Production of manufactured parts can include initial forming processes that produce an initial work piece and finishing processes that produce a final part from the initial work piece. Near net shape forming refers to initial forming processes that produce a work piece that is very close to a desired final (net) shape. As a result, finishing processes such as machining and grinding, can be reduced or substantially eliminated. Because finishing operations can represent more than half the total cost of producing a manufactured item, there is an ongoing need for new and improved near net shape forming processes.
There exist a variety of near net shape forming processes suitable for fabrication of metal and ceramic parts. In one example, powder injection molding (PIM) employs a mixture of powders of a ceramic or metal mixed with a binder to form a feedstock that is injection molded to form a green body that is subsequently processed to form a near net shape work piece. In another example, additive manufacturing (e.g., solid freeform fabrication or layer manufacturing) is a class of a manufacturing processes that can employ computer aided design (CAD) outputs to build an object on a layer-by-layer and point-by-point basis to form a green body that is subsequently processed to form a near net shape work piece.
While the manner of forming the green body can differ between PIM and the various additive manufacturing processes, the green body can be processed in a similar manner for each to form the near net shape work piece. In a debinding process, some or all of the binder is removed from the green body to form a brown body. The brown body is then heated (sintered) to consolidate the brown body and form the work piece. In certain manufacturing operations, debinding and sintering can be performed simultaneously.
Regardless of the specific manner in which the green body is formed, near net shape forming processes can commonly employ support structures. Support structures can be positioned at predetermined locations with respect to a green body for mechanical support. As an example, parts can be designed with open spaces (e.g., voids) and regions that overlie the open space, also referred to overhang. If unsupported during debinding and/or sintering, overhangs can sag or collapse under their own weight, producing a work piece that is deformed as compared to a desired near net shape.
However, the use of support structures can present challenges. As an example, a green body undergoing debinding/sintering will shrink as void space between the powder is reduced. If the support structure does not shrink at approximately the same rate as the green/brown body, the part can be deformed or damaged. In one aspect, when the support structure shrinks too fast, it can fail to support the green/brown body. In another aspect, when the support structure shrinks too slow, it can exert forces on the green/brown body that cause the green/brown body to crack or break. In another example, it can be difficult to remove support structure from the near net shape work piece. While various approaches have been developed to address this concern, such as breaking the support structure and dissolving or melting the support structure, these approaches can result in imperfections on the surface of the work piece and necessitate further finishing operations.
In general, systems and methods are provided for separation of support structures from near net shape manufactured parts.
In one embodiment, a system is provided and can include a support structure and a non-adhering material. The non-adhering material can be positioned on one or more predetermined exterior-facing surfaces of the support structure. The support system can be dimensioned for receipt within a void space of a porous green body defined by an overhang region of the porous green body. After receipt within a void space of a porous green body that undergoes a thermally-induced volumetric change, the support system can be configured to support the overhang region and the non-adhering material can be configured to inhibit adherence of the exterior-facing surfaces of the support structure to opposed surfaces of the void space.
In another embodiment, after receipt within a void space of a green body that undergoes a thermally-induced volumetric change, the support system can be configured to undergo a volumetric change that occurs at a rate that can be approximately equal to the rate of volumetric change of the void space.
In another embodiment, after receipt within a void space of a green body that undergoes a thermally-induced volumetric change, the support system can be configured to maintain at least a portion of the support structure in contact with an underlying surface of the overhang region.
In another embodiment, the support structure can be formed from a support composition that can include at least one support powder and at least one support binder.
In another embodiment, the at least one support powder includes at least one of metal powders or ceramic powders.
In another embodiment, the support binder includes at least one of an organic polymer or an inorganic material.
In another embodiment, the non-adhering material can be formed from a non-adhering composition that can include at least one non-adhering powder dispersed in at least one non-adhering binder.
In another embodiment, the at least one non-adhering powders can include at least one of oxides, carbides, sulfides, nitrides, fluorides, ceramics, or metals.
In another embodiment, the at least one non-adhering powder can include at least one of silicon dioxide, refractory sands, aluminum oxide, titanium oxide, vanadium oxide, molybdenum oxide, or zirconium oxide.
In another embodiment, a mean particle size of the at least one non-adhering powder can be approximately equal to a mean particle size of the at least one green body powder.
In another embodiment, a mean particle size of the at least one non-adhering powder can be less than 250 μm.
In another embodiment, a mean particle size of the at least one non-adhering powder can be selected from the range of about 5 μm to about 50 μm.
In another embodiment, the at least one non-adhering binder can include an organic polymer.
In another embodiment, the at last one non-adhering binder can include at least one of polyvinyl alcohol (PVA), sodium silicate, potassium silicate, polyvinyl acetate, gelatin, polyvinyl pyrrolidone, Polyacrylamide, Polyacrylic acid and copolymers, polyethylene glycols, Polyamines, polyethyleneimines, quaternary ammonium compounds, Polyvinyl methyl ether/maleic anhydride, polyurethanes and their suspensions, polyolefins, polyacetals, organic waxes, or carboxypolymethylene.
In another embodiment, a geometry of exterior-facing surfaces of the support structure can be configured to substantially mirror a geometry of opposed surfaces of a void space of a green body that the support structure can be dimensioned for receipt within.
