Sand core for casting and process for producing the same

Abstract

In the sand core, the tar reducing agent is included in at least the second coating layer, which is the outermost layer, of the coating layersand. Thus, the tar, which may be generated from the core bodyand the coating layersandwhich are positioned thereinside, can be decomposed into low molecular gases (carbon monoxide, carbon dioxide, water, and the like) by heat of the molten metal. As a result, generation of the tar from the sand coreto the outside can be prevented. In this case, since the layer which includes the tar reducing agent is the second coating layerwhich directly contacts the molten metal, the second coating layercan directly receive the heat of the molten metal, and the tar generation prevention effects can be thereby remarkably obtained. Therefore, generation of defects in cast products which may be caused by clogging in the gas drain can be prevented, and structures of the gas drain of the die and the surroundings thereof can be simplified.