Choosing which press brake machine to invest in can be a challenging task. Mechanical presses are affordable but only suitable for simple bending tasks. CNC presses are expensive but faster and more reliable. Investing in the wrong press brake can lead to damage and loss. Appropriate press brakes, on the other hand, are immensely profitable. In this article, we will give you the vital points concerning press brake selection. What are some important things to keep in mind while purchasing one? What are some things that aren’t so important? You will understand both of these after finishing this article.
What is a Press Brake?
A press brake is an industrial device used to bend metal sheets. Its main components are a vertical press and a die. The press strikes the metal sheet, which is placed upon the die, causing it to bend at the required angle. The primary use of press brakes is to bend or curve metal sheets into the specified angle. They are employed in industries, fabrication shops, and metalworks.
How to Choose a Press Brake?
If you purchase a press brake, there are a few points you should be clear on. What types of materials will you process? For example, do you want to bend lighter metals like aluminum? Medium metals like stainless steel? Or hard metals like carbon steel? If you want to bend strong materials, you will require a press brake with high tonnage.
Another factor is the plate thickness. How thick are the metal sheets that you need to bend? Electrical presses are efficient and fast, but they are not suitable for thick metal sheets.
The length of the metal sheet determines the size of the machine. You will require a machine with a large bed to bend a long metal sheet. Alternatively, using tandem machines will allow you to combine press brakes. This will increase the bending length.
For high production rates and complex bending tasks, CNC and robotic presses are the ideal choice. They are highly automated and equipped with a variety of software tools.
Understanding Press Brake Types
In the previous sections, we mentioned several types of press brake machines. In this section, we will discuss them in detail.
Hydraulische Abkantpresse
Hydraulic press brakes generate force through pressure from liquids. They have cylinders containing pressurized water, which propels the ram and drives the punch downwards. They have a high tonnage and can bend thick metal sheets.
Hydraulic press brakes have multiple oil cylinders in their assembly. These allow for various bending settings. Therefore, they can achieve a high value of precision. However, the cylinders of a hydraulic press are susceptible to leakage. These press brakes are also energy intensive, because they consume power when not in operation. They are not suited for complex bending tasks.
Mechanische Abkantpresse
These are the oldest press brakes, simple in construction and use. They consume electricity to power a flywheel, which generates the force used by the ram. Mechanical press brakes are easy to operate, and are suitable for bending thick metal sheets.
However, the mechanical press brake cannot stop once the flywheel begins rotation. Therefore, they are not suitable for multiple bending operations. In several older models, the bending angle has to be set manually, further adding to the difficulty.
Electric Press Brake
Electric press brakes operate through electricity. They generate power from servomotors. These motors provide the force that moves the ram. They are equipped with computer control and software tools. Due to this, they are also called CNC-Abkantpressen. Due to higher automation, they are suitable for multiple bending tasks. Servomotors can be turned off when not in use, making electric press brakes highly energy efficient.
While electric press brakes offer distinct advantages, they are limited in tonnage. They are not suitable for bending strong materials or thick sheets. They are expensive to set up but have lower operational costs.
Hybrid Press Brake
These combine the strengths of electric and hydraulic brakes, achieved by utilizing hydraulic cylinders along with electric motors. This reduces the reliance on the hydraulic system and saves energy. Hydraulic cylinders produce more force than servomotors, resulting in greater tonnage.
Hybrid press brakes are expensive to install, and maintenance costs in case of breakdowns are high. However, the possibility of automatic start and stop is a great advantage for complex tasks.
Which Type of Bend Should You Choose?
Three different types of bending options are available while fabricating metal. These offer distinct advantages in specific applications. Understanding these bend types will enable you to make the best decision.
Air Bend
In air bending, the punch does not enter the die completely, instead, a pocket of air is left in the space between them. The amount of force applied takes into account the spring-back of the material.
Through air bending, you can achieve several types of angles and bends with the same set of molds. This makes it a cost-effective bending technique. Refer to the tonnage chart provided by the manufacturer for the dimensions required.
The type of mold is chosen based on the properties of the metal sheet, such as hardness and ductility. Despite its advantages, this method is not ideal for bending large metal sheets.
Bottom Bend
Bottom bending is a technique where the radial punch is pressed completely into the die. The punch locks into the die, removing any air space. Driving the punch into the die requires more force than air bending. The spring-back of the metal also has to be accounted for when deciding tonnage.
Since the die determines the angle of the bend, bottom bending is reliable for long sheets of metal. However, the range of angles available in air bending is impossible here. It also requires more time and manpower as only one angle is possible in each configuration.
Imprint Bend
In imprint bending, the metal sheet is wholly compressed under the punch. It got its name from the process of imprinting text on metal sheets. The press brake works on maximum capacity to push the punch into the die. Further, an additional amount of force is applied to compress the metal, reducing its thickness by about 10-15%. Imprint bend requires the highest amount of force compared to other bending methods. It is the most accurate bending method, with the highest consistency.
What are the Other Selection Criteria for a Press Brake?
We have discussed some of the primary criteria for choosing press brakes. However, there are several secondary considerations also. Let us discuss some critical tools that help determine your ideal bending machine.
Back Gauge System
Modern press brakes often feature a device called the back gauge or backstop. It is used to position the metal sheet in the exact position required to bend it. In complex bending tasks with multiple bends, the back gauge helps in sheet alignment. It can be programmed to move with each stroke, creating multiple bends successively.
Angle Control
Angle control in bending machines is used to produce highly accurate bends. It is useful in scenarios such as industrial workshops, where the margins for error are very thin. Laser angle control and optical angle control are two popular types. They reduce the operator’s workload and help prevent program errors.
Mold System
The mold system refers to the two parts of the press brake: the punch and the die. Your choice of mold may be affected by the complexity of your bending task. You may require different molds based on the types of bending you perform.
Budget
For any metal workshop or fabricator, budget is an important concern. Price may vary drastically depending on the type of machine. Highly automated CNC machines with angle control may range from $3000 to $30,000. Alternatively, mechanical bending machines are cheaper and better suited for simple tasks. However, investing in a good-quality press brake is highly recommended.
Brand and Supplier
While buying a bending machine, ensure that the press brake supplier is well-known and reliable. Consider factors like maintenance cost, service fees, warranty, and insurance. Do not focus solely on price or ads which display press brakes for sale. Consider the company’s history in press brake manufacturing and its industry value.
Operator Status
Press brake operators are specialized technicians who work the press. They oversee the bending process and perform various quality checks. For CNC and automated press brakes, these operators must also be trained in simulation software.
The press brake you purchase must have sufficient safety features. Barrier guards restrict unauthorized entry, and light curtains shut the machine if its proximity is breached. Emergency buttons allow for manual override of machine operation. Not only are these important for operator safety, but they also ensure smooth operation and minimal accidents overall.