Understanding Aluminum Extrusion Types and Processes
October 20, 2023
Aluminum extrusion creates highly customizable profiles with consistent strength ideal for construction applications. This article provides an overview of key aluminum extrusion methods, alloys, and finishes relevant for architectural components.
The Extrusion Process
The extrusion process starts by heating aluminum billets, or large cylindrical chunks of aluminum, to reach plasticity around 900-950°F. The billets are then pushed through a steel die by a hydraulic ram, forcing the softened aluminum to conform to the die's shape. As it exits the die, the extruded aluminum profile is quickly cooled with water, freezing its new shape.
The profile is pulled through the die continuously, with extrusion speeds over 50 feet per minute possible for long uninterrupted sections. Dies provide very precise control over the resulting shape, enabling complex internal and external forms not easily produced by other fabrication methods.
Extrusion produces uniform shapes and tolerances unmatched by casting or machining aluminum. The rapid cooling as the section exits the die also results in improved structural integrity and strength consistency across the length of an extruded piece.
Beyond simple profiles, multi-void hollow shapes can be created by using bridge dies. More complex custom extruded components like louver blade segments can be formed by combining multiple integrated dies. This flexibility enables extruders to create optimized aluminum sections tailored to the load requirements and functional needs of products like architectural louvers.
Multi-Void and Bridge Dies
Bridge dies allow hollow multi-void shapes within one extrusion. More elaborate profiles like rectangular tubes with integrated internal supports can be produced through a combination of integrated dies operating in sequence.
Aluminum Alloy Options
Common Grade Alloys:
6063 - Excellent corrosion resistance and good strength-to-weight.
6061 - Medium strength with good workability for basic profiles.
Structural Grade Alloys:
6005A - Higher strength suitable for structural sections.
6061-T6 – Precipitation heat treatment increases strength.
6063-T52 – Improved properties without impact on aesthetics.
Finishing Options
Powder coating - For color and protection per AAMA 2604/2605 standards.
Anodizing - Type II or III for minimal maintenance.
Aluminum’s extrudability, combined with alloy and finishing options, make it an adaptable material for architectural components like spandrels, mullions, or louvers. Extrusion produces lightweight, high-tolerance aluminum perfect for durable building products.