Special production techniques
In order to respond to the market developments and the growing demand for high-quality springs, Alcomex developed a complete test programme. This testing programme determines the lifespan of extension, compression and torsion springs. Alcomex observes different aspects for custom products, such as: specific customer demands, the application, spring configuration, chemical composition, conversion degree and ductility of the wire, surface and thermal treatment.
Shot blasting of springs
In addition to the standard production techniques, Alcomex is also able to shot blast torsion, compression and extension springs. The purpose of shot blasting is to enhance the mechanical properties of the springs.
During production tension is created on wire surface and the inside of the spring. In case of dynamically loaded springs this surface tension ensures that the material properties are not fully utilised. By shot blasting the spring, the fatigue resistance is improved, while the following enhancements can be measured:
- More tension levels in the surface
- Less fatigue (because surface defects are closed)
- The surface hardness is increased
As a consequence of shot blasting the lifespan can easily be doubled relative to untreated springs. So shot blasting is a great solution for compression springs, that are tested on fatigue, and torsion springs in door systems where the lifespan is important.
Extension springs and torsion springs
Extension springs and torsion springs with windings close together are not usually shot blasted as the beneficial effect is limited (closed windings). Alcomex however always shot blasts door springs (torsion) where the lifespan is of importance. The surface enhancement (increase of tension and compacting) and the increase of the hardness, make it possible to significantly improve the mechanical properties of the springs.
Before use, dynamically loaded compression springs are pressed to billet length. This pressing creates a plastic deformation and tensions emerge in the surface that work in a direction contrary to that under normal load circumstances. “Setting” of the spring decreases the reduction of the coil when the spring is being used. Pre-pressing is recommended in case springs need to work under high tension. In practice, the setting is always done under normal circumstances. However if a spring is to work at high temperatures, the setting must be done at these temperatures.