A spring is an elastic object used to store mechanical energy
. Springs are usually made out of hardened steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication. Some non-ferrous metals are also used including phosphor bronze and titanium for parts requiring corrosion resistance and beryllium copper for springs carrying electrical current (because of its low electrical resistance).
The rate of a spring is the change in the force it exerts, divided by the change in deflection of the spring. That is, it is the gradient of the force versus deflection curve.
Depending on the design and required operating environment, any material can be used to construct a spring, so long the material has the required combination of rigidity and elasticity: technically, a wooden bow is a form of spring.
The name compression springs it self suggest that it is a spring that can be compressed. But when dealt in details it refers to a spring which is designed in such a way, that whenever any form of compressive load is applied on the these springs, the springs gets reduced in its size.
Basically there are many types of compression springs available in the market. Some of its types include the following:
Conical Springs: These compression springs are generally in the shape of a cone and are thus called conical springs. These springs are used to fit in designs where the helical or coil spring does not fit.
Barrel Springs: compression springs as the name suggests are in the shape of a barrel.
Hour Glass Springs: springs have a diameter that is wider than the centre.