In the Die casting process reusable dies are preheated coated with a release agent to lubricate and protect the surfaces of the dies before each use. Next premeasured amounts of molten metals are injected in to the dies at an extremely high pressures. The newly formed part is then removed from the dies the cycle is repeated after the die cools.  The die must be stronger than those used in the permanent mold process to withstand the high pressure injections.

This dies can be engineered to produce complex shapes with a high degree of accuracy and repeatability. Dies can be used many thousands   of times so the die casting process is used when very large quantities are gated. Die cast parts can be sharply defined with smooth or textured surfaces and are suitable for a wide variety of finishes. This high pressure process produces a dense fine range of physical and mechanical properties such as fatigue strength. As with the other casting processes   choosing the alloys for this process depends on their physical and mechanical properties. The ones that are often used in die casting are zinc, aluminum. Magnesium and brass alloys.

As technology advances and computerized automation in the field increases. We will be seeing even more like metal components in the future.
For additional information for die casting this page will give more detail explanation with that matter.