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Press Brake Bend Allowance Calculator
Find the flat length, the recommended V-die and the bending force from flange sizes, thickness, inside radius and angle.
Outside flange dimensions (in order)
Flat length—mm
Bend deduction (BD)—mm
Recommended V-die—mm
Bending force—t
Formulas
Bend allowance (BA) = π × angle / 180 × (R + K × T)
Outside setback (OSSB) = tan(angle / 2) × (R + T)
Bend deduction (BD) = 2 × OSSB − BA
Flat length = sum of outside flange sizes − number of bends × BD
The K-factor depends on material and R/T ratio; for mild steel it is usually 0.33–0.45. The recommended V-die opening is about 8 × thickness. Bending force is P = 1.42 × Rm × T² / V (kN/m).
The result is an estimate. We work out the exact flat pattern from your drawing and our tooling.
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