COLLAPSIBLE MOLD AND SHAKING-OUT METHOD FOR SAND IN MOLD

PURPOSE:To facilitate shaking-out of sand for a casting and to improve the workability by forming a collapsible mold with molding sand containing grains composing of beta-2CaO.SiO2 as at least a part of the component. CONSTITUTION:The collapsible mold is formed by using the molding sand (about 10mu-2mm average grain size) containing the grain composing of beta-2CaO.SiO2 as at least a part of the component (>=about 10wt.% containing quantity). At the time of executing the cast by using the mold, the beta-2CaO.SiO2 becomes alpha-2CaO.SiO2 by pouring molten metal and further becomes gamma-2CaO.SiO2 by slow-cooling this and the volume is increased by dislocation into gamma to become about 20mu grain size and the mold is collapsed. By this method, the cast for the casting having complicated shape or slender hollow part and the shaking-out of the sand are facilitated.