Cross-Reference to Related Application(s)

[0001] This application claims benefit of and priority to U.S. Provisional Patent Application Serial No. 63/081,067, filed September 21, 2020, herein incorporated by reference in its entirety as if fully set forth below and for all applicable purposes.

BACKGROUND

Field of the Invention

[0002] This application relates to methods and apparatus for 3D printing (also referred to as additive manufacturing).

Description of the Related Technology

[0003] A substantial number of metal castings are created by pouring molten metal into an investment casting shell mold. The mold is typically made of refractory materials bound together with various binders. Casting molds are used typically when a precision cast article is desired. While investment casting is commonly used in the automotive and aerospace industries, modem advancements in investment casting are providing other industries with a cost and time effective casting solution.

[0004] A casting mold is made starting from a pattern of the article to be cast. The pattern is made of a material that can be melted or burned away at a later stage in the process of making a casting mold. The pattern material is often wax, hence the process may be referred to as “lost wax casting,” but may also include patterns made via additive manufacturing, such as stereolithography (SLA) or any other additive manufacturing techniques. In some examples, the patterns are formed by molding wax around cores, or patterns may be formed using additive manufacturing techniques and a core (e.g., ceramic core) may be assembled into the pattern. For example, a pattern may be printed using AM techniques as a number of pieced that are assembled or formed around a core, such as using binding agents, glue, adhesive, etc. Not all patterns may have a core. In certain aspects, a core may generally be used to form a cavity in a casting. This pattern is dipped into a slurry having refractory materials forming a coating thereon.

[0005] The pattern is coated by first dipping with prime coat slurry having a controlled composition and rheology. Typically, the prime coat slurry forming the innermost layer of the mold is composed of relatively fine grained refractory materials, for example, so that a less porous surface of the mold contacts the metal. In multi-layered molds, the first or prime coat slurry usually has a higher viscosity than subsequent or backup coat slurries and the refractory materials contained therein typically is of finer particle size so as to produce a smoother cast surface. Backup coats are typically produced using coarser grit sizes, fibers, and lower viscosity slurries. After the application of the prime coat, the dipped pattern may receive a stucco coating of dry refractory materials and is gelled and/or gas dried in a humidity/temperature controlled environment. The prime coat slurry and optional stucco typically have refractory materials such as alumina, silica, aluminosilicates, zirconium silicate, and ceramics of a controlled particle size range. The slurries have a binder material which often has colloidal silica. After the coated pattern is dried it is subsequently dipped in the same or different slurry and optionally receives another stucco coating and dried again and/or gelled. The coated shell is repeatedly dipped into a slurry and optionally coated with stucco, gelled, and/or dried after each dip. The succession of slurries and optional stuccos may be the same or different materials and are applied until a desired build-up of refractory materials are obtained on the pattern. Each slurry is typically of a carefully controlled composition and rheology. Each stucco typically has coarse refractory materials. Several refractory materials, such as fused silica, fused alumina, tabular alumina and fused or sintered aluminosilicates are some examples of refractory materials used in the stucco. Purified and graded natural sands, for example zirconium silicate and quartz sands are sometimes also used. The desired mold is built-up in this fashion with several slurry and stucco repeat coatings until the desired mold thickness is achieved. The pattern is finally removed to leave a mold cavity having a desired shape. The resulting mold may then be fired under a precisely controlled heating cycle to increase its strength and to bum off any residual pattern material.

[0006] In some examples, it is advantageous for the pattern to be made from a strong and/or rigid material to limit deformation and breakage when submitted to the stress of weight (e.g., when transporting the pattern) or the stresses associated with coating the pattern. In such an example, an SLA generated pattern may be preferable. Such an SLA pattern may be generated using any suitable polymer, and may include lattice structures and/or other internal structural aspects, such as internal structural support aspects. In certain aspects, lattice structures and/or other internal structural aspects may strengthen the pattern and/or prevent stresses and deformations such as bending, crushing, etc. In some cases, an SLA pattern may be formed of a material with positive thermal expansion coefficient or structures that result in expansion when heated. In an example of such a case, the material of the pattern may expand when heated, and in cases involving a pattern with an internal structure, the expansion of the pattern may increase with heat. As such, if the pattern is put into an autoclave to melt out pattern material (e.g., wax), or if the pattern is otherwise burned out from the mold, the pattern may exert pressure on the mold from inside. It should be noted that the term “burn out” as used herein may refer to any suitable process or combination of processes for using heat to remove a pattern from a mold, such as one or more of using an autoclave or an oven. This pressure may result in cracks or damage to the mold rendering the mold useless or causing additional repair steps. [0007] Accordingly, techniques that reduce or eliminate expansion of the pattern during burnout would be advantageous.

