Manufacturing: Metal Forming

Sheetmetal Forming - Press braking / Brake forming

Brake 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.

The main benefit of air bending is that it uses much less force than other methods to achieve a 90° bend due to the leverage effect.

Characteristic of the metal brake forming process include:

• Its ability to form ductile materials
• Its use in both low and medium production run applications,
• The need for minimal tooling,
• Its suitability to produce smaller parts,
• Its output of long workpieces using a "V", "U", channel, or other special punch and dies.

Brake forming can commonly form metals up to 10" thick and some machinery will form pieces as long as 20 feet. Materials commonly used in the brake forming process include:

• Aluminum
• Brass
• Cold rolled carbon steel
• Hot rolled carbon steel
• Stainless steel

Tool materials for brake forming --

1. Low-carbon steel is used for low production runs, die and punch base material, and soft to medium hardness materials.
2. Tool steel is used for medium to high production, for medium to server bending, and for medium to strong materials.
3. Carbide tools are used for high production runs on materials that required severe bending, and are usually designed as tool inserts.
4. Hardwood tools are used for very low production runs, for very simple bending applications, and are normally used on very soft materials.