Typically, a spring is a metal loop or spiral that can be stretched and then returned to its original shape by applying and then releasing force. What this means is that a spring possesses elastic properties. Elasticity means that it lengthens when pressure is applied to it, but as long as the pressure isn't sustained for an excessively long time, it can go back to its original length when the pressure is withdrawn.
If you apply pressure to a spring, it will shorten, but it will go back to its original length once the force applying the compression is gone. The direction in which a spring works depends on how it was manufactured.
You can make a spring from almost any material, including paper. Still, the ones we use in machines must be rigid enough to sustain a pulling force and sturdy enough to be pulled repeatedly without breaking.
Materials like stainless steel or bronze, a tough alloy, are typically required for such applications. Some alloys possess a quality known as shape memory, indicating that they have a natural springiness. Nitinol, a shape-memory alloy combining nickel and titanium, is commonly used to make eyeglass frames.
When it comes to absorbing or storing energy, springs are second to none. In physics, work and energy are expended whenever a force is applied across a distance, such as when stretching a spring by pushing or pulling. More effort, time, and power are required to deform a spring of greater tension. The energy you expend is not wasted; instead, it is mainly converted to potential energy within the spring.
You must let go of the tension to put a stretched spring into action. Simply said, winding a mechanical watch or clock involves tightening a spring to store energy. The clock's inner workings are powered by the spring's gradual loosening, which can take a day or more. Both slingshots and crossbows function in a very similar fashion, with the exception that the bow and catapult use twisted sections of elastic for their springs rather than metal coils and spirals.
Coil springs can be divided into compression, extension, and torsion. All of them are useful in their ways and can be helpful in various contexts.
Mechanical compression springs are coil springs that are compressed to store energy and then expand to release that energy. When subjected to a load, these springs contract to accommodate the load. When the tension is released, the spring recovers its original length, and its accumulated kinetic energy is released.
The pitch in a compression spring allows it to achieve this. In a spring, the "pitch" is the spacing between adjacent coils. When coiled, the spring stores mechanical energy as its pitch decreases and gradually returns to its former size upon release.
Torsion springs transfer mechanical energy by twisting, as opposed to compression springs, that contract while storing energy. Take a door handle, for example. Applying force and twisting the handle results in minor resistance. The kinetic energy is stored in the revolving handle through a torsion spring. After being released, the handle returns to its original position as specified by the torsion spring.
Garage doors typically have torsion springs because they are reliable and easy to install. The counterbalance mechanism of a garage door would only be complete with the torsion springs. The hinges not only offer the necessary resistance to keep the door open or closed when you want it to be, but they also make the door simpler to move when the force is applied.
Coil springs used in mechanical extensions are tightly twisted with no space in between the coils. When tension is applied to an extension spring, the coils unwind, allowing the spring to grow longer. The coil's resistance to this force acts as a mechanical energy storage mechanism. When the tension is released, the spring returns to its original shape, with no space between the coils.
An extension spring is a great option if you need to move something back to its initial position after applying pressure to the spring. This is why extension springs are frequently found in garage door operating mechanisms. They assist the garage door along the pulley system by applying tension to the door.