SUMMARY

[0008] A method of casting a part, the method comprising: forming (e.g., generating, such as printing via additive manufacturing) a pattern, wherein the pattern comprises one or more regions configured for modification of one or more mechanical characteristics via one or more agents; dipping the pattern into a material one or more times to form a shell around the pattern; applying the one or more agents to the one or more regions to modify the one or more mechanical characteristics of the one or more regions; after applying the one or more agents, burning out the pattern to form a casting mold including the shell; introducing a second material into the shell to form the part; and removing the part from the casting mold.

[0009] A 3D object comprising: one or more interfaces (e.g., openings, areas for inserting a hot needle, drilling areas, openings with a removable covering, etc.) formed in an outer surface of the 3D object; and one or more channels that extend through the 3D object from the one or more interfaces to one or more regions of the 3D object.

[0010] A method for generating a modified design of a 3D object, the method comprising: receiving a design of the 3D object; identifying one or more regions of the 3D object for modification of one or more mechanical characteristics of the one or more regions via one or more agents; modifying the design of the 3D object to include: one or more interfaces formed in a surface of the 3D object; and one or more (e.g., primary) channels that extend through the 3D object from the one or more interfaces to the one or more regions of the 3D object. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a flow chart illustrating a method for changing one or more mechanical characteristics of a design of a three-dimensional (3D) object.

[0012] FIG. 2 is a diagram illustrating a computer displaying a sectional view of a 3D object.

[0013] FIGs. 3A and 3B are schematic diagrams illustrating example lattice structures.

[0014] FIG. 4 is a sectional view illustrating a modified 3D object (e.g., modified relative to the 3D object of FIG. 2).

[0015] FIG. 5 is a flow chart illustrating an example method for designing, using software, a 3D object to be used as a pattern for investment casting.

[0016] FIG. 6 is a flow chart illustrating an investment casting process using a pattern made using the modified 3D object described above in FIGs. 4 and 5.

[0017] FIGs. 7A and 7B illustrate a plurality of steps for investment casting according to aspects disclosed herein.

[0018] FIG. 8 is an example of a system for designing and manufacturing 3D objects.

[0019] FIG. 9 is a block diagram illustrating one example of a computer shown in FIGs. 2 and 8.

[0020] FIG. 10 illustrates a process for manufacturing a 3D object or device.

DETAILED DESCRIPTION

[0021] Certain aspects herein provide apparatus, methods of manufacture, methods of design, methods of use, computer-readable mediums, etc., relating to three-dimensional (3D) printed objects (i.e., objects generated using additive manufacturing) that are designed to allow introduction of one or more agents to one or more specific locations of an object in order to change one or more mechanical characteristics (e.g., a material density, shape, hardness, material composition, etc.) of the object at the one or more locations. An agent may include any suitable medium (e.g., liquid, gas, and solid) or other (e.g., light, heat, etc.) for changing a mechanical characteristic of a material. For example, the one or more agents may include ultraviolet (UV) light, a heat source (e.g., heated liquid/gas/solid or heat generated from a chemical reaction or electricity), an organic solvent (e.g., any suitable oxygenated solvents, hydrocarbon solvents, and/or halogenated solvents), and/or an inorganic solvent (e.g., water, acid, etc.).

[0022] In some examples, the one or more agents may weaken the material of one or more regions of an object to prevent thermal expansion of the material against a casting shell formed around the material. For example, an agent may cause a structural feature of a region to at least partially collapse, thereby forming a gap between the object and the shell in that region. In other examples, an agent may modify a mechanical characteristic of the material structure such that the structural feature becomes more pliable or elastic, develops a degree of adhesion (e.g., the material structure exhibits characteristics of a glue and/or lubricant, which provides adhesion for a “core fix” or core assembly scenario), reduces a strength of the material, and/or changes a shape of the material (e.g., the region of the pattern collapses due to the material no longer able to support the weight of the structure).

[0023] For example, a 3D printed object may include one or more features that allow introduction of an agent at one or more locations of the object. For example, one or more features may include one or more channels that may be included in the 3D printed object that may guide introduction of the agent to the one or more specific locations. A channel may be formed by one or more of interface layers, such as walls (e.g., walls or barriers that delimit different areas to contain or guide agents to the one or more locations), hollow structures (e.g., tubes and/or other conduit structures), semi-permeable layers or barriers, lattice structures (e.g., internal support structures within the printed object that help maintain the shape of the object), and/or the like. In certain aspects, channels allow one or more agents (e.g., gasses, liquids, gels, etc.) to the specific location to change the mechanical properties of the location, such as to make the material sticky, less sticky, or become filled with an agent, in order to support assembly of a pattern.

