Press Brake Bend Deduction & Flat Length Calculator

Inputs

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Outside flange length on one side of the bend (mould-line dimension).
mm
Outside flange length on the other side of the bend (mould-line dimension).
mm
Bend (complementary) angle — 90° for a right-angle bend.
°
Inside bend radius (set by the punch tip / die opening).
mm
Material (sheet) thickness.
mm
Ratio of the neutral-axis position to the thickness — empirical; ~0.33–0.45. Confirm with a test bend.

Results

Default result
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Flat length(L)
95.75mm

Blank = A + B − BD for one bend (BA ≈ 5.749 mm).

Sum of outside flanges minus the bend deduction.

Also computed

Bend deduction(BD)4.251mm

2 × outside setback − bend allowance.

Outside setback(OSSB)5mm

(R + t) × tan(angle/2).

Method notes 2 notes
  • Bend deduction BD = 2·OSSB − BA, where the outside setback OSSB = (R + t)·tan(angle/2) and the bend allowance BA = (π/180)·angle·(R + K·t). The flat (blank) length is the sum of the outside flanges minus one BD per bend.
  • Flange A and B are outside (mould-line) dimensions. The K-factor is empirical (~0.33–0.45) — confirm it with a sample bend before cutting a batch.

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