Bending

In the industrial field, bending is a process frequently used to manufacture a large number of parts, usually flat. Bending is generally performed using a specialized machine tool configuration known as a “press brake” (also known as a folder).

This type of press, dedicated solely to sheet metal working and fitted with specific equipment, can bend metal materials with great precision and ensure the production of small to medium-sized series. In fact, their hydraulic technology does not allow for high output rates, unlike mechanical presses, for example, and their size makes them unsuitable for bending small parts, unlike EMG presses.

In the case of bending with mechanical, manual, pneumatic or hydropneumatic presses such as those manufactured by EMG, operations concern smaller parts, and may also involve bending.

What is bending and press-bending?

Bending is an operation that consists in deforming or shaping the material according to a bend, an angle defined by a shaping tool (punch and die). During deformation, the outer part of the sheet metal bend stretches while the inner part compresses, causing the sheet metal to vary in thickness, sometimes significantly.

Each type of material (metal: steel, stainless steel, aluminum, etc.) has its own mechanical characteristics, such as its elasticity.

When designing the part, it is important to anticipate these thickness variations as far as possible, so as to respect the minimum radii of the metal sheets to be bent.

For bending, there are several abacuses with “K coefficient”, “fish coefficient” or “Young's modulus” values adapted to each type of material. Nevertheless, experience is by far the best ally of the setter, enabling him or her to make all the necessary bends with millimetre precision, without the risk of applying a force greater than the material can withstand.

Dedicated press brake or EMG press brake: what factors influence the choice of bending method?

The choice of bending method depends on a number of factors, such as the size, thickness and quality of the material.

The desired radius and angle of deformation are other important factors.

Finally, the precision required for the project often determines the method for bending or cambering, and of course the choice of press to be used.

What are the main methods for bending metal parts?

● V or U bending

V or U bending is one of the most widely used methods today. In this process, the punch presses the part into a V- or U-shaped die without compressing it completely. Steel, aluminum or stainless steel of varying thicknesses are the main materials used. A large number of different angles can be precisely achieved by adjusting the punch depth.

● Roll bending

Roll bending is ideal for bending. By passing between rollers, metal sheets are deformed. Bends are obtained according to an initially defined radius. This does exist, but not with a press. It's a rolling machine. Important for SEO?

● Impact bending

Strike bending is a technique used to achieve high-precision bends by pushing the sheet to the bottom of the die. This type of bending meets a very specific need, such as the production of metal bearings.

How does the bending process work?

Similar to bending, cambering nevertheless consists in deforming a metal part by creating a gentle, rounded curve. Once the characteristics of the sheet to be bent and the desired angle have been defined, the choice of bending press is made.

The workpiece is then fed to the bending press. As the material is pushed against the lower die, the part or sheet acquires the die shape. Initial calculations are required to define the optimum V-angle, or die shape, according to the thickness of each metal sheet, and to compensate for the sheet's tendency to return to its initial shape (springback).

Correct positioning reduces the risk of misalignment during bending or cambering operations. The press applies pressure to deform the material according to the desired result, the type of material or the thickness of the metal sheet.