Torsion Springs

Torsion Springs

Torsion Springs

Helical Torsion springs, commonly referred to as “Torsion Springs” are used to provide torque or stored rotational energy. The two most common types are single body and double bodied springs, these springs are typically mounted around a shaft/arbor and are supported at three or more points. Torsion springs are designed to be torque-loaded in the direction that decreases/reduces the body diameter because the residual forming stress are favorable in this direction and unfavorable when the spring is torque-loaded in the direction that increases the body diameter.  It is important to know how much rotation will be applied to these springs, as well as the diameter of the shaft that this will work over, to make sure that there is enough clearance so that there is no binding onto the shaft when torque/rotation is applied. The ends are formed and designed to facilitate mounting on the specific application. The direction of wind (right or left hand) will be specific to the application and will almost always be specified by the designer of the spring on the drawing. Torsion springs with legs that can be either straight or formed – and are away from the body of the spring – are designed understanding what those lengths are and how that equates to the moment arm (‘s) for achieving the desired torque values in the loaded angular positions. Rectangular shaped wire is best for these spring designs, but round wire is preferred for cost effectiveness.

Torsion springs can be made from many different wire types:

  • stainless steel
  • carbon
  • high-temperature nickel alloy
  • copper
  • many others

Sizes and shapes include:

  • round
  • square
  • rectangular
  • shaped

Designing a spring for manufacturability can at times be a challenge.  Consulting with knowledgeable spring manufacturers and their engineering departments can minimize these hurdles and result in a cost effective solution.

Customer Case Study – Torsion Springs

Problem: 

A customer had generated a torsion spring design utilizing Music Wire because it provides high tensile properties which this application required.  Unfortunately, due to the highly corrosive environment that this spring was used in, even a plated Music Wire spring did not survive long enough and eventually failed due to corrosion.  When the customer tried to re-design the spring using stainless steel wire they chose 302 stainless steel (the most common type of stainless steel spring wire), but the tensile properties of 302 are not as high as the Music Wire tensile.  Thus, the part failed to provide the required torques without creating an overstressed condition that would reduce the life cycle of the spring in this application.

Orlando Spring’s Solution: 

To solve this problem the customer and Orlando Spring worked together to develop a cost effective torsion spring design utilizing 17-7 PH stainless steel wire and, although the 17-7 wire does not match the tensile strength of Music Wire, it has a higher tensile strength than 302 stainless steel.  This quick solution, based on a combination of torsion spring industry experience and engineering wherewithal, was all that was needed to meet the torque requirements without an overstressed condition – while also providing the necessary corrosion resistance.

For your next torsion spring project please reach us on our Contact Us page or call us at (562) 594-8411.