Torque, in the simplest terms, is the measurement of rotational force. Unlike compression or extension springs, which are subject to compressive forces like squeezing, torsion springs are subject to rotational force (twisting) rather than linear force (pulling or pushing).
Torsion springs are made from a variety of steel materials, including stainless steel, hard drawn steel, steel music wire and spring steel. Spring steel is a special kind of steel with increased elasticity and return properties. The elasticity of a torsion spring enables it to return to its original position; however, this capability diminishes with use.
Torsion springs come in a wide variety of sizes and are used in an array of applications. Garage doors are an example of a mechanism that uses larger torsion springs. Smaller torsion springs are used in an assortment of products, including hinges, CD players, clothes pins and digital cameras. Mouse traps are commonly equipped with very tightly wound torsion springs. Torsion springs can range in terms of torque generation from relatively weak to very forceful.
Torsion spring manufacturers can create torsion springs to varying specifications of load, wind, deflection, spring rate and other properties. Torsion springs, like other spring varieties, can be designed with several different kinds of finishes. Such finishes include black oxide, passivate, gold irridite, zinc and many other examples.
Torsion springs can also be sold without finishes. Often, because many torsion springs are made of stainless steel or other corrosion resistant metals, a finish may not be necessary. However, especially in the case of torsion springs that will be exposed to harsh weather conditions or other situations in which they may come into regular contact with moisture, a finish may still be desirable.
Failure of a torsion spring caused by corrosion or other gradually destructive forces can be unexpected. Because torsion springs are often applied in circumstances in which they are used to store large amounts of force, their sudden, unexpected failure can cause damage to nearby objects or injury to people. For this reason, it is important to carefully pair torsion spring composition with its application.