Abstract: A method for producing a mold for making an integrally formed three-dimensional truss structure, containing outer top and bottom plane surfaces thereof comprising interconnected rod segments integrally formed at their points of intersection on the outer top and bottom surfaces, the top and bottom surfaces also integrally joined together through additional interconnected rod segments passing through an integrally formed intersection, wherein the additional interconnected rod segments passing through the integrally formed intersection form a three-dimensional continuous array of triangles.

Abstract: A wax pattern assembly (10) is removed from a ceramic shell mould (30) by removing a support member (20) from the wax pattern assembly (10). The ceramic shell mould (30) is then heated to melt the wax out of the ceramic shell mould (30). The removal of the support member (20) provides a cavity (22) into which the wax may expand without cracking the ceramic shell mould (30). The support member (20) is provided with an external thread to allow it to be easily removed from the wax pattern assembly (10).

Abstract: A golf ball mold is prepared by inserting a dimpled hemispherical male die into a chamber in a frame, admitting hot liquid wax into the chamber, cooling and curing the wax to form a wax shape, covering the wax shape with a mix slurry of ceramic particles and a binder, drying and curing the slurry to form a ceramic shell around the wax shape, removing the wax shape from the ceramic shell, casting a molten metal into the ceramic shell, cooling and solidifying the metal to form a mold half, and removing the ceramic shell from the mold half. The mold is improved in molding precision, durability and cost.

Abstract: A method of making a metal shape comprising the steps of supplying molten metal into a ceramic shell mould mounted in a container, spinning the container and the shell mould therein about an axis and permitting the metal to solidify in the shell mould and thereafter removing, for example by breaking, the shell mould to expose the metal shape. The ceramic shell moulds made by providing a pattern of flexible elastically deformable material of a required shape and supported on a mandrel, applying at least one coating of hardenable refractory material to said pattern to form a rigid shell and removing the mandrel from supporting relationship with the pattern and subsequently removing the pattern from the shell by elastically deforming the pattern. The pattern is made by moulding said material in a master mould of a required shape and removing the pattern from the master mould, after the pattern has set, by elastically deforming the pattern.

Abstract: An article has a thin wall portion with a thickness of 0.060 inches or less, a width of at least four inches, and a height of at least six inches. In order to cast the article, a pattern having a configuration corresponding to the configuration of the article is covered with a coating of wet ceramic material. In addition, a reinforcing pattern, which is spaced from the portion of the article pattern having a configuration corresponding to the thin wall portion of the article, is covered with the wet ceramic material. Space between the article pattern and reinforcing pattern is filled with the wet ceramic material. A combined mold structure and reinforcing structure are formed by drying the wet ceramic material. The article pattern is removed from the mold structure to leave a mold cavity. Molten metal is conducted into the mold cavity.

Abstract: A flexible and resilient positive pattern is made for a desired high temperature metal or ceramic part such as a gas turbine impeller having a complex geometry with walls defining undercut spaces, and the pattern with flexible walls is dipped into a ceramic molding media capable of drying and hardening. The pattern is removed from the media to form a ceramic layer on the flexible pattern, and the layer is coated with sand and air dried to form a ceramic layer. The dipping, sanding and drying operations are repeated several times to form a multiple layer ceramic shell. The flexible wall pattern is removed from the shell, by partially collapsing with suction if necessary, to form a first ceramic shell mold with a negative cavity defining the part and to provide for reusing the pattern. A second ceramic shell mold is formed on the first shell mold to define the back of the part and a pour passage, and the combined shell molds are fired in a kiln.

Abstract: A mold for a prototype metal casting or the like may advantageously be made by forming a casting pattern of adhesively bonded aggregate particles using a binder containing a principle constituent that is soluble in supercritical carbon dioxide; forming a rigid shell mold about the pattern of materials that are unaffected by supercritical carbon dioxide; thereafter exposing the pattern and mold combination to supercritical carbon dioxide to remove the pattern binder adhesive and leave unbonded aggregate particles in the mold and removing the aggregate particles from the mold to leave a mold cavity that faithfully defines the pattern shape.

Abstract: The pattern material with substantially spherical filler particulates is used to produce investment cast components with improved surface quality, reduced finishing costs, and reduced core breakage. The pattern material comprises substantially spherical particles within the particle size range of about 10 microns to about 70 microns particle diameter, the use of which reduces the number of random, localized surface depressions and pits to improve pattern surface texture and uniformity. Patterns so formed inpart the same improvements to the surface of subsequent investment cast components. The resulting castings exhibit improved as-cast surface finish and reduced random, localized surface pitting, thereby reducing or eliminating expensive post casting surface finishing operations. Moreover, the spherical morphology of the filler particulates reduces injection pressures to fill a pattern die cavity as compared to non-spherical filler particulates.

