Imagine a screen door being opened and then slamming shut as soon as you take your hand off and stop applying force to it.
When the door is closed, the loops in the spring are touching. When you push it open, these loops separate. The spring then tries to pull itself back together, which is why the door slams shut when you let go. When the force is gone, the tension spring will return to its original form.
When a tension spring is being manufactured, the force of the tension that it creates can be controlled using the cold coiled process. In this process, a wire is formed into a spring shape using a machine that is guided by a computerized controller. This cold process gives the spring added flexibility, which is much harder to create when a hot process is used to form the spring.
Flexibility is particularly important if the spring is fitted to an application where it needs to be compressed beyond the size of its original form. Having the flexibility to bend a little bit will prevent that spring from causing a malfunction.
To increase the force of a tension spring, manufacturers have to increase the wire diameter, decrease the outer diameter or increase the length of the spring’s body. End loops or hooks are shaped on either end of a tension spring so that it can be attached to the components that it will work in conjunction with.
If any of the coils in the tension spring are damaged, it will not be able to return to its original shape. Tension springs are used in many different applications such as doors, locks, industrial equipment, cars, and even as trampoline springs. Some residential and commercial garage doors are even installed with heavy duty tension springs to hold them securely in place when they are closed.