As a metal fabrication process, metal extrusion involves shaping a metal material — whether this is aluminum or steel — into the desired form. This material typically starts out as a billet or a bar of metal which is subject to further fabrication processes. In metal extrusion, the billet, usually cylindrical in shape, is forced to flow through a hollow cavity with fixed cross-sectional profiles. The resulting materials are called extrudates. The entire process has been made possible by a high-force hydraulic press and can result in many different kinds of aluminum or steel fittings for different purposes.

　　Though the metal extrusion process can involve a variety of other factors, such as temperature, the complexity of the application, and the like, the process remains relatively the same.