein. Some aspects and features of certain examples and embodiments may be implemented conventionally and these are not discussed I described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus discussed herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features.

[0022] It has been determined that a textured surface that comprises a plurality of texture features having dimensions on the micrometre scale can control the movement, passage or flow of liquid over a face on which the textured surface is provided. In the context of an aerosol provision system, such a textured surface on a face of a part of the aerosol provision system which is located within the assembled aerosol provision system can be used to manage unwanted free liquid that may become present with the system owing to internal leaks or condensation, by keeping such liquid away from locations where it may cause damage, malfunction, poor performance and / or external leaks.

[0023] Textured surfaces considered herein comprise a plurality of micrometre-sized texture features. The features are distributed over a two-dimensional area or region of the face on which the textured surface is provided. Within that area, the texture features comprise a plurality of protrusions / recesses, pits / lands, peaks / troughs, or similar, spread over the area. With respect to the level of the plane of the face around the area, the texture features can comprise protrusions / lands / peaks standing proud of the level of the plane of the face (so that spaces between the features are at the level of the plane), or may comprise recesses / pits / troughs reaching below the level of the plane of the face (so that spaces between the features are at the level of the plane), or both (so that the level of the plane of the face is intermediate between the height of a protrusions / land / peak and the depth of a recess / pit / trough).

[0024] Different configurations of the texture features can act to inhibit the flow or movement of liquid across the textured surface in different ways, caused by different interactions of the liquid’s surface tension with different feature shapes, sizes, configurations, etc. Some examples will now be described, but the present disclosure is not limited in this way, and differently configured textured surfaces can also be fabricated using the techniques proposed herein. In two particular examples, different selection of texture features can give a textured surface which is configured to inhibit the passage of liquid by causing liquid which is incident on the surface to cling to the textured surface, or by causing liquid which is incident on the surface to flow or move along one direction at the expense of limited or prohibited movement in a substantially orthogonal direction.

[0025] Figure 1A shows a highly schematic and not-to-scale plan view representation of a first example of part of a textured surface which is configured for the cling of liquid. In order to enable liquid to cling, the texture surfaces have the form of a plurality of discrete texture features 100 on the face 101 on which the textured surface is provided. The texture features 100 are arranged so as to be spaced apart from one another over the area occupied by the textured surface, over both dimensions of the plane of the face 101. In this example, the texture features 100 are arranged with regular or periodic spacing, in the form of a triangular array. Since the texture features 100 are discrete and separated from one another, each feature may comprise a protrusion or peak extending from the plane of the face 101 , or may comprise a recess or pit “dug” below the plane of the face 100, or a combination of the two. The texture features 100 are depicted as having a roughly round cross-section parallel to the plane of the face 101 , but this is not essential, and the features may have any cross-sectional shape.

[0026] Figure 1 B shows a highly schematic and not-to-scale plan view representation of a second example of part of a textured surface which is configured for the cling of liquid. This is similar to the example of Figure 1A, but in this case texture features 100 are arranged with regular spacing in the form of a square array. Other periodic distributions conforming to other regular arrays may also be used if desired. Alternatively, an irregular or non-periodic distribution may be used.

[0027] Figure 1C shows a highly schematic and not-to-scale plan view representation of a third example of part of a textured surface which is configured for the cling of liquid. In this example, the texture features 100 are randomly distributed over the face 101 , with irregular and non-constant spacing, lacking any intended periodicity. Comparing the first to third examples, a regular arrangement with constant spacing may be found most suitable for enabling the cling of a liquid with a specified viscosity, so that the spacing and regularity may be selected accordingly so as to target a particular liquid, such as water or a chosen type of aerosolisable substrate material. Conversely, a non-periodic arrangement with a range of spacings between the texture features could be used to provide some cling for liquids with viscosities within a range, so that a single textured surface can manage different liquids.

