Method for improving aerodynamics by directly applying surface textures using inkjet printer
Directly applying surface texture on the curved surface through inkjet printing technology, solving the problem of difficulty in aligning texture decals on the curved surface, achieving efficient surface modification, and improving aerodynamic or fluid dynamics performance.
Patent Information
- Application Number
- CN202411199352.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-11-17
- Filing Date
- 2024-08-29
- Publication Date
- 2025-05-20
AI Technical Summary
Difficult to align texture decals on curved surfaces, resulting in poor surface modification effects and affecting aerodynamic or hydrodynamic performance.
Inkjet printing technology is used to directly apply surface texture on the surface of the part, and high-precision texture deposition is achieved by defining the geometry of the texture, generating motion paths, determining the parameters of the inkjet printer and aligning the parts.
Improves surface modification accuracy and effect on curved surfaces, reduces friction between fluid and solid surfaces, thereby improving aerodynamic or hydrodynamic performance.
Smart Images
Figure CN120019964A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure generally relates to surface modification techniques, and more particularly, to a method of directly applying surface textures using an inkjet printer. Background Art
[0002] Surface modification techniques are used to manipulate the flow of fluids (e.g., air or water) over the solid surface of an object to minimize friction and drag, thereby ultimately improving the efficiency and performance of the object. One surface modification technique involves introducing a texture or pattern onto the solid surface in a manner that alters the interaction between the fluid and the solid surface. By creating a texture or pattern on the surface, the effective contact area between the fluid and the solid is reduced. This reduction in contact area decreases the frictional force experienced by the object as it moves through the fluid. The texture or pattern on the surface disrupts the laminar flow of the fluid. This disruption effectively reduces the surface friction, which is a major source of drag in hydrodynamics, thereby improving the aerodynamic or hydrodynamic performance.
[0003] An existing surface modification method involves a technique called decal. Decal is a technique in which a sheet, fabric, or layer having a microtexture formed thereon is attached or stitched to another surface. By covering the solid surface with a texture or pattern, the frictional force experienced by the object as it moves through the fluid is reduced.
[0004] A major challenge is that most surfaces, such as aircraft wings or fuselages, are curved rather than flat. Aligning these texture decals on a curved surface can be difficult. Achieving perfect alignment is difficult, and mismatches can cause wrinkles or misalignments on the surface, which can have a negative impact on the expected improvement in aerodynamic or hydrodynamic performance. The size of the decal must be precise to match the contour of the curved surface. If the size is slightly off, it may result in overlaps, gaps, or distortions in the applied texture, thereby reducing the effectiveness of the surface modification. Summary of the Invention
[0005] An exemplary embodiment provides a method of directly applying a surface texture on a part surface to reduce drag. The method includes: defining the geometry of the surface texture on the part surface; and generating a path for an inkjet printer to move on the part surface. The method includes determining the number of passes and the firing schedule for the inkjet printer to create the surface texture. The method includes positioning and aligning the part in a work cell. The method includes depositing droplets onto the surface by the inkjet printer to create the surface texture.
[0006] In an exemplary embodiment, the surface texture includes a plurality of ribs formed on the surface. The surface texture can be formed by controlling the size of the droplets. The size of the droplets can be changed to continuously decreasing droplets to form a texture pattern of ribs on the surface.
[0007] In an exemplary embodiment, the inkjet printer includes a piezoelectric actuator in contact with a fluid. The piezoelectric actuator is configured to change shape in response to an electrical pulse applied to the piezoelectric actuator, thereby generating a pressure wave in the fluid and forcing a controlled amount of the fluid to flow out of the inkjet printer as the droplets.
[0008] In an exemplary embodiment, the method includes adjusting the size of the droplets by changing the amplitude and pulse width of the electrical pulse.
[0009] In an exemplary embodiment, the method includes curing the droplets, thereby polymerizing the material in the droplets and binding to the surface.
[0010] Another exemplary embodiment provides a method for creating ribs on a part surface to reduce drag. The method includes defining the geometry of the ribs on the part surface and generating a path for the inkjet printer to move on the part surface. The method includes determining the number of passes and firing schedule for the inkjet printer to create the ribs. The method includes positioning and aligning the part in a work cell and depositing the droplets onto the surface by the inkjet printer to create the ribs.
