CROSS-REFERENCES TO RELATED APPLICATIONS/PATENTS

[0001 ] This application claims the benefit of U.S. Patent Application No. 15/173,158, filed on 03-JUN-2016, which claims priority to U.S. Provisional Application No. 62/305,144, filed on 08-MAR-2016, and to U.S. Provisional Application No. 62/171,690, filed on 05-JUN-2015, all of which are incorporated in their entireties by this reference.

FIELD OF TH E INVENTION

[0002] The present invention relates generally to apparatuses and methods for manufacturing, and particularly to apparatuses and methods for casting and additive manufacturing.

BACKGROUND AND DESCRIPTION OF THE PRIOR ART

[0003] It is known to use additive manufacturing to manufacture three- dimensional (3D) products. Conventional apparatuses and methods for additive manufacturing, however, suffer from one or more disadvantages. For example, conventional additive manufacturing apparatuses and methods are undesirably slow and expensive. Conventional additive manufacturing is also limited to an undesirably small number of material options and the manufactured product has undesirable directional mechanical properties and other manufacturing defects. In addition, conventional additive manufacturing is not well-suited to handle multi-material applications.

[0004] It is also known to use casting to manufacture 3D products. Conventional apparatuses and methods for casting, however, suffer from one or more disadvantages. For example, conventional casting apparatuses and methods require expensive molds that are time-consuming and require skilled labor to produce. Conventional casting molds are also not dissolvable or otherwise easily disposed, and the manufactured product frequently includes undesirable voids and other manufacturing defects.

[0005] It would be desirable, therefore, if an apparatus and method for hybrid manufacturing could be provided that would increase the speed at which products could be manufactured and reduce the cost and difficulty of manufacturing products. It would also be desirable if such an apparatus and method for hybrid manufacturing could be provided that would increase the number of material options and minimize or eliminate directional mechanical properties, voids, and other manufacturing defects. It would be further desirable if such an apparatus and method for hybrid manufacturing could be provided that would allow for the use of multiple different materials in a single product. It would be still further desirable if such an apparatus and method for hybrid manufacturing could be provided that would utilize dissolvable molds.

ADVANTAGES OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0006] Accordingly, it is an advantage of the preferred embodiments of the invention claimed herein to provide an apparatus and method for hybrid manufacturing that increase the speed at which products could be manufactured and reduce the cost and difficulty of manufacturing products. It is also an advantage of the preferred embodiments of the invention claimed herein to provide an apparatus and method for hybrid manufacturing that increase the number of material options and minimize or eliminate directional mechanical properties, voids, and other manufacturing defects. It is another advantage of the preferred embodiments of the invention claimed herein to provide an apparatus and method for hybrid manufacturing that allow for the use of multiple different materials in a single product. It is still another advantage of the preferred embodiments of the invention claimed herein to provide an apparatus and method for hybrid manufacturing that utilize dissolvable molds.

[0007] Additional advantages of the preferred embodiments of the invention will become apparent from an examination of the drawings and the ensuing description.

SUMMARY OF THE INVENTION

[0008] The apparatus of the invention comprises an apparatus for hybrid manufacturing. The preferred apparatus for hybrid manufacturing comprises a frame, a build plate that is adapted to move relative to the frame, a material pump that is adapted to pump one or more materials, a mixing head that is adapted to mix the one or more materials, a mixing hose that is in fluid communication with the material pump and the mixing head, a vacuum pump that is adapted to remove air from a mold, a vacuum hose that is in fluid communication with the vacuum pump and the mold, a vat that is adapted to retain a liquid, and a radiation source that is disposed adjacent to the vat. The preferred apparatus prints the mold and fills the mold.

[0009] The method of the invention comprises a method for hybrid manufacturing. The preferred method comprises providing an apparatus for hybrid manufacturing. The preferred apparatus for hybrid manufacturing comprises a frame, a build plate that is adapted to move relative to the frame, a material pump that is adapted to pump one or more materials, a mixing head that is adapted to mix the one or more materials, a mixing hose that is in fluid communication with the material pump and the mixing head, a vacuum pump that is adapted to remove air from a mold, a vacuum hose that is in fluid communication with the vacuum pump and the mold, a vat that is adapted to retain a liquid, and a radiation source that is disposed adjacent to the vat. The preferred apparatus prints the mold and fills the mold. The preferred method further comprises printing the mold with one or more mold materials, removing air from the mold, filling the mold with one or more primary materials, and dissolving the mold.

BRIEF DESCRIPTION OF THE FIGURES

[001 0] The presently preferred embodiments of the invention are illustrated in the accompanying drawings, in which like reference numerals represent like parts throughout, and in which:

[001 1 ] Figure ι is a front view of the preferred embodiment of the apparatus for hybrid manufacturing in accordance with the present invention.

[0012] Figure 2 is a left side view of the preferred apparatus for hybrid manufacturing illustrated in Figure l.

[0013] Figure 3 is a partial sectional view of a first exemplary mold in accordance with the present invention.

[0014] Figure 4 is a partial sectional view of a second exemplary mold in accordance with the present invention.

[0015] Figure 5 is a partial sectional view of a third exemplary mold in accordance with the present invention shown in an environmentally-controlled chamber.

[0016] Figure 6 is a partial sectional view of a fourth exemplary mold in accordance with the present invention shown with a filling material.

[0017] Figure 7 is a partial sectional view of a fifth exemplary mold in accordance with the present invention shown in an environmentally-controlled chamber.

[001 8] Figure 8 is a partial sectional view of the preferred mixing head in accordance with the present invention.

[0019] Figure 9 is a partial sectional view of the preferred vat in accordance with the present invention.

[0020] Figure 10 is a partial sectional view of a sixth exemplary mold in accordance with the present invention.

[0021 ] Figure 11 is a partial sectional view of a seventh exemplary mold in accordance with the present invention.

[0022] Figure 12 is a partial sectional view of an eighth exemplary mold in accordance with the present invention.

[0023] Figure 13 is a partial sectional view of a ninth exemplary mold in accordance with the present invention.

[0024] Figure I4A is a partial sectional view of a tenth exemplary mold.

[0025] Figure 14B is a partial sectional view of the exemplary mold illustrated in Figure 14A filled with a primary material.

[0026] Figure 14C is a partial sectional view of the primary material illustrated in Figure 14B after the exemplary mold has been dissolved.

[0027] Figure 15 is a flow chart detailing, in part, the preferred method for hybrid manufacturing in accordance with the present invention.

[0028] FIGURE 16 is a flowchart representation of a method.

[0029] FIGURE 17 is a schematic representation of an apparatus.

[0030] FIGURE 18 is a schematic representation of one variation of the apparatus.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

[0001 ] The following description of embodiments of the invention is not intended to limit the invention to these embodiments but rather to enable a person skilled in the art to make and use this invention. Variations, configurations, implementations, example implementations, and examples described herein are optional and are not exclusive to the variations, configurations, implementations, example implementations, and examples they describe. The invention described herein can include any and all permutations of these variations, configurations, implementations, example implementations, and examples.

1. First Apparatus

[0031 ] Referring now to the drawings, the preferred embodiments of the apparatus and method for hybrid manufacturing in accordance with the present invention is illustrated by Figures 1 through 15. As shown in Figures 1-15, the preferred apparatus and method for hybrid manufacturing are adapted to increase the speed at which products could be manufactured and reduce the cost of manufacturing products. The preferred apparatus and method for hybrid manufacturing are also adapted to increase the number of material options and minimize or eliminate directional mechanical properties, voids, and other manufacturing defects. The preferred apparatus and method for hybrid manufacturing are further adapted to allow for the use of multiple different materials in a single product. The preferred apparatus and method for hybrid manufacturing are still further adapted to utilize dissolvable molds.

[0032] Referring now to Figure l, a front view of the preferred embodiment of the apparatus for hybrid manufacturing in accordance with the present invention is illustrated. As shown in Figure l, the preferred apparatus for hybrid manufacturing is designated generally by reference numeral 20.

