Abstract: A cast tubular structure including an integral hose connection element formed thereon is produced by lost foam casting wherein a circular socket seat is formed on a pattern for a body portion of the cast tubular structure and a cylindrical pattern for the integral hose connection element is formed by a mold without vent openings on the mold surface in the area of the cyclindrical pattern corresponding to the hose sealing surface of the cast tubular structure. The pattern sections are joined with the pattern section for the hose connection element sealing within the circular socket seal formed in the body portion of the cast structure. The pattern assembly is coated with a slurry and, after drying, is placed in a casting flask. Molten metal is then poured within the coated pattern assembly dissolving the foam patterns and forming the cast tubular structure.

Abstract: An expendable pattern of an article to be cast comprises a meltable material that expands upon heating (e.g., a wax pattern). The pattern is invested with particulate mold material to form a thin, layered shell having a wall thickness not exceeding about 0.12 inch. The thin shell wall thickness unexpectedly reduces damage and distortion to the shell during removal of the pattern therefrom by steam autoclaving. After firing, the thin gas permeable shell mold is surrounded by a refractory particulate support media in a vacuum housing. The vacuum housing is then evacuated to evacuate the mold cavity defined by the thin shell and concurrently a pressure is applied to the support media so as to compress the support media about the thin shell to support the shell against casting stresses when molten metal is countergravity cast into the evacuated mold cavity.

Abstract: A precision cast connecting rod which has an elongate tubular shank member defining a hollow section for producing desired stiffness to weight characteristics. Piston and crankpin connecting members are attached to opposite ends of the shank member. The connecting members are provided with passages which extend axially therewithin from the hollow section. Defined within the elongate tubular shank member is a radially extending central aperture. A precision casting method for preparing the hollow connecting rod includes forming an elongate core with a locating member positioned at each end thereof and a disk-shaped protuberance extending radially therefrom. The core is secured in a die and defines a cavity therebetween for preparing a pattern of the connecting rod using a molding material which substantially encapsulates the core within the cavity. After removing the pattern from the die, coatings of refractory material are applied to form a shell mold which encrusts the pattern.

Abstract: A precision cast connecting rod which has an elongate tubular shank member defining a hollow section for producing desired stiffness to weight characteristics. Piston and crankpin connecting members are attached to opposite ends of the shank member. The connecting members are provided with passages which extend axially therewithin from the hollow section. Defined within the elongate tubular shank member is a radially extending central aperture. A precision casting method for preparing the hollow connecting rod includes forming an elongate core with a locating member positioned at each end thereof and a disk-shaped protuberance extending radially therefrom. The core is secured in a die and defines a cavity therebetween for preparing a pattern of the connecting rod using a molding material which substantially encapsulates the core within the cavity. After removing the pattern from the die, coatings of refractory material are applied to form a shell mold which encrusts the pattern.

Abstract: Reactive metals, such as titanium or nickel-chrome superalloys containing rare earths, are cast with mold and/or core surface areas formed from an improved slurry. The improved slurry contains yttria to form an inert surface which is exposed to the molten reactive metal. In order to prevent premature gelation of the slurry, the forming of defects in the mold and/or core surface areas, and the forming of defects in the cast article, the slurry contains a source of hydroxyl ions. The source of hydroxyl ions is sufficient to result in the slurry having a pH of at least 10.2 six days after initially mixing the slurry. The source of hydroxyl ions may be a metal alkali or an organic hydroxide. It is believed that the source of hydroxyl ions functions as a hydration suppressant for the yttria to prevent premature gelation of the slurry. The slurry contains a silicon oxide (SiO.sub.2) to alkali ratio which is equivalent to a silicon oxide to sodium oxide (Na.sub.

Abstract: A fired ceramic core for use in aluminum investment casting, which will withstand steam autoclaving and which may be rendered water disruptible; comprising from about 20 to 50% by weight of one or more water soluble salts, together with inert ceramic fillers selected to meet desired thermoexpansion compatability for the shell with which said core is to be used; said core being vacuum impregnated with ethyl silicate and a cured phenolic resin.

