Aluminum Extrusion Design Tips

Aluminum extrusion offers designers freedom from “standard” shape restrictions that is unrivaled among structural materials. With aluminum extrusion you can design exactly the shape you need, putting metal only where you need it and let the production process accommodate itself to your design. Careful design is the way to gain maximum benefit from the many valuable characteristics of aluminum alloys and the flexibility of the extrusion process.

Shape Configuration

The designer’s first priority is to satisfy a specific need. Aluminum Extrusions can be designed to aid in assembly, improve product appearance, reduce or eliminate forming and welding operations, and achieve many other purposes. Basically, aluminum extrusion allows you to design the shape that best meets your functional, structural, and aesthetic requirements.

Extruded shapes are described in three general categories: solid, hollow, and semi-hollow.

Hollow Shapes

A hollow shape is simply an extruded shape that completely encloses a void anywhere in its cross-section. The void itself may have any shape, and the complete profile may include a variety of other forms.

Solid Shapes

A solid extruded shape is any shape that is not a hollow or semi-hollow shape. This covers a wide range including, for example, compact cross-sections with or without projections.

Semi-hollow Shapes

A semi-hollow shape is one that partially encloses a void—for example, a circle or rectangle with a gap in one side; but a solid shape can also partially enclose a void, and the difference may not be obvious. An extruder can help you define a semi-hollow versus a solid shape.

Extrusion Design Guidelines

Here are some tips to help you better design a profile for the best cost and process efficiency.

Practice Symmetry

Keep the shape as symmetrical as possible; minimize asymmetrical details. By keeping the void symmetrical you lessen the chances that the die tongue may break. Outside corners should be at a minimum of .020”.

Keep Wall Thicknesses Uniform

Thick-thin junctions give rise to distortion, die breakage, or surface defects on the extrusion. Plus, it’s useful to note that thicker walls may be less expensive; very thin walls are costly to extrude.

Smooth All Transitions

Transitions should be streamlined by a generous radius at any thick-thin junction. Also, avoid knife edges by rounding sharp corners and providing generous tapers. Inside corners should be a minimum of .015”. Change the profile to blunt of rounded point. If a sharp corner is needed, consider a corner relief.

Enhance Visual Surfaces

Use grooves, webs, and ribs. Wide, thin sections can be hard to straighten after extrusion. Ribs help straighten operation, reduce twisting, and improve flatness. With a little extra effort or cost, designers can add grooves, ridges, or other decorative detail. Shallow groove marks make drilling, punching, and assembly easier by eliminating the need for center punching. Index grooves can also be used to help identify pieces that are similar in appearance, or to distinguish an inside vs. outside surface.

Note: The design tips presented above should be viewed as guidelines to optimize process efficiency. Complex profile designs, which violate many of these guidelines, are also possible and may lead to the most appropriate solution. Discuss your needs with a qualified extruder who can help determine the best overall design.

Aluminum Extrusion Manual

Many more design tips are available in the AEC Aluminum Extrusion Manual.

Download the manual (free)

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