One of the first casting decisions is the choice of a molding method, which will affect the surface finish and the dimensional tolerances of the finished casting. 

GREEN SAND MOLD
Moist, clay-bonded sand is tightly packed around a wood or metal pattern in mold boxes to form a rigid mold cavity. The  two pattern halves are removed, and the mold is assembled with or without cores.

NO-BAKE SAND MOLD
Chemically bonded sand is packed around a wood or metal pattern in mold boxes. At room temperature, the sand mold become rigid. Pattern halves are removed and the mold is assembled with or without cores.