Abstract: A process for preparing an investment casting mold is provided. A kneaded compound composed of an aggregate and an organic binder is cast into a core molding mold to be solidified therein to produce a core matrix which is impregnated with a heat resisting binder to an appropriate depth followed by coating with a wax, whereby a core mold is formed. The core mold is placed in position within a lost model molding mold followed by injection of a lost model forming material. A slurry and stucco particles are alternately coated over the lost model for plural times to form a refractory layer. The lost model is removed to obtain a final mold which is baked to effect simultaneous baking of the core mold and the refractory layer, the former forming the mold core and the latter forming the exterior shell mold.

Abstract: A core mold to be assembled with a shell mold for use in an investment casting process is provided. The core mold comprises a core matrix essentially consisting of an aggregate and an inorganic binder, a binder layer impregnated from the surface of said core matrix, a coating layer formed by coating a slurry over said binder layer, and a paraffin wax layer covering the exterior periphery of said coating layer. Also provided are a process for preparing the core mold and a process for preparing an investment casting mold in which the core mold is assembled.

Abstract: An aqueous bath or slurry for use in forming a shell mould, comprising from 20 to 40 wt. % of colloidal silica, from 20 to 40 wt. % of finely ground zircon, from 15 to 25 wt. % of silica sand, from 15 to 35 wt. % of finely ground fused silica, and from 1 to 5 wt. % of finely ground cristobalite. The shell-mould is made by repeatedly dipping a wax model into the bath or slurry to form a coating of the desired thickness, and then thermally treating the shell-mould so formed by placing the mould into an oven, heating the oven to a temperature between 1050.degree. C. and 1200.degree. C., maintaining the temperature for a period of between 1 and 2 hours, and then allowing the oven and mould to cool to ambient temperature. The mould obtained contains from 10 to 30 wt. % of cristobalite at ambient temperature.

Abstract: The pins which are used for the support of a core in a lost wax casing process are provided with caps. The caps provide sufficient surface area for encapsulation by ceramic slurry. Heat loss from the metal melt via the pins is thus obviated along with undesirable grain nucleation.

Abstract: Improved small dendrite arm spacings and good technical values, regarding the technical properties of aluminum alloys, particularly tensile strength, yield strength and elongation percent, can be reliably obtained by refining the grain of the casting to provide the smallest possible spacings between the secondary dendrite arms, by casting the aluminum alloys in a ceramic mold provided with numerous micro-sized rough spots and pores and to the inner wall of which mold after it is dried and fired has been applied a thin layer of a salt mixture in which the cations are primarily from the alkalis and/or alkaline earths and the anions are primarily from halogens and which applied salt mixture has a liquidus temperature lower than the casting temperature of the alloy.

Abstract: The sand-binder mixture in a sand casting mold is controlled so that it contains sufficient binder to enable it to set to form a mold, yet the resulting set mold is sufficiently porous to receive liquids and vapors from a disposable pattern and sufficiently rigid to retain the pattern shape after the pattern is removed. At the proper binder loading, the mold has porosity such that the pattern will evacuate the cavity prior to casting when heated at relatively low temperatures (well below pattern combustion temperatures) that do not harmfully affect the mold and do not necessarily remove all of the pattern material from the mold. Thus, the pattern is removed from the mold cavity, before the molten metal is added, by heating the pattern and mold to cause the pattern to become fluid and to flow both into the sand mold and out of openings in it, without the need for high temperature combustion. The molten metal is then added to the cavity, and allowed to solidify before it is removed.

Abstract: A process is disclosed for the preparation of ceramic cores which includes injection by means of a press of low power of liquid wax into cavities of a ceramic core disposed in a mould of elastomer produced by moulding of a dummy core which is a replica of the core to be produced.

