GB703607A - Improvements in thin-walled moulds and cores for casting metals - Google Patents

Abstract

703,607. Moulds; cores. GENERAL MOTORS CORPORATION. Nov. 13, 1952 [Nov. 14, 1951], No. 28596/52. Class 83 (1) A process of reinforcing a thin-walled mould or core for casting comprises coating the back of the mould or core with a mixture of comminuted refractory material and a waterglass solution, and then drying the coating. Two thinwalled mould halves 12 are shown, and the coating 10 which, e.g., consists of 98 per cent sand, 1 per cent commercial waterglass containing approximately 37 per cent sodium silicate, and 1 per cent additional water, may either have a flat exterior surface 11 or follow the contour of the mould half as at 13, and be between ¢ and 2 inches thick. The drying comprises baking the mould half and its coat in a circulating air oven at a temperature within the range of 300‹ F. to 700‹ F. The water glass may consist of sodium silicate, potassium silicate, a mixture of these two, or sodium tertrasilicate. In the case of cores, the coating consists in filling the interior of the 'core with the mixture. The mould halves and core are made by allowing a dry mixture of sand and resin powder, e.g. phenol formaldehyde or melamine formaldehyde, to contact a hot metal pattern to thereby form a shell on the pattern, which is subsequently aired at a temperature between 300‹ F. and 600‹ F.