[0024] Additionally, or alternatively, one or more features may be formed at the one or more locations that may better react to the agent to give a changed mechanical characteristic. For example, the 3D printed object may be designed such that it is constructed having one or more features including specific lattice or surface structures. The object design may also provide for location specific qualities, such as amount of power used during printing (e.g., laser power), material thickness, shape, orientation, section variations, doping variation, and/or any other suitable parameter settings during the 3D printing process to allow for location specific characteristic adjustments. [0025] For example, the 3D printed object may be designed to include one or more channels comprising one or more hollow (with or without a lattice or support structures) “conduit” structures (such as tubes) to direct an agent (e.g., UV light, gas, liquid, pressure, temperature, etc.) and/or a tool (e.g., guided by the conduit structure) to a specific location where a mechanical characteristic of the object is to be changed. In some examples, a same or different hollow conduit structure can be used to remove and/or clean the agent from the specific location. In certain aspects, the 3D printed object may be designed to include one or more interfaces (e.g., openings, areas for inserting a hot needle, drilling areas, openings with a removable covering, etc.) on a surface of the 3D printed object to allow one or more agents or tools access to the one or more channels.

[0026] In certain aspects, the 3D printed objects designed to allow change of one or more mechanical characteristics of the object are designed using software. For example, certain aspects provide for software that can be used by a user to select particular regions of an existing design of an object where change of one or more mechanical characteristics of the object are desired. Further, one or more types and/or degrees of change of the one or more mechanical characteristics may be identified by the user for each location. The software may be configured to automatically create one or more features in the object that allow the change of one or more mechanical characteristics of the object as desired.

[0027] In certain aspects, a 3D printed object that is designed to allow change of one or more mechanical characteristics of the object is a pattern used in investment casting. Though investment casting is described as one use of such a 3D printed object, it should be understood that such a 3D printed object may be used for any suitable purpose.

[0028] FIG. 1 is a flow chart illustrating a method for changing one or more mechanical characteristics of a design of a 3D object. Initially, at a first block 102 a 3D object is designed, and a pattern is manufactured using the 3D object. The 3D object may be designed on a computing system using any suitable computer-aided design (CAD) software. The pattern may be manufactured using any suitable means for manufacturing 3D objects (e.g., additive manufacturing devices such as 3D printers).

[0029] The design of the 3D object may be changed or modified to include one or more features, such as one or more channels and/or other structural devices configured to allow a user to introduce an agent to one or more locations (e.g., also referred to as regions) of the pattern after manufacture. As discussed in more detail below, the design may be modified, via software, to include the channels so that when the pattern is manufactured according to the design of the 3D object, the pattern includes the one or more features.

[0030] At a second block 104, the user may introduce the agent to the one or more locations of the pattern.

[0031] FIG. 2 is a diagram illustrating a computer 208 displaying a sectional view of a 3D object 200. The computer 208 may be part of a computing system (e.g., computing system 800 illustrated in FIG. 8) or a standalone computer. The computer 208 may include the CAD software described above. As discussed, the software may provide a user with a means for designing and modifying the 3D object 200.

[0032] As illustrated, the design of the 3D object 200 comprises an outer surface 202 and a volume 204. The design may indicate a defined shape and thickness of the outer surface 202, as well as a size of the volume 204 and any structures within the volume (e.g., a lattice structure or any other suitable structure to support and maintain the integrity and shape of the outer surface 202). In this particular example, the 3D object 200 is designed such that it includes four pointed regions (e.g., regions 206a-206d, collectively referred to as regions 206). Here, the outer surface 202 of each of the regions 206 has a large surface area and encompasses a relatively small volume.

[0033] In such cases, because there is a relatively larger surface area to volume ratio, thermal expansion of the outer surface 202 in the regions 206 may result in an outward expansion because there is limited room (e.g., relatively little volume 204) to accommodate inward expansion. Thus, if the 3D object 200 remains unmodified and is used to produce a pattern for investment casting, the outward expansion of the material in the regions 206 may cause a casting shell to crack or even break when the pattern is burned out. It should be noted that there may be other reasons for a casting shell to crack or even break when the pattern is burned out. Aspects described herein (e.g., the process illustrated in FIG. 6) may prevent and/or eliminate such damage to the casting shell regardless of the reason that burn out causes such damage.

[0034] The volume 204 of the 3D object 200 may include one or more of a solid structure, no structure, or a lattice structure, depending on the shape and size of the 3D object 200. However, it should be noted that the volume 204 need not be entirely solid in order for a pattern manufactured from a 3D object 200 to possess excellent structural support properties to withstand damage and/or shape deformation. In some examples, the strength-to-weight ratio of a pattern may be improved in some cases by designing the 3D object 200 to include an internal lattice structure instead of having an entirely hollow or solid structure. Accordingly, the software may be used to define the internal structure of the 3D object 200. Such structures may be defined using software, for example Materialise® 3-matic® and/or Magics® software modules, to create an internal lattice structure within the outer surface 202 boundary of the 3D object 200 (e.g., inside of the external walls of the 3D object 200). The internal lattice structure may be defined by a plurality of internal, interconnected cavities.

