Aluminium Company Profile: How a 90 x 90 mm Section Is Made and Inspected

01What are the seven operations between billet and bundle?

Every aluminium extrusion goes through the same sequence, and the sequence is the reason a lead time can be quoted honestly rather than guessed. For a 90 x 90 mm eight slot section the steps are: billet homogenisation, billet preheat, extrusion with online quench, tension stretching, cut to length, artificial ageing, and then either packing as mill finish or anodising before packing.

Two of those seven are commonly skipped in conversation and never in production: homogenisation and tension stretching. Both exist to remove internal stress, and both are the reason a long length arrives straight rather than bowing after machining.

02What can go wrong at each step, and how is it detected?

The useful way to read a quality system is not the certificate, it is the list of defects it can catch and the instrument used for each. Below is the list for this section, with the detection method that actually works.

03Why are T5 and T6 different, and what does the 200 C hold actually do?

Both are artificial ageing treatments applied after quenching; the difference is how much the material is allowed to deform between quenching and ageing. T5 is cooled from the press and aged without any further cold work. T6 is solution treated, quenched and then aged, and can involve controlled stretching before ageing. For an extruded architectural section, T5 is the normal temper because the section is quenched at the die and stretched, and there is no separate solution treatment furnace.

The ageing hold does one thing: it precipitates magnesium silicide out of a supersaturated solid solution. The 200 C for roughly two hours is the window where those precipitates reach a size that blocks dislocation movement without coarsening. Under-age and the material is soft; over-age and the precipitates coarsen and the strength falls again. There is no visual difference between the three states.

• Ask for the furnace chart, not just the hardness result. A chart shows the actual ramp and hold, which is what an auditor wants to see.
• Hardness should be read on the same lot that is shipped, not on a sister lot from the same week.
• If the part is to be welded, say so at enquiry. Welding 6063-T5 drops the strength in the heat affected zone by 40 to 50 percent, and no ageing treatment restores it without a full solution treatment.

04What does the anodising line add, and what can it ruin?

Anodising adds corrosion resistance, abrasion resistance and colour, and it is also where a good extrusion can be turned into a rejected one. The line sequence is degrease, etch, desmut, anodise, colour if required, seal. Each step has one characteristic failure mode that shows up on the finished face.

The line length is the real constraint on batch size, not the press. A 90 x 90 section at 7.60 kg/m has a large surface per metre, so a rack holds fewer metres than it would of a 40 x 40. That is why anodised quantities are quoted in rack loads and why the price steps sit where they do.

05How is the lead time actually built up?

Four stages, each with a floor. Quoting a single number hides which stage is the constraint, which is why delivery arguments usually start at the end of the chain.

So a mill finish order with an existing die is roughly 12 to 20 days to load, and an anodised order with a new die is roughly 30 to 40. Neither number is a promise; both are the sum of four floors that we will quote separately if you ask.

06What should a factory audit actually look at?

Not the size of the building. Four things tell you more than a tour of the floor, and all four are documents rather than equipment.

07What five numbers should be on the enquiry?

The section, the length, the finish, the quantity and the end use. The end use is the one that changes the advice, because a 90 x 90 used as a machine base needs a different conversation from one used as a guard post.

Section and temper

90 x 90 mm eight slot, 6063-T5, 7.60 kg/m, or the 9.00 kg/m heavy wall

Total length and cut list

how the metres split, because the saw and the cradle follow the cut list

Finish

mill, AA15, AA20 or AA25, and whether the visible face is the 90 mm face or the slot face

Quantity and repeat

one order or a schedule, because a schedule changes the die and press planning

End use

machine base, robot pedestal, gantry column or guard, which sets the tolerance conversation

Anything welded

stated at enquiry, because welding changes the strength assumption

Related sections and categories

The 90 x 90 sits in the 45 Series Aluminium Profiles family at a 45 mm slot pitch, alongside the 90 x 90 mm heavy wall version at 9.00 kg/m. Heavier sections in the same system are listed under aluminium sections.