[0028] Figure 1 D shows a highly schematic and not-to-scale plan view representation of a first example of part of a textured surface which is configured for the direction or control of the direction of movement of flow of liquid incident on the textured surface. In order to manage liquid movement direction in this way, a textured surface can have the form of a plurality of continuous texture features 100 on the face 101 on which the textured surface is provided. The texture features 100 comprise a plurality of substantially parallel ridges 102 extending from the plane of the face 101 , and / or grooves / troughs / channels “dug” below the plane of the face 100, or a combination of the two. The ridges / grooves are substantially straight in this example. Hence the texture features 102 are continuous along one direction (the length direction along which the ridges / grooves extend), and spaced apart from one another (by a substantially constant spacing) in the orthogonal direction. The effect of this configuration of the texture features 102 is to interrupt or impede the movement of any incident liquid in the orthogonal direction, indicated by the arrow X, while enabling or promoting the movement of any incident liquid in the length direction, indicated by the arrow Y. In the context of the use of textured surfaces to which the present disclosure relates, the orthogonal direction can be considered as an “across” direction, along which it is desired to inhibit the passage of liquid, so that liquid is inhibited by the textured surface from reaching the far side of the textured surface. Hence, a location on the far side of the textured surface can be protected from exposure to any liquid passing over the face on which the textured surface is provided. Conversely, the movement of incident liquid is encouraged along the length direction of the ridges / grooves, so can be directed away from the across direction, or intentionally encouraged along the length direction, or both.

[0029] Figure 1 E shows a highly schematic and not-to-scale plan view representation of a second example of a textured surface which is configured for the control of the direction of liquid movement. The texture features 102 again comprise a plurality of substantially parallel ridges / grooves, but in this example, the ridges / grooves are formed in ring shapes and arranged substantially concentrically. The depicted example shows the ring shapes as circular, but this is not essential, and other shapes may be used in configurations where the grooves / ridges are not defined as straight lines over the extent of the textured surface. The concentric arrangement defines the across direction X of the textured surface as being between the centre and the outer edge of the area covered by the textured surface. In this way, liquid may be inhibited from moving from a point near the centre of the textured surface outwardly, or from a point beyond the textured surface inwards towards the centre. The direction Y along which the textured surface allows liquid movement is the circumferential direction.

[0030] Figure 2 shows a highly schematic and not-to scale cross-sectional view through an example textured surface, in order to indicates some parameters of interest. In this example, the texture features comprise pits or grooves formed in the face on which the textured surface is provided. Three texture features are shown, but in reality many more features may be present along a line through the textured surface. A first parameter of interest is the spacing s, shown as the centre-to-centre distance or separation between adjacent texture features. Purely as an example, the spacing s may be around 20 pm or around 25 pm. More generally, the spacing may be in the range of 15 pm to 30 pm, although larger and smaller spacings are not excluded, for example in the range of 10 pm to 50 pm. Within a textured surface or a region within a textured surface, the spacing may be constant (within manufacturing tolerances, and might be within 2 pm or within 5 pm, for example), or may be chosen to take a variety of values that vary within a range of up to about 10 pm, for example, such as to better manage liquids with different viscosities. A second parameter of interest is the size or sizes of the dimensions of an individual texture feature, indicated in Figure 2 as a width w in a direction parallel to the plane of the textured surface and the face on which the textured surface is provided, but more generally including the height of protruding features and the depth of recessed or pitted features. These dimensions may or may not be substantially the same size within an individual feature, so that the width may be about the same as the height / depth, or the width may be smaller or larger than the height / depth but typically within the same order of magnitude. For example, the individual dimensions may have sizes around 2 pm or around 3 pm, although larger or smaller dimensions are not excluded, and may be, for example, at least 1 pm, or up to 5 pm, or up to 10 pm. For example, in some cases, the texture features may have dimensions of a size or sizes in the range of 2 pm to 5 pm, or 1 pm to 10 pm. Within a textured surface or a region within a textured surface, the dimension sizes for all texture features may be constant (within manufacturing tolerances, and might be within 0.5 pm or within 1 pm, for example), or may be chosen to take a variety of values that vary within a range, for example, such as to better manage liquids with different viscosities.

