Extension springs are designed to absorb and store energy by creating a resistance to a pulling force. All coils are active in an extension spring. Each spring is wound with initial tension which keeps the coils closed and must be overcome before the coils start to open.
Commerce Spring custom manufactures extension springs using round wire between .008 and .162 in diameter in a variety of material. Most commonly used are Music Wire, Stainless Steel 302, Hard Drawn MB and Galvanized Hard Drawn. Other materials available are Stainless Steel, Type 316 and 17-7 PH, Plated Music Wire, Oil Tempered, Beryllium Copper, Phosphorous Bronze, Inconel, Monel, Brass, Chrome Silicon and Chrome Vanadium and more high temperature and corrosion resistant alloys.
Various types of hook ends are used to attach the extension spring to the source of the force. Most common hooks are machine loops, cross over loops, side loops, extended hooks or a combination of hooks on each end. Hooks may be rounded or squared. All ends can be produced to vary in distance from the spring body.
Once springs are formed, a variety of finishes are available including passivation, zinc, cadmium, black oxide, copper, tinned, paint and others.
Experienced engineers are available to help you determine the best material, hook configurations and finish to meet your requirements.