How to Use a Sheet Metal Press Brake?

The sheet metal press brake is a machine tool used, as its name indicates, to bend these plates, but it is also used for forming them. But how do you use a sheet metal press brake and why does it bring such great benefits to machine shops?

What is sheet metal bending?

Sheet metal bending is a type of machining whose function is to shape a metal plate or sheet through a deformation process. To carry out this process, the use of a precision machine tool called a press brake is essential. The press brake is a very precise machine that requires a qualified operator, since to deform these parts it is necessary to apply a specific pressure to the material so that it bends or takes on the desired shape.

The piece is placed between the punch and the die of the machine and is bent gradually, thanks to the pressure exerted on it. Thus, the force applied by the operator is what defines how the piece is bent and shaped.

The sheet metal press brake also works to create angles and curves in these metal parts, which are used in the various industries. Thus, a sheet can be used in metalworking and distributed to the food, canning, automotive, aerospace and construction sectors, etc.

This machine tool is characterised by its great versatility, since it is not only used in many industries and accepts different types of materials, but it can also machine parts up to 20 millimetres thick.

What materials can be bent?

On a sheet metal press brake it is possible to machine parts made of different materials. That is why these machines are very versatile and useful for machine shops. A press brake can work with:

• Stainless steel
• Aluminium
• Low-alloy copper
• Mild or soft steel
• Brass
• Unalloyed steel or carbon steel

The sheets bent on these machine tools are mostly stainless steel meeting the AISI 304, AISI 316 and AISI 430 criteria. AISI 304 has a high degree of oxidation resistance and is non-magnetic; AISI 316 is very resistant to corrosion, to sea water and to some chemical agents, while AISI 430 is magnetic and difficult to bend. That is why it is one of the least common in bending.

What you need to know about how to use a sheet metal press brake

It is important to stress that sheet metal bending is a type of machining even though it generates no swarf or waste, being merely a plastic deformation in which the piece is bent until the desired angle is obtained. The press or press brake is the machine tool that makes these operations possible. To achieve this transformation, the piece is placed on the die and deformed by the action of the punch, which is driven by the moving part of the machine tool.

If you are wondering how to use a sheet metal press brake, you should know that it requires qualified personnel who know how to apply the pressure needed to deform the piece. This is because during sheet metal forming, compression occurs on the inner side of the piece being deformed while tension occurs on the outer side: this establishes a stress gradient between one end and the other, with a neutral point or line in between. This causes thinning at the bend of the sheet, which is more noticeable at its centre.

It is important to stress that presses or sheet metal press brakes can pose a risk to operators if the machines are not used properly. The risk with these machines is usually from trapping or cutting when the piece to be machined is fed in. Special attention must be paid when the sheet is smaller or the bending rate is higher; these two circumstances pose a greater danger to the operator. In addition, of course, the people in charge of operating this machine must be highly qualified.

Types of sheet metal press brake

All sheet metal press brakes follow the same basic operating principle, although four different types can be distinguished according to the mechanism used.

Manual	Limited to the bending of small sheets up to 9 mm thick. The dimensions of the machine are small.
Mechanical	It has a flywheel that generates the energy to activate the punch.
Hydromechanical	The flywheel is replaced by a hydraulic pump, which provides the inertia needed to drive the machine. A hydraulic motor is used.
Hydraulic	It uses a pump and hydraulic cylinders that drive the machine's operating mechanism. These are the most modern press brakes and some are equipped with computer numerical control (CNC) technology. This makes them more precise and safer.