The basic raw materials for manufacturing molding sand are molding sand and sand binder. The most commonly used foundry sand is silica sand. The high temperature performance of silica sand cannot meet the use requirements of zircon sand, chromite sand, corundum sand and other special sands. In order to ensure that the molding sand and core have a certain strength and will not be deformed or damaged when handling, shaping and pouring liquid metal, a molding sand binder is generally added during casting to bind the loose sand grains into molding sand. sand. The most widely used sand binder is clay. Various drying oils or semi-drying oils, water-soluble silicates or phosphates, and a variety of synthetic resins can also be used as sand binders.