[0033] Preferred apparatus for hybrid manufacturing 20 comprises a 3D printer having frame 22 which is adapted to provide support for the other components of the 3D printer. Preferred frame 22 defines chamber 24. Preferred apparatus for hybrid manufacturing 20 also comprises build plate 26 which is adapted to move relative to frame 22. Preferably, build plate 26 is adapted to move vertically along the z-axis relative to frame 22. Preferred apparatus for hybrid manufacturing 20 also comprises material pump 28 which is adapted to pump one or more materials to one or more mixing heads (see Figures 3-8) via mixing hose 30. The preferred mixing head is adapted to mix the materials pumped by material pump 28, and preferred mixing hose 30 is in fluid communication with the material pump and the mixing head. Preferred mixing hose 30 is connected at build plate 26. In the preferred embodiments of apparatus for hybrid manufacturing 20, the 3D printer is adapted to the print mixing head and mixing hose 30. Still referring to Figure 1, preferred apparatus for hybrid manufacturing 20 further comprises vacuum pump 32 which is adapted to remove air from a mold via vacuum hose 34. Preferred vacuum hose 34 is in fluid communication with vacuum pump 32 and the mold and is connected at build plate 26. In the preferred embodiments of apparatus for hybrid manufacturing 20, the 3D printer is adapted to print vacuum hose 34. Preferred apparatus for hybrid manufacturing 20 further comprises vat 36 which is adapted to retain a liquid. Preferred vat 36 comprises at least one of a PVDC layer and a FEP layer. Preferred apparatus for hybrid manufacturing 20 also comprises radiation source 38 which is disposed adjacent to the vat. The preferred radiation source 38 is a high-power light-emitting diode (HP- LED) light such as a near UV spectrum, 405 nanometer light that is adapted to cure the printing materials used by the apparatus via photoreaction, but it is contemplated within the scope of the invention that any suitable radiation source may be used including without limitation a laser. In the preferred embodiments of the apparatus for hybrid manufacturing, the 3D printer prints the mold with one or more mold materials and fills the mold with one or more primary materials. While Figure 1 illustrates the preferred configuration and arrangement of the apparatus for hybrid manufacturing, it is contemplated within the scope of the invention that the apparatus for hybrid manufacturing may be of any suitable configuration and arrangement.

[0034] Referring now to Figure 2, a left side view of preferred apparatus for hybrid manufacturing 20 is illustrated. As shown in Figure 2, preferred apparatus for hybrid manufacturing 20 comprises frame 22, chamber 24, build plate 26, material pump 28, material hose 30, vacuum pump 32, vacuum hose 34, vat 36, and radiation source 38.

[0035] Referring now to Figure 3, a front sectional view of a first exemplary mold is illustrated. As shown in Figure 3, the first exemplary mold is designated generally by reference numeral 120. Exemplary mold 120 is in fluid communication with mixing head 122 and vacuum hose 124. Exemplary mold is also in fluid communication with build plate 126 and material hose 128.

[0036] Referring now to Figure 4, a front sectional view of a second exemplary mold is illustrated. As shown in Figure 4, the second exemplary mold is designated generally by reference numeral 220. Exemplary mold 220 is in fluid communication with mixing head 222 and vacuum hose 224.

[0037] Exemplary mold is also in fluid communication with build plate 226 and material hose 228.

[0038] Referring now to Figure 5, a front sectional view of a third exemplary mold is illustrated. As shown in Figure 5, the third exemplary mold is designated generally by reference numeral 320. Exemplary mold 320 is in fluid communication with mixing head 322 and vacuum hose 324. [0039] Exemplary mold is also in fluid communication with build plate 326. and material hose 328. Exemplary mold 320 is disposed in chamber 330 which is adapted to be sealed, pressurized, vacuumed, and otherwise environmentally controlled, e.g. temperature, humidity, and the like.

[0040] Referring now to Figure 6, a front sectional view of a fourth exemplary mold is illustrated. As shown in Figure 6, the fourth exemplary mold is designated generally by reference numeral 420. Exemplary mold 420 is in fluid communication with mixing head 422 and vacuum hose 424.

[0041 ] Exemplary mold is also in fluid communication with build plate 426 and material hose 428. Exemplary mold 420 is disposed in chamber 430 which is filled with a refractory material such as supporting sand 432 for pouring molten or heavy primary materials.

[0042] Referring now to Figure 7, a front sectional view of a fifth exemplary mold is illustrated. As shown in Figure 7, the fifth exemplary mold is designated generally by reference numeral 520. Exemplary mold 520 is in fluid communication with mixing head 522 and vacuum hose 524. Exemplary mold is also in fluid communication with build plate 526 and material hose 528.

[0043] Exemplary mold 520 is disposed in chamber 530. Preferred chamber 526 is adapted to control the environment in the chamber, e.g. the temperature, the humidity, and the like.

[0044] Referring now to Figure 8, a partial sectional view of a preferred embodiment of the mixing head is illustrated. As shown in Figure 8, the preferred mixing head is designated generally by reference numeral 620. Preferred mixing head 620 comprises first inlet 622, second inlet 624, and outlet 626. The inlets and the outlet are in fluid communication with each other. Preferably, helix 628 is disposed between the inlets and the outlet. While Figure 8 illustrates preferred helix 628, it is contemplated that mixing head 620 may be of any suitable configuration and arrangement adapted to mix primary materials.

[0045] Referring now to Figure 9, a partial sectional view of an exemplary vat is illustrated. As shown in Figure 9, the exemplary vat is designated generally by reference numeral 720. Preferred vat 720 comprises liquid plastic 722, PVDC or FEP layer 724, silicone or PDMS 726, and acrylic 728. Mold wall 730 is illustrated slightly adhering to PVDC or FEP layer 724. While Figure 9 illustrates the preferred vat materials and the preferred layer arrangement, it is contemplated within the scope of the invention that other suitable vat materials may be used and any suitable layer arrangement may be used.

[0046] Referring now to Figure 10, a partial sectional view of a sixth exemplary mold is illustrated. As shown in Figure 10, the sixth exemplary mold is designated generally by reference numeral 820. Exemplary mold 820 is supported by support structures 822 and comprises negative space supports 824 which may be filled in during post processing steps. Preferred support structures 822 break through the produced part and are in direct contact with build plate 826.

[0047] Referring now to Figure 11, a partial sectional view of a seventh exemplary mold is illustrated. As shown in Figure 11, the seventh exemplary mold is designated generally by reference numeral 920. Exemplary mold 920 is adapted to manufacture a product comprising more than one material. More particularly, exemplary mold 920 is adapted to manufacture a product in which a secondary material is encased within a primary material. Exemplary mold 920 comprises primary opening 922 which is adapted to allow a primary material to be filled into the mold. In addition, exemplary mold 920 comprises solid sacrificial positives 924 and solid sacrificial sprues 926 which are adapted to be filled with a secondary material.

[0048] Referring now to Figure 12, a partial sectional view of an eighth exemplary mold is illustrated. As shown in Figure 12, the eighth exemplary mold is designated generally by reference numeral 1020. Exemplary mold 1020 is also adapted to manufacture a product comprising more than one material. More particularly, exemplary mold 1020 is adapted to manufacture a product having two different materials adjacent to each other. Exemplary mold 1020 comprises first material opening 1022 which is adapted to receive a first material, second material opening 1024 which is adapted to receive a second material, and dividing wall 1026 which is adapted to keep the first material and the second material separated from each other. While Figure 12 illustrates a mold adapted to manufacture a product having two different materials adjacent to each other, it is contemplated within the scope of the invention that a mold may be adapted to manufacture a product having more than two different materials, some or all of which are adjacent to each other or some or all of which are spaced apart from each other.

[0049] Referring now to Figure 13, a partial sectional view of a ninth exemplary mold is illustrated. As shown in Figure 13, the ninth exemplary mold is designated generally by reference numeral 1120. Exemplary mold 1120 is also adapted to manufacture a product comprising more than one material. More particularly, exemplary mold 1120 is adapted to manufacture a product comprising interlocking parts made from different materials. Exemplary mold 1120 comprises female part opening 1122 which is adapted to receive a first material and male part opening 1124 which is adapted to receive a second material.

