Spring rate

Where it comes up

• Springs, wire forms, and fourslideCompression, extension, and torsion springs, wire forms, and fourslide clips made from round wire and flat strip.

Related terms

Free length

Free length is the overall length of a spring with no load applied. For compression springs it is measured end to end; for extension springs it is usually measured inside the hooks. Free length, spring rate, and solid height together define how the spring works in an assembly.

Solid height

Solid height is the length of a compression spring when it is compressed until all coils touch. A design should never drive a spring to solid in service, and most designs keep maximum working deflection to about 80–85% of the travel available before solid height.

Fourslide

Fourslide is a forming process that uses four tool slides moving in from different directions to bend wire or flat strip into complex shapes in one machine cycle. It suits clips, wire forms, and small stampings with multiple bends, and its tooling usually costs less than a progressive die.