RESIN COATED SAND FOR CASTING

摘要

PURPOSE:To obtain resin-coated sand for castings which permits the improvement in hot strength without increase in the amt. of a thermosetting resin in the stage of producing the coated sand with said resin by combining fibers with the resin. CONSTITUTION:A binder prepd. by adding 5-50pts.wt. inorg. or org. fibers to 100pts.wt. thermosetting resin is added and mixed the molding sand which is charged in a mixer in, for example, a heated state. The thermosetting resin is then cured to produce resin-coated sand. The resin-coated sand is coated with the thermosetting resin by the binder compounded with the thermally stable fibers having high tensile strength, wherein at least part of the compounded fibers are disposed perpendicularly to the surfaces of sand grains. The hot strength in the stage of forming a casting mold and a core is thus improved remarkably and since the amt. of the resin is reduced by the compounded fibers, the generation of gaseous defect of casting is prevented.