[0031] Since the size of individual features and the spacing between adjacent features can be selected, a further parameter that may be of interest when characterising a textured surface is the density of the texture features within the textured surface. The density can be defined as the number of texture features per unit area, or more usefully so as to cover both discrete texture features and parallel grooves / ridges, the number of texture features per unit length across the textured surface. For example, the density may be selected to be about 3 or 4 or 5 features per 100 pm (so about 9 or 16 or 25 features per 100 pm2), although higher or lower values may also be used as required, such as within a range of about 2 to 10 features per pm. Again, the density may be roughly constant across the whole textured surface, or may be chosen to vary in order to provide a textured surface more capable of handling liquids with a range of viscosities.

[0032] The texture features may be tailored to direct the liquid management properties of the textured surface to liquids of different viscosity, since different viscosities give rise to different surface tension forces in a small volume of the liquid. As noted, the liquids of interest within an aerosol provision system are water arising from condensation out of air flowing in the aerosol provision system, and liquid aerosolisable substrate material that may leak from the reservoir or other liquid storage portion, drip from a saturated wick, or condense out of aerosolisable substrate material that has previously been vaporised for aerosol formation. Liquid aerosolisable substrate material typically has a higher viscosity than water, and the texture features may be sized to handle whichever of these liquid types is considered to represent a main issue within an aerosol provision system, or texture features addressed to both liquid types may be provided, either in separate textured surfaces or different regions within a textured surface, or combined within a single textured surface. Texture features might also be sized over a range to target different viscosities of aerosolisable substrate material if it is envisioned that a user may use different aerosolisable substrate materials in a single aerosol provision system. As noted above, a suitable example range of sizes for the texture features making up the textured surface is, in general, 1 pm to 10 pm.

[0033] Figure 3 shows a highly schematic and not-to scale cross-sectional view through another example textured surface, in which the individual texture features have the form of protrusions or ridges extending outwardly from the face carrying the textured surface. Figure 4 shows a photographic image of a portion of a non-limiting example of a textured surface comprising a plurality of discrete texture features in the form of spaced apart pits. A 100 pm scale is indicated.

[0034] Figure 5 shows a photographic image of a portion of a non-limiting example of a textured surface comprising a plurality of texture features in the form of spaced apart parallel grooves. A 100 pm scale is indicated.

[0035] A textured surface such as those described above may be provided on a face of an aerosol provision system part in a number of ways, by forming the textured surface after the part has been made. The textured surface might conveniently be implemented before the part is assembled into the whole aerosol provision system, while the face of the part can be readily accessed. For example, a liquid granular formulation might be applied over the relevant area of the face by spraying, printing or painting, and allowed to dry. Otherwise, the texture features might be created by machining of the face to remove portions of the material from which the part is made. Techniques such as these, requiring dedicated working of individual parts of many aerosol provision systems, add an extra fabrication step and thus increase costs and manufacturing time, which for very high volume products such as aerosol provision systems, is not desirable. There are also issues relating to repeatability; the techniques may produce inconsistent results between parts so that there is variability between individual aerosol provision systems. Additionally, coatings capable of providing a suitable texture may not be safety-approved for use in aerosol provision systems, and may interact with liquid aerosolisable substrate materials.

[0036] An approach that avoids these issues is to use moulding to create the textured surface simultaneously with fabrication of the part on which the textured surface is provided. The part, if itself fabricated by moulding, can be made with the textured surface as an inherent feature if the mould includes an inverse textured surface over an area that forms a face of the aerosol provision system part on which the textured surface is required, where the inverse textured surface has a surface shape which is the inverse of the required surface shape for the desired textured surface. The size or sizes of the texture features of the inverse textured surface match the required size or sizes of the texture features required for the textured surface to be provided on the aerosol provision system part, since they are the inverse of one another. Hence, the inverse textured surface comprises texture features having dimensions of a size or sizes in the range of 1 pm to 10 pm, as described above with regard to the textured surface itself.

