Since the castings cool and solidify faster in the metal mold than in the sand mold, and the metal mold has no tolerance, the casting stress generated in the casting is larger than that in the sand casting. The cracking tendency is also greater, and it is easy to produce pouring. Insufficiency, cold barrier, white mouth (for castings) and other defects. Therefore, when buying sand casting products, you must find large-scale casting manufacturers to ensure the quality.