What is the Difference Between Bending and Rolling Metal? 

What is the difference between bending and rolling a metal sheet?

At Toledo Metal Spinning, when we fabricate our cylindrical tanks and tubes, we use the process of roll bending.

Roll Bending

Also known as angle bending or plate rolling, this is the process of bending the metal sheet or blank into a curved shape. This is typically achieved by passing metal through a series of rolls that progressively bend the material into the desired curve. Roll bending is achieved by determining the angle of the rollers and the exact pressure from the rollers. At Toledo Metal Spinning Company, we use the roll bending process in our daily routines to roll our cylindrical tanks and tubes.

There are a few different types of machines designated for roll bending. They are often very similar, but have a different number of rollers. A 3-Roll Bending Machine has three rolls in a triangular shape, while a 4-Roll Bending Machine has a fourth roller, which helps to increase the control and accuracy of the shape.

The rolls, or rollers, are the pieces that support the metal sheet or blank. These apply a specific amount of pressure (designated by the controller) to ensure the material is formed into the proper shape. It is also extremely important to keep in mind the minimum and maximum radii, because that will directly impact the size of the cylinder or tube being formed. Another important term to understand is the amount of pinch given in the initial bend of the material. In the video below, notice the pinch happening between 3-5 seconds in, and then again from the front point of view, between 13-15 seconds. The pinch bends the metal, while holding it between the two rolls. There is a certain amount of pressure applied to ensure that the material is bent and rolled through the rolls at the correct angle.