How the extrusion process works
A billet of aluminum alloy is heated to a plastic state and forced under pressure through a steel die whose opening is shaped like the desired cross-section. The profile emerges continuously, is cooled, stretched to straighten it, and cut to length. If the part needs heat treatment or aging (as with T5 and T6 tempers), that happens next.
Because the shape is produced continuously along the length, extrusions are ideal for parts that repeat a profile: rails, frames, trims, tubes, heat sinks and enclosure sections.
- Die design determines the achievable cross-section and its tolerances
- Solid shapes use simple dies; hollow shapes need bridge or porthole dies
- The circumscribing circle (bounding circle) of the profile dictates press size
- Alloy selection balances strength, extrudability and surface finish quality
Common aluminum extrusion alloys
Most commercial extrusions use 6xxx-series alloys. 6063 is the default for architectural and general-purpose profiles because it extrudes smoothly and finishes beautifully. 6061 is chosen where strength matters more than surface refinement. 6005/6005A and 6082 serve structural roles, and 6463 is used for decorative applications.
- 6063 — excellent finish, easy to extrude, general and architectural use
- 6061 — higher strength, structural applications, slightly rougher finish
- 6005/6005A — structural strength with good extrudability
- 6082 — structural, widely used outside North America
Standard profiles vs. custom shapes
Standard profiles — angles, channels, tees, tubes and framing sections — are catalog shapes that suppliers run routinely: no tooling cost and short lead times. Custom shapes are extruded to your own cross-section and require a die, but they can integrate features that would otherwise need machining or assembly.
The decision is usually economic: custom tooling pays off across production programs, while standard sections win for prototypes, low volumes and generic construction.
What buyers should prepare before requesting quotes
Suppliers price extrusions from a specification, not a product name. Before you contact any supplier, assemble the profile drawing or dimensions, the alloy and temper, the quantity and expected repeats, the finish, any fabrication steps, packaging and the delivery destination. That single package is what a quote request should contain.