Sand casting is a low cost casting method which employs a mold made from a sand mixture.  First the molten metal is poured  into the cavity in the mold. The mold is then cooled until the metal has solidified. Finally the casting is separated from the mold.

 

The following sketch illustrates the process of metal casting poured into a sand mold (courtesy Krzysiulek from Wikipedia):

 

Sand casting materials are broad, including gray iron, ductile iron, carbon steel,  alloy steel, brass and bronze, aluminum.