[0035] FIGs. 3A and 3B are schematic diagrams illustrating example lattice structure configurations for the volume 204 of the 3D object 200. Specifically, FIG. 3A is a tetrahedron (e.g., diamond lattice) lattice structure, and FIG. 3B is a hexagon lattice structure. It should be noted that there are a variety of lattice structures suitable for use in a 3D object 200. For instance, a suitable internal lattice structure for use in a disclosed 3D object 200 and pattern may include one or more of a graph based lattice structure (e.g., Sierpinski triangle), a surface based lattice structure (e.g., a periodic minimal surface), square, tetrahedron, hexagon, quadrate lattice structures, and/or the like.

[0036] Turning now to FIG. 4, a modified 3D object 400 may be designed, using the computer 208 and software described in FIG. 2, to include one or more primary channels 408 and secondary channels 410 configured to provide access to regions 406a-406d (collectively referred to as regions 406) of the modified 3D object 400. FIG. 4 is a sectional view illustrating a modified 3D object 400 (e.g., modified relative to the 3D object 200 of FIG. 2). Here, a modification to the design of the 3D object 200 of FIG. 2 includes the addition of one or more openings 412 in the outer surface 402 of the modified 3D object 400, as well as a primary channel 408 and secondary channels 410. Though one or more openings 412 are shown for ease of discussion, as discussed, the opening could be any suitable type of interface. Though use of the terms primary and secondary channels are discussed, it should be noted that any suitable one or more channels in any suitable arrangement may be used.

[0037] The combination of the primary channel 408 and the secondary channels 410 provide a means to access the regions 406 of the pattern after the pattern is manufactured from the modified 3D object 400. As illustrated, the primary channel 408 provides a path from outside the 3D object 400, into the volume 404 of the 3D object 400 via the opening 412 in the outer surface 402. Each of the secondary channels 410 similarly provide a path from an opening in the primary channel 408 to one of the regions 406. In some examples, the primary channel 408 and the secondary channels 410 are defined as one or more of a tube or a network of surfaces that extend through the volume 404 of the 3D object 400 configured to direct a tool, instrument (e.g., endoscope), and/or an agent from the opening 412 to the one or more regions 406.

[0038] FIG. 5 is a flow chart illustrating an example method 500 for designing a 3D object to be used as a pattern for investment casting using software. In some examples, the software may be executed by the computer 208 of FIG. 2.

[0039] At a first block 502, the software may receive or be used to generate a design of a 3D object (e.g., the 3D object of any of FIGs. 2-4). The design may be provided as a CAD file operable by the software. The design of the 3D object may be characterized by an outer surface and a volume (e.g., an interior of the 3D object), wherein the outer surface has a defined shape and thickness, and the volume includes, for example, a lattice structure configured to reinforce the outer surface.

[0040] At a second block 504, the software may (e.g., open the CAD file and) identify one or more regions of the 3D object for modification of one or more mechanical characteristics of the one or more regions via one or more agents. For example, the software may automatically identify regions of the 3D object that may expand and cause adjacent areas of a molded shell (e.g., ceramic shell) (and/or when present a ceramic core inserted into the pattern), to be damaged (e.g., cracking in the shell caused by thermal expansion) during burnout of the pattern.

[0041] In one example, the software may include an algorithm configured to analyze the design of the 3D object to determine whether any regions of the 3D object have a surface area to corresponding volume of the region ratio that is greater than a threshold. In this example, the software may determine any such region with a surface area to corresponding volume of the region ratio that is greater than a threshold may be more susceptible to thermal expansion that may crack a casting shell covering that region during burnout of the pattern. That is, the software may identify regions where the volume of the region may not provide adequate room to accommodate thermal expansion of the surface area. Accordingly, the identified region may be a candidate for modification of one or more mechanical characteristics of the material in the region, as discussed below. The software may use any suitable metric to identify the one or more regions of the 3D object for modification (e.g., by providing access via one or more channels). However, it should be noted that in some examples, a user of the software can manually identify the one or more regions. [0042] At a third block 506, the software may modify the design of the 3D object to include: (i) one or more interfaces formed in a surface of the 3D object, and (ii) one or more (e.g., primary) channels that extend through the 3D object from the one or more interfaces to the one or more regions of the 3D object. For example, the software may generate an interface in the surface of the 3D object and a channel that extends from the interface. In certain embodiments, the channel is constructed of one or more of a tube or a network of surfaces that extend through the 3D object to the identified region. In certain embodiments, the tube or the network of surfaces are configured to allow a user to insert a tool into a pattern and reach the identified region, and/or introduce an agent to the region via the interface and channel.