In another embodiment, the non-adhering material can be in the form of a coating on the exterior-facing surfaces of the support structure.
In another embodiment, a geometry of exterior-facing surfaces of the support structure does not substantially mirror a geometry of opposed inward facing surfaces of a void space of a green body that the support structure can be dimensioned for receipt within, and wherein the non-adhering material can be in the form of a paste that can be configured to fill one or more gaps between the exterior-facing surfaces of the support structure and the opposed surfaces of the void space.
In another embodiment, the support system includes a plurality of support sub-structures having a portion of the non-adhering material interposed between respective ones of the support sub-structures.
Embodiments of the support sub-structures can adopt a variety of configurations. In one aspect, the support sub-structures can be pyramids. In another embodiment, the support sub-structures can be plates.
In a further embodiment, a method is provided. The method can include providing a porous green body formed from at least one green body powder and at least one green body binder, the green body including a geometry including a predetermined void space defining an overhang region; applying a non-adhering material to one or more predetermined exterior-facing surfaces of a support structure while the support structure is distanced from the void space to form a support system, inserting at least a portion of the support system within the void space; debinding the green body after insertion of the support system according to a predetermined debinding temperature profile to remove a predetermined portion of the green body binder from the green body; and sintering the green body according to a predetermined sintering temperature profile after insertion of the support system to form a consolidated work piece including a predetermined porosity. The non-adhering material can be configured to inhibits adherence of the green body and the consolidated work piece to the support structure. The support system can be dimensioned to support at least a portion of the overhang region during debinding and sintering.
In another embodiment, the method can also include removing the support system from the consolidated work piece after sintering.
In another embodiment, providing the green body can include forming the green body by injection molding a green body composition including the at least one green body powder and the at least one green body binder.
In another embodiment, providing the green body can include forming the green body from successively deposited layers of a green body composition including the at least one green body powder and the at least one green body binder.
In another embodiment, depositing the layers can include extruding a second green body composition including the at least one green body powder and the at least one green body binder.
In another embodiment, depositing the layers can include spraying the at least one green body binder onto a bed of the at least one green body powder.
In another embodiment, the at least one green body powder can include at least one of metal powders or ceramic powders.
In another embodiment, the at least one green body binder can include an organic polymer.
In another embodiment, the support structure can be formed from a support composition that can include at least one support powder and at least one support binder.
In another embodiment, the at least one support powder can include at least one of metal powders or ceramic powders.
In another embodiment, the at least one support binder can include at least one of an organic polymer or an inorganic material.
In another embodiment, the non-adhering material can be formed from a non-adhering composition including at least one non-adhering powders dispersed in at least one non-adhering binder.
In another embodiment, the at least one non-adhering powders can include at least one of oxides, carbides, sulfides, nitrides, fluorides, ceramics, or metals.
In another embodiment, the at least one non-adhering powder can include at least one of silicon dioxide, refractory sands, aluminum oxide, titanium oxide, vanadium oxide, molybdenum oxide, or zirconium oxide.
In another embodiment, a mean particle size of the at least one non-adhering powder can be approximately equal to a mean particle size of the at least one green body powder.
In another embodiment, a mean particle size of the at least one non-adhering powder can be less than 250 μm.
In another embodiment, a mean particle size of the at least one non-adhering powder can be selected from the range of about 5 μm to about 50 μm.
In another embodiment, the at least one non-adhering powder does not undergo sintering at the predetermined sintering temperature.
In another embodiment, the at least one non-adhering powder undergoes sintering at a higher temperature than the at least one green body powder.
In another embodiment, the at least one non-adhering powder undergoes sintering to itself at the predetermined sintering temperature and does not undergo sintering to the green body at the predetermined sintering temperature.
In another embodiment, the at least one non-adhering binder includes an organic polymer.
In another embodiment, the at least one non-adhering binder includes at least one of polyvinyl alcohol (PVA), sodium silicate, potassium silicate, polyvinyl acetate, gelatin, polyvinyl pyrrolidone, Polyacrylamide, Polyacrylic acid and copolymers, polyethylene glycols, Polyamines, polyethyleneimines, quaternary ammonium compounds, Polyvinyl methyl ether/maleic anhydride, polyurethanes and their suspensions, polyolefins, polyacetals, organic waxes, or carboxypolymethylene.
In another embodiment, a volumetric concentration of the at least one green body powder in the green body composition forming the green body can be approximately equal to a volumetric concentration of the at least one non-adhering powder in the non-adhering material composition.
In another embodiment, a rate of volumetric reduction of the void space occurring during sintering can be approximately equal to a rate of volumetric reduction of the support system during sintering.
In another embodiment, the support system can be configured such that at least a portion of exterior-facing surfaces of the non-adhering material remain in contact with the green body during sintering.
In another embodiment, debinding can be performed concurrently with sintering.
In another embodiment, a geometry of exterior-facing surfaces of the support structure positioned opposite inward facing surfaces of the void space can be configured to substantially mirror a geometry of the opposed inward facing surfaces of the void space.
In another embodiment, the non-adhering material can be in the form of a coating on the exterior-facing surfaces of the support structure.