[0011] Another exemplary embodiment provides a method for directly applying a surface texture onto a part surface to reduce drag. The method includes defining the geometry of the surface texture on the part surface and generating a path for the inkjet printer to move on the part surface. The method includes determining the number of passes and firing schedule for the inkjet printer to create the surface texture. The method includes positioning and aligning the part in a work cell. The method includes adjusting the size of the droplets in response to input data related to the geometry of the surface texture. The method includes firing the droplets to selectively position the droplets on the surface to achieve the desired texture pattern. The method includes controlling the movement of the inkjet printer relative to the surface to change the thickness of the surface texture. Description of the Drawings
[0012] The novel features of the exemplary embodiments are set forth in the appended claims. However, the exemplary embodiments, and their preferred modes of use, other objects and features, will be best understood when read in conjunction with the following detailed description of the exemplary embodiments of the present disclosure, where:
[0013] Figure 1 depicts a system according to an exemplary embodiment;
[0014] Figure 2A and Figure 2B illustrates droplets that achieve a desired texture;
[0015] Figure 3 illustrates a technique for creating a desired texture;
[0016] Figure 4A 、 Figure 4B and Figure 4C illustrates a perspective view of exemplary ribs formed on a surface;
[0017] Figures 5A to 5D illustrates changing the height and width of a surface texture by varying the speed of an inkjet printer; and
[0018] Figure 6 depicts a flowchart that illustrates a method of directly applying a surface texture onto a surface. DETAILED DESCRIPTION
[0019] The exemplary embodiments recognize and account for one or more different considerations. For example, the exemplary embodiments recognize and account for the fact that most surfaces such as aircraft wings or fuselages are curved rather than flat. Therefore, it can be difficult to align texture decals on a curved surface. The exemplary embodiments recognize and account for the difficulty of achieving perfect alignment on a curved surface, and that a mismatch can result in wrinkles or misalignment on the surface, which can have a negative impact on the expected aerodynamic or hydrodynamic performance improvements. The exemplary embodiments recognize and account for the fact that the size of the decal must be precise to match the contour of the curved surface. If the size is slightly off, it can result in overlaps, gaps, or distortions in the applied texture, thereby reducing the effectiveness of the surface modification.
[0020] The exemplary embodiments provide a method and system for applying a surface texture onto a solid surface using inkjet printing. Compared to traditional methods that rely on decal techniques, the exemplary embodiments provide a direct surface texture through inkjet printing. The exemplary embodiments provide a higher level of precision and control over the texture application process, especially on complex curved surfaces.
[0021] Figure 1FIG. 0 depicts a system 100 according to an exemplary embodiment. The system 100 utilizes an inkjet printer to directly apply surface texture to a solid surface for surface modification. The surface modification technique of applying texture is also known as micro-texturing. The purpose of surface modification by applying texture is to reduce drag or surface friction by manipulating a fluid (e.g., air or water) as it flows over the solid surface. By introducing surface texture, the effective contact area between the fluid and the solid surface is reduced, thereby reducing friction. This reduction in friction results in a decrease in drag, thus improving the aerodynamic or hydrodynamic performance of the object.
[0022] The system 100 can be used to apply surface texture to various solid surfaces. For example, the system 100 can be used to directly apply surface texture to the surface of an aircraft wing or fuselage. Additionally, the system 100 can be used to directly apply surface texture to the hull of a ship or boat.
[0023] Referring Figure 1 , the system 100 includes an inkjet printer 104, which has at least one nozzle 106 for ejecting droplets 108 of a selected material onto a substrate 110. In Figure 1 , although the inkjet printer 104 is shown as having a single nozzle 106, the inkjet printer 104 can include many (e.g., hundreds or thousands) of nozzles.
[0024] The inkjet printer 104 includes a fluid reservoir 112 that stores a fluid 114. The fluid can include ink, a resin dissolved in a solvent, or any other suitable material. The inkjet printer 104 includes an actuator 116 that can be positioned behind the nozzle 106. The actuator 116 can be in contact with the fluid 114. In response to a drive signal 118, the actuator 116 changes shape, thereby generating a pressure wave in the fluid 114. The effect of this pressure wave is to force a controlled amount of the fluid to flow out of the nozzle 106 as droplets 108.