[0037] In this way, the part and its textured surface are fabricated together in a single manufacturing step, thereby saving time and cost. The use of a mould to define the texture features of the textured surface also gives consistency; every part made in the same mould will have the same textured surface pattern defined thereon. However, recall that the textured surface comprises texture features with micrometre sized dimensions (height / depth, width, spacing). Very small features can be difficult to accurately form by moulding.

[0038] Accordingly, the present disclosure proposes to fabricate a part for an aerosol provision system by moulding, where the mould is made from a metal, and the required inverse textured surface is defined on the relevant part of the mould (i.e. the part of the mould corresponding to the face of the aerosol provision system part requiring a textured surface) by etching or engraving with one or more laser beams. The use of metal as a mould material enables laser working to be applied to the mould without damage from melting or other heat exposure problems, and the use of laser beams, which can be focussed to very small spot size, allows the micrometre scale detail required for the inverse textured surface to be achieved. The texture features are etched into the metal, i.e. formed, by laser ablation of the metal material of the mould. Ablation is a process by which material is removed from a larger volume (substrate, in this case the bulk metal of the mould) by being irradiated with a high intensity focussed beam of laser light, delivering a high level of flux typically as short pulses, the energy of which is transferred to the irradiated material, which is converted into a plasma and carried away from the substrate. Additionally, in order to accurately reproduce the tiny details of the surface shape defined on the mould, injection moulding is used to fabricate the aerosol provision system part using the mould. A liquid plastics material of a type appropriate for the part is injected into the mould, under an appropriate pressure that forces the liquid plastics material fully into the cavities and recesses of the inverse textured surface to ensure that the textured surface on the moulded part properly includes, in inverse, all features of the inverse textured surface.

[0039] Figures 6A-6F show, in pictorial form as highly simplified and schematic, not-to-scale, cross-sectional representations, steps in an example method of fabricating a part for an aerosol provision system according to this proposed technique.

[0040] Figure 6A shows a first mould portion 10, made from a metal, which will be assembled with one or more other mould portions to make a complete mould. The mould portion 10 comprises a base and side walls that together define a recess 10b that will be all or part of the inner void or cavity of the complete mould. An inner face 10a of the mould portion 10 is provided by an upper (in the depicted orientation) surface of the base of the mould portion 10a, and provides a face on which an inverse textured surface is to be defined. Note that for the purposes of illustration, a very simple rectangular recess 10b is shown; in reality the inner cavity will likely have a more complex and detailed shape corresponding in inverse to the required outer shape of the aerosol provision system part to be fabricated in the complete mould. Figure 6B shows a simplified example apparatus for defining an inverse textured surface on the inner face 10a of the mould portion 10. An optical source 12 in the form of a laser is provided, which emits a beam 14 of laser light. The beam 14 is passed through a focussing arrangement comprising one or more lenses and / or mirrors or other beam shaping and directing optical elements 16, to create a focussed laser beam 18 which is directed onto the inner face 10a. An etching or ablating process is carried out, during which the focussed beam 18 is directed onto different locations on the inner face 10a in order to remove metal material from the mould portion 10 at required positions and to required depths to define the desired texture features of the inverse textured surface. The required locations can be accessed by causing relative movement (indicated by the double-headed arrows) in the plane of the inner face 10a between the focussed beam 18 and the mould portion 10, either by movement of the optical source 12, of the optical elements 16, or of the mould portion 10, or some combination of these. In effect the focussed beam 18 is scanned over at least a part of the inner face 10a, corresponding to the required extent of the textured surface of the aerosol provision system part, in order to “write” the inverse textured surface. Hence, the inverse textured surface covers at least a part of the mould, and may in some cases be defined over all of the inner cavity, depending on the required extent of the textured surface on the aerosol provision part. One or more of the optical source 12, the optical elements 16 and the mould portion may be mounted on a translation stage (not shown) or otherwise provided with movability to enable the relative movement. The required depths to which the metal material is removed by the etching can be achieved by variation of the characteristics of the laser beam, including power of the focussed beam 18 (to change the intensity of the focussed beam at the inner face 10a, for a given focussed spot size of the beam) and / or the duration of any optical pulses by which the laser beam 14 is emitted by the optical source 12, and / or the total exposure time of each location to the focussed beam 18. The width or widths of the texture features can be achieved by adjustment of the focal spot size of the focussed beam 18 at the face 10a, and / or by relative movement. The movement and optical beam variation can be implemented by a controller 20 that is configured to generate and send control signals to the optical source and / or any stages for moving the mould portion 10, the optical source or the focussing arrangement, in response to programming specified to cause appropriate pattern of ablation to define the required inverse textured surface. One or more additional laser beams may be used in parallel or series with the depicted laser beam in order to increase the speed of etching (so that more than one location may be ablated at one time) or to provide a laser beam with different characteristics to modify the ablation process.