In another embodiment, a geometry of exterior-facing surfaces of the support structure positioned opposite inward-facing surfaces of the void space does not substantially mirror a geometry of opposed inward facing surfaces of the void space, and wherein the non-adhering material can be in the form of a paste that fills one or more gaps between exterior-facing surfaces of the support structure and the opposed inward facing surfaces of the void space.
In another embodiment, the support system includes a plurality of support sub-structures having a portion of the non-adhering material interposed between respective ones of the support sub-structures.
Embodiments of the support sub-structures can adopt a variety of configurations. In one aspect, the support sub-structures can be pyramids. In another aspect, the support sub-structures can be plates.
In another embodiment, a system is provided and it can include a green body and a support system. The green body can be porous and it can include layers of a green body composition. The green body can also include a geometry including a predetermined void space defining an overhang region. The a support system can include a support structure and a non-adhering material, the support structure including layers of a support composition and the non-adhering material including layers of a non-adhering composition. The non-adhering material can be interposed between the green body and the support structure. The support system can be positioned within a void space of the porous green body defined by an overhang region of the porous green body. In response to the porous green body undergoing a thermally-induced volumetric change, the support system can support the overhang region, and the non-adhering material can inhibit adherence of exterior-facing surfaces of the support structure to opposed surfaces of the void space.
In another embodiment, wherein the support system can be configured to undergo a volumetric change that occurs at a rate that can be approximately equal to a volumetric change of the void space.
The system of claim 0, wherein the support system can be configured to maintain at least a portion of the support structure in contact with an underlying surface of the overhang region.
In another embodiment, the layers of the green body can be are formed from a green body composition that can include at least one green body powder and at least one green body binder.
In another embodiment, the at least one green body powder can include at least one of metal powders or ceramic powders.
In another embodiment, the at least one green body binder can include an organic polymer.
In another embodiment, the layers of the support structure can be formed from a support structure composition that can include at least one support powder and at least one support binder.
In another embodiment, the at least one support powder can include at least one of metal powders or ceramic powders.
In another embodiment, the at least one support binder can include at least one of an organic polymer or an inorganic material.
In another embodiment, the green body and the support structure can be formed from the same material.
In another embodiment, the non-adhering composition can include at least one non-adhering powder dispersed in at least one non-adhering binder.
In another embodiment, the at least one non-adhering powder can include at least one of oxides, carbides, sulfides, nitrides, fluorides, ceramics, or metals.
In another embodiment, the at least one non-adhering powder can include at least one of silicon dioxide, refractory sands, aluminum oxide, titanium oxide, vanadium oxide, molybdenum oxide, or zirconium oxide.
In another embodiment, a mean particle size of the at least one non-adhering powder can be approximately equal to a mean particle size of the at least one green body powder.
In another embodiment, a mean particle size of the at least one non-adhering powders can be less than 250 μm.
In another embodiment, a mean particle size of the at least one non-adhering powders can be selected from the range of about 5 μm to about 50 μm.
In another embodiment, a maximum particle size of the at least one non-adhering powder can be less than a thickness of the layers containing the non-adhering material.
In another embodiment, the at least one non-adhering binder can include at least one of polyvinyl alcohol (PVA), sodium silicate, potassium silicate, polyvinyl acetate, gelatin, polyvinyl pyrrolidone, Polyacrylamide, Polyacrylic acid and copolymers, polyethylene glycols, Polyamines, polyethyleneimines, quaternary ammonium compounds, Polyvinyl methyl ether/maleic anhydride, polyurethanes and their suspensions, polyolefins, polyacetals, organic waxes, or carboxypolymethylene.
In another embodiment, in response to the green body undergoing a thermally-induced volumetric change, the support system can be configured to undergo a volumetric change at a rate that can be approximately equal to a rate of volumetric change of the void space.
In another embodiment, in response to the green body undergoing a thermally-induced volumetric change, the support system can be configured such that at least a portion of exterior-facing surfaces of the non-adhering material remain in contact with the green body.
In another embodiment, the non-adhering material can be formed from reagents that are configured to undergo a chemical and/or physical reaction in combination to form the non-adhering material.
In another embodiment, the reagents can include a water soluble salt of a heavy metal; and hydroxide or a salt of a weak acid that thermally decomposes. The decomposition products can be at least one of a water insoluble hydroxide; or an inorganic material capable of dissolution in a solvent and recovered by drying. The hydroxide can be sodium hydroxide and the salt of a weak acid can be a sodium or a potassium salt.
In another embodiment, the support system comprises a plurality of support sub-structures having a portion of the non-adhering material interposed between respective ones of the support sub-structures.
Embodiments of the support sub-structures can adopt a variety of configurations. In one aspect, the support sub-structures can be pyramids. In another aspect, the support sub-structures can be plates.
In another embodiment, a method is provided. The method can include forming a porous green body from successively deposited layers of a green body composition, the green body including a geometry including a predetermined void space defining an overhang region and forming a support system concurrently with the green body from successively deposited layers of a support structure that can include a support composition and a non-adhering material that can include a non-adhering composition. The non-adhering material can be interposed between the green body and the support structure. The method can further include debinding the green body after formation of the support system according to a predetermined debinding temperature profile such that a predetermined portion of the green body binder is removed from the green body; and sintering the green body according to a predetermined sintering temperature profile to form a consolidated work piece including a predetermined porosity. The non-adhering material can be configured to inhibits adherence of the green body and the consolidated work piece to the support structure. The support system can be dimensioned to inhibit sagging of the overhang region during debinding and sintering.
