Most Common Types of Springs
A spring is a common mechanical element that can elastically absorb applied loads by deflecting, either via extension, compression, or torsion. Once the load is removed, the spring will return to its original position (provided the load was within the spring material’s elastic limit). Materials with high yield strengths are often used for springs to account for high loads. Springs are among the most common solutions for devices that must absorb energy, store energy for later use, or measure an applied force.
There are three main types of spring, categorized based on their function. Springs can create opposing tension, compression, and torsional forces to achieve specific mechanical goals. Springs are typically made by coiling wire into helical patterns. The coil pitch, the number of coils, and the wire thickness will determine the spring’s properties. Springs are designed to resist with a specific force when compressed or tensioned a certain distance. In the case of torsional springs, this resistance force is instead measured against a given rotational angle. The force exerted by a spring can be determined using the spring constant and the distance of deflection. In addition to the three main spring categories, a spring can also be designed with different force characteristics.
- Linear Rate Spring: This is the most common type of spring. When a load is applied, it produces an opposing force with a constant rate of change.
- Variable Rate Spring: These types of springs produce a variable opposing force when compressed or extended. There are generally two types. A progressive-rate spring provides a smooth change in force whereas a dual-rate spring will exhibit one rate then abruptly change to another rate after a certain amount of deflection.
- Constant Force Spring: These types of springs will produce the same force regardless of how far they are compressed or extended. They typically have a conical helical shape.
This type of spring is designed to provide an opposing force when compressed. They’re found in everything from automotive shock absorbers to retractable pens. A compression spring has a simple maximum compression length defined as the point when the coils touch each other. The ends of compression springs are often ground flat to ensure the force is applied axially along the spring.
Helical Compression Springs
These types of springs provide an opposing force when extended. An example of this would be the springs in a trampoline. An extension spring does not have a maximum extension length because it can be extended far past its elastic limit, causing permanent failure. This can be mitigated by making use of a drawbar spring wherein the extension is limited by an insert. In this case, the spring itself is a compression spring but the whole assembly extends in length the way an extension spring would. As the drawbar is extended the spring will compress (refer to the image below). Extension springs are often manufactured with either hooks or loops at the ends to act as attachment points.
Helical Extension Springs
This type of spring has a coiled circular shape that creates opposing forces either radially towards its center or radially outwards. These are respectively called compression and extension garter springs. They work similar to elastic bands but provide significantly more force. These springs are used to maintain seal pressure on shafts.
A volute compression spring is a flat rectangular plate that has been coiled in a volute shape. These types of springs can provide significantly more compressive force compared to other spring types of the same size. This makes them ideal for applications where high compressive forces are needed but space is limited. They also have excellent fatigue life.
Volute Compression Spring
A flat spring is a type of compression spring that provides a counteracting force when compressed. Their method of construction means a flat spring can be custom-shaped to fit into various devices. Another type of flat spring is the linear wave spring which is simply a long flat plate with a wave-shaped profile. These types of springs are designed to provide constant pressure along the length of an object, typically between two mating components.
This type of spring provides an opposing force when twisted about its axis. Common examples can be found in clothespins and claw-style hair clips. Like a compression spring, a torsion spring only has a limited range of motion, often in the neighborhood of 360 degrees. Torsion springs are often supplied with their ends either unmodified or specially bent to suit their application.
A disc spring is a type of compression spring that is shaped like a washer but is either formed in a wave pattern (also known as a wave disc spring), or beveled towards the center (known as a Belleville spring). These types of springs are mostly used with fastening elements like a bolt. The added tensile force on the bolt limits the effects of vibration and makes it far less likely to loosen over time. As the bolt is tightened the spring is compressed, thus generating the necessary opposing force.
When a gas is compressed it behaves much like a spring would. This makes gas cylinder effective stand-ins for solid-state springs. They are typically filled with inert gasses. These types of springs are used in the automotive industry on things like the lids of car trunks. Compressed gas can store far more energy per unit volume than a normal compression spring which makes these types of springs ideal for lifting heavy objects. In addition to this, their total compressive force can be adjusted by adding or venting out gas. However, a good seal is critical to maintaining the spring’s capability.
A leaf spring is a type of compression spring used in trucks and trailers. It is made by stacking several flat springs of similar curvature on top of each other. It is installed with the curved end facing downwards so that the reaction load pushes up onto the spring. These types of springs are best used for heavy-duty applications.
When deciding on the type of spring to use, the direction of applied force, the loads involved, the corrosive environment, and potential space limitations must be characterized. Other factors may include the required force profile. To learn how to use these properties to select the ideal spring for your application, contact a Xometry expert today or if you have custom parts you need made, get an instant quote today.