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ResourcesMachining DesignSheet Metal Bending: The Basics
Sheet metal being bent

Sheet Metal Bending: The Basics

An overview of minimum bend radii and bend orientation.

Xomety X
By Team Xometry
 2 min read
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Bending is a common sheet metal operation used to create flanges, curls, and seems. Additionally, sheets with bends are stiffer than their flat counterparts. For example, a flat sheet of aluminum is less stiff than that same sheet of aluminum bent into a V cross section. 

For all metals, however, there is a minimum bend radius at which the outer edge of the bend will crack. Minimum bend radii are typically specified in terms of sheet thickness (t) such as 1t, 2t, 3t, etc... We recommend a minimum bend radius of 1t for all sheet metal parts. Thus the smallest radius of any bend in a sheet should be at least equal to the thickness of the sheet. For example, if the thickness of the sheet is 1 mm, the minimum bend radius should be 1 mm. 

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

Minimum Bend Radius Reference Table (inches)
GaugeMinimum Bend Radius: SteelMinimum Bend Radius: Aluminum
Gauge

3

Minimum Bend Radius: Steel

0.239

Minimum Bend Radius: Aluminum

0.229

Gauge

4

Minimum Bend Radius: Steel

0.224

Minimum Bend Radius: Aluminum

0.204

Gauge

5

Minimum Bend Radius: Steel

0.209

Minimum Bend Radius: Aluminum

0.182

Gauge

6

Minimum Bend Radius: Steel

0.194

Minimum Bend Radius: Aluminum

0.162

Gauge

7

Minimum Bend Radius: Steel

0.179

Minimum Bend Radius: Aluminum

0.144

Gauge

8

Minimum Bend Radius: Steel

0.164

Minimum Bend Radius: Aluminum

0.129

Gauge

9

Minimum Bend Radius: Steel

0.150

Minimum Bend Radius: Aluminum

0.114

Gauge

10

Minimum Bend Radius: Steel

0.135

Minimum Bend Radius: Aluminum

0.102

Gauge

11

Minimum Bend Radius: Steel

0.120

Minimum Bend Radius: Aluminum

0.091

Gauge

12

Minimum Bend Radius: Steel

0.105

Minimum Bend Radius: Aluminum

0.081

Gauge

13

Minimum Bend Radius: Steel

0.090

Minimum Bend Radius: Aluminum

0.072

Gauge

14

Minimum Bend Radius: Steel

0.075

Minimum Bend Radius: Aluminum

0.064

Gauge

15

Minimum Bend Radius: Steel

0.067

Minimum Bend Radius: Aluminum

0.057

Gauge

16

Minimum Bend Radius: Steel

0.060

Minimum Bend Radius: Aluminum

0.051

Gauge

17

Minimum Bend Radius: Steel

0.054

Minimum Bend Radius: Aluminum

0.045

Gauge

18

Minimum Bend Radius: Steel

0.048

Minimum Bend Radius: Aluminum

0.040

Gauge

19

Minimum Bend Radius: Steel

0.042

Minimum Bend Radius: Aluminum

0.036

Gauge

20

Minimum Bend Radius: Steel

0.036

Minimum Bend Radius: Aluminum

0.032

Gauge

21

Minimum Bend Radius: Steel

0.033

Minimum Bend Radius: Aluminum

0.029

Gauge

22

Minimum Bend Radius: Steel

0.030

Minimum Bend Radius: Aluminum

0.025

Gauge

23

Minimum Bend Radius: Steel

0.027

Minimum Bend Radius: Aluminum

0.023

Gauge

24

Minimum Bend Radius: Steel

0.024

Minimum Bend Radius: Aluminum

0.020

Gauge

25

Minimum Bend Radius: Steel

0.021

Minimum Bend Radius: Aluminum

0.018

Gauge

26

Minimum Bend Radius: Steel

0.018

Minimum Bend Radius: Aluminum

0.016

Gauge

27

Minimum Bend Radius: Steel

0.016

Minimum Bend Radius: Aluminum

0.014

Gauge

28

Minimum Bend Radius: Steel

0.015

Minimum Bend Radius: Aluminum

0.013

Gauge

29

Minimum Bend Radius: Steel

0.014

Minimum Bend Radius: Aluminum

0.011

Gauge

30

Minimum Bend Radius: Steel

0.012

Minimum Bend Radius: Aluminum

0.010

Bend Orientation Rules

Another important consideration when designing sheet metal parts is bend orientation. Bends originating from the same plane should be oriented in the same direction to avoid the need of reorienting the part. This will save both money and time. Keeping a consistent bend radius across all bends will also make designs more cost-effective because the features can be produced with the same tooling and setup. Finally, it is important to note that bend accuracy increases as sheet metal thickness decreases. If bend precision is a critical requirement for your part, we recommend minimizing sheet thickness.

Let's take a look at some examples. There are two images below that show the correct bend radius for a 1 mm thick sheet (top) and the correct bend orientation for two bends in the same plane (bottom).

For more information on sheet metal fabrication, download our Sheet Metal Design Guide here.

Slide 1 of 2
  • Correct Bend Radius

Correct Bend Radius

Xomety X
Team Xometry
This article was written by various Xometry contributors. Xometry is a leading resource on manufacturing with CNC machining, sheet metal fabrication, 3D printing, injection molding, urethane casting, and more.