Abstract: An apparatus and method for automatically forming ceramic shell molds as part of an investment casting process. The apparatus includes structure defining a plurality of processing stations which together define a process line through which set ups are conveyed and coated with cermic material. The first station includes a pickup arm assembly operative to transfer a set up from a transfer cart to a slurry tank where it is released. A transfer arm forming part of a second station engages the set up rotates it within the slurry tank for a predetermined time, after which, the slurry transfer arm transfers it to a spin-off tank and releases it. A stucco transfer arm assembly forming part of a third station engages the set up and rotates it to spin-off excess slurry solution after which the stucco transfer arm transfers it to a stucco tank and releases it.

Abstract: To form a turbine engine component, metal airfoils are positioned in an annular array. Outer end portions of the airfoils are embedded in a wax outer shroud ring pattern and inner end portions of the airfoils are embedded in a wax inner shroud ring pattern. A mold is formed by covering the metal airfoils and the shroud ring patterns with ceramic mold material. The wax of the shroud ring patterns is then removed from the mold to leave inner and outer shroud ring mold ring cavities. The shroud ring mold cavities are filled with molten metal which is solidified to form inner and outer shroud rings interconnecting the airfoils. To accommodate thermal expansion of the airfoils relative to the shroud rings, a slip joint is provided between at least one end portion of each of the airfoils and a shroud ring. To enable the slip joint to be formed, molten metal solidifies in the shroud ring to be formed, molten metal solidifies in the shroud ring cavities free of metallurgical bonds to the airfoils.

Abstract: An article having a thin wall portion with a thickness of 0.050 of an inch or less, and a surface area of at least 16 square inches is cast as one piece. A mold for the article has a pair of surface areas with a configuration corresponding to the configuration of the thin wall portion of the article and spaced apart by a distance of 0.050 of an inch or less. The mold surface areas have an extent of at least four inches along orthogonal axes with a total surface of at least 16 square inches. Although the extent of the surfaces may vary, depending upon the design of the article to be cast, the thin wall forming portion of the mold has a minimum extent or length, as measured from a center of the thin wall forming portion to the closest edge of the thin wall forming portion, such that the ratio of this minimum distance divided by the thickness is equal to at least 40.

Abstract: A process for producing a hollow metal cast product having a desired interior contour is provided. The process comprises the steps of preparing a first lost model having an outer contour substantially corresponding to a desired interior contour of the finished product, depositing a metallic or ceramic material or a mixture thereof over the surface of said first lost model by spraying to form a layer defining a hollow core block, placing said hollow core block in a first mold, pouring or injecting a material for forming a second lost mold into said first mold to form a second lost model, coating a refractory material over said second lost model to form a second mold for casting, removing second lost mold to form a cavity, casting a molten metal or alloy into said cavity, and staving said second mold to take out a finished product.

Abstract: Ceramic porous bodies, including ceramic foam filters and smooth-faced ceramic objects, e.g., ceramic foam bricks, ceramic foam melting crucibles, and ceramic foam cores, made in accordance with the present invention are suitable for use with molten metal in general and molten superalloys in particular. The invention also provides a tundish for use with ceramic foam filters to filter metal en route from a metal furnace to a casting mold, and a melting device for use in casting metal which employs a ceramic foam filter as a bottom pour valve for a melting crucible such that the ceramic foam filter valve regulates the flow of molten metal therethrough in order to permit an entire ingot of metal to melt in the melting crucible before any metal begins to pour from the melting device into a casting mold.

Abstract: A foam mold pattern assembly comprising a pattern having opposite first and second ends, a first projection connected to the pattern for facilitating suspension of the foam mold pattern assembly with the first end facing generally upwardly, and a second projection connected to the pattern for facilitating suspension of the foam mold pattern assembly with the second end facing generally upwardly.

Abstract: The mold body contains a cavity and at least one vent passage for venting gas from the cavity through the body. The vent passage has a portion of predetermined regular shape extending part-way through the cavity wall defining at one end an inlet portion opening into a portion of the cavity with a substantially greater resistance than the cavity to penetration therein of casting material. The vent passage further has an outlet portion formed by an irregular crack in the mold body extending from an inner end exposed to the inlet portion through the mold body, the crack having one of its transverse cross-section dimensions short enough to prevent leakage of casting material therethrough. The mold is made by forming a partially bonded ceramic material containing a casting cavity and incorporating in a wall of the cavity a vent pattern of a shape to mold the portion of predetermined regular shape of the vent passage.