[0043] In some examples, the software may further modify the design of the 3D object to include one or more additional (e.g., secondary) channels that branch off of one or more channels. For example, a secondary channel may start from an interface in a primary channel and extend to a first region of the one or more regions of the 3D object. Thus, a primary channel may provide access to multiple regions via one or more secondary channels. It should be noted that while the foregoing discusses software automated design modifications, a user of the software may also utilize the software to manually modify the design of the 3D object.

[0044] In some examples, the modification of the 3D object design may include a modification of a material used to construct the actual pattern based on the 3D object. For example, the software may be used to change the material or a material doping in one of the identified regions. Such a change may reduce the thermal expansion of the material in the identified region. In some examples, the modification of the 3D object design may include a modification of the structure of the identified region. For example, a surface structure or an internal lattice structure may be modified to reduce thermal expansion. Such a modification may include a reduced or increased thickness of the surface structure, and/or a reduced or increased density of the lattice structure in the identified region.

[0045] By modifying the design of the 3D object, a user may reduce risks to the structural integrity of a casting shell that is formed over the pattern made from the 3D object. For example, the interface and a channel may provide accessibility to one or more regions that may be prone to thermal expansion that could jeopardize the structural integrity of a shell. As such, once a shell is made, the user may introduce one or more agents to the one or more regions prior to a burnout in order to change a mechanical characteristic of the pattern in the regions. [0046] FIG. 6 is a flow chart illustrating an investment casting process 600 using a pattern made using the modified 3D object described above in FIGs. 4 and 5.

[0047] At a first block 602, a pattern may be generated (e.g., printed) from the 3D object using any suitable additive manufacturing technique (e.g., SLA). In some examples, the pattern is generated and formed at least partially over one or more cores that are used to form/define one or more cavities in the object being cast. For example, the pattern may be printed in multiple parts, or cut into multiple parts after printing, that are assembled around one or more cores that are fixed to the parts using, for example, a binding agent such as glue. As discussed, the pattern may be designed such that one or more regions are accessible by one or more agents configured to modify a mechanical characteristic of the region. For example, the pattern may include one or more interfaces and channels providing access to the one or more regions.

[0048] At a second block 604, the pattern (by itself or with the core) may be dipped into a material one or more times to form a shell around the pattern. For example, the pattern may be coated with one or more layers of one or more slurries of varying material compositions to form the shell.

[0049] At a third block 606 (e.g., once the shell has cooled and/or cured or hardened, and prior to burnout), one or more agents may be applied (e.g., by tool, or simply inserted through the one or more interfaces) to the one or more regions to modify the one or more mechanical characteristics of the regions. As discussed, the pattern in these regions may compromise the structural integrity of the shell, for example due to thermal expansion of the pattern structure during burnout, shrinkage of the pattern structure during burnout, or material creep (e.g., deformation of the pattern structure) during burnout. For example, thermal expansion may push on the shell, causing the shell to crack. Shrinkage of the pattern structure, such as at an accelerated rate, may cause the shell to collapse by the sudden change in pressure exerted on the shell. Material creep may cause uneven pressure on the shell, causing cracks to form. It should be noted that the pattern in these regions may compromise the structural integrity of the shell during burnout for other reasons as well. Accordingly, one or more agents may be applied to the material of these regions to modify the mechanical characteristics of structural features of the pattern in these regions, thereby reducing and/or eliminating potential damage caused by thermal expansion.

[0050] Structural features may include one or more of a lattice structure of a volume of the pattern, a surface structure of a surface of the pattern, a thickness of one or more of the lattice structure or the surface structure, one or more of a material or material doping of one or more of the lattice structure or the surface structure, a shape of one or more of the lattice structure or the surface structure, and/or an orientation of the lattice structure.

[0051] The agent(s) may be used to change mechanical characteristics of the structural features of a region by weakening the material of the one or more regions of the pattern to prevent thermal expansion of the material structure against the shell. For example, an agent may cause a structural feature of a region to at least partially collapse, thereby forming a gap between the pattern and the shell in that region. As discussed, an agent may modify other mechanical characteristics of a material such that the structural feature becomes more pliable or elastic, develops a degree of adhesion and/or lubricant, reduces a strength of the material, and/or changes a shape of the material

[0052] At a fourth block 608, and after applying the one or more agents to the regions of the pattern, the pattern may be burned out of the shell to form a casting mold including the shell (e.g., and may include in some cases one or more cores). The bum out may not cause the shell to crack, as the modified pattern may advantageously not exert too much pressure through heat expansion at the one or more modified regions.

