Abstract: A melt core constructed of a low temperature melting point alloy for producing a cavity in a structural part manufactured by injection molding, the melt core being formed as a hollow body. Depending upon the production process employed, the hollow body is provided with an opening, which is tightly sealed by a separately produced cover constructed of the same material as the hollow body that it seals.

Abstract: The present invention relates to a heat resistant composition which exhibits excellent heat and wear resistances after being cured. Further, it has excellent releaseability and durability, and the cured film thereof has a more excellent stability than a prior art adhesive of this type, by preparing it from two components: a powder mixture consisting of 20% by weight or more of zirconium oxide, 1 to 10% by weight of sodium titanate, 2 to 15% by weight of yttria based on the zirconium oxide and the balance of silica; and a sodium silicate containing a small amount of water added thereto.

Abstract: This invention includes an apparatus and method for molding and curing a curable composite patch used for repairing damaged contoured surface structures. The molding apparatus has a fluid impermeable outer container having a flexible outer wall. A flexible, fluid impermeable inner container containing a moldable granular material is positioned within the outer container and has a flexible molding wall on which the composite patch can be placed. Inner and outer ports are located on the inner and outer containers for evacuating the inner and outer containers. A model of an undamaged surface is formed by positioning the molding wall of the inner container against an unaffected surface and evacuating the inner container so that the granular material is rigidly held in a molded form. The patch is placed on the molding wall and the outer container is sealed with the outer wall positioned over the patch and molding of the inner container.

Abstract: The knee orthesis appliance is made of carbon-fiber composite material with an integral Menshik linkover four bar chain (21) made of titanium. It provides the knee joint with secure and reliable support. Owing to its low weight, it is extremely comfortable to wear. The angle of bend (22) can be adjusted to suit the individual as prescribed by the doctor. The shells of the appliance are made from a positive plaster cast (1), using vacuum composite production techniques. This simple process enables the appliance to be manufactured to a high standard of quality in orthopaedic workshops. The joint plates (5,6) are inserted between the individual layers of the composite. Following filling and curing, the sidepieces (16,17) only have to be riveted to the joint plates to complete the four bar chains and hence the finished appliance.

Abstract: A two-phase thermoplastic composition adapted for forming thermoplastic patterns. The composition comprises an organic thermoplastic pattern material and at least about 5% by weight of discrete particles of cross-linked poly(methylmethacrylate) that are physically stable at temperatures above 130.degree. F. Also disclosed are investment casting patterns of such composition and processes utilizing such composition.

Abstract: A method for molding experimental, prototype and replacement parts from rubber-like materials using a frangible core wherein a core is made by coating a cavity with a mold release agent, coating the release agent with a quick set resin, pouring a two-part polyurethane resin into the cavity, sealing the cavity and allowing the polyurethane to foam, expand and adhere to the quick set resin.

Abstract: A film-like molded body having a hollow portion of a predetermined contour and made from a disappearing material is formed first using a mold. Also, a disappearing model is prepared by dividing it into a plurality of disappearing model elements. Then, the disappearing model elements are placed so as to enclose the film-like molded body with the film-like molded body as a core and are bonded together and fixed using an adhesive. Accordingly, the disappearing model can be prepared easily while preventing the adhesive from being forced out into the disappearing model and dispensing with extraction of the film-like molded body.

Abstract: This invention offers a unique method to fabricate unique, straight, curved, or coiled tubes as small as 5 nanometers in diameter with wall thicknesses starting at about 1 nanometer. These tubes can be made from many materials such as polymers, ceramics and metals that can be applied to a surface of carbon, glass, or other tube forming fibers and then made to withstand the environment used to remove the fiber.

Abstract: A method and system for making a three dimensional product wherein the size and shape of a plurality of cross-sectional segments of the three dimensional object are determined which when assembled together in a particular sequence form the desired three dimensional shape. Thin layers of material in the shape of each of the cross-sectional segments are applied in the particular sequence in which they form the three dimensional object. The application of each of the layers is much like a lithographic printing process in that a resin may be applied by a roller in the shape of the cross-sectional segments.

