What minimum radius can I bend a profile to?

The achievable minimum radius depends above all on the profile height in the bending plane, its orientation and the material. A tall profile bent about its strong axis reaches a much larger minimum radius than the same profile about its weak axis: the more section to bend, the harder to close small radii. Material also rules: a low-ductility one cracks before reaching tight radii.

Below the reasonable minimum radius, the profile stops bending clean. The section distorts: the compressed leg wrinkles or buckles, the stretched one thins, and the profile can twist or lose its shape. At that point the limit is not the machine's force, but the integrity of the section, and forcing it produces parts out of tolerance.

The real minimum radius should be set for the working profile, orientation and material, not for the most favorable case. If the project demands tight radii, that figure becomes as decisive as the profile size, and defines the tooling and even the bending method. How it combines with the rest of the variables is developed in the article on how to specify a profile bending machine.

The minimum radius a profile allows depends on its height, its orientation and its material, and marks the limit below which the section is ruined. Defining it from the project stage —for the real case, not the favorable one— is what avoids finding out on the fly that the part cannot be closed. It is an input specification, as important as the profile itself.