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Press Brake Tonnage

Air bending: F ≈ 1.42·Rm·t²/V per metre of bend. Rule of thumb — die opening V ≈ 8×t, and an air bend lands near an inside radius of 0.16×V. Pair with the bend allowance tool for the flat pattern.

Calculator

Thickness t (mm)

Die opening V (mm)

Tensile strength Rm (MPa)

Bend length (mm)

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Force

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Per metre

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Recommended V

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Inside radius (≈0.16V)

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Mild steel Rm ≈ 450, stainless ≈ 650, aluminium ≈ 250 MPa. Bottoming/coining needs far more force.

Empirical air-bend estimate — verify against your machine's tonnage chart. A helper, not a substitute for engineering judgment.