Torsion springs are produced from rectangular or round wire. It is more typical for a manufacturer to use round wire because of the premium cost of rectangular wire. Additionally, torsion springs are normally heat-treated at a low temperature to stabilize the end positions. These types of springs are used to apply a torque or store rotational energy and can also be referred to as helical springs.
Torsion springs can be found in many day-to-day applications, such as clothespins, ratchets, window shades and other types of machine components.