In another embodiment, the method can include removing the support system from the consolidated work piece after sintering.
In another embodiment, the green body composition can include at least one green body powder and at least one green body binder.
In another embodiment, the at least one green body powder can include at least one of metal powders and ceramic powders.
In another embodiment, the at least one green body binder can include an organic polymer.
In another embodiment, the support composition can include at least one support powder and at least one support binder.
In another embodiment, the at least one support powder can include at least one of metal powders or ceramic powders.
In another embodiment, the at least one support binder can include at least one of an organic polymer or an inorganic material.
In another embodiment, the green body composition and the support composition can be the same.
In another embodiment, the non-adhering composition can include at least one non-adhering powder dispersed in at least one non-adhering binder.
In another embodiment, the at least one non-adhering powder can include at least one of oxides, carbides, sulfides, nitrides, fluorides, ceramics, or metals.
In another embodiment, the at least one non-adhering powder can include at least one of silicon dioxide, refractory sands, aluminum oxide, titanium oxide, vanadium oxide, molybdenum oxide, or zirconium oxide.
In another embodiment, a mean particle size of the at least one non-adhering powder can be approximately equal to a mean particle size of the at least one green body powder. In another embodiment, a mean particle size of the at least one non-adhering powder can be less than 250 μm.
In another embodiment, a mean particle size of the at least one non-adhering powder can be selected from the range of about 5 μm to about 50 μm.
In another embodiment, a maximum particle size of the at least one non-adhering powder can be less than a thickness of the layers containing the non-adhering material.
In another embodiment, the at least one non-adhering powder does not undergo sintering at the predetermined sintering temperature.
In another embodiment, the at least one non-adhering powder can undergo sintering at a higher temperature than the predetermined sintering temperature.
In another embodiment, the at least one non-adhering powder undergoes sintering to itself at the predetermined sintering temperature and does not undergo sintering to the green body at the predetermined sintering temperature.
In another embodiment, the at least one non-adhering binder can include at least one of polyvinyl alcohol (PVA), sodium silicate, polyvinyl alcohol (PVA), sodium silicate, potassium silicate, polyvinyl acetate, gelatin, polyvinyl pyrrolidone, Polyacrylamide, Polyacrylic acid and copolymers, polyethylene glycols, Polyamines, polyethyleneimines, quaternary ammonium compounds, Polyvinyl methyl ether/maleic anhydride, polyurethanes and their suspensions, polyolefins, polyacetals, organic waxes, or carboxypolymethylene.
In another embodiment, a volumetric concentration of the at least one non-adhering powder in the non-adhering composition can be approximately equal to a volumetric concentration of the at least one green body powder in the green body composition.
In another embodiment, a volumetric reduction of the support system during debinding and sintering of the green body can occur at a rate that can be approximately equal to a volumetric reduction of the void space.
In another embodiment, the support system can be configured such that at least a portion of exterior-facing surfaces of the non-adhering material remain in contact with the green body during sintering.
In another embodiment, debinding can be performed concurrently with sintering.
In another embodiment, the non-adhering material can be formed from reagents configured to undergo a chemical and/or physical reaction in combination to form the non-adhering material.
In another embodiment, the reagents can include a water soluble salt of a heavy metal; and a hydroxide or a salt of a weak acid that thermally decomposes. The thermal decomposition product can include at least one of a water insoluble hydroxide or an inorganic material capable of dissolution in a solvent and recovered by drying. The hydroxide can be sodium hydroxide and the salt of a weak acid can be a sodium or a potassium salt.
The support system can include a plurality of support sub-structures having a portion of the non-adhering material interposed between respective ones of the support sub-structures.
Embodiments of the support sub-structures can adopt a variety of configurations. In one aspect, the support sub-structures can be pyramids. In another aspect, the support sub-structures can be plates.
These and other features will be more readily understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
It is noted that the drawings are not necessarily to scale. The drawings are intended to depict only typical aspects of the subject matter disclosed herein, and therefore should not be considered as limiting the scope of the disclosure. Those skilled in the art will understand that the systems, devices, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the presently disclosed embodiments is defined solely by the claims.
As discussed above, there exist a variety of near net shape forming processes suitable for fabrication of metal and ceramic parts, and these processes can employ support structures positioned at predetermined locations with respect to a green body for mechanical support. However, in use, support structures can damage the green body during manufacturing or the fabricated near net shape part when removed. Accordingly, improved systems and methods are provided for removal of support structures from near net shape manufactured parts. Near net shape manufactured parts can also be referred to herein as work pieces.
In an embodiment, operation 102 of the method 100 of
The green body 200 can be formed by a variety of manufacturing processes. In one example, the manufacturing process can be an injection molding process (e.g., powder injection molding) that employs a composition including the at least one green body powders and the at least one green body binder. As an example, a metal green body can be formed by a metal injection molding (MIM) process, while a ceramic green body can be formed by a ceramic injection molding (CIM) process.
In another example, the manufacturing process can be an additive manufacturing process. The additive manufacturing process can form the green body 200 from successively deposited layers of a green body composition including the at least one green body powder and the at least one green body binder.
