Work out press brake tonnage instantly with clear inputs, formula shown and shareable results.
Air bending force per metre is roughly 1.33 x tensile strength x thickness squared divided by die opening. Thickness dominates because it is squared, and a wider die reduces force but increases the bend radius, so the usual compromise is a die opening of six to eight times the thickness.
Air bend force
kN per metre = 1.33 x Rm x t² / V
Preliminary estimate only. Confirm tonnage and tooling capacity against the press brake and tooling manufacturer's data before forming.
kN per metre = 1.33 x Rm x t² / V. Air bending force per metre is roughly 1.33 x tensile strength x thickness squared divided by die opening.
Air bending only bends the sheet; coining forces the material into the die to set the radius permanently, which takes roughly five to ten times the tonnage.
This calculator takes 4 inputs: Material thickness, Die opening (V), Bend length, Material tensile strength. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.