[0050] Referring now to Figures 14A-C, a partial sectional view of three stages of the preferred hybrid manufacturing process is illustrated. As shown in Figure 14A, the first stage is the 3D-printed empty mold designated generally by reference numeral 1220. Preferred mold 1220 comprises opening 1222 disposed at the top of the mold. As shown in Figure 14B, the second stage of the preferred hybrid manufacturing process is mold 1220 filled with product material 1224. As shown in Figure 14C, the third stage of the preferred hybrid manufacturing process is the finished product comprising product material 1224 after the dissolvable mold has been dissolved.

[0051 ] Referring now to Figure 15, a flow chart detailing, in part, the preferred method for hybrid manufacturing in accordance with the present invention is illustrated. The preferred method for hybrid manufacturing comprises providing an apparatus for hybrid manufacturing such as the 3D printer described hereinabove. As shown in Figure 15, the preferred method for hybrid manufacturing further comprises printing the mold with one or more mold materials, removing air from the mold, filling the mold with the one or more primary materials, and dissolving the mold. In the preferred embodiments of the method for hybrid manufacturing, the 3D printer prints the mold and fills the mold. Preferably, the mold is continuously printed via continuous energy and continuous build plate movement or stereolithography. In addition, the preferred mold is water-soluble and comprises at least one of a high impact polystyrene, a polyvinyl alcohol, an acrylic monomer, a sugar, and a wax. In one preferred embodiment, the mold comprises a solution including methacrylic acid, polyvinylpyrrolidone, methacrylic anhydride, phenylbis (2, 4, 6 -trimethylbenzoyl) phosphine, and N, N-dimethlyacrylamide. The preferred primary material comprises at least one of a resin, a ceramic, a metal powder, a silicon, a urethane, a clay material, a plastic, a fiber, a biological material, and a bio-active material.

[0052] In other preferred methods for hybrid manufacturing, the method also comprises placing a solid sacrificial material within the mold, connecting the solid sacrificial material to the mold via a sprue, dissolving the solid sacrificial material after the mold is filled with the primary material, and conveying a secondary material into an open space left by the dissolved solid sacrificial material. In still other preferred methods for hybrid manufacturing, the method further comprises 3D printing the mixing head, the mixing hose, the vacuum hose, and the support structures. In other preferred methods for hybrid manufacturing, the method still further comprises controlling water permeation, detecting manufacturing defects, controlling the environment in the chamber, and mixing multiple materials during the printing stage, including but not limited to multiple photocurable resins, multiple powder materials in a sintering process, and/or multiple thermoplastic extrusion feedstocks. Preferably, the method of the invention may utilize one or more of the following print technologies: SLS, SLA, FDM, and the like. In operation, several advantages of the preferred embodiments of the apparatus and method for hybrid manufacturing are achieved. Initially, a 3D model file or other digital file used to demonstrate points in space is resampled with an offset of varying unit of its original size. This process essentially finds a collection of points in space that are a uniform distance from the original model, thereby producing an "offset" model that is larger than the original at all points. The original file is then converted into negative digital space and digitally placed within its resampled counterpart. One or more holes or negative spaces are then placed through the resampled file intersecting its original negative space counterpart. The output this process produces is an extremely material efficient mold or shell of the original 3D data. Optionally, an algorithm can be run on a set of multiples of these output files that produces small digital model "ties" or lines between them while also orienting each model with the holes pointing up. This optional action enables the models to stand upright once digitally manufactured with holes pointing up such that they are adapted to be filled with their counterpart material.

[0053] The digital output from the former process (3D data model of a material efficient mold) may then be used to produce a physical version of the 3D data via additive manufacturing/3 D printing. The part can be produced using material extrusion, powder fusion, material jetting, vat photopolymerization, continuous energy and build platform movement, sintering, binder jetting, or other additive means. The material of the mold or shell commonly produced using this process is a sacrificial material such as HIPS (high impact polystyrene), PVA (Polyvinyl Alcohol), sugar, or other materials suitable for additive manufacturing that are soluble in water or another solvent or that melt away when heat is applied. Optionally, the mold/shell's materials may not be sacrificial.

[0054] The output physical mold or shell is then filled with any thermosetting resin that cures via a combination of chemical reaction and heat. The mold may be filled manually or via automated equipment that both mixes and disperses a calculated amount of material such as resin. A dispersion system could be mounted on an industrial robot to automate the filling of the mold or built into or retrofitted to the additive platform producing the mold. To ensure no bubbles are formed within the resin and end use product, bubbles may be removed by placing the mold filled with material inside a vacuum or on a shaking/ vibrating table, or by applying ultrasound to the mold filled with material. Optionally, any of these technologies could be built into or retrofitted to the original additive machine that produced the mold. The material in the mold is then left to cure for the amount of time necessary to demold the product. The curing process can be expedited by heating the material as it cures. [0055] The output of the former process (mold filled with cured material/end product) is then submersed in water or another solvent, and/or heated in order to remove the sacrificial mold. Optionally, one or more solvents may be placed inside an ultrasonic cleaner or heated bath in order to expedite the dissolving process. Once the sacrificial mold dissolves all that remains is a solid end product which is produced more quickly than additive by itself, has no directional mechanical properties, and maybe made from a broader range of materials than additive manufacturing by itself can produce. Also, the end product may be injected with materials different than itself, allowing for products that contain multiple materials. Optionally, when the additively produced molds are not made from sacrificial material, the final product consists of both the original 3D-printed mold and the internal cured material. When producing products with sacrificial molds, the cured material is the final product output. It is contemplated within the scope of the invention that end products can be finished with any traditional finishing processes such as sanding, wet sanding, media blasting, media vibration, heat treatment, kiln firing, spray coatings, plating, and the like.

[0056] It is also contemplated within the scope of the invention that the materials maybe infused with ceramics and metal powders up to a necessary loading value for firing processes to produce ceramic and metal parts with either of both the primary filling resin or printed mold material serving as a sacrificial binder.

[0057] Multi-material printing using this process involves the placement of solid sacrificial material where a material other than the primary material is desired when the secondary material is completely encased in the primary material. The solid sacrificial part is connected to the external of the original sacrificial mold via a thin sprue. The sprue and the solid sacrificial material are dissolved during the solvent process. Secondary material is then injected into the hollow cavity of the product where the dissolved sacrificial solid part was originally via the thin cavity left by the dissolved sprue. Once the desired secondary material is cured, the sprue cavity can then also be filled with the primary material if desired for either aesthetics or any other reason. This process allows multi- material parts to be produced with this process when secondary materials are encased within the primary material.

[0058] Where multi- material products are required and multiple materials are in direct contact with each other the sacrificial molds and process described herein can be carried out separately, and the different materials can be connected to one another via a fastening means such as glue, tape, or another adhesive, a threaded fastener, such as screws or bolts, rivets, nails, staples, hook and loop fasteners, and the like. It is also contemplated within the scope of the invention that two abutting part may be connected by breaking down the chemicals of the abutting surfaces of the product to produce bonds.

[0059] Where multi-material products are required and the multiple materials are interlocking, a slightly different process is used. The separate molds overlap one another and therefore, while they are their own separate cavities within the product their molds are interconnected. In addition, each cavity has its own hole for receiving material. After both materials have set, the sacrificial mold is dissolved leaving a tiny gap as thin as the shell between the interconnected parts. Thereafter, the gap left behind can be filled with a desired material and left to set to produce a fully solid multi-material part where interconnecting materials are required. Alternatively, gaps can be left between interlocking parts where desired for moving parts and many more applications.

