What is Press Brake – A Complete Guide

One of the most critical machines in sheet metal fabrication is the press brake or brake press. With the right tooling system, you can manipulate sheet metals into complex shapes.

In this article, we shall explore all the fundamental aspects of press brake machines. From design, parts, classification criteria, working principle to key benefits in the sheet metal fabrication industry.

Let’s dive right:

What is Press Brake Machine?

A press brake is a sheet metal bending machine, which you can use to bend, fold, or shape sheet metal into a suitable design.

With this machine, you can easily fabricate sheet metals by applying force to transform material into a desired shape.

How Press Brake Works

The working principle of press brake involves exerting force on sheet metals using a combination of die and punches. By doing so, you will bend sheet metal into a predetermined angle.

But more importantly, the mechanism for bending sheet metal will vary based on the machine design. For instance, you may use mechanical, electric or hydraulic press brake.

To get more insights on how this machine operates, it will be critical to explore some of its main parts and their functions.

The way in which you bend the metal sheet varies with the result. Let’s explore some popular techniques that are common in the industry:

· Air Bending (The Most Common Method)

In air bending, the punch forces the sheet between two die edges, making no contact with the bottom. The depth of the punch allows you to fabricate different angles according to your design. This technique is versatile, and it is very common in contemporary sheet metal fabrication.

· Bottoming

In bottoming, the sheet is in direct contact with the bottom of the die. In most machine designs, the die angle is equivalent to the punch angle.

With this technique, you can achieve accurate bend angles, though this method offers less flexibility compared to air bending. It needs greater tonnage than air bending.

· Coining

Coining employs great pressure to press the sheet metal into the precise form of the die. It generates bends that are very precise. Nevertheless, it uses more energy and lowers the life of tools.

Major Types of Press Brake

1. Mechanical Press Brake

Mechanical press brakes feature a specially designed flywheel and clutch mechanism. It is this systems that push the ram thereby providing high cycle rates and uniform bends.

Mechanical press brakes are operated with the help of flywheel and clutch mechanism to push. However, these machines are not flexible in stroke control.

2. Hydraulic Press Brake

Hydraulic brake press uses hydraulic power to transform sheet metals into desirable shapes. Through the hydraulic cylinders, pistons and various ram movements, hydraulic brake presses control the force that transforms metal into suitable shapes.

With these machines, you can easily adjust the speed, pressure and stroke to make accurate parts with tight tolerances.

They are more accurate and safer compared to mechanical types. These are the most popular types of today because of their versatility.

3. Synchronized vs. Unsynchronized Hydraulic Press Brake

Synchronized types involve sensors to make both cylinders move in a uniform manner. While on the other hand, unsynchronized types work with mechanical linkages, which are not so precise.

4. Electric Press Brake (Servo-electric Press Brake)

Unlike hydraulic brake press, these systems use servo motors instead of hydraulic power. They offer clean, energy-efficient, and fast bending operations. You’ll also enjoy minimal maintenance and high precision.

5. Hybrid Press Brake

Hybrid press brakes combine hydraulic and electric technologies. They consume less energy and provide smoother operation than pure hydraulic types.

6. CNC Press Brake

These are fully automated brake press machines that use computer numerical control systems to operate the machine. Once you input the bending angles, sequence, and back gauge location, it automatically conducts the bending process seamlessly.

They ensure precision, reproducibility, and short set-up times. They are suitable for large-volume fabrication of sheet metal.

Benefits in Sheet Metal Fabrication

· High Precision and Repeatability

You get repeatable bends on multiple parts. A good example is the CNC press brake where the machine eliminate possible errors that can result into uniform angles.

· Versatile Bending Operations

Press brakes are used on varying materials and thicknesses. You can easily bend mild steel, stainless steel, and aluminum, among other metals.

· High Production Efficiency

Automated press brakes save time in setup and produce more, which is suitable for large scale production.

· Produce Complex Shapes and Parts

Having multi-axis control, CNC press brakes enable you to achieve complex profiles with precision.

How to Choose Press Brake for Sheet Metal Fabrication

The decision on which press brake to buy is based on your production requirements. Consider these key factors:

· Tonnage

The amount of force that the machine can exert is determined by tonnage. You require more tonnage for your thicker materials.

Here is a sample press brake tonnage chart:

To purchase your machines, use a tonnage calculator or chart to estimate the capacity of your machine.

Reference only: The sample values above are not universal machine requirements. Actual tonnage changes with material tensile strength, V-die opening, tooling and bending method.

· Bed Length

The length of the bed must be equal or more than your full sheet length. A machine with a longer bed can handle a wide range of tasks.

· Bending Speed

Test the approach speed, bending speed, and return speed of the machine. The increase in speed can also enhance productivity, although it can lead to low accuracy in cases where it is not properly managed.

· Bending Accuracy

Premium models that have CNC systems offer precision. Ram control and back gauge precision are some of the key elements of accuracy.

· Inside Radius

Make sure that the punch radius is equal to the inside bend radius of the material. An appropriate match does not lead to cracking and gives the bends a smooth edge.

· Tooling Requirements (Dies and Punch)

Select matching dies and punches. V-dies are needed in air bending, and precise matching sets of punch and die are used in bottoming.

· Minimum Flange Length

Minimum length of flange should be more compared to the die opening. This eliminates deformation and provides correct bending.

· Bending Force

You need to compute bending force depending on material thickness, bend length, and type of bending. Always add a safety margin.

Key Applications

Press brakes play an important role in sheet metal shaping and forming industries. Some of the most practical and common uses include:

• Production of electrical enclosures, cabinets, and panels
• Fabricating automotive parts and body parts
• Manufacturing of structural materials used in building
• Bracket making, frame making, and support structures
• Manufacturing metal furniture and fixtures

Conclusion

Sheet metal fabrication involves using press brake machines to make simple to complex parts. Once you choose a machine with a suitable tonnage, and tooling system, you can make different sheet metal parts.

At KDM, we use press brake to fabricate different sheet metal parts that are custom-made according to our client requirements. For all your custom-made sheet metal parts, send an inquiry now.

FAQs

1. When was the press brake invented?

The earliest press brake was introduced in 1880s. Advanced technology later came in with modern designs.

2. What are the limitations of press brakes in sheet metal fabrication?

Yes. Fabricating thicker materials can be a challenge. Furthermore, making complex parts and high initial investments costs are other limitations.

3. Is press brake a sheet metal bending machine?

Yes. A press brake forms sheet metal into various shapes or angles with the help of punching and die.

4. How does air bending vs. bottom bending compare?

In air bending less force is needed, but you must take care of spring-back compensation. On the other hand, bottom bending is more accurate, since the high pressure reduces possibility of spring back.

5. How do you calculate press brake tonnage?

You determine it by the thickness of the material used, tensile strength of the material, and the width of the die opening. Use the formula:

Required tonnage depends on the unit system, material tensile strength, sheet thickness, bend length, V-die opening, forming method and tooling. Use the estimator above only as a planning reference, then confirm the result against the press brake and tooling load charts.

6. How do you compensate for spring back in sheet metal bending?

You can overbend the sheet a bit more, or you can change the depth of a punch. Remember, coining also reduces spring-back.