Sheet metal brackets are the workhorses of mechanical assemblies. You’ll find their diverse geometries everywhere. A bracket is any device that affixes one component to another, usually larger, one. One example is the caliper bracket that attaches a brake caliper to your car’s brake rotor. The smaller caliper attaches to the larger wheel hub. This relationship is critical to the role of a bracket.
Brackets vary so much, that it’s tough to find similarities by size and shape. Here are a few things they have in common. Often, they need to be stiff. Depending on the load, they need to be heavy-duty. They have to be made from thick, robust materials. This is most common with structural or architectural brackets. Sometimes you need threaded features, tapping, or clinch hardware to secure components.
Stiffness: Securing Parts in Heavy Load Situations
Brackets that hold up heavy loads often need more stiffness. There are many features and design tactics you can leverage to achieve this. One way to increase a part’s rigidity after forming is with formed gussets. Here’s a tip: It’s most cost effective to design these features as 90-degree bends. Also, be flexible on their exact geometry. This makes it easier to work with your manufacturer’s tooling. Or, a welded gusset could achieve even better results. This approach takes a second piece of sheet metal and welds it into your bracket, adding stiffness. While you aren’t limited by bend angle and in-house tooling, you are limited in your minimum material thickness. Most vendors will not want to weld less than 0.040 in. (1.016mm) material thickness.
Choosing the Best Material for Your Sheet Metal Brackets
FInding the right metal for your application will depend on your design and your material properties.
Always think about the material qualities when making aluminum brackets.
- 5052-H32 yields a far more robust and stiff component after forming than 6061-T6 or 3003
- 6061-T6 loses strength when formed, to the degree that most manufacturers are unwilling to form it at all
- 3003 is on the opposite end of the spectrum. It’s typically too ductile to produce a stiff, strong bracket
Steel is a good option for brackets, but it corrodes easily. In fact, if you don’t request a finish or plating your manufactured parts likely will arrive with some surface rust. Weight is another concern. Steel brackets with strength equal to an aluminum one will be heavier and thicker.
Stainless steel doesn’t readily corrode and is naturally stiffer than steel and aluminum, but it’s pricier. Because stainless is stiffer and stronger than steel, you can use thinner sheets and get the same strength.
Including Threaded Features
Clinch fasteners are a great way to add threaded features to your brackets and there are limited restrictions based on material thickness. This is handy if your bracket’s material thickness isn’t large enough to handle the thread engagement required by the load placed on your bracket. The opposite is true, too. When material thickness increases, you should exceed the thread engagement threshold for your load for more robust tapped holes. But be mindful of material type and hardware availability. If you use stainless steel, you will need to use hardened stainless clinch fasteners. Sometimes, these can be hard to find as in-stock items.
It’s hard to avoid sheet metal brackets when designing an assembly. Design success comes down to understanding the load requirements, material characteristics, and design features that your manufacturer can accommodate. In the end, the sky is the limit with brackets, so don’t be afraid to leverage this workhorse in your design.
Related Design Tips
For more helpful sheet metal design tips, download our Design for Manufacturing (DFM) Guide.