Aluminum castings are formed by pouring molten metal into molds that have been shaped by a pattern of the desired final product. The mold must be made with precision because it's quality will have a direct impact on the shape and surface finish of the finished aluminum casting.
The mold can be made from many different materials, including tool steel, because aluminum has a lower melting point than steel. Another material that a mold can be made out of for aluminum casting is sand. For this, the sand is pressed to take the form of the desired finished part. Once the sand is formed, the liquid aluminum is poured into it and allowed to cool.
Aluminum castings have properties similar to other aluminum components. Once the casting process is complete the aluminum castings quickly form an exterior layer of aluminum oxide that helps protect against corrosion.