[0041] Figure 6C shows the complete mould 22, formed from the mould portion 10 with the inverse textured surface 20 defined on its inner face 10a, and a second mould portion 11. The second mould portion 11 comprises side walls and a top defining a recess, such that when the second mould portion 11 is correctly coupled to the mould portion 10, the recesses of the two mould portions 10, 11 combine to define the inner void or cavity 23 of the mould 22. An opening 21 is provided in the second mould portion 11 that gives access to the inner cavity 23 for the purpose of filling the mould 22. Two mould portions are shown for simplicity; more mould portions may be used to make the complete mould 22, and additional textured surfaces may be defined on the inner faces of the mould portions if required for the aerosol provision system part. A mould portion having a textured surface may alternatively have the form of an insert that fits with a larger mould portion or the whole mould, rather than a portion that actually defines part of the mould cavity.

[0042] Figure 6D shows filling of the mould 22. A supply of a liquid form of a plastics material 26 from which the aerosol provision system part is required to be made is provided in a reservoir or hopper 24. The plastics material 26 is injected into the mould 22 through the opening 21 in order to fill the cavity 23. The injection is carried out at a suitable pressure P and speed, which may vary of the course of the filling, to ensure that the liquid plastics material flows into and fills all and any recesses, nooks and crevices of the cavity 23, including all the texture features of the inverse textured surface 20.

[0043] Figure 6E shows the filled mould 22. The cavity 23 is filled with the liquid plastics material 26, which is then hardened to form the aerosol provision system part. The hardening may arise simply by the elapse of time, or a curing process may be carried out, as will be understood by the skilled person.

[0044] Figure 6F shows a final step in the fabrication method, namely, the release of the now-hardened plastics material from the mould. The second mould portion 11 has been removed to open the cavity and expose the hardened plastics, which now forms the required aerosol provision system part 25. The part 25 is removed from the mould portion 10, and comprises a textured surface 27 having surface shape which is the inverse of the surface shape of the inverse textured surface 20 on the mould portion 10. Final finishing steps (not shown) may be carried to remove any mould details or other surface imperfections from the aerosol provision system part 25 and otherwise prepare it for assembly with other aerosol provision system parts to form a complete aerosol provision system or a component for an aerosol provision system.

[0045] The mould can then be used repeatedly to fabricate further identical aerosol provision system parts, all having the same textured surface, thereby conveniently providing consistency and reproducibility in the manufacture of aerosol provision systems that are enabled for the management of free liquid such as water condensate and escaped liquid aerosolisable substrate.