Abstract: A method of integrating detailed features into a spray formed rapid tool includes the steps of making a model of a desired tool and constructing a ceramic pattern as the inverse of the model. The method also includes the steps of locating at least one detailed feature insert on the ceramic pattern and thermally spraying metal material against the detailed feature insert and ceramic pattern to form the desired tool and embedding the detailed feature insert into the desired tool.

Abstract: A method for casting a turbine bucket with at least one surface cooling hole. The method comprises positioning at least one preformed spacer device on a core, where the preformed spacer device is formed of ceramic materials and comprises opposed end plates and at least one interconnecting crossover pin connecting the end plates; forming a layer of temporary material, such as wax, over the core and around the at least one preformed spacer device; forming a shell mold over the layer of temporary material to cover it, the core and the at least one preformed spacer device. The shell mold is maintained stably positioned and spaced from the core by the at least one preformed spacer device, which connects and maintains the shell mold and the core as a stable body. The wax is removed to form a casting space for the turbine bucket between the shell mold and the core and around the at least one preformed spacer device.

Abstract: Methods and compositions for forming shells for investment casting and methods for casting metal articles using the shells are described. One embodiment of the method comprises serially immersing a pattern in at least one, and perhaps several different slurries, each of which slurries comprises refractory material and from about 0 to about 30 volume percent inorganic binder. This forms a facecoat and plural refractory backup layers about the pattern, the facecoat and at least one backup layer defining a shell. The facecoat and/or the shell is then infiltrated with a binder. Infiltrating the shell with a binder is a key feature of the present invention. Infiltration refers to any process whereby a binder can be introduced into the facecoat and/or the subsequent layers built up about the shell.

Abstract: An investment casting shell is made by providing an investment casting pattern that defines a cavity and filling the cavity with a fluid. The fluid is sealed within the cavity and a ceramic material is applied to the exterior of the pattern. The ceramic-encased pattern is heated and the pattern and fluid are removed from the ceramic.

Abstract: A method of making an investment casting mould comprises producing a CAD definition of a turbine blade, and determining the distribution of isosurfaces of constant temperature around the CAD definition of the at least one article if the external surface of the CAD definition of the at least one article was at a high temperature (Thigh). One of the isosurfaces of constant temperature is selected to define the external shape and the thickness of an investment casting mould. A pattern of the turbine blade is produced from the CAD definition of the turbine blade. The investment casting mould is made with an internal shape defined by the pattern of the turbine blade and an external shape and thickness distribution defined by the selected isosurface of constant temperature. The pattern is then removed from the investment casting mould.

Abstract: A wax article pattern having a cavity corresponding to a cavity in a metal article is provided. The cavity in the wax article pattern is filled with a slurry of ceramic core material. The slurry of ceramic core material is solidified to form a core. The wax article pattern is enclosed by ceramic mold material. The ceramic mold material is solidified to form a mold. The wax pattern is removed from the mold to leave an article mold cavity. The article mold cavity is filled with molten metal which is solidified to form the metal article. A passage in the metal article may be formed by a pin which extends from the wax article pattern into the cavity in the wax article pattern and is enclosed by the slurry of ceramic core material.

Abstract: A titanium aluminide is composed of 31.5 to 33.5 weight % of Al, 1.5 to 2.3 weight % of Fe, 1.5 to 2.1 and 3.7 to 4.8 weight % of Nb, 0.07 to 0.12 weight % of B with remainder being Ti and inevitable impurities. The 1.5-2.0 weight % of Nb may be replaced with 0.5 to 2.0 weight % of V if severe oxidation resistance is not necessary. The titanium aluminide is melted and poured into a mold, and the melt is cooled in the mold naturally.

Abstract: The inside surface of the mold used to cast gamma titanium aluminide articles is pretreated with a facecoating of an inoculant such as titanium diboride or titanium carbide. When the molten metal of the composition that produces the gamma titanium aluminide is cast into the mold, the facecoating nucleates grains at the surface of the casting, which inhibits the formation of surface-connected porosity in the casting. Subsequent hot isostatic pressing of the article produces a sounder article than otherwise could be achieved.

