A casting green sand mold comprising at least a pair of green sand mold parts each having a cavity portion, which are stacked with their cavity portions aligned to form a metal-melt-receiving cavity; each of the green sand mold parts being formed by casting sand containing a binder and water; a hardening-resin-based coating layer being formed on at least the cavity portion of each green sand mold part; the coating layer having gas-permeable pores having sufficient permeability to permit a gas generated by pouring a metal melt to escape; and a water content in a surface layer including the coating layer in a range from the cavity surface to the depth of 5 mm being smaller than that in the inner portion of the green sand mold.

A method of reusing core sand includes crushing a core used for casting into granules, the core includes water glass as a binder, and the water glass includes water-soluble water glass and water-insoluble water glass; heating the core; detaching the water glass from the core sand; and separating and collecting the core sand from a mixture of the water glass and the core sand.

The invention relates to a composition for forming a casting mold, the composition containing heat-resistant inorganic particles; a waterglass-based binder; a surfactant; a silicon-containing compound; activated carbon powder and grain; and water; and the silicon-containing compound contains at least one of metal silicon and ferrosilicon.

Compositions useful for foundry processes such as green sandcasting are discussed. The compositions may include ball clay, bentonite, and a carbonaceous material. The ball clay may include leonardite and/or causticized lignite, e.g., as a portion of the natural ball clay deposit. The composition may further include sand, such that the resulting mixture may be formed into a green sand mold for use in casting molded articles. Incorporation of ball clay materials in the compositions may help to improve the quality of the casted article.

A composition which comprises a soluble or partially soluble phosphate, a refractory material and less than 1% of an oxide or hydroxide of magnesium or calcium. The composition may be mixed with water to form an investment casting slurry into which a wax pattern may be dipped. Slurry coated onto the pattern may be set by applying a stucco composition which comprises an oxide or hydroxide of magnesium or calcium. Coats of set slurry may be built up on the pattern to form an investment casting shell.

The present invention provides a gypsum-based embedding material composition for casting useful for forming a rapid-heating type gypsum-based embedding material and a method for producing the same. The gypsum-based embedding material is formed of the gypsum-based powdery embedding material composition by adding a malaxation liquid into the composition and heating the mixture in a high-temperature furnace. The gypsum-based embedding material composition contains as main components, at least one co-pulverized material selected from a co-pulverized material of calcined gypsum and quartz, that of calcined gypsum and cristobalite, and that of calcined gypsum, quartz, and cristobalite. The composition further contains a powdery moisture-retaining component or a liquid moisture-retaining component having a low water content, and has an average particle diameter of 30 μm or less.

The present invention provides a gypsum-based embedding material composition for casting useful for forming a rapid-heating type gypsum-based embedding material and a method for producing the same. The gypsum-based embedding material is formed of the gypsum-based powdery embedding material composition by adding a malaxation liquid into the composition and heating the mixture in a high-temperature furnace. The gypsum-based embedding material composition contains as main components, at least one co-pulverized material selected from a co-pulverized material of calcined gypsum and quartz, that of calcined gypsum and cristobalite, and that of calcined gypsum, quartz, and cristobalite. The composition further contains a powdery moisture-retaining component or a liquid moisture-retaining component having a low water content, and has an average particle diameter of 30 μm or less.

The invention relates to a method for more quickly producing molds (2) or cores (2′) for foundry purposes by adapting the specific electrical resistance in the selection of the core box to the mixture (9) of a molding material and of a water-containing binder, which binder, when dissolved, forms an electrolyte and has a sufficient electrical conductivity. It is essential to the invention that an electrically conductive material (7) for holding the mixture (9) is introduced into an electrically non-conductive housing (3), wherein the specific electrical conductivity of the material (7) at operating temperature (7) at least approximately corresponds to the specific electrical conductivity of the mixture (9) at temperatures between 100° C. and 130° C., and that electrical energy and thus heat are supplied to the material (7) via electrodes (10) arranged in/on the housing (3) (resistance heating principle), leading to curing of the mixture (9). Depending on the sand core, up to 30% shorter cycle times can be achieved.

The invention relates to a method for more quickly producing molds (2) or cores (2′) for foundry purposes by adapting the specific electrical resistance in the selection of the core box to the mixture (9) of a molding material and of a water-containing binder, which binder, when dissolved, forms an electrolyte and has a sufficient electrical conductivity. It is essential to the invention that an electrically conductive material (7) for holding the mixture (9) is introduced into an electrically non-conductive housing (3), wherein the specific electrical conductivity of the material (7) at operating temperature (7) at least approximately corresponds to the specific electrical conductivity of the mixture (9) at temperatures between 100° C. and 130° C., and that electrical energy and thus heat are supplied to the material (7) via electrodes (10) arranged in/on the housing (3) (resistance heating principle), leading to curing of the mixture (9). Depending on the sand core, up to 30% shorter cycle times can be achieved.

A description is given of a method for producing a molding material mixture or for producing a molding material mixture and a molding therefrom, preferably casting molds or cores, for use in the foundry industry, where the molding material mixture comprises a mold base material and a solution or dispersion comprising lithium-containing waterglass, comprising the following steps: (1) producing or providing a kit at least comprising as separate components: (K1) an aqueous solution or dispersion comprising waterglass and (K2a) a first waterglass-free solution or dispersion comprising lithium ions in solution in water, and also preferably (K2b) a second waterglass-free solution or dispersion, preferably comprising lithium ions in solution in water with a lower concentration than in component (K2a), and thereafter (2) producing a mixture of the mold base material with a fraction of component (K1) and with a fraction of component (K2a), and also optionally with a fraction of component (K2b). Further described is an aforementioned kit, more particularly for application in the method of the invention. An installation is specified as well for producing an intermediate solution or dispersion, comprising lithium-containing waterglass, for use in producing a molding material mixture or for producing a molding material mixture and a molding therefrom.