[0046] Figure 7 shows an example method according to the present disclosure, in the form of a flow chart showing method steps, for example as exemplified in Figures 6A-6F. In a first step S1 , a mould is made from a metal, the mould having an internal cavity shaped for fabricating a part for an aerosol provision system. A second step S2 is carried out as part of making the mould, and comprises performing laser etching, using one or more laser beams, to define, by the process of ablation of the metal material of the mould, an inverse textured surface on at least part of the mould, on an inner face of the cavity of the mould corresponding to a required location for a textured surface on the aerosol provision system part. The inverse textured surface has a surface shape which is the inverse of a required textured surface for the aerosol provision system part, the surface shape comprising a plurality of texture features such as recesses / pits / grooves / troughs and / or lands / peaks / protrusions. The texture features have dimensions of one or more sizes that are in the range of 1 pm to 10 pm. A microscale textured surface enables the management of liquid movement over faces in the aerosol provision system, by the interaction of surface tension forces in the liquid with the texture surfaces, so that the flow of liquid incident on the textured surface can be prevented, inhibited or directed.

[0047] In a third step S3, liquid plastics material, being the type of plastics from which the aerosol provision system part is to be made, is injected into the mould, to fill its inner cavity. A suitable pressure (constant or varying) can be applied to the liquid plastics material to force it into all recesses in the mould cavity, including the micrometre sized surface features of the inverse textured surface.

[0048] In a fourth step S4, the liquid plastics material is hardened, optionally using a curing process for the liquid plastics material, or simply by the elapse of time over a hardening period. In a fifth step, the hardened plastics material is released from the mould, to obtain the aerosol provision part with a textured surface corresponding to the inverse textured surface defined on the mould. If additional identical aerosol provision system parts are required, a sixth step S6 comprises repeating steps S3 to S5 to obtain as many aerosol provision system parts as needed.

[0049] While a complete manufacturing method for fabrication of an aerosol provision system part comprises the steps S1-S5, from initial manufacture of a suitable mould to final production of the aerosol provision system part, further methods according to the present disclosure are enabled by carrying out a subset of the steps of Figure 7. For example, an alternative method for fabrication of an aerosol provision system part comprises taking a suitable mould having an inverse textured surface defined by laser etching, and executing steps S3, S4 and S5 only, namely injecting a liquid plastics material into the mould, hardening the liquid plastics material in the mould, and releasing the hardened plastics material from the mould to obtain the aerosol provision system part with a textured surface.

[0050] Also, a method for fabricating a machine component for use in fabricating a part for an aerosol provision system can comprise steps S1 and S2 only, namely making a mould for the aerosol provision system part from a metal, and using laser etching to define an inverse textured surface on at least part of the mould, where the inverse textured surface has a surface shape with micrometre sized surface features which is an inverse of a textured surface required for the aerosol provision system part. In this example, the machine component comprises a mould for injection moulding to form an aerosol provision system part by injection moulding.

[0051] In another example, the machine component may comprise an embossing die, rather than a mould. In this case, the steps S1 and S2 are modified such that step S1 comprises making an embossing die from metal, the embossing die for use in fabricating a part for an aerosol provision system having a textured surface. Step S2 comprises, within the step of making the embossing die, using one or more laser beams to carry out laser etching to define an inverse textured surface on at least part of the embossing die, where, as before, the inverse textured surface has a surface shape which is the inverse of a textured surface required for the aerosol provision system part, and the surface shape comprises a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm. The embossing die can then be used to apply a textured surface to a part for an aerosol provision system by embossing a face of the part, the part being made from a suitable material that can receive a surface modification by embossing, in other words the material is appropriately malleable. Metals and plastics may be suitable for this.

[0052] More generally, therefore, there is disclosed a method for fabricating a machining component that comprises making the machining component from a metal and using one or more laser beams to define an inverse textured surface on at least part of the machining component, using laser etching / ablation processes as described above, where the machining component may be a mould for injection moulding, or may be an embossing die.

[0053] The type of optical source used for the laser ablation of the metal can be selected according to the type of metal used to make the mould, the amount of material required to be removed from the metal to create the inverse textured surface, and the desired speed of the etching process. The skilled person will be aware of how to select an appropriate optical source (type of laser), and how to operate it in terms of any pulsed operation, focussing, power and the like in order to achieve etching of the required inverse textured surface onto the mould part or portion. The skilled person will understand how to select appropriate parameters and characteristics for the one or more laser beams in order to create the required textured surface in a given metal.