Additive manufacturing processes can include, but are not limited to, VAT photo polymerization, material jetting, binder jetting, material extrusion, powder bed fusion, sheet lamination, directed energy deposition, or combinations thereof. In one embodiment, the layers of the green body 200 can be formed by deposition of a bed of the green body powder (e.g., ceramic powder, metal powder, etc.) and the green body binder can be jetted over a predetermined cross-sectional area for the geometry of the green body 200 at the location of respective deposited powder layers. In another embodiment, the layers of the green body 200 can be formed by extrusion of a composition including the at least one green body powder and the at least one green body binder can be extruded. In a further embodiment, the green body 200 can be formed according to International Application No. PCT/US2017/042223, filed on Jul. 14, 2017 and entitled “Method of Fabricating A Three Dimensional Object With Removable Support Structure,” the entirety of which is hereby incorporated by reference.
In an embodiment, operation 104 of the method of
The support structure 206 can be formed from a support structure composition including at least one support structure powder and at least one support structure binder. The at least one support structure powder can include least one of metal powders, ceramic powders, or combinations thereof. The support structure binder can include at least one of organic polymers or inorganic materials.
The support structure 206 can be formed from the support structure composition by any manufacturing process. As an example, the support structure 206 can be formed by at least one of injection molding or additive manufacturing, as discussed above. In certain embodiments, the support structure 206 can be formed by the same manufacturing process as the green body.
The support structure 206 can be configured such that it undergoes a rate of volumetric reduction during sintering that is approximately equal to a rate of volumetric contraction of the void space 202 in which it is received. This rate of volumetric contraction can ensure that the non-adhering material 300 remains in contact with opposed surfaces of the green body 200 during manufacturing. In another aspect, this rate of volumetric contraction can inhibit exertion of force on the green body 200 due to differential contraction of the support structure 206 and the green body 200. As a result, the support structure 206 can support the green body 200 sufficiently during manufacturing to avoid undesired deformation, cracking, and/or failure of the green body 200.
The non-adhering material 300 can be formed from a non-adhering material composition including at least one non-adhering powder and at least one non-adhering binder. A volumetric concentration of the at least one non-adhering powder in the non-adhering material composition can be approximately equal to a volumetric concentration of the at least one green body powder in the green body composition.
The at least one non-adhering powder can include, but is not limited to, at least one of oxides, carbides, sulfides, nitrides, fluorides, ceramics, or metals. In certain embodiments, the at least one non-adhering powder can include at least one of silicon dioxide, refractory sands, aluminum oxide, titanium oxide, vanadium oxide, molybdenum oxide, or zirconium oxide
The non-adhering binder can include at least one organic polymer. In certain embodiments, the at least one non-adhering powder can include at least one of polyvinyl alcohol (PVA), sodium silicate, potassium silicate, polyvinyl acetate, gelatin, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid and copolymers, polyethylene glycols, polyamines, polyethyleneimines, quaternary ammonium compounds, polyvinyl methyl ether/maleic anhydride, polyurethanes and their suspensions, polyolefins, polyacetals, organic waxes, or carboxypolymethylene. Other powders and binders are also contemplated.
As discussed below, the non-adhering material 300 can be configured to inhibit adherence of the support structure 206 to the green body 200 and the work piece. In this manner, damage to the near net shape part formed from the green body 200 can be avoided when removing the support structure 206.
The non-adhering material 300 can inhibit adherence in a variety of ways. In one aspect, the non-adhering material 300 can remain interposed between the part and the support structure 206 during manufacturing.
In another aspect, the non-adhering material 300 can be configured to undergo sintering at a temperature that is higher than a starting sintering temperature of the one or more green body powder. As an example, the at least one non-adhering powder can be configured to undergo sintering at a temperature that is about 20° C. or greater than a starting sintering temperature of the at least one green body powder.
In a further aspect, the non-adhering material 300 can undergo sintering within itself during manufacturing of the part but is configured to not sinter to the green body 200 or the part. As an example, the part can be formed from a material to which the non-adhering material 300 does not sinter. In one embodiment, the part can be formed from metal powders and the non-adhering material 300 can be formed from ceramic powders.
In an additional aspect, embodiments of the non-adhering material 300 can be configured to undergo a chemical and/or physical reaction to form a modified non-adhering material. The modified non-adhering material can be configured to inhibit adhesion of the support structure 206 from the green body 200 and work piece (e.g., debinded and/or sintered work piece, as discussed below) according to any of the mechanisms discussed above. It can be understood that discussion of the non-adhering material 300 herein is inclusive of such modified non-adhering materials.
A composition of the modified non-adhering material can include a water soluble salt of a heavy metal and sodium hydroxide or a sodium or potassium salt of a weak acid that thermally decomposes. The thermal decomposition products can be a water insoluble hydroxide or an inorganic material capable of dissolution in a solvent and recovered by drying.
The size of the non-adhering powders can be selected such that a mean particle size (e.g., mean diameter) of the non-adhering particles is approximately equal to a mean particle size of the green body powder. In one example, the mean particle size of the non-adhering particles can be less than 250 In another example, the mean particle size of the non-adhering particles can be less than 250 μm and greater than 50 In a further example, the mean particle size of the non-adhering particles can be less than 50 In an additional example, the mean particle size of the non-adhering particles can be selected from the range of 5 μm to 50 μm.
