Processing techniques for aluminum profiles (extrusions) cover the entire path from raw aluminum to the finished product. These can be grouped into four main stages: casting, extrusion, surface treatment, and fabrication/finishing. Here’s a full breakdown 👇
1. Casting (Billet Preparation)
The first step is to produce aluminum alloy billets suitable for extrusion.
Main Processes:
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Batching (Alloying): Weigh and mix pure aluminum with alloying elements (e.g., Mg, Si, Cu, Zn).
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Melting: Heat and stir to form a uniform molten alloy.
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Refining and Degassing: Remove hydrogen and inclusions using inert gases (e.g., argon).
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Casting: Use a semi-continuous casting machine to form cylindrical billets.
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Homogenization: Heat-treat billets to relieve stress and improve extrudability.
2. Extrusion
Extrusion shapes the heated billet into a profile with the desired cross-section through a die.
Process Steps:
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Heating: Preheat billets (typically 450–500 °C) for optimal plasticity.
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Extrusion: Push the billet through a steel die using an extrusion press.
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Cooling: Air or water cooling stabilizes the profile shape.
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Stretching (Straightening): Removes internal stress and corrects bending.
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Cutting: Profiles are cut to required lengths (usually ~6 m or as specified).
3. Surface Treatment
Improves appearance, corrosion resistance, and durability.
| Technique | Description | Key Features |
|---|---|---|
| Mechanical Finishing | Polishing, brushing, sanding | Smooth finish but no corrosion protection |
| Anodizing | Electrochemical oxidation forms an oxide layer | Hard, corrosion-resistant, can be colored |
| Electrophoretic Coating | Adds a transparent protective film over anodized layer | Uniform gloss and color |
| Powder Coating | Electrostatic spraying of powder resin | Durable, colorful, weather-resistant |
| Wood Grain Transfer | Heat transfer for decorative wood-like appearance | High aesthetics |
| PVDF Coating | Fluorocarbon painting for architectural use | Excellent UV and chemical resistance |
4. Fabrication / Finishing
After surface treatment, profiles may undergo precision machining or assembly.
Typical Operations:
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Cutting, drilling, tapping, milling
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CNC machining for precision parts
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Bending or forming (cold or hot)
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Punching, riveting, or welding (TIG, MIG)
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Assembly of frames or mechanical structures