[0025] In an exemplary embodiment, the actuator 116 is a piezoelectric actuator configured to change shape in response to an electrical pulse (e.g., drive signal 118) applied to the actuator 116. By varying the amplitude and pulse width of the electrical pulse, the size of the droplets 108 can be adjusted. In other exemplary embodiments, the inkjet printer 104 can be a thermal printer or a mechanical printer.
[0026] In an exemplary embodiment, for example, the substrate 110 can be a section of an aircraft, such as a wing, fuselage, or vertical stabilizer. In other embodiments, the substrate 110 can be the hull of a ship or boat.
[0027] In an exemplary embodiment, a droplet 108 is deposited on a substrate 110 to modify a solid surface 120 by forming a texture or pattern on the solid surface 120. The purpose of surface modification by applying a texture or pattern is to reduce drag or surface friction by manipulating the flow of a fluid (e.g., air or water) when it moves over the solid surface 120.
[0028] In an exemplary embodiment, the size of the droplets is controlled to achieve a desired texture or pattern on the substrate. In Figure 2A , droplets 202, 204, and 206 of the same size are deposited on a substrate 210. First, droplet 202 is deposited, and then the next droplet 204 is deposited on droplet 202. This process is repeated until droplet 206 is deposited on droplet 204, thereby building the droplets one on top of another. The effect is that the resulting texture 212 has a mound-like profile. In Figure 2B , droplets 220, 222, and 224 of continuously decreasing size are deposited on a substrate 230. The effect is that the resulting texture 232 has a rib-like profile.
[0029] Figure 3 An example shows how to create a desired textured surface on a substrate. The process involves depositing materials in a layer-by-layer manner to create the desired textured surface. In an exemplary embodiment, an inkjet-based manufacturing is used to create a textured surface including ribs. Ribs are small, parallel, and regularly spaced ridges or grooves that are molded or etched onto the surface of the substrate. The size and spacing of the ribs can vary according to the desired effect. The ribs are typically oriented in the desired fluid flow direction (e.g., the air flow direction on an aircraft wing or the water flow direction on a hull).
[0030] Referring to Figure 3 , a two-dimensional model such as image 302 is generated, which defines the geometry of the ribs on the surface. The geometry can define the height, spacing, and other properties of the ribs. For example, computer-aided design (CAD) software can be used to define the geometry.
[0031] In an exemplary embodiment, a software program interprets the two-dimensional model (e.g., image 302) and generates a series of instructions including the sizes of droplets 302, 304, and 306 to create a rib-like structure on a surface 310. An inkjet printer 104 ( Figure 3 not shown in Figure 3In the embodiment, droplets 302, 304 and 306 have successively decreasing sizes. Thus, droplet 304 is smaller than droplet 302, and droplet 306 is smaller than droplet 304. By repeating this process, droplets 302, 304 and 306 are built up one on top of the other. By continuously depositing decreasing droplets, rib 314 acquires a triangular profile.
[0032] To create a textured surface across surface 310, a software program calculates the optimal speed at which to move inkjet printer 104 during the deposition process. The speed can be adjusted based on factors such as the viscosity of the droplets and the height of the desired texture. Initially, inkjet printer 104 moves to a starting position. It then ejects droplets of material according to a predetermined pattern. The speed of the inkjet printer is controlled, and the process is repeated until small, parallel, and regularly spaced ribs 316 are molded onto surface 310.
[0033] In an exemplary embodiment, after deposition, the droplets are cured, allowing the material in the droplets to polymerize and bond to the surface. The material may include ink, resin, or any other suitable material.
[0034] Figure 4A 、 Figure 4B and Figure 4C Illustrate a perspective view of an exemplary rib formed on a surface according to an exemplary embodiment. In Figure 4A In , the ribs 402 have a peak-to-peak spacing of 9.3283 mm, in Figure 4B In , the ribs 404 have a peak-to-peak spacing of 10.0 mm, and in Figure 4C In the example, rib 406 has a peak-to-peak spacing of 11.7859 mm. Depending on the surface on which the ribs are created, the drag reduction performance of the ribs will vary depending on the peak-to-peak spacing of the ribs. In an exemplary embodiment, a laser scanner or stereo camera can be used to scan, for example, a vertical tail or wing of an aircraft and generate images. A software program interprets these images and calculates the optimal geometry and location of the ribs to be formed on the surface of the part to maintain the desired peak spacing. In an exemplary embodiment, for example, a wing or vertical tail of an aircraft is scanned, and the software program calculates the geometry of the ribs based on the scanned images to maintain the desired peak spacing (e.g., 10 mm) to achieve the desired aerodynamic results.
