Bending aluminum tubing can be a challenge. For example, the grade 6061-T6 tubing in the picture below measures 6 x 6 x 1/4″ and is rolled to a 95″ inside radius with 15 feet of good arc as measured on the outside of the tube. The tubes were rolled and then saw cut. (You can see the shavings from saw cutting on the floor and just inside the tubes.)
There are several challenges involved in bending such a tube to such a radius. First of all, the tube must be internally supported so that it does not crush. Then care must be taken not to have the inside wall go concave as it sometimes does. The right tooling must be used to avoid distortion including, for example, tooling that will match the sharp, square corners of the raw material.
And 6 x 6 x 1/4″ has a rather thin wall for a rather large tube. Lastly, rolling aluminum often scratches the surface of the material. A certain amount of scrubbing is necessary to maintain the cross-section of the tube while bending it to the desired radius. The challenge is how to keep the scratching to a minimum. Fortunately, the tubes in the picture above were curved with absolutely minimal distortion, scrubbing and scratching.
Depending on the application, all the above concerns may or may not apply. The curved aluminum tubes may be hidden from view and function just fine without great attention to minor imperfections. On the other hand, they may be exposed as an architectural feature that calls for great care.
Along with a number of 3 x 3 x 1/3″ aluminum tubes, the 6 x 6 x 1/4″ tubes will form a 3600lb frame for a canopy in front of a government building. Surprisingly, the tubes will be painted even though they are made of aluminum.