The earliest known metal casting is believed to have been formed around 3200 B.C.E. and was made of copper. The first examples of cast iron appeared around 800 B.C.E and were followed closely by sand castings around the sixth century B.C.E. Since those first developments, the concepts and operating principles behind metal casting have not changed; casting involves melting a metal and forcing it into a mold in order to give it a shape. Today, cast metal products can be found in all kinds of industrial, commercial and consumer products contexts, and they are applied in many ways. In the automotive industry, most engine block varieties are made with die casters. Cast aluminum valve covers are also widely used in automotive applications. Steering wheel structures can often be made of cast magnesium, which is among the more versatile casting materials. Alloy castings of all varieties are used in commercial and residential plumbing systems. There are several ways in which metals can be cast, but one of the most efficient and advanced methods is die casting.Die casting involves pressurizing molten metal and injecting it into a mold in order to shape it. Aluminum, brass, bronze, zinc, magnesium, lead and several other metal varieties can be die cast, though not all metals can be die cast using the same methods and machinery. As the molten metal cools, it takes the shape of the mold and solidifies into that shape, at which point it is removed from the mold. Metal castings are very useful and common for several reasons. They can produce complex parts of all shapes and sizes. Also, the metal casting process is very economical and produces little waste; extra metal in castings can be collected, reheated and reused. There are many different types of metal castings. Die casting is so widely used because of the precision with which it can create parts. Metal shaping operations that require greater accuracy and intricacy, such as gear manufacturing, usually employ die casting as their metal shaping method. Other types of casting methods include centrifugal molds, permanent molds, expendable pattern and investment castings. The particular type of metal casting chosen depends on the requirements of the application.