What is Sheet Metal Bending?

Sheet metal bending is a manufacturing process that forms flat sheet metal into a desired shape by applying force along a straight axis. Using CNC press brakes and precision tooling, sheet metal can be bent into brackets, enclosures, chassis, panels, and structural components while maintaining tight tolerances and repeatability.

Understanding basic bending requirements during the design stage helps ensure your parts are manufacturable, accurate, and cost-effective.

Available Materials

Sheet metal bending can be performed on a variety of materials, including:

• Mild Steel
• Stainless Steel
• Aluminium
• Galvanised Steel
• Zincanneal Steel

Bend Radius Guidelines

The inside bend radius is the radius formed on the inside of the bend. As a general rule:

Minimum Inside Bend Radius = Material Thickness

Tighter radii may be possible depending on material type and tooling availability, but larger radii typically produce more consistent results and reduce cracking risk.

Material Thickness	Recommended Minimum Inside Radius
1.0 mm	1.0 mm
1.6 mm	1.6 mm
2.0 mm	2.0 mm
3.0 mm	3.0 mm
5.0 mm	5.0 mm

Minimum Flange Length

A flange is the portion of material extending from a bend. To achieve accurate bending, the flange must be long enough for the press brake tooling to properly support the material. If the flange length is no too short for the required tooling, the part can not be bent or it may risk slipping into the dies.

Recommended Minimum Flange Length

Material Thickness	Recommended Minimum Flange
0.4mm - 2mm	8mm
2.5mm-3mm	12mm
4-5mm	20mm
6mm	30mm
8mm	45mm
10mm	55mm

 

Distance of Cutouts to Bends

Features placed too close to a bend can distort during forming. The edge of a hole, slot, or cutout should be located at least the same distance of the minimum flange length. This helps prevent:

• Hole deformation
• Material stretching
• Dimensional inaccuracies
• Cosmetic defects

Relief Cuts for Adjacent Bends

When bends terminate near an edge or intersect another bend, relief cuts may be required to prevent tearing and material deformation.

Recommended Relief Dimensions

• Relief Width ≥ Material Thickness
• Relief Length ≥ Bend Radius + Material Thickness

Adding bend reliefs improves part quality and reduces stress concentration at bend corners.

Tolerances

Critical dimensions should be clearly identified on engineering drawings. Typical CNC press brake bending tolerances are:

Feature	Typical Tolerance
Bend Angle	±1°
Linear Dimensions	±1 mm
Flange Lengths	±1 mm

 

Bend Allowance & Bend Deduction

When sheet metal is bent, the material stretches along the bend zone. This affects the final flat pattern size. Our manufacturing systems automatically account for:

• Bend allowance
• Bend deduction
• Material stretch factors
• Tooling characteristics

Designers should provide either:

• A fully dimensioned folded model, or
• A flat pattern generated using verified bend data

Common Design Tips

Do

✓ Use inside bend radii equal to or greater than material thickness
✓ Maintain adequate hole-to-bend spacing
✓ Keep flange lengths above minimum recommendations
✓ Consider grain direction during design
✓ Provide clear bend directions on drawings

Avoid

✗ Sharp internal bends
✗ Features too close to bend lines
✗ Extremely short flanges
✗ Overlapping bends without clearance
✗ Unspecified critical dimensions

Need Help With Your Design?

Our engineering team can review your sheet metal design and provide recommendations to improve manufacturability, reduce costs, and ensure successful production. Contact us for assistance with:

• Design for Manufacture (DFM)
• Bend feasibility reviews
• Material selection
• Tolerance requirements
• Production optimisation