The non-adhering material 300 can be applied to exterior-facing surfaces of the support structure 206 in a variety of ways. In one example, the non-adhering material 300 can be in the form of a coating applied to the support structure 206 by dipping the predetermined exterior-facing surfaces of the support structure 206 in the non-adhering material coating. In another example, the non-adhering material 300 can be in the form of a coating applied to the green body 200 by dipping at least a portion of the green body 200 containing the void space 202 in the non-adhering material coating. At least a portion of the non-adhering material 300 can be further transferred from the outer surface of the void space 202 to the predetermined exterior-facing surfaces of the support structure 206 when the support structure 206 is inserted within the void space 202.
In an embodiment, operation 106 of the method 100 of
In an embodiment, the method 100 of
As shown in
In one aspect, the debinding enclosure 500 can include a heater 502 in communication with a controller (not shown) configured to regulate a temperature of the enclosure according to a predetermined debinding temperature profile (time as a function of temperature) to remove a predetermined portion of the green body binder 504 from the green body. Generally, the temperature profile can be varied for different compositions of the binder 504. As an example, the debinding temperature profile can be selected based upon a thermogravimetric analysis (TGA).
The debinding enclosure 500 can include an inlet 506 and an exhaust 510. The inlet 506 can be in fluid communication with one or more gases. The exhaust 510 can be in fluid communication with a fan or pump configured to apply a negative pressure to the enclosure 500 sufficient to extract gas(es) from the enclosure.
In certain embodiments, debinding can be performed according to a catalytic debinding process. As an example, a highly concentrated acid can be supplied to the enclosure 500 at an elevated temperature (e.g., below a softening temperature of the binder) to create a gaseous acid environment. The acid can include, but is not limited to, concentrated nitric acid and concentrated oxalic acid. The acid can act as a catalyst in decomposition of the binder. Reaction products can be vented through the exhaust 510.
In an embodiment, operation 112 of the method 100 of
As an example, the predetermined sintering temperature profile can be selected based upon the composition of the green body 200, 602, as well as the gas environment of the sintering enclosure 600. In certain embodiments, the predetermined sintering temperature profile can be configured to achieve a green body porosity less than 5% on the basis of an amount of porosity present prior to sintering. In further embodiments, the predetermined sintering temperature profile can be configured to achieve a green body porosity within the range from about 1% porosity to about 5% porosity on the basis of an amount of porosity present prior to sintering.
As discussed above, in certain embodiments, the support structure 206 can exhibit a rate of volumetric reduction during sintering that is approximately equal to a rate of volumetric contraction of a void space 202 in which it is received. In this manner, the support structure 206 can support the green body 200, 602 sufficiently during manufacturing to avoid undesired deformation, cracking, and/or failure of the green body 200, 602.
As further discussed above, the behavior of the non-adhering material 300 during sintering can vary. In one aspect, the non-adhering material 300 can remain unsintered at the temperatures of the predetermined sintering temperature profile. In another aspect, the non-adhering material 300 can sinter to itself but not to the green body 200, 602 at the temperatures of the predetermined sintering temperature profile. In a further aspect, the non-adhering material can undergo a chemical and/or physical reaction to form a modified non-adhering material configured to inhibit adhesion of the support structure from the green body 200, 602 and sintered work piece 700 according to any of the above-noted mechanisms.
In an embodiment, operation 114 of the method 100 of
The method 800 of
In an embodiment, operation 802 of the method 800 of
In an embodiment, operation 804 of the method 800 of
The composition of the support structure and process of manufacturing the broken support structure 906 can be the same as that discussed above with respect to the support structure 206 of the method 100 of
The non-adhering material 900 can be applied to predetermined exterior-facing surfaces of the broken support structure 906 in a variety of ways. In one embodiment, the non-adhering material 900 can be applied to fill all incipient gaps 904, 910 and other exterior-facing surfaces that will be positioned opposite the green body 200. In another embodiment, the non-adhering material 900 can be applied to completely encapsulate the broken support structure 906. In a further embodiment, the non-adhering material 900 can be applied to completely encapsulate the green body 200. The broken support system 906 so formed can be subsequently inserted within the void space 202.
The remaining insertion, debinding, sintering, and removing operations of the method 800 of
In certain embodiments, combinations of intact support systems 302 and broken support systems 902 can be employed, as illustrated in
In an embodiment, operation 1502 of the method 1500 of
A support system 1602 is positioned within the void space 202 of the porous green body 200 as defined by the overhang region 204. That is, the support system 1602 is formed concurrently with the green body 200. As illustrated in
In certain embodiments, the composition of the support structure 1606, and process of manufacturing the support structure 1606, can be the same as that discussed above with respect to the method 100 of
In another embodiment, the non-adhering material 1600 can be formed in situ. That is, while the support structure 1606 is positioned within the void space 202. Thus, the operation of deposition/application of the non-adhering material 1600 to the support structure 1606 while the support structure 1606 is positioned outside of the void space 202 can be avoided. In one example, reagents can be deposited sequentially through a single channel of a single print head of an additive manufacturing device. In another example, reagents can be concurrently deposited through different channels of a single print head of an additive manufacturing device. In a further example, reagents can be deposited through a single channel of respective print heads of an additive manufacturing device.
