Prestressing

In our latest blog Mike Hales, our Production Manager, will look at the benefits of prestressing when manufacturing springs.
 
Prestressing can increase the load-carrying capability and the spring’s ability to withstand stress ultimately improving the fatigue life of a spring.
 
Dimensional changes will take place when a spring is prestressed during its manufacture. The process of prestressing a compression spring is relatively simple. The manufacturing process involves the spring being coiled, stress relieved and ground. After this process has taken place, the spring is placed on a press and compressed to a fixed or solid position which is greater than its maximum working position.
 
Repeating this process at least three times will result in the spring being shorter than the coiled spring, with the correct initial set-up it will be possible to achieve the required final length.
 
Tension and torsion springs can also utilise prestressing during the spring manufacturing process. When it comes to the manufacture of tension springs, the amount of initial tension is reduced and is therefore not often carried out.
 
In order to successfully prestress torsion springs, special jigs are required. The leg relationship will change (the number of coils slightly increases).
 
As prestressing is an additional operation in the manufacture of a spring, this will increase its unit cost. However, the benefits of prestressing during the manufacturing process will generally outweigh the additional cost.
 
Next month our Managing Director, Tim Page will look at the use of conical compression springs.