A straightening machine is a device used to straighten metal profiles, bars, tubes, and wires. The straightening machine uses straightening rollers to compress the material, altering its straightness. Generally, there are two rows of straightening rollers, with varying numbers of rollers. There are also two-roller straightening machines, which rely on the angle change of two rollers (with a concave, hyperbolic shape) to straighten materials of different diameters.