Rapid Custom Torsion Spring Manufacturing

Torsion springs apply torque, or rotational force, instead of a linear push or pull. When components need to return to a fixed angular position, a torsion spring is usually the right call. We manufacture custom torsion springs in short runs and prototype quantities with fast turnaround, working directly with engineers to get the design right and deliver on time.

What Is a Torsion Spring?

A torsion spring is a helically wound spring with two legs, or arms, extending from the body of the coil. When you rotate one leg relative to the other, the spring winds tighter or unwinds, depending on the direction of load, storing energy and pushing back with a restoring torque.

Torsion springs are specified by angular deflection and torque rather than linear force and displacement. They're wound in either a right-hand or left-hand direction, and the load needs to be applied in the same direction as the wind for the spring to work correctly. One thing to keep in mind: the inside diameter gets smaller as the spring winds tighter under load, which matters for shaft fit.

Leg and End Configurations

The legs of a torsion spring are critical to how it mounts and functions in an assembly. We manufacture torsion springs with a wide range of leg configurations:

•       Straight legs (tangent or axial)

•       Angled legs, at any specified angle relative to the coil body

•       Hooked or looped legs for pin or post attachment

•       Custom leg lengths to match your assembly geometry

The angle between the two legs at free position, called the body angle, is a key spec. It determines the preload condition of the spring once it's in the assembly.

Wind Direction and Assembly Considerations

Torsion springs are made in either right-hand (clockwise) or left-hand (counterclockwise) wind. Which one you need depends on how the spring will be loaded. Winding the spring tighter under load is standard for most applications and gives you a more stable stress distribution than unwinding under load.

Because the inside diameter shrinks as the spring deflects, shaft clearance needs to account for that change. Our engineers check ID reduction during design review to make sure the spring won't bind on its shaft at maximum deflection.

Applications

•       Door and lid hinges, used as return mechanisms for panels, lids, and enclosures

•       Counterbalance mechanisms, providing controlled restoring torque against gravity or other forces

•       Valve controls, in spring-returned valve actuators for fluid and pneumatic systems

•       Automotive, including seat adjusters, latching mechanisms, and pedal return springs

•       Medical devices, including surgical clamps, instrument handles, and injection pen mechanisms

•       Consumer products, including clothespins, clipboards, and folding furniture mechanisms

•       Electronics, including keyboard mechanisms, USB port covers, and battery contacts

Torsion Spring Design Parameters

To spec out a custom torsion spring, here's what we'll need:

•       Wire diameter

•       Outside diameter (keep in mind that ID under load will be smaller than free-position ID)

•       Leg length and orientation for both legs

•       Body angle, the angle between legs in the free, unloaded position

•       Spring rate, expressed in torque per degree or torque per radian (in·lb/deg or N·mm/deg)

•       Required torque at a specified angular deflection

•       Wind direction: right-hand or left-hand

•       Material

•       Number of coils

Frequently Asked Questions: Custom Torsion Springs

Q: What is a torsion spring and how does it work?
A: A torsion spring is a helically wound spring that applies rotational force, or torque, instead of a linear push or pull. It has two legs extending from the coil body. When one leg is deflected angularly relative to the other, the spring stores energy and pushes back with a restoring torque, returning to its original position once released. Garage door springs, mousetraps, and door hinges are all common examples. 

Q: What is the difference between right-hand and left-hand wound torsion springs?
A: Wind direction describes which way the coils spiral. Right-hand wound springs coil clockwise when you view them from one end, and left-hand wound springs coil counterclockwise. The correct wind direction depends on which way the spring will be loaded in the assembly. Generally, you want the spring to wind tighter, not unwind, under load for the best stress distribution and stability.

Q: Why does the inside diameter of a torsion spring change under load?
A: As a torsion spring winds tighter under load, the coils compress inward and the inside diameter shrinks. That's just how torsion spring geometry works. If the spring mounts on a shaft, the shaft needs to be small enough to allow for that ID reduction at maximum deflection without the spring binding.

Q: Can Quick Spring manufacture double-torsion springs?
A: Yes. We make both single-body and double-body (tandem) torsion springs. Double torsion springs have two coil bodies wound in opposite directions, and they're used where you need balanced torque or the spring has to be centered on a shaft. Reach out to our engineering team to talk through your application.

Q: What is the minimum order quantity for custom torsion springs?
A: There isn't one. Prototype and short-run torsion spring manufacturing, anywhere from a single piece to large quantity delivery are available.

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