The spring wire is wound through a cold coiling process. It is pushed forward to coiling pins, which, in accordance with their settings and positions, define the spring's outer diameter. Meanwhile the pitch (distance between successive coils) is formed by the pitch wedge, a guiding mechanism. Finally, the wire is cut in the predefined length.
Coiling creates stress within the material. To relieve this stress and allow the steel to maintain its characteristic resilience, springs must be tempered by heat treatment. Depending on spring shape and material we use different ovens to achieve the best possible product quality.
When material is subjected to stress above its elastic limit, the spring can be deformed plastically without getting back to the initial length after being released. This leads to a decrease in strength. To permanently fix the desired length and pitch of the spring, it is compressed over a defined period of time. This helps to avoid loss of length and strength when the spring is exposed to stress above its elastic limit in later operation.
Depending on the intended purpose, we have different machines for cold and hot setting.
Compression spring ends must be on axis with adjacent parts to ensure optimum power transmission. Ground ends and closed coils as ends (i.e. reduced end coils' pitch) provide greater contact area in right angle to spring axis.
We use different grinding machines for varying spring shapes and wire diameters.
This surface treatment strengthens springs, especially dynamically stressed compression springs, to resist metal fatigue and cracking in order to significantly extend lifetime. To achieve an extra high surface finish, we use different shot peening facilities. They not only compress the steel but also deburr compression springs.