[0060] In addition, the preferred embodiments of the apparatus and method for hybrid manufacturing reduce the adherence of cured mold material to the build vat in a vat polymerization printing method system. More particularly, the use of a thin film made of a polyvinyl chloride based polymer such as PVDC or fluorinated ethylene propylene (FEP), such that the film is completely supported by a layer underneath the film which has some adherence to the film. This allows the film to locally deform, causing release of the cured artifact, without distorting other parts of the print. The tension built up in the film locally by any adhered regions as the artifact is pulled away from the surface then pulls the film off the adhered region. The film then re-attaches to the supporting structure underneath, allowing the next layer to be cured. [0061 ] An additional method of reducing adherence is the use of a semipermeable membrane that allows some flow of a liquid solvent, potentially but not limited to H20, through the membrane. This solvent allows curing of photopolymer to a limited degree in the region of the build vat. This system does not require high-pressure introduction of a material to the membrane, since sufficient concentrations can be achieved under normal pressures due to the higher density of liquid solvent.

[0062] Because of the unique geometry of the printed artifacts produced by the preferred process, positive air pressure can be introduced through the vacuum and mixing hoses included in each geometry. This positive pressure can aid in releasing the artifact from the build vat without damaging the artifact or the vat. Especially this can be used in conjunction with locally deformable thin film coverings or solvent diffusing release layer.

[0063] The preferred embodiments of the apparatus and method for hybrid manufacturing also reduce or eliminate voids in the end product. More particularly, in order to prevent voids in final products manufactured in molds, vacuum force may be applied to the interior of a mold to evacuate the mold of any air that might otherwise be trapped. This vacuum force may also "pull" material into voids due to air trapped in the material. Additionally, positive air pressure force can also be applied to the interior of molds to force material already introduced into the mold into any voids.

[0064] The preferred embodiments of the apparatus and method for hybrid manufacturing also combine the process of producing a mold and the process of filling the mold. To accomplish in-situ molding and casting, the materials to be introduced to the mold must be pre-mixed, degassed, mixed together, and optionally degassed after the second mixing. The preferred embodiments include several processes to accomplish these requirements that are unique to the situation of in- situ casting and molding into an additively manufactured mold.

[0065] Pre-mixing of molding components, which can include but are not limited to two-part resins, ceramic slurries, and waxes, can be accomplished via several methods. Preferably, a vibrational actuator can induce vibrations into the molding material components which cause even mixing of its constituent materials. This vibrational actuator can be composed of piezo materials, unbalanced rotational actuators, linear actuators using fluid or electrical power, or voice coils actuators. Optionally, magnetic or ferrous items placed in the material containers can be moved by moving electromagnetic fields to stir and evenly mix the constituents. Applied to each constituent separately, this vibrational motion can remove entrapped gases within the individual constituent materials, as well as evenly mix ingredients of each individual constituent material.

[0066] Vacuum gauge pressure can be applied to the interior of the containers of molding material to remove dissolved or mixed gasses in the mold material. Ambient pressure or higher pressure can then also be introduced to cause gas bubbles that formed during the vacuum stage of the process to collapse, along with applying vibration via piezo or other vibratory energy to the container.

[0067] This can be done in cycles to completely eliminate entrapped gasses in the mold making materials.

[0068] The nature of additively manufactured molds can make vacuum or pressure degassing of the molded part difficult. Gasses introduced during the mixing stage then pose a problem for in-situ molding and casting. To solve this problem, a static mixing head in used in the system that combines parts of multi-part materials that require mixing. This part is evacuated of air along with the entire part and runner network. The evacuated mixing head does not supply gases that can be mixed into the material upstream of the mold. This mixing head can be, but does not have to be additively manufactured along with the mold and runner network. Additively manufacturing this mixing head has the advantage of being eas,ier to maintain and clean, protecting the machine from having cured multi-part resin or material slurry in the machine components or tubing.

[0069] The runner network allows multiple parts to be manufactured with the in-situ casting process. This is a requirement to enable cost-effective production of parts with the combination of additive manufacturing and in-situ casting. These runners can be additively manufacture with the same process as the mixing head. Mold materials in these runners can be easily removed after the cast or molded part is removed from the build chamber. The ease of removal can be increased by designing the gate or entry of the runner into the mold to be easily broken in a post-processing step, or by the action of removal of the mold from the build chamber.

[0070] The molding materials can be metered and introduced into the mold or network of molds via, either singly or in combination, the differential pressure caused by the vacuum in the mold and/or the action of pumps designed to control the flow of molding materials. In all situations, flow measurement of the molding materials can be provided to ensure accurate amounts of materials are dispensed. This measurement can be used, either alone or in combination with other measurements, for error detection in the molding or casting process.

[0071 ] To support geometry that is difficult to print in the proper shape for in- situ casting, support structures can be added through the region that the final cast part would otherwise occupy. This then becomes un-filled negative space in the final part, which can be filled via post processing.

[0072] Post processing for this type of "negative support" may be accomplished with a syringe and molding tool whose geometry is created during the slicing process of the print job, and which is printed alongside the part.

[0073] The build volume can be heated for improved material properties of the final part, and also improved curing of the 3D printed casting mold artifact. This heating can be accomplished with a variety of means, preferably Infrared surface heating elements, but also volumetric heating methods such as resistance coils.

[0074] The preferred embodiments of the apparatus and method for hybrid manufacturing are also adapted to detect leaks in molds. Vacuum pump pressure (negative gauge pressure) may be pulled on the interior of a mold. Depending on the vacuum readings measured by a sensor while running the pump, conclusions can be drawn about whether or not there is a hole or that the mold is not watertight. If vacuum force is pulled and the rate of pressure readings adjust too slowly it can be inferred that there is a hole or leak. Additionally, if vacuum pressure is applied and vacuum pressures do not build up within the mold network, the presence of a hole in the mold can be inferred or identified. This allows for determining error modes in processes requiring this sort of check. Additionally, positive air pressure may also, be applied to determine the same readings with a similar method reading positive gauge pressure.

[0075] The preferred embodiments of the apparatus and method for hybrid manufacturing are also adapted to detect errors in the material injection process. Leakage from molds and improperly filled molds can be detected using various sensors. Level or mass sensors reading the amount of material in a drip tray or other catch device positioned beneath a mold can detect material filling the tray, which can be inferred to be caused by a leak in a mold being filled with material.

[0076] Sensors that can detect a disruption in a light path, or detect some object passing through or nearby them could be used underneath the mold system in a similar manner to detect material leaking from a mold network.

[0077] Torque measurements for pump motors or flow measurement sensors placed in the supply lines of a system used to introduce material into a mold could also be used to detect excess material flowing into a mold, indicating either the loss of material through leakage, or excess material being expelled through unintentional openings or expansions of the mold. In addition, this sort of sensor could detect unwanted deflection of the mold or thermal expansion of the molding system.

[0078] Thermal imaging systems may be used to detect exothermic or endothermic reactions of chemically reactive or photo-chemical materials that either comprise the mold or the mold filling materials, allowing for the measurement and assessment of mold condition and fill level of the mold.

[0079] Other light measuring systems could measure photons being reflected from surface, such as a laser measuring system or a structured light scanning system, which could be used to assess the completeness and imperviousness of the mold.

[0080] Preferably, a camera that is situated in the optical path so that it can image the outline of an exposed layer for metrology purposes. This image can be used to measure a profile and detect unwanted gaps that can become errors and leaks. This camera can be situated as part of a prism that aligns beams to the build vat.

[0081 ] The preferred embodiments of the apparatus and method for hybrid manufacturing are also adapted to produce molds suitable for investment casting. More particularly, the preferred embodiments are adapted to produce an additively manufactured mold to cast a wax pattern for further use in casting or molding processes. This is especially useful for metal investment casting that requires high purity and detailed positives. These in-situ molded wax positives created from additive methods can also include an appropriate gate, sprue, runner, and venting system, •including all special modifications to such things, that the final positive will need for proper casting or molding operations.

[0082] In addition to wax, positive artifacts can be made with materials such as slurries of ceramic, metal, metal-bearing clay, plastic and thermoplastic, fibrous and fiber bearing versions of any of the materials, biological materials such as cells or tissue or castable bio-active materials (such as sugars, proteins, cartilage-type materials). This is beneficial due to the fact that these materials all have special processing needs when cast or molded separately.

