Square Tube Straightening: A Shangda Specialty
Square tube is not round tube with corners. When you straighten a rectangular or square section, the same force that removes bow can push the side walls into a belly or collapse the corner radius. Most straightening suppliers avoid this profile because it requires different support dies, a different ram path, and more measurement points. Shangda runs square tube straightening as a core application, not an afterthought. We set the support rollers to contact the tube at the neutral axis points, measure straightness in two planes simultaneously, and adjust ram pressure so the section's flat sides stay flat while the bend comes out. The result: square and rectangular tube leaves the cell with straightness under 0.2 mm per meter and corners that still pass weld-prep and assembly checks. If your current supplier only quotes round tube, that is usually because square tube demands a machine designed from the start to handle profile shapes.