Abstract: A method for forming a three-dimensional object by applying segments of complementary material and deposition material so as to form layers of material. Selected segments of material are then shaped after one or more segment is formed. In this manner, layers of material form a block containing the object made of deposition material and surrounded by complementary material. Then, the complementary material which serves as a support structure during forming is removed. Preferably, the complementary material has a lower melting temperature than the deposition material and is removed by heating the block. The deposition material and complementary material are preferably applied by thermal spray deposition but may be applied by weld deposition, liquid slurry, gravity drop or any manual means such as a hand sifter. It is also preferred but not necessary to use masks when applying the material.

Abstract: A method of making a fused polycarbonate pattern for casting alloy structures, particularly gas-turbine blades, or components. A plurality of powder layers are fused together by a laser beam in a layer-by-layer fashion to produce the pattern. A pattern/casting mold is made and the pattern is burned out in a flash flame oven at a temperature ranging from about 1600.degree. F. to about 2100.degree. F. Preferably the burn-out step is conducted in the presence of an air stream so that the polycarbonate pattern is burned out ash free.

Abstract: Para-polyphenylene sulfide, a non-composite, ultrahigh-temperature-resist, thermoplastic resin, is employed for the manufacture of interceptor motor cases. The thermoplastic resin, para-polyphenylene sulfide, has a combination of properties which are of particular interest in the fabrication of interceptor rocket motor cases. Para-polyphenylene sulfide in ribbonized form is wound directly onto the required mandrel and then fused into a solid mass. The fused, solid mass has the properties which enables it to serve as both insulator and motor case material. The manufacture of a combination insulated motor case is achieved by the following method: The equipment, first, involves the fabrication of a breakout mandrel by one of several methods. The para-polyphenylene sulfide is ribbonized by extrusion and wound down on the breakout mandrel to the required thickness and fused into a solid mass by heating to its melt temperature of about 285.degree. C.

Abstract: An improved process for slip casting ceramic articles that does not employ parting agents and affords the casting of complete, detailed, precision articles that do not possess parting lines. A wax pattern for a shell mold is provided, and an aqueous mixture of a calcium sulfate-bonded investment material is applied as a coating to the wax pattern. The coated wax pattern is then dried, followed by curing to vaporize the wax pattern and leave a shell mold of the calcium sulfate-bonded investment material. The shell mold is cooled to room temperature, and a ceramic slip is poured therein. After a ceramic shell of desired thickness has set up in the shell mold, excess ceramic slip is poured out. While still wet, the shell mold is peeled from the ceramic shell to expose any delicate or detailed parts, after which the ceramic shell is cured to provide a complete, detailed, precision ceramic article without parting lines.

Abstract: A method of removing a core from a molded product in which the core is formed of a particulate inert material, such as sand, bound together by a cured water soluble binder. The binder is cured by heat. The core and molded product are exposed to water, preferably heated water in a bath or steam, after the product has been molded to rapidly disintegrate the core and remove it from the molded product.

Abstract: A casting method for manufacturing various types of ceramics products having an intricate configuration and a partly diversified wall thickness, such as compressor scroll blade and a screw rotor, by casting a slurry including ceramics, etc. in a mold, includes an arrangement wherein the mold is partly or entirely formed of a flexible gel material which can be melted by heating at a temperature lower than the boiling point of the dispersion medium, whereby the stresses generated when molding the product can be mitigated. Thus, the molding of a product having a high level of dimensional accuracy can be carried out with ease.

Abstract: A method of removing a core from a molded product in which the core is formed of a particulate inert material, such as sand, bound together by a cured binder of a water soluble carbohydrate alone or mixed with a silicate is disclosed. The silicate is preferably an alkali earth metal silicate, preferably sodium silicate, and the carbohydrate is preferably a saccharide or starch. The binder is cured by heat. The core and molded product are exposed to water, preferably heated water in a bath or steam, to rapidly disintegrate the core and remove it from the molded product.

Abstract: A method of forming a fastener member having a base and a plurality of headed stems arranged in columns and rows and projecting from the base. The fastener member is formed by injection molding a molten material into a base mold, sacrificial stem mold and head mold, wherein the material is solidified. After the base mold and head mold are removed, the stem mold may be destructively removed to release the fastener member.

Abstract: A process for producing a sturdy refractory metal oxide article includes the steps of heating a substrate of organic material impregnated with a metal compound to thermally decompose the compound without substantial thermal decomposition of the substrate, further heating to decompose and remove the organic material and complete conversion of the compound to a metal oxide so that a metal oxide replica of the substrate remains and further heating to sinter and densify the replica such that the replica has a strength (shock resistance) figure of merit of at least three g-meters and the replica retains such strength after heating to 1500 C.