[0053] At a fifth block 610, a second material (e.g., a molten metal alloy) may be introduced to the casting mold to form a part. The molten metal may include any suitable metal for casting, including aluminum, brass, stainless steel, steel, magnesium, titanium, etc.

[0054] At a sixth block 612, the part is removed from the casting mold.

[0055] FIGs. 7A and 7B illustrate a plurality of steps for investment casting according to aspects disclosed herein. It should be noted that the investment casting process is not limited to the steps illustrated in FIGs. 7A and 7B. As can be appreciated by those having skill in the art, additional elements, components, steps, and/or functions may also be added without departing from features disclosed herein.

[0056] Turning now to FIG. 7A, at a first step 700, a 3D object 702 may be designed using CAD design software on a computer (e.g., computer 208 of FIG. 2).

[0057] At a second step 706, the software may be used to modify the 3D object 702 and generate a modified 3D object 704. The modified 3D object 704 may include additional structural features, such as one or more channels, a lattice structure within a volume of the modified 3D object 704, and one or more interfaces in an outer surface of the modified 3D object 704. [0058] At a third step 708, a pattern 712 is manufactured. The manufacturing may include additive manufacturing techniques using the modified 3D object 704. The pattern 712 may be manufactured using any suitable 3D printer 710. At a fourth step 714, the pattern 712 is completed, and may be cleaned and finished to prepare for shell casting. It should be noted that the additional structural features of the modified 3D object have been incorporated into the pattern 712.

[0059] Turning now to FIG. 7B, at a fifth step 716, the pattern 712 may be coated with a slurry of refractory materials, such as ceramics. Then, once the coating has sufficiently cured, the pattern 712 may be burned out of the shell casting 718. Prior to burnout, a user may introduce one or more agents to one or more regions internal to the pattern 712 via one or more channels that form part of the pattern 712. Here, the one or more agents are configured to change the mechanical characteristics of the one or more regions to prevent the pattern in those regions from damaging the shell casting 718 during burnout. For example, the one or more agents may increase material pliability (e.g., soften) and/or dissolve the pattern to reduce its size. Accordingly, when the burnout process occurs, thermal expansion of the pattern in the one or more regions is less likely to damage the structure of the shell casting.

[0060] At a sixth step 720, a molten material 722 (e.g., a metal alloy) may be introduced to the shell casting 718. At a seventh step 724, the shell casting 718 may be broken and discarded, thereby providing a part 726 that is shaped substantially identical to the shape of the pattern 712.

[0061] Though certain aspects of the disclosure are described with respect to certain additive manufacturing techniques using certain building materials, the described systems and methods may also be used with certain other additive manufacturing techniques and/or certain other building materials as would be understood by one of skill in the art.

[0062] Embodiments of the invention may be practiced within a system for designing, simulating, and/or manufacturing 3D objects. Turning to FIG. 8, an example of a computer environment suitable for the implementation of 3D object design, build simulation, and manufacturing is shown. The environment includes a system 800. The system 800 includes one or more computers 802a-802d, which can be, for example, any workstation, server, or other computing device capable of processing information. In some embodiments, each of the computers 802a-802d can be connected, by any suitable communications technology (e.g., an internet protocol), to a network 805 (e.g., the Internet). Accordingly, the computers 802a-802d may transmit and receive information (e.g., software, digital representations of three dimensional (3D) objects, commands or instructions to operate an additive manufacturing device, etc.) between each other via the network 805.

[0063] The system 800 further includes one or more additive manufacturing devices (e.g., 3D printers) 806a-806b. As shown the additive manufacturing device 806a is directly connected to a computer 802d (and through computer 802d connected to computers 802a- 802c via the network 805) and additive manufacturing device 806b is connected to the computers 802a-802d via the network 805. Accordingly, one of skill in the art will understand that an additive manufacturing device 806 may be directly connected to a computer 802, connected to a computer 802 via a network 805, and/or connected to a computer 802 via another computer 802 and the network 805.

[0064] It should be noted that though the system 800 is described with respect to a network and one or more computers, the techniques described herein also apply to a single computer 802, which may be directly connected to an additive manufacturing device 806.

[0065] FIG. 9 illustrates a functional block diagram of one example of a computer of FIGs. 2 and 8. The computer 902a includes a processor 910 in data communication with a memory 920, an input device 930, and an output device 940. In some embodiments, the processor is further in data communication with an optional network interface card 960. Although described separately, it is to be appreciated that functional blocks described with respect to the computer 802a need not be separate structural elements. For example, the processor 910 and memory 920 may be embodied in a single chip.