[0054] Ultrashort pulse of laser light are commonly used for laser ablation and similar materials processing applications.. Shorter laser pulses can cause less damage to surrounding material due to the shorter light-material interaction time, and therefore are particularly suitable in the present context where the features to be etched have sizes on the micrometre scale. Pulse of duration on the femtosecond scale (1 fs - 1000 fs) are particularly useful, and may be used here. However, longer laser pulses, such as picosecond and nanosecond pulses can be used where suitable, and indeed, laser ablation can be carried out with a continuous wave (unpulsed) laser beam if the intensity of the laser beam is high enough. Hence, any of these regimes may be used.

[0055] A variety of metals can be used to make the mould (and more generally, a machining component), where selection of the metal should include reference to its suitability for laser etching and its durability to provide a mould portion with an inverse textured surface that will maintain its feature definition for a long period over repeated use. Purely as an example, suitable metals include pre-hardened types of steel that have a chemical composition with relatively low carbon content, such as Toolox (RTM) 33, Toolox (RTM) 40 and Toolox (RTM) 44. Other metals may be used as preferred, however.

[0056] A variety of plastics materials may be used to make the aerosol provision system part, provided that they are suitable for injection moulding, and also suitable for use in an aerosol provision system, where factors such as heat resistance, resistance to exposure to aerosolisable substrate material, safety compliance such as being food-grade, and cosmetic appearance and colour may be significant. Suitable plastics include readily available polymers such as polycarbonate, acrylonitrile butadiene styrene, and blends of these two, polypropylene, and liquid silicone rubber. A further example is polyether ether ketone (PEEK) which is regarded as easily mouldable and has other properties suitable for use in aerosol provision systems, such as an ability to withstand high temperatures, low thermal conductivity, electrically insulating, zero porosity and outgassing, strong and rigid, and lead- free. Other plastics material are not excluded, however.

[0057] As noted, the liquid plastics material should be injected into the mould under sufficient pressure to ensure that the liquid plastics material properly fills the mould cavity to receive all the micrometre-scale details of the inverse textured surface. The pressure selected will depend on many variables including the type of plastics material which is used, its flow rate and the geometry and temperature of the mould. The pressure is typically increased over the injection time to maintain the plastics material flow rate since viscosity of the liquid plastics material causes an increased resistance to flow as the mould fills. A later part of the injection process is known as packing, during which the pressure is controlled rather than the flow rate, so that the flow rate can slow as the mould cavity becomes full. The pressure for packing may be around half of the peak injection pressure, but the relationship is unique for each moulding process. The skilled person will understand how to select and control the pressure required.

[0058] The skilled person will be aware of appropriate techniques that may be employed to harden the liquid plastics material once it is inside the mould, depending on the type of plastics material chosen. As an example, which is in no way limiting, it is possible to include a heating system under the surface of the mould cavity in order to improve the hydrophobicity of micro- and nano-scale textured surfaces formed by moulding [1],

[0059] While it has been noted above that the use of a mould having an inverse textured surface to fabricate aerosol provision systems parts is advantageous, the described laser etching technique for forming the inverse textured surface on the mould may also be used to directly define the textured surface onto the aerosol provision system part. This might be relevant in circumstances where there is no requirement for a large quantity of identical aerosol provision system parts (for example, if a low volume production run for a particular design of aerosol provision system is to be implemented), so that it is not considered worthwhile to make a mould. Accordingly, a further method disclosed herein is a method for fabricating a part for an aerosol provision system that comprises using one or more laser beams to etch, directly onto the aerosol provision system part, a textured surface with the features described above, in particular being made up of a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm.

[0060] The aerosol provision system part may be formed from a metal, in which case the parameters of the laser beam used for the ablation may be, for example, the same or similar to the examples given above for etching an inverse textured surface onto a metal mould. If the aerosol provision system part is made a non-metallic material, for example, a plastics material, the parameters and characteristics of the laser beam may be modified accordingly to take account of differences in the interaction between the light and the plastics material compared to that for light and metals.

