Method of casting a metal article having a thinwall

A method for casting a metal article, comprising the steps of:

• injecting investment casting wax into a metal wax injection die to form a wax assembly;
• repeatedly dipping said wax assembly in a ceramic slurry and allowing to dry at least two times, resulting in a mold with a mold cavity having an outer diameter, height, thinwall portion, a base wall portion with at least two gates, wherein said thinwall portion is less than 0.05 inches thick and free of gating;
• cleaning said mold;
• coating said mold with a final coat;
• positioning said mold in a preheated furnace so that the furnace substantially surrounds the mold and so that a longitudinal axis of the long thin portion of the mold cavity is in an upright orientation;
• heating said mold in said furnace;
• drawing a vacuum in said furnace;
• heating a metal until it forms a molten metal;
• pouring said molten metal into the mold cavity;
• breaking said vacuum;
• withdrawing said mold, wherein said molten metal has been poured;
• and
• solidifying said molten metal in said mold cavity so as to cause said molten metal to solidify to form a metal article with an equiaxed grain structure.

A method for casting a metal combustion case, comprising the steps of:

• injecting investment casting wax into a metal wax injection die to form a wax assembly;
• washing said wax assembly;
• drying said wax assembly;
• dipping said wax assembly in a primary coat;
• allowing said primary coat to dry;
• dipping said wax assembly in at least one backup coat;
• allowing said backup coat to dry, resulting in a mold with a mold cavity having an outer diameter between 12 and 22 inches, a height between 5 and 10 inches, a thinwall portion with a thickness less than 0.035 inches and free of gating, a base wall portion with a thickness less than 0.30 inches and with twelve gates and twelve atomisers, wherein said twelve gates are between said twelve atomisers;
• placing said mold in a Boilverclave;
• and
• placing said mold in a Dewax kiln;
• coating said mold with a final coat;
• wrapping said mold in Kerlane;
• positioning said mold in a preheated furnace so that the furnace substantially surrounds the mold and so that a longitudinal axis of the long thin portion of the mold cavity is in an upright orientation;
• heating said mold in said furnace to a temperature between 1045° C. and 1055° C.;
• drawing a vacuum in said furnace;
• heating a nickel based alloy metal until it forms a molten metal;
• pouring said molten metal at a temperature between 1560° C. and 1570° C. into the mold cavity;
• breaking said vacuum;
• withdrawing said mold, wherein said molten metal has been poured;
• and
• solidifying said molten metal in said mold cavity so as to cause said molten metal to solidify to form a metal article with an equiaxed grain structure.

A method for casting a metal combustion case for use within a gas turbine engine, comprising the steps of:

• injecting investment casting wax into a metal wax injection die to form a wax assembly;
• washing said wax assembly;
• drying said wax assembly;
• dipping said wax assembly in a primary coat;
• allowing said primary coat to dry;
• dipping said wax assembly in at least one backup coat;
• allowing said backup coat to dry, resulting in a mold with a mold cavity having a height, a thinwall portion less than 0.05 inches thick and free of gating and a base wall portion with a thickness less than 10 times the thickness of the thinwall portion and having at least one gate;
• placing said mold in a Boilverclave;
• and
• placing said mold in a Dewax kiln;
• coating said mold with a final coat;
• wrapping said mold in Kerlane;
• positioning said mold in a preheated furnace so that the furnace substantially surrounds the mold and so that a longitudinal axis of the long thin portion of the mold cavity is in an upright orientation;
• heating said mold in said furnace to a temperature between 1045° C. and 1055° C.;
• drawing a vacuum in said furnace;
• heating a nickel based alloy metal until it forms a molten metal;
• pouring said molten metal at a temperature between 1560° C. and 1570° C. into the mold cavity;
• breaking said vacuum;
• withdrawing said mold, wherein said molten metal has been poured;
• and
• solidifying said molten metal in said mold cavity so as to cause said molten metal to solidify to form a metal article with an equiaxed grain structure.