[0035] In an exemplary embodiment, the height and width of the texture features (e.g., ribs) formed on the surface with each pass are varied by adjusting the speed of the inkjet printer relative to the surface. Slower speeds produce taller texture features, while faster speeds produce shorter texture features. In Figure 5A and Figure 5B Inkjet printers ( Figure 5A and Figure 5Bis not shown) moves across the surface at a speed of 6 inches per second in one pass. Figure 5A illustrates a top view of the resulting texture 504 having a width of 0.18 inches, while Figure 5B illustrates a cross-sectional view of the texture 504 having a height of 10 microns.
[0036] In Figure 5C and Figure 5D the inkjet printer moves across the surface at a speed of 1 inch per second in one pass. Figure 5C illustrates a top view of the resulting texture 508 having a width of 0.03 inches, while Figure 5D illustrates a cross-sectional view of the texture 508 having a height of 60 microns.
[0037] Figure 6 Depicts a flowchart 600 of a method for directly applying a surface texture onto a surface according to an exemplary embodiment. In the illustrative embodiment, the surface texture includes ribs created through inkjet-based manufacturing. The ribs are small, parallel, and regularly spaced ridges or grooves that are molded or etched onto the surface. The size and spacing of the ribs can vary according to the desired effect. The ribs are typically oriented in the desired fluid flow direction, such as the airflow direction on an aircraft wing or the water flow direction on a hull.
[0038] The process 600 begins with defining a ribbed geometry of the part surface (step 604). For example, the part may be a wing or fuselage section of an aircraft where ribs are to be applied. For example, computer-aided design (CAD) software can be used to define the geometry.
[0039] In an exemplary embodiment, a software program interprets the geometry and generates a path for the inkjet printer to move across the part to cover the desired area for rib application (step 606). The software program can generate an optimized path or grid to achieve a specific ribbed pattern on the part surface and ensure complete coverage of the surface. The inkjet printer can be held or retained by an automated system, which can include one or more robots that precisely control the movement of the inkjet printer. This controlled movement ensures uniform rib application across the entire surface.
[0040] Based on the size and shape of the ribs, the software program determines the number of passes and nozzle firing schedule required to achieve the desired geometry (step 608). For example, for a given fluid material, if the printhead of the inkjet printer deposits 10um per pass and a rib with a 30um high triangular profile needs to be created, the desired rib can be created in three passes, where smaller droplets are used with each successive pass. The process is as Figure 2BAs illustrated, droplets 220, 222, and 224 having continuously decreasing sizes are deposited on a surface to create ribs.
[0041] Then, the part is positioned in a working unit relative to the inkjet printer (step 610). In an exemplary embodiment, a laser tracker alignment system or a robot-mounted vision system can be used to align the part with the inkjet printer. With the part in place and the inkjet printer ready, the rib deposition process begins (step 612). The inkjet printer deposits droplets directly on the surface of the part. These droplets form the desired ribbed pattern, thereby reducing aerodynamic drag.
[0042] In addition, this application includes embodiments according to the following examples:
[0043] 1. A method (600) for directly applying a surface texture to a part surface to reduce drag, the method comprising:
[0044] Defining the geometry of the surface texture on the part surface (604);
[0045] Generating a path for the inkjet printer (104) to move on the part surface (606);
[0046] Determining the number of passes and the firing schedule for the inkjet printer (104) to create the surface texture (608);
[0047] Positioning and aligning the part in the working unit (610); and
[0048] Depositing droplets onto the surface by the inkjet printer (104) (612) to create the surface texture.
[0049] 2. The method according to example 1, wherein the surface texture includes a plurality of ribs (316) formed on the surface.
[0050] 3. The method according to example 1, wherein the surface texture is formed by controlling the size of the droplets (302, 304, 306).
[0051] 4. The method according to example 1, the method further comprising:
[0052] Changing the size of the droplets (302, 304, 306) to continuously decreasing droplets; and
[0053] Forming a texture pattern of ribs (316) on the surface.
