Aluminum extrusion is a manufacturing process that forces heated aluminum through a shaped die to create objects with a uniform cross-section.
Through the process of aluminium extrusion, heated aluminum alloy is forced through a shaped steel die under high pressure to create objects with a uniform cross-sectional profile. Unlike casting or melting, the process never melts the metal — it heats it to a plastic state, typically 700–925°F, and uses hydraulic pressure up to 15,000 tons to push it through the die. The result is everything from window frames to aircraft components, combining strength with the natural corrosion resistance aluminum is known for. The process produces three profile types: solid (no enclosed voids), hollow (one or more enclosed cavities), and semi-hollow (partially enclosed spaces).
The Aluminum Extrusion Process Step by Step
Aluminum extrusion follows a standardized 10- to 13-step workflow that converts a heated billet into a finished profile through controlled pressure, cooling, and aging. The metal never melts — it stays solid throughout, reaching a plastic state that allows it to flow evenly through the die.
Cast billets often undergo a pre-treatment at 500–550°C for 6–12 hours to reduce chemical segregation within the alloy. After that, billets are heated to 800–925°F. Most 6xxx-series alloys require 400–520°C, while 7xxx-series alloys use slightly lower temperatures to prevent excessive grain growth. The billet and ram are lubricated, then the billet is loaded into a container where a hydraulic ram applies up to 15,000 tons of force to push it through the die.
From there, the profile is quenched rapidly using air fans or water baths to lock in its metallurgical properties. It is then stretched to correct any warping and perform work hardening. Profiles undergo artificial aging in ovens at roughly 180°C for 5–8 hours to increase strength and hardness. Saw cutting to length follows, with tolerances typically 1/8 inch or greater. Surface finishes can be applied as a final step if required.
Inadequate lubrication causes the billet to stick inside the container, while overheating 7xxx-series alloys leads to excessive grain growth that degrades the final material properties. Equipment operates under high pressure, and handling billets at these temperatures requires proper heat-resistant gear.
Why Aluminum Works So Well for Extrusion
Aluminum’s combination of malleability, strength, light weight, and corrosion resistance makes it the ideal extrusion material. The process naturally forms a thin aluminum oxide layer on the surface, providing built-in corrosion protection without additional coatings or treatments.
Because aluminum is highly plastic at extrusion temperatures, it flows evenly through complex die shapes, producing consistent profiles with tight tolerances. The material’s high strength-to-weight ratio makes it a favorite in construction, transportation, and consumer goods. Extrusions can be produced as solid, hollow, or semi-hollow profiles, giving designers wide flexibility in shape and function while maintaining uniform mechanical properties along the entire length.
Common Alloys and What They’re Used For
The 6xxx-series alloys dominate aluminum extrusion for structural applications, while 7xxx-series alloys handle high-strength needs where weight savings are most critical.
Alloy 6061 is the workhorse for structural frames, automotive parts, and marine components — it combines high strength with good weldability and corrosion resistance. Alloy 6063 is preferred for architectural applications like window frames and doors because of its smooth surface finish and moderate strength. For demanding aerospace components and high-performance sporting goods, 7xxx-series alloys deliver very high strength, though they require careful temperature control during extrusion to avoid grain growth and maintain their mechanical properties.
If you’re comparing material options for a project, our roundup of top aluminum extrusion profiles covers well-rated choices for different applications and budgets.
| Alloy Series | Key Properties | Common Applications |
|---|---|---|
| 6061 (6xxx) | High strength, good weldability, corrosion resistant | Structural frames, automotive, marine |
| 6063 (6xxx) | Smooth surface finish, moderate strength | Window frames, doors, architectural trim |
| 7xxx-series | Very high strength, lower plasticity, sensitive to overheating | Aerospace, high-performance sporting goods |
FAQs
Does aluminum extrusion involve melting the metal?
No. Extrusion is a solid-state process. The aluminum is heated to a plastic, workable temperature — between 700°F and 925°F — but never reaches its melting point. This preserves the material’s metallurgical structure and avoids the defects that come with melting and casting.
How much force is used in aluminum extrusion?
Hydraulic rams in extrusion presses can apply up to 15,000 tons of force to push the heated billet through the die. The exact pressure depends on the alloy, the complexity of the profile shape, and the size of the extrusion. Softer 6xxx-series alloys typically require less force than harder 7xxx-series alloys.
What products are commonly made with aluminum extrusions?
Construction uses extrusions for high-rise buildings, windows, and doors. Transportation relies on them for automobile frames, aircraft components, and speedboat hulls. Consumer goods like patio furniture, sports equipment, and home appliances also use extruded profiles, as do electronics enclosures and industrial machinery such as conveyors and generators.
References & Sources
- Aluminum Association. “Introduction to Aluminum Extrusion” Covers the extrusion process, alloys, and applications.