Abstract: Methods are provided for producing investment cast articles, such as orthopedic implants, or portions thereof, having at least a partially textured surface that is formed during casting of the article. In an exemplary method, a textured metal casting is produced by creating a heat destructible pattern and spraying the pattern with a texturing material to cause the texturing material to form a textured surface on at least a portion of the pattern. In another embodiment, a textured template is pressed against a heat softenable pattern to provide a textured pattern. With respect to each of these methods, a shell is the created around the textured pattern to form a mold, and the pattern is removed from the shell. Molten metal is introduced into the mold and allowed to harden, after which the mold is removed.

Abstract: A method of making a custom, bioimplantable article, such as a joint prosthesis component, is provided using computer aided design, rapid prototyping, and investment casting techniques. The method includes the creation of a data file, using computer aided design (CAD) techniques, that defines a negative or a shell of a portion of a bioimplantable article that is custom configured for a specific arthroplasty patient. The data file for the shell of the custom portion of the bioimplantable article is accessed by a rapid prototyping machine, such as a three-dimensional printer, to create a mold that corresponds to the shell. The mold, generally a heat-resistant ceramic, is positioned relative to an existing, non-custom representation of a bioimplantable article to define a hybrid component. A heat-resistant shell is formed around the hybrid component and the non-custom representation of a bioimplantable article is removed from the shell using heat.

Abstract: Methods are provided for producing investment cast articles, such as orthopedic implants, or portions thereof, having at least a partially textured surface that is formed during casting of the article. In an exemplary method, a textured metal casting is produced by creating a heat destructible pattern and spraying the pattern with a texturing material to cause the texturing material to form a textured surface on at least a portion of the pattern. In another embodiment, a textured template is pressed against a heat softenable pattern to provide a textured pattern. With respect to each of these methods, a shell is created around the textured pattern to form a mold, and the pattern is removed from the shell. Molten metal is introduced into the mold and allowed to harden, after which the mold is removed.

Abstract: Investment casting molds, and particularly mold cores, are formed of sintered ceramics to near net shape and are then machined to net shape, dimensions and surface finish, by ultrasonic machining with formed tools having the final configuration in mirror image form. Form machining of fired mold shells and cores is rapid, precise, readily controlled, and can produce castings of exceptional accuracy of shape, dimensions and surface finish.

Abstract: The investment casting process utilizes an investment assembly that includes one or more vents in each casting mold. Vents facilitate the extraction of the pattern material while preventing expansion of the pattern material to the extent that mold fracture or cracking results. The vents can be formed by incorporating within the patterns of articles to be cast one or more protrusions that cause the pattern to deviate from the size and shape of the article to be cast. After assembly of one or more patterns to a riser to form a cluster, the cluster is coated with a refractory material and the refractory material is removed from the protrusions either before the refractory dries or after the refractory dries, thus producing the vents.

Abstract: An implantable article having on at least a portion of its exterior surface an integral, as-cast macrotextured surface having pores with undercut edge profiles is provided. The integral, as-cast macrotextured surface is able to be formed on the implantable articles by a modified casting process. As part of a casting process, positive models of the articles to be cast, or parts thereof, are formed by stereolithographic techniques. Cavities or molds, representing negative images of the articles to be cast, are then formed by encasing one or more models in a refractory material. The positive models are then extracted by heating and thus melting the material from which they are made. Thereafter, molten casting material can be poured into the resulting mold to obtain the implantable articles.

Abstract: A method of making a single crystal or columnar grain superalloy casting comprises casting a superalloy in a mold wherein at least one of the mold and optional core comprises an oxygen-bearing ceramic, directionally solidifying the superalloy to form a single crystal or columnar grain superalloy casting, and solution heat treating the superalloy casting. The heat treatment is conducted under an atmosphere including a carbon-bearing gas, such as a carbon monoxide and inert gas mixture, wherein the carbon-bearing gas is present in an effective amount to reduce loss of carbon from the casting during the heat treatment. The heat treatment can be conducted prior to removal of all of the mold and core, if present, such as, for example, when the cast mold is in the as-knocked out condition wherein residual mold and/or core material is present on the casting. Alternately, the heat treatment can be conducted after removal of the mold and core, if present.

Abstract: An investment casting process which includes: attaching a gate to a pattern made of a plastic to form a pattern assembly; forming a mold by applying a plaster slurry on an outer surface of the pattern assembly; dissolving and removing the pattern assembly in the mold by applying an organic solvent; burning the mold from which the pattern has been removed; casting by pouring a molten metal into the burned mold; and breaking the mold to take out a cast product.