[0054] 5. The method according to Example 1, wherein the inkjet printer (104) includes a piezoelectric actuator (116) in contact with a fluid, and wherein the piezoelectric actuator (116) is configured to change shape in response to an electrical pulse (118) applied to the piezoelectric actuator, thereby generating a pressure wave in the fluid (114) and forcing a controlled amount of the fluid to flow out of the inkjet printer as the droplet (108).
[0055] 6. The method according to Example 5, the method further comprising adjusting the size of the droplets (302, 304, 306) by varying the amplitude and pulse width of the electrical pulse (118).
[0056] 7. The method according to Example 1, the method further comprising curing the droplets (302, 304, 306) so that the material in the droplets polymerizes and binds to the surface.
[0057] 8. The method according to Example 1, wherein the fluid (114) includes a resin dissolved in a solvent.
[0058] 9. The method according to Example 1, the method further comprising controlling the movement of the inkjet printer (104) relative to the surface to change the thickness of the surface texture.
[0059] 10. The method according to Example 9, wherein the thickness of the surface texture is controlled by varying the speed of the inkjet printer (104).
[0060] 11. A method (600) for creating ribs (316) on a part surface to reduce drag, the method comprising:
[0061] defining the geometry (604) of the ribs on the part surface;
[0062] generating a path (606) for the inkjet printer (104) to move on the part surface;
[0063] determining the number of passes and firing schedule (608) for the inkjet printer (104) to create the ribs;
[0064] positioning and aligning the part in a work cell (610); and
[0065] depositing (612) droplets onto the surface by the inkjet printer (104) to create the ribs (316).
[0066] 12. The method according to Example 11, wherein the inkjet printer (104) includes a piezoelectric actuator (116) in contact with a fluid (114), and wherein the piezoelectric actuator (116) is configured to change shape in response to an electrical pulse (118) applied to the piezoelectric actuator, thereby generating a pressure wave in the fluid and forcing a controlled amount of the fluid to flow out of the inkjet printer as the droplet (108).
[0067] 13. The method according to Example 12, the method further comprising adjusting the size of the droplets (302, 304, 306) by varying the amplitude and duration of the electrical pulse (118).
[0068] 14. The method according to Example 11, the method further comprising:
[0069] changing the size of the droplets (302, 304, 306) to successively decreasing droplets; and
[0070] creating the ribs (316) on the surface.
[0071] 15. The method according to Example 11, the method further comprising controlling the movement of the inkjet printer (104) relative to the surface to change the thickness of the ribs (316).
[0072] 16. The method according to Example 15, wherein the thickness of the ribs is controlled by changing the speed of the inkjet printer (104).
[0073] 17. A method (600) for applying a surface texture to a part surface to reduce drag, the method comprising:
[0074] defining a geometry (604) of the surface texture on the part surface;
[0075] generating a path (606) for an inkjet printer (104) to move on the part surface;
[0076] determining the number of passes and firing schedule (608) for the inkjet printer (104) to create the surface texture;
[0077] positioning and aligning the part in a work cell (610);
[0078] adjusting the size of the droplets (302, 304, 306) in response to input data related to the geometry of the surface texture;
[0079] firing the droplets (302, 304, 306, 612) to selectively position the droplets on the surface to achieve a desired texture pattern; and
[0080] Control the movement of the inkjet printer (104) relative to the surface to change the thickness of the surface texture.
[0081] 18. The method according to Example 17, wherein the surface texture includes a plurality of ribs (316).
[0082] 19. The method according to Example 17, the method further comprising:
[0083] Changing the size of the droplets (302, 304, 306) to successively decreasing droplets; and
[0084] Forming a texture pattern of ribs (316) on the surface.
[0085] 20. The method according to Example 17, the method further comprising curing the droplets (302, 304, 306) to harden and bond to the surface.
[0086] 21. The method according to Example 17, wherein the droplets (302, 304, 306) comprise ink or coating material.
[0087] As used herein, the phrase "a number of" means one or more. When used with a list of items, the phrase "at least one" means that different combinations of one or more of the listed items can be used, and it may only be necessary to have one of each item in the list. In other words, "at least one" means any combination of the items and the number of items that can be used in the list, but not all of the items in the list are required. The item can be a specific object, thing, or category.