[0083] Although this description contains many specifics, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments thereof, as well as the best mode contemplated by the inventors of carrying out the invention. The invention, as described herein, is susceptible to various modifications and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

2. Second Apparatus and Method

[0084] As shown in FIGURES 16 and 17, an apparatus 100 for fabricating a solid part includes: a fabrication chamber 120 defining a transparent floor; a reservoir 126 containing photocurable mold material and configured to release mold material into the fabrication chamber 120; a projection system 122 facing the fabrication chamber 120 and configured to project light, at a wavelength that cures the photocurable mold material, through the transparent floor of the fabrication chamber 120; a pressure chamber 142; and a platen 110 defining a downward-facing planar build surface, a first injection port 111 intersecting the planar build surface, a second injection port 112 intersecting the planar build surface adjacent the first injection port 111, and a pressure port 113 intersecting the planar build surface and laterally offset from the first injection port 111. The apparatus 100 also includes a linear motion system 124 configured: to locate the platen 110 inside the fabrication chamber 120 with the planar build face facing the transparent floor of the fabrication chamber 120; to raise the platen 110 away from the transparent floor as the reservoir 126 releases mold material into the fabrication chamber 120 and as light output by the projection system 122 cures mold material in layers suspended from the planar build face in the form of a shell fluidly coupled to the first injection port 111, the second injection port 112, and the pressure port 113; to extract the platen 110 from the fabrication chamber 120 upon completion of the shell; and to locate the platen 110 sealed against the pressure chamber 142 with the shell suspended inside the pressure chamber 142. The apparatus 100 further includes: a wash system 130 configured to flush uncured mold material from an interior volume of the shell upon completion of the shell; an injection system 150 configured to inject a first part of an injection material into the interior volume of the shell via the first injection port 111 and to inject a second part of the injection material into the interior volume of the shell via the second injection port 112; and a pressure system 140 configured to pressurize the interior volume of the shell via the pressure port 113 to a target pressure and to pressurize the pressure chamber 142 outside the shell to approximately the target pressure to support the shell as the first part of the injection material hardens the second part of the injection material to a gel phase.

[0085] As shown in FIGURE 16, a method S100 for fabricating a solid part includes: locating a platen 110 inside a fabrication chamber 120 in Block S110; in the fabrication chamber 120, releasing photocurable mold material between the fabrication chamber 120 and a build surface on the bottom side of the platen 110 in Block S112; projecting light toward the build surface to selectively cure layers of mold material suspended from the build surface in Block S120; in response to completion of fabrication of a shell, in the mold material, defining an interior volume fluidly coupled to a first injection port ill, to a second injection port 112 adjacent the first injection port 111, and to a pressure port 113 in the platen 110, transitioning the platen 110 to a pressure chamber 142 to seal the platen 110 against the pressure chamber 142 with the shell suspended into the pressure chamber 142 in Block S130; flushing uncured mold material from the interior volume of the shell via the pressure port 113 in Block S140; injecting a first part of an injection material into the interior volume of the shell via the first injection port 111 and injecting a second part of the injection material into the interior volume of the shell via the second injection port 112 in Block S150; and, in response to injection of a target volume of the first part of the injection material and the second part of the injection material pressurizing the interior volume of the shell via the pressure port 113 to a target pressure and pressurizing the pressure chamber 142 outside the shell to approximately the target pressure to support the shell as the first part of the injection material hardens the second part of the injection material to a gel phase in Block S160.

[0086] The method Sioo can also include, in response to gelling of the first part and the second part of the injection material into a solid body within the interior volume of the shell, transitioning the platen 110 to a water bath 160 to dissolve the shell and to release the solid body from the platen 110 in Block S170.

2.1 Applications

[0087] Generally, the method Sioo can be executed by the apparatus 100 to fabricate a shell: suspended from a platen 110; defining an internal mold volume representing a final solid part; defining a static mixing head configured to merge and mix two discrete fluid streams inbound from two injection ports in the platen 110; defining a set of gates and runners extending from the static mixing head to the internal mold volume; and defining a set of vents extending from the internal mold volume to a pressure port 113 in the platen 110. Blocks of the method Sioo can be further executed by the apparatus 100 to: evacuate uncured mold material from the internal mold volume; inject a two-part injection material (e.g., silicone and a catalyst, ceramic and a catalyst, metal particles in a two-part resin binder, etc.); pressurize the internal mold volume via the pressure port 113 while the injection material cures in order to reduce porosity in the injection material as the injection material cures; and to pressure the exterior of the shell as the injection material cures in order to support the shell and prevent the shell from cracking under elevated pressures inside the shell.

[0088] In particular, the apparatus 100 can execute the method S100 automatically to fabricate a one-time-use thin-shell injection mold, to inject injection material into the injection mold as the injection material solidifies (e.g., cures), and to control the pressures inside and outside of the mold as the injection material cures into a final part in order to achieve low porosity (e.g., minimal air bubbles) in the final part while minimizing risk of rupturing the mold. The apparatus 100 can fabricate the onetime-use thin-shell injection mold with a water-soluble photocurable mold material, such as including: a water-soluble resin; a photoinitiator that decomposes into a reactive species that triggers the mold material to locally crosslink when exposed to a target wavelength of electromagnetic radiation (e.g., light); and a UV-blocker that limits depth of transmission of light at the target wavelength through the mold material. The apparatus 100 can therefore fabricate the one-time-use thin-shell injection mold within the fabrication chamber 120 by projecting light from the projection system 122 toward the platen 110 - to selectively cure layers of mold material according to a predefined shell geometry - as the platen 110 is drawn away from the projection system 122 and as fresh (i.e., uncured) mold material is introduced between the platen 110 (and cured mold material suspended from the platen 110) and the projection system 122. Once all layers of the shell have been fabricated - suspended from the platen 110 to define an internal mold volume - within the fabrication chamber 120, the shell can be removed from the fabrication chamber 120 and flushed (e.g., with alcohol) to remove uncured mold material from the internal mold volume. The internal mold volume can also define catches configured to catch and retain uncured mold material - still trapped in the shell following a flush cycle but flowing down to low points in the internal mold volume - outside of a part envelope defined by the internal volume of the shell.

[0089] In addition to a part envelope for a final part formed by material injected into the shell, the shell can also define: a static mixing head fluidly coupled to the two discrete injection ports in the platen no; all gates and runners fluidly coupling the static mixing head to the part envelope; and all vents fluidly coupling the part envelope to the pressure port 113 in the platen 110. During a mold cycle, the apparatus 100 can inject separate reactive components of a two-part injection material into the mold via the first and second injection port 112s; the static mixing head - which is integral to the shell - can fully mix these components of the injection material before the injection material flows to, fills, and cures inside the part envelope defined by the shell. Therefore, substantially all mixed (e.g., cured and semi-cured) injection material dispensed by the apparatus 100 during a mold cycle can be contained within the mold itself, thereby simplifying cleanup, simplifying transition between different injection materials, and limiting material waste. By also pressurizing the interior of the shell, the apparatus 100 can suppress porosity in the injection material while the injection material cures inside the shell; by pressurizing the volume outside and around the shell as the injection material cures, the apparatus 100 can limit a pressure gradient across walls of the shell, thereby limiting deformation of the shell and reducing likelihood of rupture of the shell under elevated internal pressures without necessitating greater wall thickness of the shell, which may otherwise require extended fabrication time and yield greater material waste.

[0090] Furthermore, because the mold material is water soluble once cured, removal of the mold material from the platen 110 can be completed by immersing the platen 110, mold, and solid part - contained inside the mold - into a water bath 160. Furthermore, because the solid part is connected to the platen 110 via the shell, dissolution of the mold material in water can also serve to cleanly separate the solid part from the platen 110. Solubility of the mold material in water - a non-toxic and accessible fluid - can therefore simplify extraction of the solid from the one-time-use thin-shell injection mold upon completion of the mold cycle without sacrificing dimensional stability or detail of the internal mold volume during injection of the mold material during the mold cycle. 2.2 Virtual 3D Shell Geometry

[0091 ] In one variation, the method Sioo includes generating a 3D shell geometry defining the part envelop, resin catches coupled to the part envelope, a static mixing head aligned to injection ports in the platen 110, gates and runners extending between the static mixing head and the part envelope, and vents running from the part envelope to the pressure port 113 in the platen 110. Once the 3D shell geometry is calculated, such as by a computing device (e.g., a local computer or remote computer network), the apparatus 100 can execute Blocks of the method Sioo to fabricate the 3D shell geometry inside the fabrication chamber 120 in preparation for injecting the corresponding shell with a selected injection material.

