I don't know how this is made and I don't know the name of the method to search for it to learn more.
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Aluminum sections are extruded from billets heated to 800-925F under high pressure and then pushed through a die.
During the entire process temperature is carefully controlled, because depending on the aluminum alloy and performance expected heat stages at the beginning and exit out of die are crucial.
here is the diagram of the extrusion machine.
If the extruder has a die in the exact shape you're wanting, it might be worth asking them. If you can get past the extruder's quote filter (our's is at hundreds of thousands of pounds per year), if they don't have a die for the part you're wanting, you'll be buying an extrusion die (think $3k - $6k). Do you want close tolerancing, that'll be extra. Depending on the cross-sectional area of the part, you could wind up with 1,000's of parts just from one billet, which you're paying for as well. With a solid shape, very little is wasted, except for maybe the charge-welds and an inch or two of the billet butt-discard (where the impurities, oxides, etc are, you don't want those). If you're planning on purchasing a lot of parts or parts that the extruder already does, you can get it done, but they aren't interrupting their schedule for a billet or two of a one-off. To explain the process the easiest, we always tell our customers to imagine a very large Play-Doh fun factory, except the Play-Doh is near 1,000f, and instead of your hand providing the horsepower, there's probably 4 huge hydraulic pumps supplying 5,000 tons of it.