Abstract: Golf balls are manufactured by supplying a golf ball - forming material into a mold defining a cavity of a predetermined surface pattern, thereby forming a golf ball having a surface pattern transferred from the mold cavity surface pattern. The mold is prepared by way of electroforming. First using an elastic non-metal profiling material, a male duplicate master is fabricated from a female standard mold having at least one accessory for assisting molding or post machining such as a parting surface and reference surface. An electroformed mold is fabricated from the male duplicate master. This electroformed mold is ready for use as the ball manufacturing mold.

Abstract: A process for obtaining precision castings of body parts wherein the body part is first immersed in a ice and water slush, immediately removed therefrom and immersed in a melted paraffin wax-water container, immediately removed therefrom and the body part extracted from the resulting wax mold. At least the interior surface of the hollow wax mold is coated with a casting material and permitted to cure at room temperature. The cured casting is heated by immersion in the wax-water container or in a separate heated water container for a period of at least ten minutes to remove the wax mold and recover a casting of the body part. The removed wax molding material may be recycled and employed in subsequent castings and recover a casting of the body part.

Abstract: A method for manufacturing a plastic hollow product with complicated geometry using water soluble resin. The method includes the steps of making a half shell of the core out of the water soluble resin, joining the half shells together into a piece by solvent welding, ultrasonic welding, vibration welding, or the like, overmolding the core with water resistant resin, and dissolving the core away from the overmolded product by spraying hot water thereto. The injection conditions such as injection time, injection speed, and injection pressure are varied in the respective zone which is divided into several divisions by same distance in the injection cylinder. Therefore, injection procedure is performed in a stepwise manner to make a hollow product.

Abstract: A spiral cutter for use in an electric razor in which the lower end of a band-shaped blade made of elastic material is embedded in the peripheral surface of a body with the band-shaped blade torsionally deformed. The spiral cutter is manufactured by the steps of: mounting a band-shaped blade made of an elastic material in a body molding die with the band-shaped blade torsionally deformed; molding a base; and removing a molded product from the body molding die after the body is molded.

Abstract: Novel ceramic filamentary micro-tubular materials are described. An entirely fluid-phase method has been devised for producing such interwoven ceramic filamentary tubular materials. The process depends for its success the ability to generate a three-dimensional random weave of ceramic tubes, with diameters in the range of about 0.01 to 2.0 microns, by forming carbon filaments by catalytic decomposition of a hydrocarbon feed, coating the filaments with a ceramic coating and then oxidizing the coated filaments to remove the carbon core leaving behind hollow ceramic micro-tubular filaments. The ceramic micro-tubular materials may be free-standing porous structures and may have a variety of uses as thermal insulators, catalyst supports, superconductor supports, filters or as reinforcements for composites.

Abstract: This invention relates to investment casting compositions comprising (i) a refractory material, e.g., a ceramic material, and (ii) a soluble core material comprising one or more block polymers characterized by an ABCBA structure. This invention also relates to methods for investment casting and to the manufacture of molded articles. The soluble core materials exhibit desirable breaking strength, dissolution rate and surface characteristics.

Abstract: The present invention is a wax-based material for use in the lost wax process where the wax must be capable of withstanding temperatures of up to 350.degree. F., the wax-based material including: (a) a high temperature brittle wax; (b) about 5-30 wt % organic plasticizer including polyfunctional amines and alcohol amines and (c) about 5-10 wt % paraffin wax.

Abstract: A multiple metallic core assembly for use in production of a plastic injection-molded component is formed by injecting molten metal alloy into a core die at a fill stage of an indexing system, indexing the core die through a cooling stage to an unloading stage, and removing the core from the core die and inserting the core in one of a plurality of locations of the core assembly. Individual cores are continued to be formed as discussed above until all the locations of the core assembly are filled, and the core assembly is complete. Therefore, the core assembly is removed and transported to a plastic molding machine to produce the plastic component. Then, the core assembly is melted out from the plastic component in hot oil, and the molten metal alloy produced thereby is returned to a molten metal alloy tank.

