Aluminium Angle Profile 35x35x4 mm 6061 T6 Extruded Equal Angle

Where the 35 mm module comes from

Window, door and facade ranges are not designed section by section; they are designed as a module, and the module sets the leg width of everything inside it. A 35 mm leg turns up again and again in European ranges because it leaves room for a glazing rebate, a gasket groove and a screw line inside a typical sash depth without making the frame look heavy. Once a system is built that way, every accessory in it — the pressure plate, the corner cleat, the threshold, the closing strip — is dimensioned to sit against a 35 mm leg.

That is what makes this angle a system part rather than a generic one. It is used three ways in practice, and all three depend on the leg width matching rather than on the strength of the section. It is a different animal from the general-purpose aluminium angle profiles bought by the metre, and it belongs with the window and door elements that surround it.

Why 35 is not a stock size in China

An extruder runs a die when there is enough tonnage to make the run worth setting up. The dies that stay in the press are the ones that sell by the tonne every month: 20 x 20, 25 x 25, 30 x 30, 40 x 40, 50 x 50. A 35 x 35 x 4 angle sits in a gap. It is too big to be a light trim section and too small to be a structural default, so no mill keeps it hot. When a customer asks for it, it is made the way any non-standard section is made — as a die run.

A die run is not expensive in itself; it is expensive in small quantity. The die is a one-off cost, the press has a minimum billet, and the finishing line has a minimum batch for anodising. Spread over a tonne the die cost is a few cents a metre; spread over fifty metres it dominates the price. That is the whole economics of this size, and it is why the same section can look cheap or absurd depending on the order.

Ordering the original size, or substituting 30 or 40

Substituting a nearby size looks like a saving and is usually a hidden cost. The problems do not appear at the bench; they appear at the joint, and they appear one at a time, which makes them expensive to chase.

Work through the list before deciding. If more than one of these applies, the substitution will cost more than the die run.

• Screw centres: an existing hole pattern is set by the original leg. A 30 mm leg moves the screw line 5 mm inboard, which either misses the substrate or puts the screw into a chamber with nothing behind it.
• Gasket and glazing grooves: where the angle backs a gasket or a glazing bead, the leg depth sets the compression, and a gasket that is under- or over-compressed leaks.
• Fit in a chamber: a 40 mm leg will not enter a 35 mm chamber, and a 30 mm leg rattles, which leaves the hardware screws as the only thing locating it. Forcing a 40 into a 35 opening pre-loads the assembly, so the frame distorts and the glazing cracks at the first thermal cycle.
• Visible joint lines and certification: a substituted width shows as a step at every junction, and where the system carries a test certificate, changing a member size invalidates it.

Specifying a 35 x 35 x 4 order

1. Send the original section drawing if you have it The leg width alone is not enough. We need the internal radius, the leg thickness and any asymmetry, because a 35 x 35 that is R3 and 4 mm thick is not the same section as a 35 x 35 that is R5 and 3 mm thick. A trace of the old section on paper is enough to start.
2. State the alloy and the temper 6061-T6 for a reinforcing member or anything drilled as a bracket; 6063-T5 where the angle is visible and has to anodise cleanly. The two are not interchangeable on a visible facade detail.
3. Give the cut list, not a total length We cut to plus or minus 0.5 mm and deburr. On a repair job the cut list matters more than the tonnage, because the pieces are the deliverable. Say also which faces are seen, because a die line is invisible on a hidden reinforcement and obvious on a visible trim.
4. Fix the finish before the die run Anodising is a batch process. If the order is part anodised and part mill, split the quantities at the enquiry stage, because a small anodising batch added later costs far more than one included in the run. Colour-matched and brushed finishes are handled as anodised aluminium profiles, and any mitring, notching or drilling is done on CNC machining centres before the finish is applied.

6061-T6 or 6063-T5 on this section

The same die can be run in either alloy and the choice is decided by what the angle does. 6061-T6 has a yield strength of roughly 240 MPa against roughly 110 to 150 MPa for 6063-T5, so as a reinforcement inside a window profile or as a drilled bracket it is the correct alloy and it holds a thread and a bearing load noticeably better. Where the angle is a structural member of the assembly, specify 6061-T6.

6063-T5 is the alloy for anything seen. It extrudes with a cleaner surface, anodises to a brighter and more consistent colour with less risk of streaking, and takes a tight bend without tearing where 6061-T6 will crack. On a facade trim or a visible guard edge the appearance usually outranks the strength, so 6063-T5 is the right answer even though it is the weaker alloy.

Frequently asked questions