Press Brakes for Metal Forming
One of the advantages of many metals is that they are relatively ductile; ductility ensures that the metal can be bent before breaking. This property allows them to be formed into specific shapes and sizes. This makes metals very versatile, as flat sheets of metal often need to be changed in shape before they can be put to use. Although there are a variety of forming equipment used for this purpose, one of the most common is a press brake.
What is a press brake?
A press brake is a piece of manufacturing equipment used to bend sheet metal. Press brakes are usually narrow and long, so they can be used to bend large pieces of metal. Press brakes bend metal by lowering a punch onto a sheet of metal that has been placed on top of a die. Metal can be bent multiple times in a press brake until the desired shape is achieved.
What types of press brakes are there?
Bending sheet metal requires a lot of force, and in order to achieve and transmit this force, the punch can be lowered onto the sheet of metal in several different ways. The force can be applied hydraulically, pneumatically, electrically, or mechanically. The force is often reflected in the name of the press brake (e.g. hydraulic press brake, servo-electric press brake).
Press Brake Types Comparison
| Type | Force Level | Precision | Speed | Common Applications |
|---|---|---|---|---|
| Hydraulic | Very High | Moderate | Slower | Heavy industrial, thick metals |
| Pneumatic | Low | Good | Faster | Lighter gauge metals |
| Servo-Electric | Low to Moderate | Highest | Faster | Precision work |
| Mechanical | Moderate to High | Good | Slower | Various applications |
The amount of force provided by different press brakes also varies. In the press brake world, this is called tonnage; it measures the number of tons of force that the press brake can provide. Typically, hydraulic presses are used to achieve very high forces, while pneumatic and servo-electric presses provide relatively low forces.
There are also differences in speed and precision between different types of press brakes. Servo-electric press brakes generally have the highest precision. Pneumatic and servo-electric press brakes, on the other hand, generally operate faster than hydraulic and mechanical press brakes.
What to consider when bending metal with a press brake?
Press brakes can perform a variety of bends on many different types of metals. When setting up a bending process, it is important to consider the type of metal being bent, the die, the punch, and the bending force.
Key Considerations
| Factor | Importance |
|---|---|
| Metal Type | Different metals have varying ductility and strength properties |
| Minimum Bend Radius | Each metal has a recommended minimum to prevent damage |
| Die Selection | Must match desired shape and material requirements |
| Punch Selection | Must be precisely matched with die for proper bending |
| Force/Tonnage | Must be appropriate for the material thickness and type |
Knowing the type of metal is critical because of the differences in physical properties between metals. For example, high carbon steel is generally more difficult to bend than many aluminum alloys due to differences in ductility and strength. Metals generally have a recommended minimum bend radius to which the material can be bent without sustaining damage.
The die and punch used on the press brake have a significant impact on the bending process. The die is the hollow material onto which the metal is placed before bending. It is made of a very hard and strong material and is shaped close to the desired shape of the metal being bent. The punch is a solid material that is pressed onto the metal. Since the pressing action of the punch against the metal and the die is what causes the metal to bend, both shapes must be precisely matched for the bending job. The correct shape of the metal after the bending operation depends on the size and shape of the punch and die. Dies and punches are usually designed to be easily interchangeable to suit a variety of job requirements.
Common Press Brake Applications
- Automotive Panels
- Fuselage Bodies
- Metal Artwork
- Furniture
- Metal Containers
- Many Other Sheet Metal Forming Applications