Abstract: In a method of investment casting a turbine nozzle which includes an outer band, an inner band and an airfoil section extending between the inner and outer bands, an improvement including shaping a temporary wax form, and external shell and internal core components used in casting such that during pouring of molten metal into a space created by removal of the wax form, shell material lies on opposite sides of an outer fillet connecting the outer band to the airfoil section. The resulting gas turbine nozzle includes first and second horizontally oriented ribs extending about interior peripheries of the airfoil section vertically adjacent the outer and inner band fillets.

Abstract: Method of making a rapid tool, comprising: making a plastic pattern of the tool by free form fabrication techniques following a computer aided design, the design having a base and no undercuts taken in a direction perpendicular to base; constructing a ceramic mold as the inverse of the pattern; separating the pattern from the mold by a separating movement in a direction perpendicular to the base to leave a surface defining a casting cavity within the mold; and thermally spraying tool steel particles against the casting cavity surface is a thickness exceeding 1 inch while rapidly cooling the sprayed particles to effect a net shape tool without the need for further working or heat treatment.

Abstract: Time-stable yttria slurries, and a method for forming such yttria slurries and articles therefrom are described. The method involves forming an intimate mixture comprising yttria and at least about 0.1 weight percent of a dopant material. An aqueous slurry is then formed comprising from about 1 weight percent to about 95 weight percent of the intimate mixture. The intimate mixture may be formed by heating the mixture to a temperature sufficient to calcine the mixture. Alternatively, the intimate mixture may be formed by heating the mixture to a temperature sufficient to fuse the mixture. The dopant also may be provided as a surface coating on the yttria particles.

Abstract: Disclosed is a practical aluminum-based alloy containing 1 to 99 weight percent beryllium and improved methods for the investment casting of net shape aluminum-beryllium alloy parts.

Abstract: The present invention relates to a method and apparatus for producing a cast structure. In one embodiment of the present invention an alloy casting mold has molten alloy injected therein to facilitate completely filling a part cavity within the mold. Further, an alloy charge pressure control device is utilized to reduce the charge pressure of the molten alloy during its injection into the mold cavity to minimize distortion and creep of the ceramic shell. In one form of the present invention the charge pressure control device removes excess alloy so as to reduce the head pressure of the molten alloy thereby eliminating the undesirable creep of the ceramic shell.

Abstract: The invention relates to a water based binder for use in a slurry for investment casting. The binder includes a mixture of a colloidal silica sol and at least one latex polymer. The latex polymer is preferably an acrylic latex or a styrene butadiene polymer (or a combination of these) which reduces the processing time between dips during shell mold making for investment casting. The latex polymer further lowers a critical concentration point or gelation point of the colloidal silica sol. The binder may be used as a primary binder or a backup binder in the shell mold making process. To make the slurry, the binder is combined with at least one refractory powder, preferably a refractory powder selected from the group of: aluminosilicates, fused silica, quartz silica, alumina, zircon, and zirconia.

Abstract: An apparatus and method for use in casting a metal article includes a mold structure having wall sections with pins extending between the wall sections. The pins have opposite end portions which are embedded in the wall sections of the mold structure to interlock the pins and the wall sections of the mold structure. When molten metal is poured into the mold structure, the molten metal urges the wall sections away from each other. The wall sections are retained against movement relative to each other by the pins. Although the apparatus and method of the present invention can be utilized to cast many different types of articles, the invention is advantageously utilized in the casting of thin metal articles and specifically a thin metal article which is formed as a single crystal.

Abstract: The golf club head comprises a head body which defines the front striking face of the club head. Disposed within the head body is a ceramic insert which defines the rear face of the club head. The head body is cast about the insert in a manner wherein the insert is partially encapsulated by the head body and rigidly captured therewithin.

Abstract: A wax shell covered pre-formed core body is provided, the thickness of the wax shell corresponding to the desired thickness of the wall structure. A ceramic shell is formed about the wax shell. The wax shell is removed by melting the wax, thereby to form an opened gap between the ceramic shell and the core body. Molten metal is cast into the opened gap, thereby to form the wall structure extending about the core body and at the sole, while forming and maintaining port structure through the wall structure and spaced from the sole, and allowing the wall structure to solidify to form the head. The ceramic shell is removed from the wall structure, and the core body is removed from the interior of the solidified head, and via the port structure.

