Aluminium extrusion process — 450–500 °C heated billet pressed through an H13 steel die and T5/T6 artificial aging

Knowledge HubShaping a billet into a profile

What is extrusion?

A heated aluminium billet is pushed through a die to form a continuous profile.

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Key Extrusion Takeaways

01Billet shaped at 450–500 °C
02Section geometry defined by the die
03Temper achieved through heat treatment

Aluminium Extrusion Process Mechanics and Thermal Stages

In extrusion the billet is heated to about 450–500 °C and pushed from the container through the die. The profile is cooled at the die exit, then cut to length and straightened.

The section geometry comes from the die: wall thickness, corner radii and cavities are defined at the design stage. Cooling rate and temper directly affect the mechanical properties.

Aging in the furnace delivers T5 or T6 tempers, followed by the surface treatment and machining steps.

Aluminium Extrusion Process Stages & Metallurgical Parameters
Process Stage	Typical Parameter / Range	Metallurgical & Dimensional Purpose
1. Billet Preheating	450 °C – 500 °C	Homogenize Mg₂Si phase and achieve plastic flow
2. Die Extrusion	Flat (solid) or Porthole (hollow) die	Form profile cross-section per EN 755-9 / EN 12020-2
3. Press Exit Quenching	Forced air or water-mist quench	Lock alloying elements in supersaturated solid solution
4. Cold Stretching	0.5% – 2.0% controlled elongation	Relieve residual stress and straighten twist/bow
5. Artificial Aging	175 °C – 205 °C (4 – 8 hours)	Precipitate Mg₂Si to achieve T5, T6 or T66 strength

FAQ

How are hollow multi-chamber aluminium profiles extruded?

Using a two-part porthole mandrel die: heated aluminium splits around internal bridges and solid-state welds back together inside the welding chamber before exiting the die bearing.

What determines the minimum wall thickness in extrusion?

Minimum wall thickness (down to 0.8 mm on our 5–7 inch presses) depends on alloy flow stress, circumscribing circle diameter (CCD) and section symmetry—6060/6063 allow the thinnest walls.