Abstract: An investment material for dental casting comprises 100 parts by weight of a mixture of hemihydrate gypsum, quartz and/or cristobalite and 2 to 5 parts by weight of natural starch optionally with 0.1 to 1.0 part by weight of soluble starch.

Abstract: An improved system for the preparation of ceramic shell molds comprises a rotary disk which is mounted for rotating in a substantially horizontal plane. A plurality of wax master mounting bars are pivotally carried by the rotary disk to move around the periphery of the rotary disk. The mounting bars have free ends loaded with the wax masters. The rotary disk is operatively associated with the wax master mounting bars for swinging and rotating the bars on their own axes as the rotary disk rotates continuously. The preferred embodiment comprises a cam of generally twisted undulating cam strips and a roller attached to the base ends of the bars for frictionally engaging the cam face of the cam strip to swing the bars and to rotate them on their own axes. A slurry bath, a drain bath, and a stucco bath are arranged around the exerior side of the periphery of the rotary disk.

Abstract: A method of manufacturing a mould for use in the investment casting of a hollow gas turbine engine blade in which a ceramic core is coated with a surface modifying material prior to the application of wax thereto to define a pattern of the object to be cast. The surface modifying material adheres to the core and provides a textured surface to which the wax keys, thereby preventing the wax lifting from the core.

Abstract: A process for manufacturing shell molds for investment casting using an artificial stucco material is disclosed. The stucco particles comprise refractory powder held together by a binder which volatilizes or otherwise disintegrates at firing temperatures. Since the particles lose their structural integrity in the firing process, the shell mold may be more easily broken away from the finished casting.

Abstract: A method and a support structure for use in casting metal articles which define at least one internal passage and wherein the support structure is associated with a core or cores employed during the casting operation. In that operation, the cores are confined within a disposable pattern, and a ceramic mold is formed around the pattern. When the pattern material is removed, a mold cavity is provided with the core positioned in the cavity to form the desired opening in the cast article. The support structure for the core comprises a member positioned between the core surface and the opposing mold surface. This member is encompassed by the pattern material when the pattern material is formed around the core. During the subsequent removal of the pattern material and also during curing of the ceramic mold, the support member serves to hold the core in place so that the dimension of the casting wall surrounding the internal passage can be precisely maintained.

Abstract: A method of making at least the aerofoil of a blade for a gas turbine engine in which the cooling air exit passages, whether at the trailing edge or in other parts of the aerofoil, are cast rather than machined subsequently. In the method a disposable piece is formed with holes of the shape of the holes eventually required in the blade aerofoil. The piece is placed in a die and used to define part of the ceramic core required in the casting process, the die being arranged to produce a channel portion interconnecting the otherwise free ends of the parts of the core which will form the passages. The ceramic core thus formed in a lost-wax casting process to form the blade aerofoil, the channel portion being embedded in the shell mould to support the parts which define the passages.

Abstract: A blade or vane structure for a gas turbine engine comprises a hollow aerofoil member and a cooling air entry tube within the hollow aerofoil member, the aerofoil and the tube comprising a unitary cast structure. To make this structure it is proposed that a lost wax casting process should be utilized, with the internal cavities formed using ceramic cores formed with the aid of temporary, disposable pieces which define the space eventually occupied by the tube.

Abstract: A method of making a two part aerofoil gas turbine engine blade consisting of casting each individual part separately, the parts being cast by the lost wax process, and subsequently joining the parts together after machining.

Abstract: The material used for the production of cores for precision molds is a metal which is oxidizable at relatively low temperatures, i.e., below the solidification temperature of the melts for pouring, and which passes directly from the solid state to the gas state by oxide sublimation. This greatly speeds up the dissolving of cores, particularly small diameter cores, out of the castings.