Sheet Metal Bend Allowance & K-Factor (DIN 6935)
Calculate sheet metal neutral axis K-factor, bend allowance (BA), bend deduction (BD), and flat pattern blank development per DIN 6935.
Loading...
▸Formula · assumptions · example(DIN 6935 · ISO 6892-1 · VDI 3388)
Formula
BA = \frac{\pi}{180} \cdot (R + K \cdot t) \cdot \alpha, \quad BD = 2(R + t)\tan(\alpha/2) - BA
DIN 6935 neutral axis shift (K-factor), bend allowance (BA), and bend deduction (BD) for precision sheet metal blank development.
Assumptions
- · Uniform plastic deformation during air bending across the tooling V-die opening
- · K-factor calibrated by material type and inside bend radius-to-thickness ratio (R/t ≈ 0.33 to 0.50)
- · Springback compensation considered based on material yield strength and die geometry
Worked example
Worked example — 2.0 mm S235 Steel (90° bend, R = 2.0 mm, K = 0.40)
Calculates neutral axis radius rn = 2.80 mm, Bend Allowance BA = 4.40 mm, and Bend Deduction BD = 3.60 mm for exact CAD flat blank sizing.