What Are Sheet Metal Workpieces for Press Brakes Like?

The press brake or press is a machine tool used for machining by bending or forming metal plates known as sheets. Bending is considered a type of machining without swarf removal, since it is simply the deformation of a piece of metal to obtain a specific shape and dimensions.

What is a sheet metal press brake?

The press is a machine tool designed exclusively for sheet metal bending and forming operations and is generally used for cold working. These machines are usually hydraulic and mechanical. The press brake consists of a support system, which is where the piece is placed before machining; in addition, it has a punch, which is the moving part of the machine and serves to push the sheet against the die. The latter is the fixed part of the machine.

In addition, these machines have a device that allows the machine to be operated. This device varies according to the type of press brake used, and can even be computer numerical control (CNC).

These machines can be mechanical, hydraulic, hydromechanical or pneumatic. All of them carry out the same operations, but each has its own specific characteristics and a common operating principle: the sheet is placed on the table and the punch presses on the piece until it reaches the die and takes the desired shape. The movement of this machine is therefore rectilinear.

What is sheet metal?

It is common to find information about the press brake, its characteristics, benefits and the different types that exist in industry; however, have you ever wondered what the parts that are machined on this machine are like?

Sheets are metal surfaces of different dimensions (length, width and thickness). Their thickness varies, and those with a thickness of less than three millimetres are considered thin; those with a thickness greater than three millimetres are called thick. The press brake is used to form these parts, although the sheet may later undergo other machining processes, as is the case with perforated sheets.

All sheets usually receive additional treatments to prevent corrosion and oxidation. For this, chrome plating, galvanising and some paints are frequently used. Sheets are among the most widely used parts in metalworking thanks to their versatility. They can be found in the food, automotive or aerospace industries, among many others.

Characteristics of sheet metal

These parts are usually made of stainless steel, carbon steel (very ductile and useful in making vehicle bodies and household appliances); although there are also aluminium sheets, used for cars and in the aerospace industry. It is also possible to find sheets in other materials such as copper, titanium, iron and brass.

It is worth noting that, because they are made of different materials, not all sheets will have the same characteristics with respect to temperature. For example, those with a low steel content and a small thickness respond better to ambient temperatures. Conversely, those that are thicker reduce the elastic limit of the steel and ductility increases.

Sheets have three different dimensions: length, width and thickness. This last dimension is, in fact, the one used to determine, for example, the price of the plate. In the metalworking industry sheets are not sold according to their dimensions, but by the weight in kilos of the plate. To calculate the kilos of a sheet there are plenty of calculators online.

Sheet metal materials

The material from which sheets are made is of vital importance for bending them, as well as for determining the uses the parts will be put to. A press brake can handle different materials. These materials can be:

• Black and galvanised iron. The former is used for making welded tubes and sections, containers and blacksmith work; galvanised iron, for its part, is coated with a layer of zinc to prevent corrosion and is generally used in the automotive industry.
• Corten or weathering steel. This is a steel alloy with copper, chromium, phosphorus and nickel that makes the sheet resistant to corrosive agents.
• Stainless steel. This is the most common material from which these parts are made and it is an alloy of iron and chromium, which makes it very resistant to corrosion. This type of sheet can be manufactured to the AISI 304 and AISI 316 standards, the second being more resistant to corrosion than the first.
• Aluminium. This type of plate is very strong and corrosion-resistant.
• Insulating materials. They offer great durability and a very good finish.