Aluminium Angle Extrusion Dies: Standard Sizes and Custom Tooling

How an aluminium angle die works

An angle is an open, solid profile: it has no enclosed hollow. That means it is made on a solid die (also called a flat die), a hardened steel disc with an L-shaped aperture machined through it, rather than the more complex porthole or bridge dies used for tubes.

In the press, a billet heated to roughly 450 – 500 °C is forced through the aperture. The metal leaves the die as a continuous angle, is cooled on the run-out table, stretched by a small percentage to straighten it and relieve stress, cut into lengths and aged to temper (T5 or T6). The die itself is supported by a backer and bolster, and is usually made from H13 hot-work tool steel that is hardened and often nitrided to resist wear.

The critical feature inside the die is the bearing: the short land around the aperture that controls the speed of the metal. Thick sections flow faster than thin ones, so the die maker uses longer bearings where the angle is thick (the corner) and shorter bearings at the thin toes. When these are balanced correctly, both legs come out straight, flat and at a true 90°. Poorly balanced dies give twisted angles, wavy toes or an angle that is open or closed beyond tolerance.

Standard equal angle die sizes (A = B)

The sizes below are commonly tooled metric equal angles. Weights are calculated from the nominal section (2A − t) × t at 2.70 g/cm³ and ignore the small root fillet; use them for estimates.

Inch-based equal angles (for example 1 × 1 × 1/8 in, 2 × 2 × 1/4 in or 4 × 4 × 3/8 in) also have widely available tooling, both as structural angle with root radius and as sharp-corner architectural angle. See the aluminium angle bar guide for inch sizes and weights.

Standard unequal angle die sizes (A ≠ B)

Unequal angles with very long, thin legs, such as 100 × 20 × 1.8 mm or 150 × 50 × 8 mm, also exist as standard tooling in many markets, usually with small root radii. They are useful as edge trims and panel seats where one leg is hidden and the other forms a visible return.

Round-corner, lipped and irregular angle dies

Design rules for a new angle die

Angles are among the easiest shapes to extrude, but a few limits decide whether a profile is practical and economical:

These are general industry guidelines. The extruder's die designer confirms final limits for each alloy, press and profile.

Alloy matters too. 6060 and 6063 flow easily and suit thin, sharp, decorative angles. 6061 and 6082 are stiffer to push, so they need slightly thicker walls and generous radii. 7075 and 2024 angles are extruded at much lower speeds, which is why they cost more and why fewer die sizes exist for them.

Tolerances for extruded angles

Under these standards the allowed deviation grows with the size of the section and its CCD. For buyers, the points that cause most problems are the included angle (squareness), twist over the length, and straightness of the toes. If an angle will be used as a precision stop, a datum or a visible trim, call out tighter tolerances on the drawing, and ask for the inspection method to be agreed before production.

When to order a custom angle die, and how it works

A new die is justified when a standard size does not meet the function, when a lip, groove or radius saves later machining, or when the annual volume is large enough that a lighter, optimised section saves more in metal than the die costs. Extrusion dies are relatively low-cost tooling compared with casting or stamping tools, so even modest volumes can justify them.

1. Drawing reviewSend a dimensioned drawing (DWG, DXF or PDF), alloy, temper, finish and expected volume. The die designer checks wall, radii and CCD.
2. Design adjustmentSmall changes are suggested if needed, such as adding radii or evening out thicknesses, to improve yield and straightness.
3. Die manufactureThe die is machined from H13 steel, heat-treated and finished with wire EDM for the bearing surfaces.
4. Trial and sampleA first extrusion run produces samples that are measured against the drawing and approved by the buyer.
5. ProductionOnce approved, the same die is reused for future orders. Dies wear over time and are refurbished or replaced as part of normal tooling maintenance.

How to order angle from standard or custom dies

• Profile size A × B × t, root and toe radii, and included angle (or a drawing)
• Alloy and temper, for example EN AW-6063-T5, 6061-T6 or 6082-T6, and the standard (EN 755, ASTM B221 or B308)
• Length: mill length or cut length, and tolerance on length
• Finish: mill, anodised, powder coated or brushed, and which faces are visible
• Quantity, packing (interleaved, filmed, bundled or crated) and delivery terms (EXW, FOB, CIF or DAP)
• Documents: mill test certificate to EN 10204 3.1, dimensional report or first-article report if required

Metline supplies standard and custom angle extrusions in all common alloys to fabricators and project buyers worldwide, with cutting and finishing on request.

Related die catalogues and profiles

Aluminium angle extrusion dies: frequently asked questions