[0092] In one implementation, a computer system accesses a 3D part model of a final part, such as through a web browser or native application executing on a computing device or from a remote server or database. The computer system then orients the 3D part model relative to a virtual representation of the platen 110 (e.g., a "virtual platen 110") within a virtual environment, such as offset slightly below and centered between injection and pressure port 113s represented by the virtual platen 110 with a minimum number of convex surfaces facing downward and away from the virtual platen 110. The computer system can also: segment the 3D part model into multiple regions, wherein each region contains a single convex surface facing downward and away from the virtual platen 110, which may represent a low point in the one-time use injection mold created according to the resulting virtual 3D shell geometry; and add one virtual drain catch volume to the lowest point on each segment of the 3D part model, as shown in FIGURE 17. For example, each virtual drain catch volume can represent a virtual rectilinear volume that intersects the low point in the 3D part model (i.e., a region furthest from the virtual platen 110); when represented as negative space by the shell, the resulting catch may collect uncured mold material trapped inside the shell that naturally flows downward into the catch due to low viscosity of the uncured mold material. In particular, a small volume of uncured mold material may remain in the shell following removal of the shell from the fabrication chamber 120 and completion of a flushing cycle, as described below, to remove the bulk of uncured mold material from the shell; the catches can thus collect and retain this uncured mold material outside of the part envelope as injection material is injected into the shell during a subsequent injection cycle. In this example, for each virtual drain catch, the computer system can: implement a preset virtual drain catch volume; calculate the volume of the virtual drain catch based on (e.g., proportional to) the surface area of the corresponding segment of the 3D part model; or based on the volume of a corresponding segment of the 3D part model. Furthermore, in this example, the computer system can calculate a volume of each virtual drain catch such that a virtual drain catch is sufficiently large to both 1) collect all trapped uncured mold material within the corresponding segment of the 3D part model and 2) function as a riser that fills with injection material during an injection cycle and permits injection material to move back into and fill the part envelope as the injection material shrinks while curing.

[0093] Once the 3D part model is oriented relative to the virtual platen 110 and virtual drain catches are appended to low points on the 3D part model, the computer system can add virtual flow pathways extending from virtual injection ports represented by the virtual platen 110, to the 3D part volume, and terminating at the virtual pressure port 113 represented by the virtual platen 110. For example, the computer system can: retrieve a predefined static mixing head model, such a representing a generic static mixing head or representing a custom static mixing head model associated with the injection material selected for the final part represented by the 3D part model; insert the predefined static mixing head model into the virtual environment; and align two discrete virtual inlet ports of the static mixing head model with the virtual injection ports of the virtual platen 110, as shown in FIGURE 17. In this example, the computer system can then: calculate lengths and cross-sections of gates, runners, and vents that achieve limit pressures inside the shell during an injection cycle to below a threshold pressure while also achieving at least a minimum dwell time for an injection material selected for the final part represented by the 3D part model based on a known (static or time-dependent) viscosity and known cure time of the injection material; and populate the virtual environment with virtual gates and runners that connect the static mixing head model to the 3D part model based on these length and cross-section parameters, such as by connect gates to sides or tops of segments in the 3D part model. The computer system can similarly populate the virtual environment with virtual vents that connect the 3D part model to the virtual pressure port 113 on the virtual platen 110, such as by adding virtual vents that intersect the 3D part model near the bottom of each segment (e.g., opposite corresponding gates) in the 3D part model in order to permit the system to flush uncured mold material out of a shell - defining the negative space represented in the 3D part model - and to then wash solvent out of the internal volume of the shell via these vents, as shown in FIGURE 16.

[0094] In one variation, the computer system can also locate a virtual premix reservoir (or "resin catch") between the outlet of the static mixing head model and runners extending toward the 3D part model, as shown in FIGURE 17. When realized by the apparatus 100 when fabricating the shell, the premix reservoir can fill with an initial volume of mixed injection material exiting the static mixing head model; once the premix reservoir is filled, additional injection material mixed by and passing through the static mixing head moves into the runners and gates, then into the part envelope defined by the shell, and then into the vents to completely fill the mold. In particular, the premix reservoir can collect and retain an initial volume of mixed injection material exiting the static mixing head in order to avoid introducing this initial volume of injection material - which may exhibit poor mixing, inconsistent composition, or improper ratio of resin components - into the part envelope. The computer system can thus insert a virtual premix reservoir of generic or custom geometry into the virtual environment. For example, the computer system can: calculate a target volume of the premix reservoir based on known mixing characteristics, a known viscosity of the injection material, and a target dwell time assigned to the injection material; and than scale a generic virtual premix reservoir to this target volume.

[0095] The computer system can thus extend the 3D model of the part to include virtual representations of the flow pathway, including a virtual representation of a static mixing head, gates, runners, vents, and/ or a premix reservoir. The computer system can then generate a virtual 3D volume containing and offset from virtual surfaces of the 3D part model, such as according to a uniform offset distance equal to a preset shell thickness assigned to the injection material specified for the final part. Alternatively, the computer system can calculate target shell wall thicknesses along the 3D model of the part based on a known viscosity of the injection material and lengths and geometries of the static mixing head, gates, runners, vents, and final part represented by the 3D part model, etc. For example, the computer system can estimate pressure drops over discreet regions of the 3D part model from the injection port to the pressure port 113 based on the foregoing parameters and then assign a shell thickness to each region of the 3D part model proportional to corresponding pressure drop values. In this example, the computer system can then generate the virtual 3D volume containing and offset from virtual surfaces of the 3D part model by offset distances corresponding to these varying shell thicknesses.

[0096] The computer system can then subtract the 3D part model from the virtual 3D volume to generate a virtual 3D shell geometry. The computer system can also add support structures to the exterior of the virtual 3D shell geometry to support the virtual 3D shell geometry below the virtual platen 110, such as by adding longitudinal and circumferential ribs along junctions between gates and regions of the shell defining the part envelope, between gates and runners, and/or between runners and the mixing head, etc. The computer system can also: segment (or "slice") the virtual 3D shell geometry into a sequence of virtual layers parallel to the virtual platen 110; and represent each virtual layer as a 2D image associated with a discrete height of the shell and that, when projected onto mold material in the fabrication chamber 120 by the projection system 122, selectively cures a thin layer of the mold material in the form of the virtual layer from the virtual 3D shell geometry, as shown in FIGURE 16.

2.3 Mixing Head Variations

[0097] Therefore, the computer system can incorporate a static mixed head into the virtual 3D shell geometry such that a shell - later printed by the apparatus 100 according to the virtual 3D shell geometry - defines a physical static mixing head through which two separate components of the injection material can be pumped to fully mix these components, thereby catalyzing the injection material that then hardens inside the shell to create a physical object representing the original 3D part model. In particular, the shell - once fabricated - can define a static mixing head arranged over and fluidly coupled to injection ports on the platen 110. The static mixing head can be coupled to canisters 152 containing separate components of the designated injection material via hoses coupled to the injection ports such that injection material enters the shell in unmixed components and is mixed only inside of the shell as it passes through the static mixing head segment of the shell, thereby: limiting a distance from the static mixing head to the part envelope defined by the shell, which reduces waste; ensuring that all cured injection material is fully contained inside the shell prior to dissolution of the shell, which eases cleanup; and simplifying detachment and reattachment of the same injection material canisters 152 to the platen 110 in preparation for a next part cycle in which a new shell is fabricated and injected with the injection material.

