Forming is a process by which metal can be deformed by bending the material and changing its shape. The material is stressed beyond the yield strength but below the ultimate tensile strength. The surface area of the material does not change much. Bending usually refers to deformation about one axis.
Brake forming is one of the most common mechanical metal bending process. During the process, a piece of sheet metal is formed along a straight axis. This may be accomplished by a "V" - shaped, "U" - shaped, or channel - shaped punch and die set. Bending metal in a press brake appears to be a simple concept but maintaining accuracy can often be quite difficult.
Precision bending used rely more on the operator than the machine. Modern press brakes with CNC controls and super precision ground tooling has changed the process dramatically.