[0066] The processor 910 can be a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof designed to perform the functions described herein. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0067] The processor 910 can be coupled, via one or more buses, to read information from or write information to memory 920. The processor may additionally, or in the alternative, contain memory, such as processor registers. The memory 920 can include processor cache, including a multi-level hierarchical cache in which different levels have different capacities and access speeds. The memory 920 can also include random access memory (RAM), other volatile storage devices, or non-volatile storage devices. The storage can include hard drives, flash memory, etc.

[0068] The processor 910 also may be coupled to an input device 930 and an output device 940 for, respectively, receiving input from and providing output to a user of the computer 802a. Suitable input devices include, but are not limited to, a keyboard, buttons, keys, switches, a pointing device, a mouse, a joystick, a remote control, an infrared detector, a bar code reader, a scanner, a video camera (possibly coupled with video processing software to, e.g., detect hand gestures or facial gestures), a motion detector, or a microphone (possibly coupled to audio processing software to, e.g., detect voice commands). Suitable output devices include, but are not limited to, visual output devices, including displays and printers, audio output devices, including speakers, headphones, earphones, and alarms, additive manufacturing devices, and haptic output devices.

[0069] The processor 910 further may be coupled to a network interface card 960. The network interface card 960 prepares data generated by the processor 910 for transmission via a network according to one or more data transmission protocols. The network interface card 960 also decodes data received via a network according to one or more data transmission protocols. The network interface card 960 can include a transmitter, receiver, or both. In other embodiments, the transmitter and receiver can be two separate components. The network interface card 960, can be embodied as a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof designed to perform the functions described herein.

[0070] FIG. 10 illustrates a process 1000 for manufacturing a 3D object or device. As shown, at a step 1005, a digital representation of the object is designed using a computer, such as the computer 208 of FIG. 2 and the computer 802a of FIG. 8. For example, two dimensional (2D) or 3D data may be input to the computer 802a for aiding in designing the digital representation of the 3D object. Continuing at a step 1010, information corresponding to the 3D object is sent from the computer 802a to an additive manufacturing device, such as additive manufacturing device 806, and the device 806 commences a manufacturing process for generating the 3D object in accordance with the received information. At a step 1015, the additive manufacturing device 806 continues manufacturing the 3D object using suitable materials, such as a polymer or metal powder. Further, at a step 1020, the 3D object is generated.

EXAMPLE ASPECTS

[0071] Implementation examples are described in the following numbered clauses:

[0072] 1. A method of casting a part, the method comprising: forming a pattern, wherein the pattern comprises one or more regions configured for modification of one or more mechanical characteristics via one or more agents; dipping the pattern into a material one or more times to form a shell around the pattern; applying the one or more agents to the one or more regions to modify the one or more mechanical characteristics of the one or more regions; after applying the one or more agents, burning out the pattern to form a casting mold including the shell; introducing a second material into the shell to form the part; and removing the part from the casting mold.

[0073] 2. The method of aspect 1, wherein the one or more agents comprise one or more of: ultra-violet (UV) light; a heat source; or a solvent.

[0074] 3. The method of any of aspects 1 and 2, wherein the pattern comprises: an outer surface having a thickness; a volume comprising a lattice structure configured to reinforce the outer surface; and a channel that extends through the pattern from one or more interfaces formed in the outer surface of the pattern to the one or more regions.

[0075] 4. The method of any of aspects 1-3, wherein the pattern further comprises another channel that extends through the pattern from a first interface in the channel to a first region of the one or more regions.

[0076] 5. The method of any of aspects 1-4, wherein each of the one or more channels comprise one or more of a tube or a network of surfaces that extend through the pattern from the one or more interfaces to the one or more regions, and wherein the tube or the network of surfaces are configured to direct a tool or the one or more agents from the one or more interfaces to the one or more regions.

[0077] 6. The method of any of aspects 1-5, wherein applying the one or more agents to the one or more regions further comprises introducing the one or more agents to the one or more regions via the one or more interfaces or via a tool inserted through the one or more interfaces.

[0078] 7. The method of any of aspects 1-6, wherein modification of one or more mechanical characteristics of the one or more regions comprises modification of one or more of: a pliability of a material of the one or more regions; a degree of adhesion of the material; a strength of the material; or a shape of the material.

[0079] 8. A 3D object comprising: one or more interfaces formed in an outer surface of the 3D object; and one or more channels that extend through the 3D object from the one or more interfaces to one or more regions of the 3D object.

[0080] 9. The 3D object of aspect 8, further comprising: the outer surface having a thickness; and a volume comprising a lattice structure configured to reinforce the outer surface.

