CAD Bending Reference

Machine and standard tooling

Machine: 200 t / 3000 mm. Published force limit: 170 t. K-factor: 0.42.

The standard rule is V ≈ 8 × sheet thickness. Use the actual V-die listed for each thickness in the table below.

Standard tooling examples:

t = 2 mm: V16
t = 5 mm: V35

Inside radius and minimum flange

Ri is the indicative inside radius in mm. h is the recommended minimum flange/support dimension measured from the bend line.

Use the radius and flange values for the selected tooling and thickness. Maximum bend length also depends on the material.

Bend allowance and bend deduction

Use K = 0.42 when entering these standard sheet-metal rules in CAD.

BA = angle(rad) × (Ri + K × t). For a 90° bend, BD = 2 × (Ri + t) - BA.

Definitions:

BA = Bend Allowance
BD = Bend Deduction
t = sheet thickness in mm
Ri = inside bend radius in mm
K = K-factor

Individual review

For thicknesses above 12 mm, non-standard radii, short flanges or critical tolerances, please request an individual review.

Standard tooling and capacity

Standard values for 90° air bending on a 200 t / 3000 mm machine, with a published force limit of 170 t and K-factor 0.42.

Tooling and maximum bend lengths for S355, 304/304L and aluminium. All dimensions are in mm.
Thickness (t)	V-die	Inside radius (Ri)	Min flange (h)	K-factor	S355 max L	304/304L max L	Al max L
0.5	V8	1.3	5.7	0.42	3000	3000	3000
0.8	V8	1.3	5.7	0.42	3000	3000	3000
1	V8	1.3	5.7	0.42	3000	3000	3000
1.5	V12	1.9	8.5	0.42	3000	3000	3000
2	V16	2.6	11.4	0.42	3000	3000	3000
2.5	V22	3.5	15.6	0.42	3000	3000	3000
3	V22	3.5	15.6	0.42	3000	3000	3000
4	V35	5.6	24.8	0.42	3000	3000	3000
5	V35	5.6	24.8	0.42	3000	3000	3000
6	V50	8.0	35.5	0.42	3000	3000	3000
8	V63	10.1	44.7	0.42	2350	2220	3000
10	V80	12.8	56.8	0.42	1910	1800	3000
12	V100	16.0	71.0	0.42	1660	1560	3000

Ri = indicative inside radius. h = recommended minimum flange/support dimension from the bend line. Max L = maximum bend length, limited to 170 t and 3000 mm. Thicknesses above 12 mm, non-standard radii, short flanges and critical tolerances require individual review.

CAD values - 90° bend

Useful when entering sheet-metal rules in CAD. BA = Bend Allowance; BD = Bend Deduction.

Standard CAD values for a 90° bend with K-factor 0.42. All dimensions are in mm.
Thickness (t)	V-die	Inside radius (Ri)	BA 90°	BD 90°	K-factor
0.5	V8	1.3	2.34	1.22	0.42
0.8	V8	1.3	2.54	1.62	0.42
1	V8	1.3	2.67	1.89	0.42
1.5	V12	1.9	4.01	2.83	0.42
2	V16	2.6	5.34	3.78	0.42
2.5	V22	3.5	7.18	4.86	0.42
3	V22	3.5	7.51	5.53	0.42
4	V35	5.6	11.44	7.76	0.42
5	V35	5.6	12.10	9.10	0.42
6	V50	8.0	16.52	11.48	0.42
8	V63	10.1	21.11	15.05	0.42
10	V80	12.8	26.70	18.90	0.42
12	V100	16.0	33.05	22.95	0.42

CAD formula: BA = angle(rad) × (Ri + K × t). For a 90° bend, BD = 2 × (Ri + t) - BA. Values are practical standard settings for air bending and are intended as design guidance. Actual radius and flat pattern may vary with material grade, tensile strength, grain direction and springback. Critical dimensions should be verified before series production.

These values are practical standard settings for air bending and are intended as design guidance. Actual bend radius and flat pattern may vary with material grade, tensile strength, grain direction and springback. Critical dimensions should be verified before series production.

For individual review or further clarification, please email us at post@metalldel.no