Sheet Metal Minimum Bend Radius Reference Guide

In sheet metal fabrication, curving sheets according to a specific bend radius is one of the most common operations used to create flanges, curls, seams etc. Moreover, bending imparts much strength to the sheet metal compared to their flatter counterparts. 

For example, an aluminium sheet bent into a V cross section will be much stiffer and stronger than the same flat sheet.

Bending a metal sheet usually comes with a set of calculations and design requirements. The bend’s outer edge would crack if it exceeds the minimum bend radius which is typically specified according to the metal sheet thickness (t) like 1t, 2t, 3t etc.

A typical recommendation is 1t for all sheet metal parts, which means the smallest bend radius should be at least equal to the sheet thickness. For example, if the thickness of the sheet is 2mm, the minimum bend radius should be 1t which is 2mm.

What is the right bend radius for sheet metal?

Below is Xometry’s minimum bend radius reference table which is based on theoretical sheet metal gauge thicknesses.

Steel bend radius reference table

Standard gauge	Thickness (mm)	Minimum bend radius (mm)
3	6.350	6.073
4	5.954	5.695
5	5.558	5.314
6	5.159	4.935
7	4.763	4.554
8	4.366	4.176
9	3.970	3.797
10	3.571	3.416
11	3.175	3.038
12	2.779	2.657
13	2.383	2.278
14	1.984	1.897
15	1.786	1.709
16	1.588	1.519
17	1.430	1.367
18	1.270	1.214
19	1.113	1.062
20	0.953	0.912
21	0.874	0.836
22	0.795	0.759
23	0.714	0.683
24	0.635	0.607
25	0.556	0.531
26	0.478	0.455
27	0.437	0.417
28	0.396	0.378
29	0.358	0.343
30	0.318	0.305

Aluminium bend radius reference table

Standard gauge	Thickness (mm)	Minimum bend radius (mm)
3	6.350	5.827
4	5.954	5.189
5	5.558	4.620
6	5.159	4.115
7	4.763	3.665
8	4.366	3.264
9	3.970	2.906
10	3.571	2.588
11	3.175	2.304
12	2.779	2.052
13	2.383	1.829
14	1.984	1.628
15	1.786	1.450
16	1.588	1.290
17	1.430	1.151
18	1.270	1.024
19	1.113	0.912
20	0.953	0.813
21	0.874	0.724
22	0.795	0.643
23	0.714	0.574
24	0.635	0.511
25	0.556	0.455
26	0.478	0.404
27	0.437	0.361
28	0.396	0.320
29	0.358	0.287
30	0.318	0.254

Bend Orientation Rules

The next important consideration while designing sheet metal parts is the bend orientation. In order to save time and money, the bends originating from the same plane should be oriented in a similar direction to avoid the reorientation of the part. 

Moreover, keeping a consistent bend radius across all the bends results in decreasing the costs of sheet metal as all the features can be produced with the same setup and tooling.

It is to be noted that the bending accuracy is inversely proportional to the thickness of sheet metal. In order to achieve a great bend precision, we recommend decreasing the sheet thickness.

As an example, let us take the two images below to explain the correct bend radius for a 1mm thick sheet (top) and the correct bend orientation for two bends in a similar plane (bottom).

Designing for sheet metal with the right bend radius

As minimum bend radius is one of the most important things when it comes to sheet metal machining, we recommend expert advice even from the initial design in order to get an accurate part and avoid unnecessary expenses.

At Xometry Europe, we offer highly accurate sheet metal services as well as design consultancy services (DFM).

Through our Instant Quoting Engine and our network of over 2,000 manufacturers, we ensure that you experience a seamless part production process, from quoting to doorstep delivery.