[0061] In conclusion, in order to address various issues and advance the art, this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and / or exclusive. They are presented only to assist in understanding and to teach the claimed invention(s). It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claims. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. other than those specifically described herein. The disclosure may include other inventions not presently claimed, but which may be claimed in future. References

[0062] [1] S. Liparoti et al, “Hydrophobicity tuning by the fast evolution of mold temperature during injection molding”, Polymers 10(3), 15 March 2018

Claims

Claims1. A method of fabricating a part for an aerosol provision system, comprising: making a mould for the part from a metal, the making including using one or more beams of laser beam to define an inverse textured surface on at least part of the mould, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part, and the surface shape comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm; injecting a liquid plastics material from which the part is to be formed into the mould; hardening the liquid plastics material; and releasing the hardened plastics material from the mould to obtain the part having the textured surface.

2. A method of fabricating a part for an aerosol provision system, comprising: injecting a liquid plastics material from which the part is to be formed into a mould, wherein the mould is formed from a metal and comprises an inverse textured surface on at least a part of the mould, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part, and the surface shape comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm made by etching the metal with one or more beams of laser light; hardening the liquid plastics material; and releasing the hardening plastics material from the mould to obtain the part having the textured surface.

3. A method according to claim 1 or claim 2, wherein the plastics material comprises polycarbonate, acrylonitrile butadiene styrene, polypropylene, liquid silicone rubber, or polyether ether ketone.

4. A method of fabricating a machining component, comprising: making from a metal a machining component for use in fabricating a part for an aerosol provision system, the making including using one or more beams of laser light to define an inverse textured surface on at least part of the machining component, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part for an aerosol provision system, and the surface shape comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm.

5. A method according to any one of claims 1 to 4, wherein the laser light comprises pulses of a femtosecond duration.

6. A machining component for use in fabricating a part for an aerosol provision system, the machining component being formed from a metal, and comprising an inverse textured surface on at least a part of the machining component, the inverse textured surface having a surface shape which is the inverse of a textured surface required for the part for an aerosol provision system, and the surface shape comprising a plurality of laser-etched texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm.

7. A method or a machining component according to claim 4 or claim 6, wherein the machining component is a mould for injection moulding.

8. A method or a machine component according to claim 4 or claim 6, wherein the machining component is an embossing die.

9. A method or a machine component according to any one of claims 1 to 8, wherein the metal comprises pre-hardened steel.

10. A method or a machining component according to any one of claims 1 to 9, wherein the inverse textured surface is the inverse of a textured surface comprising a plurality of discrete pits and / or protrusions spaced apart over two dimensions.

11. A method or a machining component according to any one of claims 1 to 9, wherein the inverse textured surface is the inverse of a textured surface comprising a plurality of parallel grooves and / or ridges.

12. A method or a machining component according to claim 11 , wherein the parallel grooves are arranged as substantially straight lines.

13. A method or a machining component according to claim 11 , wherein the parallel grooves are arranged concentrically.14 A method or a machining component according to any one of claims 1 to 13, wherein the dimensions of the texture features are selected to enable the textured surface to inhibitor control the passage of liquid across the textured surface on the part, the liquid being water.

15. A method or a machining component according to any one of claims 1 to 13, wherein the dimensions of the texture features are selected to enable the textured surface to inhibit or control the passage of liquid across the textured surface on the part, the liquid having a greater viscosity than the viscosity of water.

16. A method of fabricating a part for an aerosol provision system, comprising: using one or more laser beams to etch a textured surface directly onto some or all of a part of an aerosol provision system, the textured surface comprising a plurality of texture features with dimensions of a size or sizes in the range of 1 pm to 10 pm.

17. A method according to claim 16, wherein the part is formed from a metal.

18. A method according to claim 16, wherein the part is formed from a plastics material.

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