Abstract: The present invention relates to an improved process for the preparation and fabrication of horseshoes whereby pure titanium or titanium alloys are processed with the exclusion of contaminating gases such as Oxygen, Nitrogen and Hydrogen. The titanium horseshoes have many advantages over the present state of art such as light weight, higher tensile strength, flexible, wearing resistance, abrasion resistance, hypoallergenic, workability, formability, friction-free, physiologically inert, and are easily formed and shaped into the desired configuration.

Abstract: The process consists of starting from a lace or embroidery in cotton or synthetic fibers, applying to the model wax, resins or varnishes capable of increasing the size, then coating the model with gypsum and then introducing the coated model into a furnace. The heat destroys the model and leaves a cavity which has the shape of the model. The precious metal is introduced into the cavity in the molten form. Finally the article is allowed to solidify and the gypsum is crushed. The decorative article may be used for necklaces, bracelets or similar materials.

Abstract: In an investment casting process including the known steps of injecting a molten wax into a die, allowing the wax to solidify, removing the die, investing the wax with ceramic, firing the ceramic and removing the wax so as to provide a ceramic mould, and casting a molten material into the mould, and apparatus including a ceramic core the shape and size of the cavity to be provided in the blade, a removable wax impression die surrounding and spaced from the core member so that the space between the die and the core member is the shape and size of the blade, there is provided a number of platinum chaplets adapted and arranged to support and locate the core in relation to the ceramic mould by point contact abutment with an adjacent mould surface.

Abstract: A method of making a ceramic shell mould for casting includes making a pattern having an internal cavity in two parts from a disposable material, glueing the two parts together to complete the hollow pattern, filling the internal cavity with a ceramic material, and simultaneously or subsequently forming a shell of a ceramic material around the filled pattern. The pattern can then be eliminated to obtain a casting mould with an inner core made in situ.

Abstract: An investment casting process utilizes a temporary mold which is formed by pouring a liquid over a positive pattern, and cooling the liquid until it solidifies. The positive pattern is removed, and a temporary pattern is formed by pouring another liquid into the cavity of the temporary mold, and cooling the second liquid until it solidifies. The temporary mold may then be melted or dissolved to leave a temporary pattern, which may be coated with a ceramic slurry to form a ceramic shell. The temporary pattern may then be melted or dissolved in order to remove the temporary pattern from the ceramic shell. The ceramic shell may be filled with molten metal which is allowed to solidify to form the final cast piece.

Abstract: A method is disclosed for producing a hollow airfoil, specifically, a blade or vane for a gas turbine engine, which is formed with a complex interior for cooling purposes. Broadly, the method comprises the steps of molding a green ceramic core having outer surfaces generally contoured to produce the intended interior surfaces of the completed airfoil, heating the green ceramic core to a sufficient extent to produce a fired core, and operating on the fired core with a laser to modify the characteristics of the fired core. Use of the laser enables the formation of detailed features having a transverse dimension less than approximately 0.020 inches. Specific operations may include labeling, trimming, cutting, drilling either by punching or trepanning, etching or milling, and glazing or strengthening. In another embodiment of the invention, a layer is produced on the core surface having a very high surface energy to promote the flow of the casting alloy around the core within the mold.

Abstract: The liner cap assembly includes an outer tubular sleeve, an inner cowl and a cone portion extending between the outer sleeve and the inner cowl. The cone portion includes a plurality of annular, concentrically arranged directional vanes on a downstream surface of the cone portion. At least the inner cowl and the cone portion are formed by casting. Plural apertures are formed in the cone portion during casting or after casting.

Abstract: Emissive compositions are described that can be applied as a coating to the surface of an investment casting mold to increase or decrease the rate of cooling of a casting within the mold. A coating that decreases the rate of cooling of an investment casting within an investment casting mold may comprise a compound having an emissivity less than the emissivity of the mold; a high temperature glass-forming material and a solvent to make a slurry. Similarly, a coating that increases the rate of cooling may comprise a compound having an emissivity greater than the emissivity of the mold; a low temperature glass-forming material and a solvent to make a slurry. Also disclosed in a method of investment casting wherein an emissive composition is applied to the investment casting mold.

Abstract: A new method for producing a composite ceramic mold for production of metal castings is disclosed. The composite mold is comprised of a backing layer and a facing layer. The backing layer is formed by pouring a mixture of a suitable refractory, a gelling agent, and a binder about an oversized pattern. After the backing layer hardens, it is fired and then baked. The facing layer is then formed integrally with the backing layer by pouring a mixture of comminuted highly refractory material, a gelling agent, and a binder between the oversized backing layer and a dimensionally-correct pattern. After the facing layer hardens, it is fired and then baked.