[0098] Alternatively: the platen 110 can include a single injection port configured to interface with an external prefabricated static mixing head; and the computer system can implement the foregoing methods and techniques to generate a virtual 3D shell geometry that includes a single runner extending from the single injection port. For example, a single injection port in the platen 110 can be threaded to accept a threaded output at the end of a prefabricated static mixing head; or the single injection port can include a smooth bore configured to accept an elastomeric stopper 114 coupled to a single hose extending from an outlet of a remote static mixing head (e.g., integrated into an injection material canister loaded into the injection system 150).

2.4 System Preparation For New Part Cycle

[0099] To prepare the apparatus 100 for a new part cycle, a sequence of 2D images - generated as described above based on a virtual 3D shell geometry representing a final part - is loaded onto the apparatus 100 (or loaded onto a machine nearby that drip-feeds these 3D images into the apparatus 100). A cartridge system containing separate parts of a specified injection material is shaken (e.g., in a "paint mixer") to achieve uniform distribution of their contents (e.g., metal particles), is loaded into the injection system 150, and is connected to the injection ports on the platen 110 with separate supply lines (e.g., "hoses"). For example, the cartridge system: can define two separate cylinders, each containing one of two parts of the injection material and terminating at a nozzle; can include one piston sealed inside of each cylinder; and can include one discrete supply line extending from the nozzle and configured to mate inside a polymeric (e.g., rubber) stopper 114, which is then transiently installed in one of the two injection ports on the platen 110 to fluidly couple the cylinder to a shell that is later fabricated on the bottom of the platen 110. In this example, the injection system 150 can include a linear actuator configured to drive pistons in the cylinders forward to displace injection material components out of each cylinder, through the nozzles, and toward the platen 110 via the supply lines. As described below and shown in FIGURE 18, supply lines coupling the cartridge system to the platen 110 can also include tees - with check valves - that couple the injection ports to separate solvent and air supplies.

[00100] Thus in preparation for a new part cycle, each supply line from the cartridge system can be connected to a polymeric stopper 114, and these polymeric stopper 114s can be pressed into or clamped over corresponding injection ports in the platen 110. Similarly, a third polymeric stopper 114 can be connected to the pressure system 140 and then pressed into or clamped over the pressure port 113. These stopper 114s can thus function to seal the injection and pressure system 140s to the platen 110 to prevent mold material from leaking past the injection and pressure port 113s to the top side of the platen 110 during a fabrication cycle.

2.5 Shell Fabrication According to Virtual 3D Shell Geometry

[00101 ] With the apparatus 100 thus prepared for the new part cycle, the linear motion system 124 can locate the platen 110 (e.g., a flat steel or aluminum plate) over the fabrication chamber 120 and lower the platen 110 toward the bottom of fabrication chamber 120. The bottom of the fabrication chamber 120 can be substantially transparent to a wavelength of electromagnetic radiation (e.g., UV light) that decomposes the (primary) photoinitiator in the mold material; and the projection system 122 can be arranged in the bottom of the machine, can face the platen 110 through the transparent bottom of the fabrication chamber 120, and can be configured to project UV light in the form of 2D images toward the platen 110 to activate photoinitiator at a target distance offset above the bottom of the fabrication chamber 120.

[001 02] With the platen 110 lowered, the reservoir can release mold material into the fabrication chamber 120, such as by actively pumping mold material into the fabrication chamber 120 or by passively releasing mold material into the fabrication chamber 120 as the retraction of the platen 110 from the bottom of the fabrication chamber 120 - by the linear motion system 124 - draws mold material from the reservoir into the fabrication chamber 120. The projection system 122 can then project a first 2D image - generated by the computer system as described above and representing a topmost layer of the shell - toward the bottom face of the platen 110 to selectively cure mold material onto the bottom face of the platen 110. The linear motion system 124 can then index the platen 110 up to the next layer position (i.e., offset above its initial position by a layer thickness implemented by the computer system to generate the sequence of 2D images); the reservoir can release additional mold material into the fabrication chamber 120 to fill a void between the transparent bottom of the fabrication chamber 120 and the new layer of cured mold material extending below the bottom of the platen 110 as the platen 110 rises in the fabrication chamber 120; and the projecting system can project a second 2D image - in the sequence of 2D images representing the shell - toward the platen 110 to cure a next layer of mold material in the form of a corresponding slice of the virtual 3D shell geometry represented by this second 2D image. The apparatus 100 can repeat this process until a final 2D image - in the sequence of 2D images - is output by the projection system 122 to complete the fabrication of the shell, which is still immersed in uncured mold material, as shown in FIGURE 17.

2.6 Shell Preparation for Injection

[001 03] Once the mold material has been selectively cured to form the shell - suspended from the bottom of the platen 110 - according to the 3D shell geometry defined by the computer system, the linear motion system 124 can: retract the platen no and the shell from the fabrication chamber 120: move the platen 110 horizontally into position over the pressure chamber 142; and drive the platen 110 down into contact with the pressure chamber 142, such as to seal the bottom face of the platen 110 against the top edge of the pressure chamber 142 or to seal the perimeter of the platen 110 against the interior wall of the pressure chamber 142, as shown in FIGURE 17.

[00104] After (or before) the linear motion system 124 seals the platen 110 against the pressure chamber 142, the wash system 130 can flush uncured mold material from the interior volume of the shell. In one implementation, the wash system 130 fluidly couples a tee and a supply line at one or both injection ports to a solvent supply 132; and the pressure system 140 fluidly couples a return line extending from the outlet port on the platen 110 to a waste reservoir 136, such as by selectively activating a set of valves between the waste reservoir 136 and the return line, as shown in FIGURE 18. The wash system 130 then pumps solvent into the interior volume of shell - via the injection ports - and evacuates alcohol and uncured mold material from the interior volume of the shell via the return line, as shown in FIGURE 17. For example, the solvent can include dry (i.e., 99.9% water-free) isopropyl alcohol, which may displace uncured solvent out of the shell via the pressure port 113 and which may dry relatively quickly inside the shell without dissolving cured mold material that defines the shell.

[00105] As described above, a first supply line from the injection system 150 to a first injection port 111 in the platen 110 can also include a first tap between the injection system 150 and the first injection port 111; the wash system 130 can fluidly couple to the first tap via a one-way (or "check") valve in order to supply solvent and later a gas to the shell during a flush cycle while also preventing backflow of mold material, solvent, or injection material toward the wash system 130 during the part cycle generally. The second supply line can similarly include a tap and check valve coupled to the same wash system 130.

[00106] To flush the interior volume of the shell, the wash system 130 can pump solvent into the shell over a preset duration or pump a target volume of solvent through the shell, such as proportional to (e.g., twice) a total volume of the interior cavity of the shell. Alternatively, the wash system 130 can include an optical detector arranged across the return line; and the wash system 130 can sample the optical detector to monitor the clarity or color of fluid exiting the shell via the return line as solvent is pumped through the shell and cease this flush cycle only once fluid exiting the shell exhibits at least a threshold clarity or exhibits less than a threshold change in clarity per unit volume of solvent displaced into the shell, as which time the wash system 130 can cease active displacement of solvent through the shell.

[00107] Once the solvent wash is complete, the wash system 130 can fluidly couple the supply lines to a gas supply and then pump gas (e.g., air or inert gas) through the supply lines to draw remaining solvent out of shell. (Alternatively, the wash system 130 can fluidly couple the supply lines to ambient, and the pressure system 140 can draw a vacuum on the pressure port 113 to draw air into the shell to displace solvent into the waste reservoir 136. Yet alternatively, the first supply line can be fluidly coupled to the solvent reservoir 134 of the wash system 130, the second supply line can be fluidly coupled to the gas supply, and the apparatus 100 can selectively activate the wash system 130 and the air supply to selectively pump solvent and gas, respectively, into the shell.) Once a (significant) proportion of remaining solvent is displaced out of the shell and/or evaporated from the shell, the apparatus 100 can cease the flush cycle and execute an injection cycle to fill the shell with injection material.