In one embodiment, the reagents can include a water soluble salt of a heavy metal and a hydroxide or a salt of a weak acid that thermally decomposes to form at least one of a water insoluble hydroxide or an inorganic material capable of dissolution in a solvent and recovered by drying. The hydroxide can be sodium hydroxide and the salt of a weak acid can be a sodium or a potassium salt.
The remaining debinding, sintering, and removing operations the method of
In certain embodiments, a support structure may not be needed to support the green body during formation. This circumstance can arise when the void space is relatively small. Under such circumstance, formation of the support structure with the green body can be omitted and the non-adhering material (e.g., in the form of a paste, such as non-adhering material 900) can be employed to fill the void space and avoid damage to the green body during debinding and/or sintering. In an embodiment, the non-adhering material can fill all or approximately all of the void space, as compared to the embodiment of
As discussed above, in certain embodiments, the support structure can be formed from a single body and the non-adhering material can be positioned on outer surfaces of the support structure (e.g., between the part and the support structure). In alternative embodiments, the support structure can be additively manufactured as a plurality of pieces smaller than the support structure, referred to herein as support sub-structures. The support sub-structures can be stackable, nesting, and/or interlocking so as to adopt the geometry and size of the void space within the part.
Embodiments of the support sub-structures can adopt a variety of configurations. In one aspect, the geometry and/or size of respective support sub-structures can be the same. In another aspect, one or more of the support sub-structures can have a geometry and/or size that differs from others of the support sub-structures. In an additional aspect, support sub-structures distanced from the part (e.g., within the interior of the overall support structure) can adopt a base configuration having a single size and geometry and support sub-structures adjacent to the part (e.g., separated from the part by the non-adhering material) can be modified in size and/or geometry from the base configuration to mimic the contour of the part.
The non-adhering material can be deposited not only at the interface between the part and the support structure but at interfaces between respective support sub-structures. That is, outer surface of each of the support sub-structures can be coated with the non-adhering material. In this manner, the support sub-structures can be detached from one another with similar ease discussed above with respect to the support structure from the part. Such configurations can be advantageous under circumstances where a single, large support structure cannot be easily removed from the part, such as support structures formed with a high fraction of a relatively rigid material (e.g., metals, ceramics).
One example of a support system 2000 including support sub-structures 2002 is illustrated in
A first portion of the non-adhering material 2010 is positioned between respective ones of the first pyramids 2004 and/or second pyramids 2006, while a second portion 2012 of the non-adhering material is positioned between the second pyramids 2006 and inward facing surfaces of the green body 200. As further illustrated in
It can be understood that, while the embodiments of
Another example of a support system including support sub-structures is illustrated in
In further embodiments, the thickness of respective ones of the plurality of plates 2200 can be individually selected, as necessary. In one aspect, the thickness of each of the plurality of plates 2200 can be approximately equal. In another aspect, the thickness of one or more of the plurality of plates 2200 can be different from others of the plurality of plates 2200.
As illustrated, a first portion 2202 of the non-adhering material is positioned between respective ones of the plates 2200, while a second portion 2204 of the non-adhering material is positioned between the plates 2200 and inward facing surfaces of the green body 200. As further illustrated in
Embodiments of the non-adhering material can adopt a variety of configurations. In one aspect, the first portion 2202 of the non-adhering material can be deposited between each plate. In another aspect, the first portion 2202 of the non-adhering material can be deposited after a selected number of plates are formed upon one another. The selected number of plates can be constant or varied. In one embodiment, the first portion 2202 of the non-adhering material can be deposited after five plates are formed upon one another
One skilled in the art can appreciate that the present subject matter is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The details of the description and the examples herein are representative of certain embodiments, are exemplary, and are not intended as limitations on the scope of the disclosed embodiments. Modifications therein and other uses will occur to those skilled in the art. These modifications are encompassed within the spirit of the disclosed embodiments. It will be readily apparent to a person skilled in the art that varying substitutions and modifications may be made to the embodiments disclosed herein without departing from the scope and spirit of the disclosure.
The articles “a” and “an” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to include the plural referents. Claims or descriptions that include “or” between one or more members of a group are considered satisfied if one, more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process unless indicated to the contrary or otherwise evident from the context. The disclosure includes embodiments in which exactly one member of the group is present in, employed in, or otherwise relevant to a given product or process. The disclosure also includes embodiments in which more than one, or all of the group members are present in, employed in, or otherwise relevant to a given product or process. Furthermore, it is to be understood that the disclosed embodiments provide all variations, combinations, and permutations in which one or more limitations, elements, clauses, descriptive terms, etc., from one or more of the listed claims is introduced into another claim dependent on the same base claim (or, as relevant, any other claim) unless otherwise indicated or unless it would be evident to one of ordinary skill in the art that a contradiction or inconsistency would arise. It is contemplated that all embodiments described herein are applicable to all different aspects of the disclosed embodiments where appropriate. It is also contemplated that any of the embodiments or aspects can be freely combined with one or more other such embodiments or aspects whenever appropriate. Where elements are presented as lists, e.g., in Markush group or similar format, it is to be understood that each subgroup of the elements is also disclosed, and any element(s) can be removed from the group. It should be understood that, in general, where the disclosed embodiments, or aspects of the disclosed embodiments, is/are referred to as comprising particular elements, features, etc., certain embodiments of the disclosure or aspects of the disclosure consist, or consist essentially of, such elements, features, etc. For purposes of simplicity those embodiments have not in every case been specifically set forth in so many words herein. It should also be understood that any embodiment or aspect of the disclosure can be explicitly excluded from the claims, regardless of whether the specific exclusion is recited in the specification. For example, any one or more active agents, additives, ingredients, optional agents, types of organism, disorders, subjects, or combinations thereof, can be excluded.
