Those coils which are free to deflect under load.

Heating of electroplated springs to relieve hydrogen embrittlement.

Bowing or lateral displacement of a compression spring. This effect is related to slenderness ratio L/D.

Adjacent coils are touching.

Same as closed ends, except the first and last coils are ground to provide a flat-bearing surface.

Compression spring ends with coil pitch angle reduced so they are square with the spring axis and touch the adjacent coils.

Motion imparted to a spring by application or removal of an external load.

Overall length of a spring which is not under load.

Open loops or ends of extension springs.

A force that tends to keep coils of a close wound extension spring closed and which must be overcome before the coils start to open.

Formed ends with minimal gaps at the ends of extension springs.

The average diameter of the mass of spring material, equal to one-half the sum of the outside and inside diameters. In a helical spring (compression), this is the equivalent to the outside diameter minus one wire diameter..

Distance from center to center of wire in adjacent coils in a open-wound spring.

End coils of a compression spring having a constant pitch and ends not squared.

Same as plain ends, except wire ends are ground square with the axis.

Spring gradient, or change in load per unit of deflection.

Permanent change of length, height or position after a spring is stressed beyond material’s elastic limit.

Blasting surfaces of spring material with steel or glass pellets to induce compressive stresses that improve fatigue life.

Ratio of mean diameter to wire diameter.

See closed and ground ends.

SEE CLOSED ENDS

A low temperature heat treatment given to springs to relieve residual stresses produced by prior cold forming.

The sum of the number of active and inactive coils in a spring body.