The spiral wires in compression springs are not touching when in a relaxed position and only become so under the stress of weight. In contrast, extension springs are designed so that their spiral wires are contiguous when there is no weight load and stretched apart under the stress of a weighted load. Coil springs can be made of various steel materials, including stainless spring steel hard drawn spring steel, steel music wire, and oil-tempered spring steel. Spring steel is a special kind of steel with increased elasticity and return properties. The elasticity of a spring enables it to return to its original position; however, this capability diminishes with use. In general, the larger the wire, the stronger the spring is. Spring strength can also be increased by making the coil diameter of the spring smaller.

Mandrel –A mandrel is one of the two primary methods for manufacturing coil springs. This process can be carried out using a lathe, winding machine, or hand crank machine. During production, a guide mechanism ensures that the wire is aligned correctly to achieve the desired pitch, which is the spacing between the coils as they are wrapped.