Design of springs is important

Care needs to be taken when designing a spring for a particular application. As you don’t want it to be too hard to compress, as conversely, you wouldn’t want it to be too forgiving. Typically, the number of coils and or the wire diameter determines the strength of the spring in practical terms, but too many coils will hamper the function of it, and not allow ‘even’ compression. Too few coils and the spring will be in danger of completely collapsing and not returning to its original position on return.

Strength is variable in double cone upholstery springs

The strength of the spring can be infinitely varied to adapt to the user requirements. This can be achieved using any one or all combinations of wire size, number of coils, the free length of the spring, outside diameter of the end coils (which are usually closed coils) and the amount of taper reduction in the helix of the inner reducing coils, back to its full size at the other end of the spring.

In practice the spring tend to be really strong when first fitted, but a certain amount of collapse will inevitably happen after a short time, so careful selection of all of the above variants will need to be calculated for any given application.

Fixing

The method of fixing double cone coil springs in place is the top and bottom coils are sewn into position or fixed across webbing (on furniture applications). Stability of the top and bottom of the spring is imperative, as without secure fixing the spring will become unstable and topple over from one end or the other and render its use inoperable.