Abstract: A mold and method for forming a balloon for dilatation catheters, particularly balloons with a prismlike shape with a transverse polygonal cross section when the internal pressure is at atmospheric conditions. Upon inflation to higher internal pressures, the balloon assumes a normal circular cross section. The balloon shape is particularly suitable for balloons formed of polyethylene terephthalate and the like which are not readily heat settable. Reduced deflated profiles are obtained. The mold is formed by first making a preformed core member which has the shape and dimensions which are desired for the balloon. A heat-formable tubular member, preferably formed of borosilicate glass such as PYREX, is disposed about the core member, subjected to heat and an internal vacuum so as to be shaped onto the exterior of the core member.

Abstract: A mold, having a mold cavity commensurate with the shaping, forming or welding to be made, includes an RF energized heater in close proximity to the mold cavity for heating plastic tubing placed within the mold cavity to a temperature sufficient to shape, form or weld the plastic tubing. An RF generator, electrically connected to the RF energized heater, monitors the power applied as a function of the temperature of the heater to heat the plastic tubing to a precise temperature. The mold is of thin wall construction with minimal thermal inertia to expedite both heating and cooling. Various configurations of the mold may be made to form tip shaping, forming or welding, butt welds, annular welds and the like to weld single thermoformable elements or join multiple thermoformable elements.

Abstract: A method of making a shell mould, particularly for a lost wax casting operation, includes the deposition of an adhesion agent on the pattern before the deposition of layers of ceramic material to build up the mould. The adhesion agent used is preferably a 3% solution of aminosilane in a solvent consisting of ethanol and ethyl acetate in amounts from 25% to 75% of the solvent. The method avoids the phenomenon of detachment at the pattern/ceramic interface.

Abstract: Method of producing a mold from a ceramic composition which can be washed-out with water after use thereof in a molding process, the method including forming a ceramic composition by mixing from about 30 to about 80 weight percent of at least one hemihydrate including alpha-calcium sulfate hemihydrate or beta-calcium sulfate hemihydrate, from about 5 to about 45 weight percent of fire clay, and from about 5 to about 25 weight percent of at least one silicate-based filler. About 100 parts by weight of the ceramic composition are mixed under stirring into from about 46 to about 54 parts by weight of water to form a slurry. The slurry is poured into a formation mold suitable for forming the desired mold and the slurry contained in the formation mold is allowed to set and form a set body. The set body is then removed from the formation mold and dried to provide the mold.

Abstract: A method of encasing a luminous translucent tubing (12,32) of a non-linear complex geometrical configuration in a transparent outer member (14,34) and forming a passage (25,35) of annular radial cross section therebetween, which method comprises coating the exterior of the tubing (12,32) with a viscous temporary material (17,47) which solidifies to provide a coating with smooth exterior surface, coating the temporary substance (17,47) with a permanent forming material in a viscous liquid state which hardens to form a rigid transparent outer member (14,34) in coextensive surrounding relation to the tubing (12,32) and its coating of temporary material (17,47), applying heat to said coating of temporary material at a temperature above the melting point of the temporary material and below the softening temperature of the outer member, and removing the temporary material from between the translucent tubing (12,32) and the transparent outer member (14,34) while supporting the translucent tubing in fixed relation to

Abstract: A three dimensional article is produced layer by layer by jetting droplets of at least two different hardenable materials, as appropriate, into the various layers, the first material forming the article itself, and the second material forming a support for the article as necessary. The second material is thereafter separated from the first material, e.g., by heat, to form the desired article.

Abstract: A process for producing a cylindrical reinforcing fibrous molding by sealing openings at opposite ends of a porous cylindrical disintegratable mold, immersing the mold into an aqueous solution of a molding material containing reinforcing fibers and an inorganic binder, and depositing the molding material onto the outer peripheral surface of the mold by applying suction within the mold to form a molding blank; pressing the molding blank against the mold to adjust the shape of the molding blank; disintegrating the mold to remove it from the blank; and heating the molding blank to partially bond the reinforcing fibers with the inorganic binder.

Abstract: A method and apparatus for forming a three-dimensional object by thermal spraying utilizes a plurality of masks positioned and removed over a work surface in accordance with a predetermined sequence. The masks correspond to cross sections normal to a centerline through the workpiece. One set of masks defines all cross sections through the workpiece. A second set of masks contains at least one masks which corresponds to each mask of the first set. Masks from each set are alternatively placed above a work surface and sprayed with either a deposition material from which the workpiece will be made or a complementary material. In this manner, layers of material form a block of deposition material and complementary material. Then, the complementary material which serves as a support structure during forming is removed. Preferably, the complementary material has a lower melting temperature than the deposition material and is removed by heating the block.

