There are many unique spring designs manufactured for various applications, and one of the most recognisable is the torsion spring.

What Are Torsion Springs?

Torsion springs are helical, or spiral springs optimised to maintain an impressive rotational pressure between attached surfaces. Unlike the more well-known compression springs, which work linear, torsion springs work rotationally. 

They are manufactured as coiled wire with two extended ends that will be attached to the desired application. As the spring is manipulated, the two ends are rotated, which applies a bending stress and a resistance; this built energy is stored in the spring until the exploited force is removed and the spring returns to its original resting position.

Torsion springs generally have a much closer wound coil than other spring designs like compression springs. Additionally, some torsion designs will implement a slight pitch to reduce the friction between the adjacent coils and preserve their physical integrity longer. But how does the spring achieve this? Thanks to an integral part of spring physics, Hooke’s Law.

How Does Hooke’s Law Apply to Torsion Springs?

Hooke’s Law is vital for creating the calculations required for designing springs. Hooke’s Law states that the force exerted by a spring is proportional to its displacement from its rest position. Mathematically, it can be expressed as the following:

 To elaborate, (F) is the force applied to the spring, (x) is the displacement or extension of the spring from its rest position, and (k) is the spring constant, which is a measure of the rate of the spring.

In other words, Hooke’s Law says that a spring will return to its original shape if the force acting on it is removed. The more rigid a spring is, the higher its spring constant will be, and the more pressure will be required to displace it a certain distance.

Hooke’s Law similarly applies to torsion springs; the force exerted by a torsion spring is proportional to the angle of twist from its rest position, which is the angle between the arms of the spring when it is not subjected to any external torque.

What Is the Torsion Coefficient?

Several other names are used for the coefficient, such as the torsion elastic modulus, spring rate or constant. This part of the equation dictates the amount of torque required to twist the torsion spring, a vital piece of data required for the torsion spring design to meet desired specifications.

A coefficient relates to the advanced mathematics used to design torsion springs. A coefficient is a number used to multiply a specific variable. For example, 5n (5 times n) broken down has “n” as a variable and 5 as the coefficient. It is typically measured in Newton meters per degree (Nm/degree) or Pound-inches per degree (lb-in/degree).

A torsion springs coefficient determines the spring’s load-bearing capabilities and reveals how it will perform under different conditions or with varying loads. For example, below is Hooke’s Law for torsion springs:

(T) is the torque exerted on the spring in Nm, and the ( is the angle of the torsional twist from its original equilibrium. The (k) is the coefficient with units in Nm/degrees.  As previously mentioned, torsion springs will store energy when used to return to their original resting position. This energy is measured in Joules (U) and applies in the following related equation.

Hooke’s Law is a fundamental principle in physics and engineering and is widely used in various applications, including by spring manufacturers, when creating torsion springs.

Where Are Torsion Springs Used?

Torsion springs can be found in many different domestic, commercial and industrial applications due to the versatility of their role. However, one of the most common places a person will find a torsion spring is an office clipboard or a door hinge.

The agricultural and construction sectors benefit from this spring design, especially when the correct treatments and finishes are applied to enhance protection against the containments and the weather. Large torsion springs are used in tractors, ploughs and fertiliser sprayers. They are also essential for most heavy plant machinery used in construction, such as excavators and tippers.

The marine and automotive sectors will use chrome silicone torsion springs for an increasingly smooth movement between the coils without losing the required torsional resistance.

The medical sector relies on a constantly growing collection of essential medical equipment to help people, and most of these tools and machines need high-quality springs to ensure their reliable function. Small torsion springs are often used for their required capabilities within small areas such as dental equipment or prosthetics. Larger torsion springs made from carbon steel are also used in more obvious applications such as hospital beds and gurneys.

UK Torsion Spring Manufacturer

At Airedale Springs, we specialise as a custom small spring manufacturer and wire forming supplier for industrial or commercial applications. We stock standard and double torsion springs, and our expert team of engineers will design and manufacture custom torsion springs to suit the specific specifications required for your application. Contact us if you have any questions about our high-end torsion spring manufacturing processes.