5 Design Considerations for Torsion Springs

Do you need a custom torsion spring for your assembly?

Torsion springs are an excellent choice for mechanisms that require rotational force or resistance (torque). With legs extending from both sides of the spring’s coils, the torque is transferred from the spring’s coils, through the legs, then to the component attached to the legs.

Depending on how it is designed, a torsion spring can store energy to trigger a reaction (as in a mouse trap) or resist/assist a rotational movement (as with a door hinge). 

Common Applications for Torsion Springs

Torsion springs are essential to the proper functioning of many everyday items, including:Torsion Springs

  • Clothespins
  • Hinges
  • Latches
  • Mouse traps
  • Rotating handles
  • Safety doors
  • Tailgates

5 Design Considerations for Torsion Springs 

As with all spring types, there are important factors to consider when designing torsion springs. Here is what you need to know to design the best torsion spring for your assembly: 

1. The force that powers a torsion spring is angular rather than linear

In contrast to other types of springs, which move two directions along an axis when a mechanism exerts force on them (e.g., compression springs), torsion springs rotate in a plane around a single point. As a result, this spring type is best suited for mechanisms with a rotational motion. 

2. It is difficult to measure torque load accurately

Amount of torque measured depends on where force is applied along the spring’s legs, and how the spring is fixtured for testing. Some energy will always be lost due to deflection of the legs under load, often leading to inconsistent torque measurement results. 

For this reason, we do not offer load testing for torsion springs at Gifford Spring Company. However, we do provide a calculated load based on the physical dimensions used to manufacture the spring. 

3. A torsion spring’s body diameter and length vary during use

When a torsion spring is rotated into a “closed” coil position, the diameter of the spring body decreases and the spring body elongates. Essentially, coils are being added to the spring without adding additional material.

When the coils rotate towards the “open” position, the coil diameter increases and the body length decreases as coils are “removed” from the spring.

To ensure optimal performance, the design for your torsion spring must account for the spring’s diameter and length in both open and closed positions. 

4. The direction of a torsion spring’s coils will affect how the spring functions in an assembly

While the coiling direction rarely matters for compression and extension springs, it is a critical consideration for torsion springs because it determines where the legs will sit in the assembly. 

5. For highly precise torsion springs to function properly, there must be space between the coils

When springs are wound too tightly, the coils may rub against one another, causing friction and adding tension to the coils. When wound too tightly, this can cause the spring rate and rotation to be inconsistent. If you need a highly precise spring, consider adding some amount of space between the coils.

At Gifford Spring Company, our master coilers manufacture custom torsion springs from 0.012” to 0.200” in wire diameter. If you have questions when designing springs for your assembly, we are always happy to share our expertise.

Request a quote today!