Abstract: Sand cores are removed from metal or plastic coatings by exposing the cores to a humid atmosphere for a sufficient time to weaken the binder of the sand cores. The sand is then shaken from the casting. Metal or plastic castings with hollow passages are produced by forming a casting around the sand core bound with a suitable binder followed by exposing the casting and sand core to a humid atmosphere and then shaking the sand from the casting.

Abstract: A method of making a femoral rasp wherein the hip stem implant is used to make a two part mold. The mold halves are separated and the implant removed to yield left and right mold halves representing corresponding halves of the hip stem. The cavities of the mold halves are lined with wax and a plurality of blades are imbedded into the wax such that an anchor portion of each of the blades remains exposed. The mold halves are connected together and a stem of handle is inserted therein. A moldable material such as PMMA is poured into the mold and allowed to cure. When the PMMA is hard or cured, the mold halves are separated and the wax is removed from the rasp body exposing the cutting surfaces of the teeth.

Abstract: In connection with a device for casting lead grids for electric battery plates, a highly porous ceramic mold lining, preferably of zirconium oxide, is prepared by flame-spraying. Such a lining can include a thin surface coating on a profiled, basic metallic mold or a separately prepared insert plate which is retained to a metallic mold molder. The ceramic surface coating may be accurately formed in place, or may be formed as an over-spray which is then reduced in thickess. Formation of the surface coating may be accomplished by placing masks on the basic metallic mold during the flame spraying, for those areas of the grid which tend to accumulate material, or by adjusting an initially coarse profile of the ceramic layer to the exact profile of the casting by a material-removing treatment.

Abstract: Particulate matter having precisely controlled length, width, thickness (i.e., height) and shape is produced with photolithographic techniques using a release film. In accordance with the method, a first photoresist layer is cured upon a substrate and a second photoresist layer is selectively cured upon the first photoresist to provide a desired pattern. The uncured portions of the second photoresist layer are removed so that a plurality of first and second deposition sites are produced wherein each said first and second deposition site has the desired area and wherein each first deposition site is located in a first plane and each second deposition site is located in a second plane. Further, portions of the substrate which are not part of the first deposition site are not located in the first plane and portions of the substrate which are not part of a second deposition site are not located in the second plane. The desired material is deposited using line-of-sight chemical deposition techniques.

Abstract: Novel ceramic filamentary micro-tubular materials are described. An entirely, fluid-phase method has been devised for producing such interwoven ceramic filamentary tubular materials. The process depends for its success the ability to generate a three-dimensional random weave of ceramic tubes, with diameters in the range of about 0.01 to 2.0 microns, by forming carbon filaments by catalytic decomposition of a hydrocarbon feed, coating the filaments with a ceramic coating and then oxidizing the coated filaments to remove the carbon core leaving behind hollow ceramic micro-tubular filaments. The ceramic micro-tubular materials may be free-standing porous structures and may have a variety of uses as thermal insulators, catalyst supports, superconductor supports, filters or as reinforcements for composites.

Abstract: A method of removing a core from a molded product in which the core is formed of a particulate inert material, such as sand, bound together by a cured binder of a water soluble carbohydrate alone or mixed with a silicate is disclosed. The silicate is preferably an alkali earth metal silicate, preferably sodium silicate, and the carbohydrate is preferably a saccharide or starch. The binder is cured by heat. The core and molded product are exposed to water, preferably heated water in a bath or steam, to rapidly disintegrate the core and remove it from the molded product.

Abstract: A method for producing an article having a body with one or more enclosed channels extending therethrough such as for the circulation of fluids. The body is formed preferably by metal deposition about one or more fibers to generate the enclosed channels with at least one end of the fibers extending beyond the body. The fibers are then extracted from the channels in the body to leave open the channels through which fluid may be circulated.

Abstract: A method for determining the degree of adherence to a non-flat, opaque vehicle panel surface of a component adhered thereto. The method includes providing an integrally cast clear matched surface in the panel so that the contacting surfaces of the component may be directly viewed.