[0088] For example but not limited to, "at least one of item A, item B, or item C" can include item A, item A and item B, or include item C. This example can also include item A, item B, and item C, or item B and item C. Of course, any combination of these items can exist. In some illustrative examples, "at least one" can be, for example but not limited to: two of item A; one of item B; ten of item C; four of item B and seven of item C; or other suitable combinations.
[0089] The flowcharts and block diagrams in the different depicted embodiments illustrate some possible architectures, functions, and operations in the devices and methods in the illustrative embodiments. In this regard, each block in the flowchart or block diagram can represent at least one of a module, a section, a function, or an operation or step. For example, one or more of the blocks can be implemented as program code.
[0090] In some alternative implementations of the illustrative embodiments, one or more of the functions noted in the blocks may occur in the order noted in the figures. For example, in some cases, two blocks shown in succession may be executed substantially simultaneously, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. In addition, other blocks may be added in addition to those shown in the flowcharts or block diagrams.
[0091] For purposes of illustration and description, descriptions of different illustrative embodiments have been presented, and these embodiments are not intended to be exhaustive or limited to the embodiments in the disclosed forms. Different illustrative examples describe components that perform actions or operations. In an illustrative embodiment, a component may be configured to perform the described actions or operations. For example, the component may have a configuration or design for such a structure that provides the component with the ability to perform the actions or operations described in the illustrative example as being performed by the component. Many modifications and variations are obvious to those of ordinary skill in the art. In addition, different illustrative embodiments may provide different features compared to other desired embodiments. Selecting and describing the selected one or more embodiments is intended to best explain the principles, practical applications, and to enable those of ordinary skill in the art to understand the disclosure of various embodiments with various modifications suitable for the intended specific uses.
Claims
1. A method (600) for applying surface texture directly to a part surface to reduce drag, the method comprising: defining a geometry of the surface texture on the part surface (604); generating a path (606) for the inkjet printer (104) to move over the surface of the part; determining a number of passes and a firing schedule (608) for the inkjet printer (104) to create the surface texture; Positioning and aligning the part in the work cell (610); and Liquid droplets are deposited (612) onto the surface by the inkjet printer (104) to create the surface texture.
2. The method according to claim 1, wherein: The surface texture is formed by controlling the size of the droplets (302, 304, 306).
3. The method according to claim 1, further comprising: changing the size of the droplets (302, 304, 306) into successively smaller droplets; and A textured pattern of ribs (316) is formed on the surface.
4. The method according to claim 1, wherein: The inkjet printer (104) includes a piezoelectric actuator (116) in contact with a fluid, and wherein the piezoelectric actuator (116) is configured to change shape in response to an electrical pulse (118) applied to the piezoelectric actuator, thereby generating a pressure wave in the fluid (114) and forcing a controlled amount of the fluid to flow out of the inkjet printer as the droplet (108).
5. The method of claim 4, further comprising adjusting the size of the droplets (302, 304, 306) by varying the amplitude and pulse width of the electrical pulses (118).
6. The method of claim 1, further comprising solidifying the droplets (302, 304, 306) so that material in the droplets polymerizes and bonds to the surface.
7. The method according to claim 1, wherein: The fluid (114) includes a resin dissolved in a solvent.
8. The method of claim 1, further comprising controlling movement of the inkjet printer (104) relative to the surface to vary a thickness of the surface texture.
9. A method (600) for creating ribs (316) on a surface of a part to reduce drag, the method comprising: defining a geometry of the rib on the surface of the part (604); generating a path (606) for the inkjet printer (104) to move over the surface of the part; determining a number of passes and a firing schedule (608) for the inkjet printer (104) to create the ribs; Positioning and aligning the part in the work cell (610); and Liquid droplets are deposited (612) by the inkjet printer (104) onto the surface to create the ribs (316).
10. A method (600) for applying surface texture to a part surface to reduce drag, the method comprising: defining a geometry of the surface texture on the surface of the part (604); generating a path (606) for the inkjet printer (104) to move over the surface of the part; determining a number of passes and a firing schedule (608) for the inkjet printer (104) to create the surface texture; Positioning and aligning the part in the work cell (610); adjusting the size of the droplets (302, 304, 306) in response to input data related to the geometry of the surface texture; emitting the droplets (302, 304, 306, 612) to selectively position the droplets on the surface to achieve a desired texture pattern; and The movement of the inkjet printer (104) relative to the surface is controlled to vary the thickness of the surface texture.