Tools · Sheet metal

Bend calculator

Draw a profile. Get the flat pattern, bend lines and K-factor, and a yes or no from the press brake that will form it.

Tuned to WEIYA WC67K-30T/1600 · 300 kN · 1600 mm · gooseneck 90° · multi-v 55×55

SectionMS · 2 mm · V16.5 · r 2.64 · k 0.36

Flat pattern112 mm blank · 2 bends · bend lines from the left edge

Machine check

Forms on our line

✓
Tooling
Mild steel 2 mm bends in V16.5 (V/t 8.3). Inside radius 2.6 mm, K 0.36.
✓
Force
26 kN of 240 kN planned (11%). Up to 1600 mm at this gauge.
·
Stroke
Punch depth 5.5 mm of 55 mm travel. Springback 2.8°, 2.8°: the controller overbends to compensate.
✓
Clears the tooling
Bend order 1 → 2. 1 setup. Open height under the raised punch 99.9 mm.

Quote the real partUpload runs the full 3D simulation.

Bend table

Inside radius 2.64 mm from V16.5, K 0.355. Force 26 kN over 200 mm.

Bend	Angle	Bend line	Allowance	Deduction	Min leg	Springback
1up	90°	27.99 mm	5.26	4.02	11.38	2.8°
2up	90°	83.97 mm	5.26	4.02	11.38	2.8°

Bend lines from the left edge of the flat. Allowance = θ·(R + K·T). Deduction = 2·(R + T)·tan(θ/2) − allowance. Flat = Σ legs − Σ deductions. Springback is what the controller overbends by.

In the machine

Each bend at the bottom of the stroke, in the order that clears the tooling: 1 → 2.

1 order tried · section only

1 · bend 190°

2 · bend 290°

01What it is tuned to

One brake, its die, its punch.

Every number on this page comes from one machine profile: the plate, the catalogue chart, and the tooling drawings. When the tooling changes, the profile changes and the calculator follows.

Machine: WEIYA WC67K-30T/1600, 300 kN, 1600 mm bed
We plan to: 240 kN of nameplate, 80%
Open height: 260 mm daylight, 100 mm between the raised punch and the die
Ram travel: 55 mm controlled
Punch: Gooseneck 90°, 105 mm tall, 18 mm body
Die: Multi-V 55×55. Grooves V5.8, V9, V12.5, V14.5, V16.5, V22.5, V24
V for a gauge: Nearest groove to 8× thickness. Inside radius 0.16·V
Minimum leg: The machine's own V chart, about 0.70·V at 90°, scaled for other angles
Materials: Mild steel 370 MPa · Stainless steel 570 MPa · Aluminium 230 MPa · Brass 400 MPa

Profile verified 2026-09-07. Machine, die and punch from the manufacturer's plate, catalogue and DXFs. Radii and min flanges from the WC67K chart. Materials are priors. Ram depth, die holder and punch nose radius are engineering priors until measured.

Punch over V16.5, to scale

02Bend table

Capability by gauge.

What each stocked thickness gets: the groove, the radius it makes, the K-factor, the 90° allowance and deduction, the shortest leg, and the longest bend we will make in each material.

Thickness	Groove	Inside radius	K	BA 90°	BD 90°	Min leg	MS max bend	SS max bend	AL max bend	BR max bend
0.8 mm	V5.8	0.93	0.34	1.89	1.57	3.9	1600	1600	1600	–
1 mm	V9	1.44	0.36	2.83	2.05	6.25	1600	1600	1600	1600
1.2 mm	V9	1.44	0.34	2.91	2.37	6.25	1600	1600	1600	1600
1.5 mm	V12.5	2	0.36	3.98	3.02	8.81	1600	1600	1600	1600
2 mm	V16.5	2.64	0.36	5.26	4.02	11.38	1600	~1200	1600	1600
2.5 mm	V22.5	3.6	0.36	7.09	5.11	15.75	1600	~1000	1600	~1450
3 mm	V24	3.84	0.35	7.69	5.99	16.8	~1150	~750	1600	~1100

1600 mm is the bed and exact; shorter limits are force at 80% of nameplate and approximate. Above 3 mm we quote on request.

03Method

How it is calculated.

Standard sheet-metal geometry, with the machine's own chart where the textbooks leave a range.

Inside radiusSet by the die, not the drawing: 0.16·V for an air bend, never below the punch nose.

K-factorDIN 6935 from the radius-to-thickness ratio: ½·(0.65 + ½·log₁₀(R/T)), held between 0.15 and 0.50.

Bend allowanceθ·(R + K·T), the length of the neutral axis through the bend.

Outside setback(R + T)·tan(θ/2), from the sharp corner to where the outside face starts to curve.

Bend deduction2·setback − allowance. Flat blank = Σ outside legs − Σ deductions. Bend lines sit at the centre of each bend zone.

Minimum legThe machine's V chart at 90°, about 0.70·V, scaled by cos45/cos(θ/2) so the leg still reaches the shoulder at other angles.

Force650·t²·L/V at 450 MPa, the rule printed on the machine, scaled by the material's tensile strength.

SpringbackYield moment released over the loaded span, plane-strain modulus, hardening calibrated on mild steel coupons. Shown as the overbend the controller adds.

Section checkEvery bend order. Earlier bends formed, later ones flat, the part posed in the punch and die at four points of the stroke, turned end for end when that clears. Formed legs must miss the punch, ram, die and bed and never fold through the part.

Not checked hereHoles and slots near bends, corner reliefs, the back gauge, and anything three-dimensional. Upload the part and the simulator checks all of it.

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