For sand (core) technical requirements:

　　1, strength: external forces are not easy to damage the performance, but the lack of strength will lead to the collapse of the box, trachoma;

　　2, refractory: hot liquid metal will not soften under the inadequate, if the refractory, sand bonded to the surface layer of the shell, resulting in cutting, serious sand sticking difficulties, casting waste;

　　Secondly, the technical needs of clay:

　　1, from the casting size, weight, size, volume of the impact;

　　2, cast iron, steel, copper, cast aluminum can be;

　　3, hand-made, machine molding can be;

　　4, a wide range of clay sources, cheap, recyclable!

　　Manufacturers do not require high series of automatic horizontal molding machine sand type, dry sand type and wet sand, good initial viscosity, viscosity in general, red sand, black sand beach, sand coal can be used.

　　Copper and aluminum are usually used for red sand casting, cast iron, cast steel casting usually black sand.