Technical information about springs
Coil springs have been made by Lesjöfors since 1852. These days, the group has 19 manufacturing facilities, each one of which is specialised for its market and its product range. We make all types of springs, except for air, plastic and rubber springs. Flat thickness range from about 0.05 mm up to about 3 mm and wire diameters from 0.03 to 65 mm.
The spring material is selected to suit the application and the demands made on the spring. Cold drawn wire is generally used for uncomplicated springs and normal temperatures. Copper alloys are often used for contact springs with demands for resistivity. Stainless is often used for more difficult environments. Tungsten alloys are used for certain medical components. Quench and tempering steels is used for heavy springs. And so on.
The material is formed to the correct geometry by special machinery. In most cases, the material is formed to the correct shape by plastic deformation when cold. But stampings and hot forming are also commonly used. Lesjöfors uses the most modern machinery and processes available. Numerical control and automation were brought into common use a long time ago at Lesjöfors.
Heat treatment in spring production is mainly used either to remove negative residual stress from plastic forming or to give the material its optimum strength properties. In the first case, this treatment is called stress relieving, where the temperature and time depend on the type of material. The second case is either precipitation hardening or quenching and tempering, where the methods used are in accordance with the material manufacturer's recommendations and our konwledge.
Grinding is used to make one or two flat ends on helical compression springs. Grinding to make the ends flat reduces the risk that the spring could buckle. This type of grinding is done dry, with air cooling for smaller springs and with water spray for large springs. Different deburring and shamfering methods are used on various types of products.