Air-bending force from material thickness, bend length, tensile strength and V-die opening — plus a recommended die opening, inside radius and minimum flange. A companion to the bend calculator.
Air-bend force ≈ 1.33 × Rm × L × S² ÷ V. This is the widely-used empirical estimate; real tonnage varies with die, friction, bottoming vs air bending, and exact material. Size your press with margin and confirm against your die maker's chart.