In metal working and jewelry making, casting is the process of delivering liquid metal into a mold (usually through a crucible) that contains a negative (i.e. three-dimensional negative) of the desired shape. Metal is poured into the mold through hollow channels called sprues. The metal and mold are then cooled and the metal part (casting) is removed. Casting is most often used to make complex shapes that would be difficult or uneconomical to make by other methods. 

  The casting process has been known for thousands of years and has been widely used in sculpture (especially bronze), precious metal jewelry, and weapons and tools. Highly engineered castings are used in 90 percent of all durable goods including automobiles, trucks, aerospace, trains, mining and construction equipment, oil wells, appliances, pipes, fire hydrants, wind turbines, nuclear power plants, medical equipment, defense products, toys and more.

  Traditional techniques include lost wax casting (which can be divided into centrifugal casting, vacuum assisted direct pouring casting), plaster casting and sand casting.

  Modern casting processes are divided into two categories: consumable casting and non-consumable casting. It is further broken down by mold material (such as sand or metal) and pouring method (such as gravity, vacuum or low pressure).