Whether you are designing a frame for a bicycle, a roof reinforcement for a car or solar panels, the aluminium profile will take shape on the drawing board. It is therefore essential that you understand the “basics” for the design of aluminium profiles and components.
Understanding these basics will help you identify ways to reduce weight, add functionalities, simplify assembly, and minimize costs.
Designing with the right wall thickness
Wall thickness is the single most consequential decision in aluminium extrusion design, since it governs a profile's strength, weight, cost, and how easily it can be extruded to tolerance. Profiles with uniform wall thickness are the easiest to produce, but if changes are needed, you can easily alter wall thicknesses within an aluminium profile.
The most important factors that influence wall thickness are:
- The choice of the alloy
- The shape of the profile
- Extrusion press power and speed
- The desired surface treatment
- Desired tolerances
Rounded shapes will improve your design
Corner radius is one of the most common constraints new designers underestimate: the extrusion process cannot produce sharp internal or external corners, so every profile needs rounded transitions built into the design from the start. In most cases, a radius of 0.5 to 1 mm is enough to round off corners and projections without affecting the design intent. Where a design genuinely needs a sharp internal corner, for example to enclose a box shape, this can be achieved with a hole radius rather than an actual sharp edge. Wall thickness transitions matter here too. Profiles with large variations in wall thickness cool unevenly after extrusion, which shows up as visible structural unevenness on the surface, an effect that becomes more noticeable once the profile is anodized. Rounding the transition between different wall thicknesses reduces this.
Learn more by signing up for the free aluminium extrusion design manualEnhance your products with decoration
Decoration in aluminium extrusion is not purely cosmetic. Anodizing, painting, and other surface treatments also hide process marks, protect against handling damage, and can be specified early enough in the design stage to solve functional problems as well as appearance ones. Decoration can also mask heat zones, the shadowing that sometimes appears opposite arms or screw ports as a result of the extrusion process, as an alternative or complement to using generous radii to carry the heat away. Raised decorative ribs serve a similar dual purpose: a profile can rest on the ribs during storage and handling, protecting the finished flat surface from damage.
Achieving cost-efficient production
Cost in aluminium extrusion is driven as much by shape as by material. Symmetrical profiles with consistent wall thickness extrude faster and more predictably, while asymmetry, deep narrow channels, and abrupt thickness changes slow down the press and increase scrap rates. A few concrete guidelines help here. Matching the thickness of internal and external walls reduces stress on the die and improves productivity, even when a uniform wall thickness across the whole profile is not practical. Where a profile needs cavities, fewer cavities generally means lower die costs and less stress on the die. It is worth asking whether a complex hollow profile can be replaced with two simpler telescoping profiles instead.
For pockets or channels, a useful rule of thumb is to keep the width-to-height ratio around 1:3 to protect the strength of the die. Increasing the radius at the channel opening can relax that to roughly 1:4. Channels narrower than 3 mm need to be evaluated individually rather than by rule of thumb.
Not every design should optimize purely for ease of production. Heat sinks are a good example of when it makes sense to deliberately exceed these channel ratios, since the cooling benefit from a higher fin density outweighs the added production difficulty.
