The present invention concerns a method for manufacturing a metal workpiece by casting a metal alloy in a mould, wherein prior to the casting, a chart is determined providing a risk of appearance of recrystallised grains during the casting/solidification of the metal workpiece, depending on temperature and plastic deformation energy conditions undergone by said metal workpiece, the casting of the metal alloy in the mould being implemented under casting and solidification conditions determined using the chart in order for the temperature and plastic deformation energy conditions undergone by the metal workpiece to be less than a given threshold for the risk of appearance of recrystallised grains.

A ceramic core includes sintered ceramic powder and a hole opening on a surface of the ceramic core and having an opening portion with a maximum size of 100 μm or less. A manufacturing method for a ceramic core includes: preparing an injection molding composition by mixing ceramic powder and a binder; manufacturing a ceramic compact by performing the injection molding of the injection molding composition; and manufacturing a ceramic core by sintering the ceramic compact, wherein cumulative percentage of coarse powder with a particle diameter of more than 50 μm included in the ceramic powder is 30% or less on an integrated volume particle size distribution curve of the ceramic powder.

The buoyancy transfer jig includes: a rod-shaped rod portion which is disposed extending from an outside of a pattern to an inside of a hollow portion by way of an opening portion which is formed in a foamed mold and makes the outside of the pattern and the hollow portion connected with each other, and is disposed in self hardening sand filled in the hollow portion and the opening portion; and a plate-shaped blade portion which is formed continuously with the rod portion and is disposed in the casting sand.

An opening is provided in a foam pattern, and a coating agent is applied to the opening. The coating agent applied to the opening is taken as a beam having a sectional secondary moment I, a vertical plate thickness h, and a length L. It is assumed that a volume of a cavity part in the foam pattern is V (mm.sup.3), a bulk density of the casting sand filling the cavity part is ρs (kg/mm.sup.3), a density of the melt is ρm (kg/mm.sup.3), an angle of the opening with respect to a vertical direction is θ, and a transverse strength of the coating agent at the highest temperature during pouring of the melt is σb (MPa). A sectional shape of the opening, the angle θ of the opening, and the transverse strength σb of the coating agent are selected to satisfy the expression:

σbI>V(ρm−ρs){(hL/2)sin θ−cos θ}.

In the following expression, it is assumed that a thickness of a coating agent applied to a foam pattern [2] is t (mm), a diameter of a hole part [3] is D (mm), and a normal-temperature transverse strength of the dried coating agent is σc (MPa). At the time of producing a casting provided with a hole having a diameter of 18 mm or smaller and a length of 1 (mm), a coating agent that satisfies the following expression is used when a solidification end time te (sec) at which solidification of a melt ends on a periphery of the hole part [3] is within a time t0 (sec) at which thermal decomposition of the coating agent ends.

σc≧{t0/(t0−te)}×(1.5×10.sup.−4×1.sup.2/t.sup.2+160/D.sup.2)

A mold assembly for use in forming a component having an outer wall of a predetermined thickness includes a mold and a jacketed core. The jacketed core includes a jacket that includes a first jacket outer wall coupled against an interior wall of the mold, a second jacket outer wall positioned interiorly from the first jacket outer wall, and at least one jacketed cavity defined therebetween. The at least one jacketed cavity is configured to receive a molten component material therein. The jacketed core also includes a core positioned interiorly from the second jacket outer wall. The core includes a perimeter coupled against the second jacket outer wall. The jacket separates the perimeter from the interior wall by the predetermined thickness, such that the outer wall is formable between the perimeter and the interior wall.

A mold assembly for use in forming a component having an outer wall of a predetermined thickness is provided. The mold assembly includes a mold that includes an interior wall that defines a mold cavity within the mold. The mold assembly also includes a jacketed core positioned with respect to the mold. The jacketed core includes a jacket that includes an outer wall. The jacketed core also includes a core positioned interiorly of the jacket outer wall. The jacket separates a perimeter of the core from the mold interior wall by the predetermined thickness, such that the outer wall is formable between the perimeter and the interior wall.

The present disclosure provides a method of investment casting using additive manufacturing. In one aspect, the method includes: creating a digital model of a building component using one or more software tools executed on a computer device and importing the digital model in an additive manufacturing apparatus; producing a first physical specimen by controlling the additive manufacturing apparatus in accordance with the digital model; creating a first negative mold using the first physical specimen as a template, the first negative mold having a hollow space substantially defined by a surface profile of the first physical specimen; producing a second physical specimen using the first negative mold; creating a second negative mold enclosing the second physical specimen therein; producing a casting piece using the second negative mold; and finishing the casting piece to produce the building component.

3-D printed PLA material of a selected density is formed into a pattern that is configured as the outer shell of a casting form to be used in the lost foam or evaporative casting process. The purpose of 3-D printing of the PLA material is used to maintain the proper configuration of the form to facilitate casting, and reduce buildup of carbon on the surface of the casting. Because the form is essentially hollow, PLA support pieces can be used on the interior to maintain the structural integrity of the form.

Provided is a casting method using lost foam capable of forming a small highly-finished hole with a diameter of 18 mm or less and a length of 50 mm or more by casting. A casting method using lost foam of the present embodiment includes the steps of embedding, in foundry sand, a casting pattern formed by applying a mold wash with a thickness of 1 mm or more to a surface of the foam pattern, the foam pattern having a hole with a diameter of D (mm); replacing the foam pattern with molten metal by pouring the molten metal into the casting pattern and losing the foam pattern; and forming a casting having a small hole with a diameter of 18 mm or less and a length of 50 mm or more by cooling the molten metal, and the method satisfies the following formulas (0) and (1):

2<D≦19.7   Formula (0)

σc≧−0.36+140/D.sup.2   Formula (1) where σc (MPa) is transverse rupture strength (bending strength) of the mold wash that is heated to decompose resin constituting the mold wash and then returned to room temperature.