- Brake Press Forming is one of the oldest mechanical metal deformation 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. Although press braking appears a simple concept, maintaining accuracy can often be quite difficult. Precision bending is a function of both the press, the tooling, and the work-piece material. Material properties such as yield strength, ductility, hardness, and the condition of the material, all affect the amount of spring back of the material.The most common industrial press braking process is called air bending. Air bending relies upon three point bending. The angle of the bend is dictated by how far the punch tip penetrates the “V” cavity. The greater the penetration of the punch tip the greater the angle achieved.