Designing with Sheet Metal: How Tight Can You Make a Bend?

Making a custom metal form using sheet metal is a surprisingly delicate process. To get the best results, a design engineer has to account for many factors, such as the end use of the metal form, the material the sheet metal is made of (plain steel, stainless steel, etc.), and the dimensions/shape of the final product.

Getting a single thing wrong could render the final product useless. This is why design engineers spend so much time carefully reviewing designs and using virtual physics simulation software, such as Autodesk, to vet their designs before production.

One design element that many laymen tend to forget about is the radius of each bend in a sheet metal form. Where many people might assume that all metals can be bent at perfect right angles without an issue, this is not the case.

Each and every bend in a piece of sheet metal has a certain minimum internal radius that needs to be taken into account when planning the design of a sheet metal form.

The Problem with Bending Too Tightly

If a piece of material is bent too tightly, problems can occur.

The most common problem with bending a piece of sheet metal too tightly is that you can compromise the structural integrity of your sheet metal form. Basically, you might create a weak point in the metal that can break easily, lowering the maximum load the metal can take before shattering.

Another common issue is that there can be excessive plastic deformity resulting from the stress of the bend, slightly altering the dimensions of the final work piece along the area where the bend was made.

With this in mind, what is the minimum bend radius for a piece of sheet metal?

Determining the Minimum Internal Radius for a Bend in Sheet Metal

There are a two major factors that affect how tight you can make the internal radius of a bend in a piece of sheet metal:

1. The hardness of the metal
2. The thickness of the metal

Generally speaking, the thicker a piece of sheet metal is, the wider the internal bend radius will have to be. Similarly, the harder a piece of metal is, the more room you’ll have to allocate for the bend as well, or risk fracturing the sheet metal.

Getting the actual minimum bend radius for your sheet metal typically requires more detailed knowledge of the alloy being shaped, which comes with training and education in metal forming techniques as well as a familiarity with the material(s) used for a custom sheet metal form.

For reference, here are bend radius charts for aluminum, mild steel, and stainless steel:

Let Marlin Steel Handle Your Sheet Metal Design Needs

See how Marlin Steel’s degreed engineers leverage their expertise in designing custom metal forms to optimize the production process for other companies. If you’re looking for assistance with designing sheet metal flanges, creating custom wire baskets, or welding, turn to the experts at Marlin Steel.