Abstract: A ball screw system has a screw (1, 2) and a nut (3) mounted thereon by means of balls (5). Redirecting portions (6) which delimit redirecting channels for circulating balls running in thread grooves of the screw and the nut are formed in openings extending transversely in the nut. The openings in the nut are filled with an initially liquid, solidifiable or curable material. The redirecting ball or recirculating channels are thereby cast therein.

Abstract: In one embodiment this invention provides vinylidene copolymers with alternating monomeric units as illustrated by the following structure: ##STR1## An invention vinylidene copolymer in the form of an electret film exhibits a high level of longitudinal piezoelectric effect, and has excellent processability and thermal stability properties.

Abstract: A lost positive pattern comprising an open-pored plastics substrate containing pores with an average width of from one to three millimeters is used, in which, after a negative pattern has been made, the voids which it, as a core, contains are filled with metal by casting and the negative pattern is removed. The production of the negative pattern is preceded by the following method steps in which once the substrate of plastics material has been cleaned, it is wetted throughout with a keying resin film which partially dissolves the structure of its surface and in which at least one coat of an auto-crosslinking two-pack silicone is applied onto and into the whole of the substrate of plastics material to thicken the walls and/or the interlinking webs of the porous substrate of plastics material.

Abstract: It is a method of treatment of support rods for the support of steel reinforcements in making aerated concrete, in which the support rods are first dipped into a hot bath of molten paraffin or a similar wax-like, waterproof material, which is solid at room temperature and has a softening temperature of about 50.degree. to 70.degree. C. Then the coating formed thereby is hardened by cooling. Then the steel reinforcements are suspended on the support rods and they, together with the support rods are coated with a corrosion protection medium in the form of a water-lacquer.

Abstract: The method of making a plastic article having a plurality of small openings which utilizes a plurality of thin plastic tubular members combined together in a side-by-side relationship forming an assemblage. Each tubular member has an exterior layer of a first plastic and a core of a second plastic. The second plastic is to be dissolvable by a solvent. This assemblage is passed through a furnace with the result that the assemblage is drawn into a thin filament. Once cooled, the thin filament is cut into segments of a desired length and these segments are placed within a solvent bath for a sufficient period of time in order to affect complete removal of the second type of plastic resulting in producing of a plurality of small, through openings within each section.

Abstract: A method for molding powders to form a shaped compact comprising the steps offorming a thin-wall resilient mold having an outer surface and having at least one opening adjacent a surface of a model of a desired shape, forming a mold support on the outer surface of the thin-wall resilient mold, so that the mold support adheres to the outer surface of the thin-walled resilient mold,removing the model from the thin-wall resilient mold whereby a cavity is formed in a portion of the thin-wall resilient mold, from which the model is removed, filling up the cavity of the thin-wall resilient mold with a powder as a forming material through the opening,sealing the opening of the thin-wall resilient mold after having evacuated air from the inside of the thin-wall resilient mold,removing the mold support from the thin-wall resilient mold,subjecting the thin-wall resilient mold filled with the powder to a cold isostatic press.

Abstract: Open-celled metal structures are produced which have walls and webs of uniform strength throughout. The structures may also have an irregular surface pattern. To make a strengthened positive pattern, the method comprises application of at least one layer of a strengthening agent such as poly(methyl methacrylate) or polyester resin to a plastic substrate used for ceramic mold formation. The strengthened positive pattern is embedded in a ceramic mass, and heated to incinerate and remove the plastic substrate, which results in voids in the ceramic mass. Molten metal is poured into the ceramic mass. After solidification, the ceramic mass is removed to form the open-celled metal structure.

Abstract: An improved method of manufacture is provided for producing a channeled wall thrust nozzle (10) of the type used to define a thrust chamber (12) in a jet or rocket engine. The method utilizes a precision formed mandrel (20) having an external geometry conforming generally to the converging-diverging shape of the desired thrust chamber (12), and further including longitudinally extending slots (24) for receiving channel separation ribs (26) which may be formed by die cutting from sheet stock. The channel spaces (16) between the separator ribs (26) are filled with a removable casting material (30) such as wax, and an outer housing shell (32) for the thrust nozzle is mounted about and secured to the separator ribs. The mandrel (20), which is transversely split at the throat of the thrust chamber (12), is then removed to expose the radially inboard margins of the separator ribs (26) for precision machining, followed by mounting of an inner housing shell (34) to the separator ribs.