Types of Aluminum Extrusion Profiles

The main types of aluminum extrusion are grouped by cross-section (solid, semi-hollow, hollow), by die source (standard or custom) and by extrusion route (direct, indirect, cold, impact). Each of these types of aluminum extrusion changes tooling, tolerance and cost in a different way.

Aluminium extrusion is a process in which a heated aluminium billet is forced through a shaped die to produce a continuous profile with a fixed cross-section. Buyers sort aluminium extrusion profiles by shape, die status, and alloy and temper.

Shape drives tooling and cost. Solid profiles have no enclosed void, semi-hollow profiles have a partial enclosure, and hollow profiles contain closed cavities that need porthole or bridge dies, which add complexity and can limit how thin walls can go.

Among the types of aluminum extrusion by die source, standard aluminum extrusion profiles use existing dies, so tooling cost and lead time are usually lower. Custom aluminum extrusions need a new die but can combine several functions into one profile, often removing fasteners and assembly steps. Profile weight per foot (per meter) and material yield also drive cost.

Aluminum extrusion works by heating a billet until it softens, then pushing or drawing it through a die so the metal takes the die's cross-section. Most types of aluminum extrusion share these steps; the route (direct or indirect) and the temperature range set how complex the profile can be.

1. 1. Billet preparation A cast aluminium billet is cut to length and heated to its hot-working temperature, which lowers flow stress so the metal passes through the die.
2. 2. Extrusion In direct extrusion a ram pushes the billet through a stationary die. In indirect extrusion the die moves through a relatively stationary billet, lowering friction and improving dimensional consistency for suitable profiles.
3. 3. Quench and cooling The profile is cooled under controlled conditions. Quenching rate affects the achievable temper, so temperature control is critical.
4. 4. Stretching and cutting The profile is stretched to straighten it and relieve residual stress, then cut to length. Cut-length tolerance is supplier- and order-specific.
5. 5. Aging and heat treatment Where the temper requires it, profiles are aged to develop strength. Artificial aging is typical for T5 and T6 tempers.
6. 6. Finishing and fabrication Profiles may be anodized, powder coated or left mill finish, then cut, drilled, tapped, milled, punched, bent or assembled.

An aluminum extruder may also offer routes for different part shapes. Cold extrusion forms aluminium below its hot-working temperature, giving good finish and accuracy on smaller sections at higher forming forces. Impact extrusion forces a slug around or through a punch to make short hollow parts such as cups and small housings, not long continuous profiles.

Types of extruded aluminum are best compared on four axes: cross-section class, die status, alloy and temper, and the extrusion route. The table below shows what each of these types of aluminum extrusion changes for a buyer.

Treat these figures as starting points, not guarantees. Capability across the types of aluminum extrusion depends on alloy, temper, section geometry and the standard you specify. Precision profiles under EN 12020 hold tighter dimensional and form requirements than general-purpose profiles.

Most extruded profiles are made from 6000-series aluminium alloys because they combine good extrudability with useful strength and corrosion resistance. Alloy and temper selection drives strength, finish quality and how complex the cross-section can be.

Exact properties depend on temper and product form, so always state both on the drawing. If a profile must be both strong and machined after extrusion, 6061 or 6082 is often the practical choice; if surface appearance leads, 6063 usually wins.

The main advantages of extruded aluminum profiles are long constant cross-sections and complex hollow shapes made in one operation; the main limitation is that the cross-section cannot change along the length. Weighing both sides early avoids a redesign later.

Choosing among the types of aluminum extrusion means trading die complexity, friction and equipment needs against profile capability. Indirect extrusion reduces friction but needs more specialized equipment.

Good extrusion design keeps the cross-section as uniform as possible and states tolerances that match the standard you are buying to. These rules apply to both standard aluminum extrusion profiles and new custom dies.

• Keep wall thickness as uniform as possible; abrupt thickness changes distort during quenching.
• Avoid very thin walls unless necessary; thinner walls generally require a greater percentage tolerance allowance.
• Design generous corner radii and avoid sharp internal corners that concentrate stress in the die.
• Balance the cross-section around the centreline so metal flows evenly and the profile stays straight.
• Use symmetrical, self-supporting shapes for hollow sections to reduce die deflection.
• Specify tolerances against a named standard such as EN 755 or ASTM B221 rather than leaving them open.
• State alloy and temper explicitly, for example 6063-T6, not just “aluminium”.
• Allow for machining stock if faces will be milled, drilled or tapped after extrusion.
• Agree cut-length tolerance, packaging and inspection requirements before production.
• Confirm the finish, anodized or powder coated, and the appearance criteria that apply.

Extruded aluminum profiles appear wherever a light, stiff, corrosion-resistant section is needed in long lengths. Automotive and transport are the largest users, followed by building products and industrial equipment.

• Architectural frames, window and door systems, curtain wall mullions and trim.
• Automotive structures, battery enclosures, roof rails, crash management and interior trim.
• Transport platforms, ladders, rail interiors and load-bearing frames.
• Machine frames, guards, workstations and automation structures.
• Heat sinks, lighting housings and electronics enclosures.
• Furniture, display systems and shopfitting profiles.
• Marine and heavy-duty structural profiles where 6082 is often selected.

The choice between extrusion and other processes depends on the part. Extrusion efficiently creates long constant cross-sections, while sheet fabrication creates parts by cutting, bending, forming and joining flat stock. Casting supports more three-dimensional shapes but brings different controls for porosity and dimensional variation.

Extrusion cost is driven mainly by metal weight, die cost and the amount of secondary work, not by a single headline rate. Profile weight per foot [per metre] and material yield are the biggest levers, because you pay for the metal you buy and the scrap you generate.

• Profile weight per foot [per metre] and material yield.
• Alloy and temper, since higher-strength alloys can be harder to extrude.
• Die cost and whether an existing standard die can be used.
• Section complexity, especially hollow and thin-wall shapes.
• Tolerance class and whether a precision standard such as EN 12020 applies.
• Finishing: mill, anodized or powder coated.
• Secondary operations such as cutting, drilling, tapping, milling, punching, bending and assembly.
• Quantity, packaging, freight and inspection requirements.

Supplier-published estimates report die costs of $400–$3,000+ and extrusion prices of approximately $2.50–$8.00 per kilogram [$1.13–$3.63 per pound]. These figures are unverified supplier estimates, not standards-based values, and should not replace quotations.

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