2.7 Injection Cycle

[00108] During the injection cycle, the apparatus 100 drives the injection system 150 forward to displace both components of the injection material out of the canisters 152, through the supply lines, and the shell via the injection ports in the platen 110, as shown in FIGURES 16 and 18. The two components of the injection material mix as they are displaced under pressure through the static mixing head and then enter the premix reservoir succeeding the static mixing head; once the premix reservoir is filled, additional mixed injection material exiting the static mixing reservoir can move through the runners and gates into the part envelope and then into the vents once the part envelope is filled by mixed injection material.

[00109] During the injection cycle, the apparatus 100 can advance the injection system 150 at a target injection speed (or target injection flow rate) based on: lengths and geometries of the static mixing head, gates, and runners defined by the shell; a target dwell time assigned to the injection material; and the known viscosity of the injection material, which may be time-dependent based on a cure rate of the injection material. The apparatus 100 can also monitor a torque output of the injection system 150 necessary to maintain the target injection speed, correlate this torque with a fluid pressure inside the shell, and adjust the speed of the injection system 150 to maintain fluid pressure inside the shell below a threshold fluid pressure. (Alternatively, the apparatus 100 can sample a pressure sensor coupled to one or more supply lines to monitor fluid pressure in the shell.)

[001 1 0] The apparatus 100 can then cease driving the injection system 150 forward once a displaced volume of injection material meets (or slightly exceeds) a known interior volume of the shell, such as accounting for expansion or shrinkage of the injection material during cure, and accounting for a swept volume of the supply lines less a proportion of the volume of vents in the shell in order to prevent displacement of mixed injection material through the pressure port 113, which may otherwise negative ease of removal of the final part from the platen 110.

2.8 Gelling Process and Porosity Suppression

[001 1 1 ] Once the shell is filled with injection material following conclusion of the injection cycle, the pressure system 140 can pressurize both the interior of the pressure chamber 142 - outside of the shell - and the interior of the shell in order to suppress porosity in the mixed injection material as the injection material cures inside the shell, as shown in FIGURE 16.

[001 1 2] In one example, the pressure system 140 pumps a gas (e.g., air or an inert gas, such as argon) into the shell - via the return line and the pressure port 113 - up to a target pressure (e.g., 80 psi). As pressure inside the shell is increased, the pressure system 140 can also drive the injection system 150 forward slightly to achieve and maintain this same target pressure at the injection port such that fluid pressure across the injection material within the shell is substantially uniform and such that backflow of mixed injection material through the static mixing head toward the injection ports is limited. In particular, by maintaining the fluid pressure inside the shell - currently filled with injection material - at or near the elevated target pressure, gas pockets (e.g., "air bubbles") entrapped in the mixed injection material may shrink to a point at which they are no longer visible.

[001 13] However, such elevated pressures inside the shell may induce stress in the walls of the shell that may lead to shell failure prior to complete gelling of the mixed injection material. Therefore, the pressure system 140 can also pump air or other gas into the pressure chamber 142 up to the target pressure, thereby limiting a pressure differential across the shell wall, reducing hoop stress on the shell, and thus supporting the shell against fracture due to elevated fluid pressures inside the shell. For example, the pressure system 140 can fluidly couple the return line - coupled to the pressure port 113 on the platen 110 - to the interior volume of the pressure chamber 142 and then pump air into the return line to pressure the interior volume of the shell and the pressure chamber 142 equally as the mixed injection material cures inside the shell.

[001 14] The pressure system 140 can hold the interior and exterior of the shell at this elevated pressure for at least a minimum duration corresponding to a known or estimated gel time of the injection material once mixed in order to prevent gas pockets trapped within the injection material from expanding once this elevated pressure is released.

[001 15] However, once the mixed injection material has gelled sufficiently (e.g., the gel time has passed since the injection cycle was completed, plus a time safety factor), the pressure system 140 can release pressure on the interior of the shell and the pressure chamber 142. The linear motion system 124 can then elevate the platen 110 - including the shell filled with injection material suspended from the platen 110 - out of the pressure chamber 142 in preparation for removal of the shell.

2.Q Shell Removal

[001 16] In one variation shown in FIGURE 16, the apparatus 100 further: includes a water tank 160, such as including a heating element and an ultrasonic transducer (or other agitation mechanism 162) configured to heat and agitate water contained in the water tank 160, respectively, as shown in FIGURE 17. For example, the fabrication chamber 120, pressure chamber 142, and water tank 160 can be adjacent one another and arranged in a linear or radial pattern inside the apparatus 100. In this variation, the apparatus 100 can also include a skimmer configured to remove dissolved mold material from the water tank 160, such as following a shell removal cycle.

[001 1 7] In one implementation, the apparatus 100 preheats water in the water tank 160, such as during fabrication of the shell and/or during the injection cycle. Once the injection cycle is complete and the mixed injection material has gelled, the linear motion system 124 automatically withdraws the platen 110 out of the pressure chamber 142, moves the platen 110 laterally into position over the water tank 160, and then submerges the platen 110 - with the shell and injection material suspended from below - into the water tank 160. Because the cured mold material is water soluble, as described above, the heated water in the water tank 160 can dissolve the cured mold material while the transducer agitates water around the shell, thereby improving a rate of dissolution of the mold material into the water in the water tank 160.

[001 1 8] The linear motion system 124 can maintain the platen 110 submerged in the water tank 160 for a period of time sufficient to fully dissolve all cured mold material from the platen 110 in preparation for a next part cycle. For example, the apparatus 100 can calculate a submerse time proportional to a maximum wall thickness of the shell. The linear motion system 124 can then remove the platen 110 from the water tank 160 and return the platen 110 to the fabrication chamber 120 in preparation for a next part cycle once this submerse time has passed or once a load on the linear motion system 124 indicates that a mass (i.e., the final part) has disconnected and dropped from the bottom face of the platen 110. In particular, once the shell is fully or sufficiently dissolved, the gelled injection material - now defining a solid part including gates, runners, etc. - may detach from the platen 110 and fall to the bottom of the water tank 160. With the platen 110 removed from the water tank 160, a user may manually remove the part from the bath, such as with tongs. Alternatively, the water tank 160 can be loaded with a wire basket, and the user can manually lift the wire basket out of the water tank 160 to retrieve the solid part. Yet alternatively, the linear motion system 124 can automatically elevate the wire basket out of the water bath 160 to present the solid part to a user for inspection and additional processing.

[001 1 9] Alternatively, once the injection material is fully or sufficiently gelled and the linear motion system 124 retracts the platen 110 from the pressure chamber 142, a user can manually retrieve the platen 110 and immerse the platen 110 and shell in an external water bath 160 to dissolve the shell away from the part.

[001 20] However, the apparatus 100 can include any other elements and function in any other way to automatically dissolve the shell from the solid part inside or to support a user in manually processing the platen 110 to remove the shell from the solid part inside.

2.10 Post Processing

[001 21 ] The solid part can then be post-processed, such as by manually trimming gates, runners, catches, etc. from the solid part, as shown in FIGURE 17. For the injection material that includes metal particles suspended in a resin, the resin can be burned out of the solid part to leave (substantially) only metal particles, and these remaining metal particles can then be sintered into a final near-full-density (e.g., ~ioo% dense) metal part.

[001 22] The systems and methods described herein can be embodied and/or implemented at least in part as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions can be executed by computer-executable components integrated with the application, applet, host, server, network, website, communication service, communication interface, hardware/firmware/ software elements of a user computer or mobile device, wristband, smartphone, or any suitable combination thereof. Other systems and methods of the embodiment can be embodied and/or implemented at least in part as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions can be executed by computer-executable components integrated by computer-executable components integrated with apparatus looes and networks of the type described above. The computer-readable medium can be stored on any suitable computer readable media such as RAMs, ROMs, flash memory, EEPROMs, optical devices (CD or DVD), hard drives, floppy drives, or any suitable device. The computer-executable component can be a processor but any suitable dedicated hardware device can (alternatively or additionally) execute the instructions.

[001 23] As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the embodiments of the invention without departing from the scope of this invention as defined in the following claims.