Metal forming is a general term, for a large group, that includes a wide variety of manufacturing processes. Metal forming processes are characteristic in that the metal being processed is plastically deformed in order to shape it into a desired geometry. In order to plastically deform a metal, a force must be applied that will exceed the yield strength of the material. The material actually gets stronger the more it is deformed plastically. This is called strain hardening or work hardening. Many metal forming processes are suitable for processing large quantities (i.e., bulk) of material, and their suitability depends not only upon the shape and size control of the product but also upon the surface finish produced. There are many different metal forming processes and some processes yield a better geometry and surface-finish than some others.

Metal forming processes can be classified under two major groups. Bulk deformation processes and sheet metalworking processes. Bulk deformation is characteristic in that the work formed has a low surface area to volume ratio. In sheet metalworking the metal being processed will have a high surface area to volume ratio.

Among the bulk Deformation, there are rolling, forging, extrusion and drawing method. Rolling is a metal forming process that deforms the work by the use of rolls. Rolling processes include flat rolling, shape rolling, ring rolling, thread rolling, gear rolling, and the production of seamless tube and pipe by rotary tube piercing or roll piercing. Forging is characteristic in the use of dies to compress and shape a work piece. The die may be flat or may contain an impression of a certain geometry. Extrusion involves forming by forcing metal through a die opening, producing work of variable length and constant cross section. Drawing is similar to extrusion in that a length of metal is made to flow through a die opening, and forming is done over its cross section. The difference between drawing and extrusion is the application of force to the work piece. In extrusion the work is pushed through the die opening, in drawing the work is pulled through the die opening.

As the sheet metal working, there are shearing, bending and deep drawing methods. Shearing is the cutting of the work piece, this would include punching holes. Technically shearing does not involve shaping by plastic deformation, but it is a critical process in sheet metal working operations and should be understood along with metal forming processes. Bending involves the deformation of the work by way of bending about a certain axis. Deep drawing is a forming process in which a flat piece of plate or sheet is forced into a die cavity to take a shape such as a cup.