[0081] 10. The 3D object of any of aspects 8 and 9, wherein the one or more channels comprise a primary channel and a secondary channel, wherein the primary channel extends through the 3D object from the one or more interfaces to a first region of the 3D object, and wherein the secondary channel extends through the 3D object from an interface of the primary channel to a second region of the 3D object.

[0082] 11. The 3D object of any of aspects 8-10, wherein each of the one or more channels comprise one or more of a tube or a network of surfaces that extend through the 3D object from the one or more interfaces to the one or more regions, and wherein the tube or the network of surfaces are configured to direct a tool or one or more agents from the one or more interfaces to the one or more regions.

[0083] 12. The 3D object of any of aspects 8-11, wherein a first channel of the one or more channels comprises a tube extending out of the 3D object, and wherein the tube is configured to couple to a tool for introducing an agent to a region of the 3D object.

[0084] 13. The 3D object of any of aspects 8-12, wherein at least one of the one or more regions comprises a lattice structure.

[0085] 14. A method for generating a modified design of a 3D object, the method comprising: receiving a design of the 3D object; identifying one or more regions of the 3D object for modification of one or more mechanical characteristics of the one or more regions via one or more agents; modifying the design of the 3D object to include: one or more interfaces formed in a surface of the 3D object; and one or more primary channels that extend through the 3D object from the one or more interfaces to the one or more regions of the 3D object.

[0086] 15. The method of aspect 14, wherein the design of the 3D object is characterized by an outer surface and a volume, the outer surface having a thickness and the volume comprising a lattice structure configured to reinforce the outer surface.

[0087] 16. The method of any of aspects 14 and 15, wherein modifying the design of the

3D object further comprises modifying the design of the 3D object to include another channel that extends through the 3D object from a first interface in a first channel of the one or more channels to a first region of the one or more regions of the 3D object.

[0088] 17. The method of any of aspects 14-16, wherein each of the one or more channels comprise one or more of a tube or a network of surfaces that extend through the 3D object from the one or more interfaces to the one or more regions of the 3D object, and wherein the tube or the network of surfaces are configured to direct a tool or the one or more agents from the one or more interfaces to the one or more regions.

[0089] 18. The method of any of aspects 14-17, wherein modifying the design of the 3D object further comprises modifying the design of the 3D object to change one or more of a plurality of features of the one or more regions.

[0090] 19. The method of any of aspects 14-18, wherein the plurality of features comprise: a lattice structure of a volume of the 3D object; a surface structure of a surface of the 3D object; a thickness of one or more of the lattice structure or the surface structure; one or more of a material or material doping of one or more of the lattice structure or the surface structure; a shape of one or more of the lattice structure or the surface structure; or an orientation of the lattice structure.

[0091] 20. The method of any of aspects 14-19, wherein modification of one or more mechanical characteristics of the one or more regions comprises modification of one or more of: a pliability of a material of the one or more regions; a degree of adhesion of the material; a strength of the material; or a shape of the material.

ADDITIONAL CONSIDERATIONS

[0092] Various embodiments disclosed herein provide for the use of a computer control system. A skilled artisan will readily appreciate that these embodiments may be implemented using numerous different types of computing devices, including both general purpose and/or special purpose computing system environments or configurations. Examples of well-known computing systems, environments, and/or configurations that may be suitable for use in connection with the embodiments set forth above may include, but are not limited to, personal computers, server computers, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments (e.g., networks, cloud computing systems, etc.) that include any of the above systems or devices, and the like. These devices may include stored instructions, which, when executed by a microprocessor in the computing device, cause the computer device to perform specified actions to carry out the instructions. As used herein, instructions refer to computer-implemented steps for processing information in the system. Instructions can be implemented in software, firmware or hardware and include any type of programmed step undertaken by components of the system.

[0093] A microprocessor may be any conventional general purpose single- or multi-chip microprocessor such as a Pentium® processor, a Pentium® Pro processor, a 8051 processor, a microprocessor without interlocked pipelined stages (MIPS®) processor, a Power PC® processor, or an Alpha® processor. In addition, the microprocessor may be any conventional special purpose microprocessor such as a digital signal processor or a graphics processor. The microprocessor typically has conventional address lines, conventional data lines, and one or more conventional control lines.

[0094] Aspects and embodiments of the inventions disclosed herein may be implemented as a method, apparatus or article of manufacture using standard programming or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term "article of manufacture" as used herein refers to code or logic implemented in hardware or non- transitory computer readable media such as optical storage devices, and volatile or non-volatile memory devices or transitory computer readable media such as signals, carrier waves, etc. Such hardware may include, but is not limited to, field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), complex programmable logic devices (CPLDs), programmable logic arrays (PLAs), microprocessors, or other similar processing devices.