Where the claims or description relate to a composition of matter, it is to be understood that methods of making or using the composition of matter according to any of the methods disclosed herein, and methods of using the composition of matter for any of the purposes disclosed herein are aspects of the disclosed embodiments, unless otherwise indicated or unless it would be evident to one of ordinary skill in the art that a contradiction or inconsistency would arise. Where the claims or description relate to a method, e.g., it is to be understood that methods of making compositions useful for performing the method, and products produced according to the method, are aspects of the disclosed embodiments, unless otherwise indicated or unless it would be evident to one of ordinary skill in the art that a contradiction or inconsistency would arise.
Where ranges are given herein, embodiments of the disclosure include embodiments in which the endpoints are included, embodiments in which both endpoints are excluded, and embodiments in which one endpoint is included and the other is excluded. It should be assumed that both endpoints are included unless indicated otherwise. Furthermore, it is to be understood that unless otherwise indicated or otherwise evident from the context and understanding of one of ordinary skill in the art, values that are expressed as ranges can assume any specific value or subrange within the stated ranges in different embodiments of the disclosure, to the tenth of the unit of the lower limit of the range, unless the context clearly dictates otherwise. It is also understood that where a series of numerical values is stated herein, the disclosure includes embodiments that relate analogously to any intervening value or range defined by any two values in the series, and that the lowest value may be taken as a minimum and the greatest value may be taken as a maximum. Numerical values, as used herein, include values expressed as percentages.
As used herein “A and/or B”, where A and B are different claim terms, generally means at least one of A, B, or both A and B. For example, one sequence which is complementary to and/or hybridizes to another sequence includes (i) one sequence which is complementary to the other sequence even though the one sequence may not necessarily hybridize to the other sequence under all conditions, (ii) one sequence which hybridizes to the other sequence even if the one sequence is not perfectly complementary to the other sequence, and (iii) sequences which are both complementary to and hybridize to the other sequence.
Any embodiment in which a numerical value is prefaced by “about” or “approximately” includes an embodiment in which the exact value is recited. For any embodiment of the disclosure in which a numerical value is not prefaced by “about” or “approximately”, the disclosure includes an embodiment in which the value is prefaced by “about” or “approximately”. “Approximately” or “about” can include numbers that fall within a range of 1% or in some embodiments within a range of 5% of a number or in some embodiments within a range of 10% of a number in either direction (greater than or less than the number) unless otherwise stated or otherwise evident from the context (except where such number would impermissibly exceed 100% of a possible value).
It should be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one act, the order of the acts of the method is not necessarily limited to the order in which the acts of the method are recited, but the disclosure includes embodiments in which the order is so limited. It should also be understood that unless otherwise indicated or evident from the context, any product or composition described herein may be considered “isolated”.
As used herein the term “comprising” or “comprises” is used in reference to compositions, methods, and respective component(s) thereof, that are essential to the disclosed embodiments, yet open to the inclusion of unspecified elements, whether essential or not.
As used herein the term “consisting essentially of” refers to those elements required for a given embodiment. The term permits the presence of additional elements that do not materially affect the basic and novel or functional characteristic(s) of that embodiment of the disclosure.
The term “consisting of” refers to compositions, methods, and respective components thereof as described herein, which are exclusive of any element not recited in that description of the embodiment.
Although a few variations have been described in detail above, other modifications or additions are possible.
In the descriptions above and in the claims, phrases such as “at least one of” or “one or more of” may occur followed by a conjunctive list of elements or features. The term “and/or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B;” “one or more of A and B;” and “A and/or B” are each intended to mean “A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C;” “one or more of A, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.” In addition, use of the term “based on,” above and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.
The subject matter described herein can be embodied in systems, apparatus, methods, and/or articles depending on the desired configuration. The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations can be provided in addition to those set forth herein. For example, the implementations described above can be directed to various combinations and sub-combinations of the disclosed features and/or combinations and sub-combinations of several further features disclosed above. In addition, the logic flows depicted in the accompanying figures and/or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.
This application is a US National Stage of International Application No. PCT/US19/37099, filed Jun. 13, 2019, entitled “Separation of Near Net Shape Manufactured Parts From Support Structures.” International Application No. PCT/US19/37099 claims the benefit of U.S. Provisional Patent Application No. 62/684,195, filed on Jun. 13, 2018, entitled “Separation of Near Net Shape Manufactured Parts From Support Structures,” the entirety of which is hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/US19/37099 | 6/13/2019 | WO | 00 |
Number | Date | Country | |
---|---|---|---|
62684195 | Jun 2018 | US |