Abstract: To predict the rate of flow of cooling fluid (gas) through a passage system in a proposed airfoil during operation of a Jet engine, a full size model of the passage system is prepared. The flow of air or other gas is conducted through the model of the passage system. The characteristics of the flow of air or gas through the model of the passage system is determined to enable the characteristics of the flow of cooling fluid through the passage system in the proposed airfoil to be predicted. The model of the cooling fluid passage system in the proposed airfoil is formed by covering the pattern with a layer of metal. The pattern is removed from the covering to form a passage system having a configuration corresponding to the configuration of the cooling fluid passage system in the proposed airfoil.

Abstract: The invention relates to a method of producing near net shaped metals parts from shaped wax patterns and more particularly a process whereby control of the wax pattern shape from which metal parts are to be investment cast is accomplished by machining the wax pattern after injection forming. The present invention incorporates a precision machining step whereby the injection formed wax is machined to dimensional values which more closely result in a near net shape of the cast metal part.

Abstract: A foamed pattern of a desired part is first formed. The pattern is then dipped into a ceramic slurry and the slurry dried in order to form a shell containing the foamed pattern. A heated bed of a particulate medium is formed around the ceramic shell which causes the pattern to evaporate and form a mold. A molten metal is then introduced into the mold and solidified while being held at an elevated temperature for a period of time to accomplish a desired heat treatment of the metal. With this method, the casting does not have to be subsequently heat treated in a separate operation. It can be removed as an as cast casting, having the desired microstructures.

Abstract: A rotor-shaft subassembly (33) is disclosed of the type for use in a Roots blower supercharger. The subassembly includes a rotor (39) mounted for rotation on a driveshaft (41) at forward (49,53) and rearward (57,51) axially spaced-apart locations. The rotor (39) is a cast member with each lobe thereof (61,63,65) defining a hollow chamber (71,73,75). The rotor includes a cylindrical web portion (67) disposed axially between the forward and rearward locations. Each lobe cooperates with the web portion to define a core opening (81,83,85) adapted to facilitate removal of a core from the hollow chamber after completion of the casting process. Each core opening provides open communication between its respective hollow chamber and the shaft bore, and each is disposed axially between the forward and rearward locations, so that after the rotor is press-fit on the shaft, there is no leak path of pressurized air into the hollow chambers.

Abstract: A method of making a casting having an internal passage involves the steps of forming a core having an external surface configured to form the passage in the casting and having a plurality of integrally formed protrusions extending from the external surface at stressed regions thereof (e.g., thermally stressed regions) prone to be distorted from a master core configuration, and positioning the core in a pattern molding cavity by engagement of the protrusions with rigid walls defining the molding cavity such that the core is conformed substantially to a predetermined and/or empirically determined relationship between the master core configuration and the molding cavity as if the core corresponded to the master core configuration. A fugitive pattern corresponding to the casting to be formed is then molded about the external surface of the core while the core is supported in the aforementioned relationship relative to the molding cavity, whereby the wall thickness of the pattern is controlled about the core.

Abstract: Disclosed is a single-cast, thin wall structure capable of withstanding impinging gases at temperatures of 4300.degree. F. and higher, and method of making the same. Using a bleed line of the instant invention allows for a decreasing metal pressure with respect to time which prevents any damage to the thin outer mold wall.

Abstract: A method is disclosed for the casting of metals by the use of a consumable or vaporizable pattern. In this method, a foamed pattern of a desired part is first formed. The pattern is then dipped into a ceramic slurry and the slurry dried in order to form a shell containing the foamed pattern. A bed of a particulate medium heated to a temperature of from 700.degree. to 1000.degree. F. is formed around the ceramic shell to cause the pattern to vaporize without burning and form a mold. A molten metal is then introduced into the mold, solidified and removed from the mold to form a casting. An inert atmosphere can be provided over the bed of heated particulate medium during the vaporization of the pattern to help suppress the burning of the vaporized pattern.

Abstract: A method and composition for forming investment casting patterns wherein thermally-collapsible microspheres are incorporated into the pattern composition. The patterns can be made either by conventional pattern forming techniques or by solid imaging techniques. After investing the microsphere containing pattern in the ceramic shell, the pattern and shell are heated, causing a collapse of the microspheres and thereby preventing cracking of the shell. The shell is then heated to burn-out the remaining pattern material and fire the shell, thereby creating a mold.