Basic parameters of compression springs

  • Wire material:

Most used material in the manufacturing of compression springs is spring steel 10270-1, but is some cases is used also stainless steel wire 1.4310 (it can be used in applications up to 2000C) or other steels for specific applications.

  • Wire diameter:

It determines the force of the spring- small wire diameter means low spring force. If you have small wire diameter, big outer diameter of the spring and many working coils, then the spring will be with very small force characteristic. Big wire diameter with small pouter diameter and small number of coils means very hard spring and small spring travel.

  • Travel of the spring: 

You must choose compression springs with small compression travel, because this will increase the working life of your spring. Usually the short springs must be used in their maximum travel and this decrease the service life of the spring. But if use long spring that will have small travel, then it will serve much more. If you increase the length of the spring then the total force will be the same, but the spring constant will decrease.

  • Number of coils:

If you increase the number of coils, the spring will decrease it force. Also small number of coils mean small path of the spring. If you have big distance between 2 coils, then the spring will have bigger force, and if the distance between 2 coils is small, then the travel of the spring will be small (because coils will touch each other).

  • End coils of the spring:

They can be open, close and close and ground.

  • Winding direction:

Left or right. Usually the spring are right winded. The winding direction is not important for the work of a single compression springs. But if you have two spring working one inserted in another, then they must be with different winding direction (to protect the wires to enters in the free space between the coils of the other spring.)

  • Pitch of the spring:

This is the distance between the centers of two coils. The easiest way to measure this distance is to measure the distance between two coils and then add a wire diameter. It is recommended the maximum pitch to be 0.7x inner diameter of the spring. The pitch is in relation with the force of the spring. Small number of coils are used for big force spring, but with small travel. If the pitch is too big and the spring is compressed too much, then the spring could not return its initial free length. 

  • Spring index :

This is the relation between mean diameter of the spring and wire diameter- D/d. Usually the index of a spring must be between 5-12. it is possible to manufacture springs out of this index, but it can be needed additional consultation.