- Active coils (\(n_a\)) - Coils that are free to move under load.
- Baking - Heating of electroplated springs to relieve hydrogen embrittlement.
- Buckling - Bowing or lateral displacement of a compression spring when compressed, related to slenderness ration L/D.
- Close wound - Adjacent coils are touching.
- Closed ends - The ends of a compression springs with coil pitch angle reduced to touch the adjacent coil, can be one or more coils.
- Closed and ground ends - Same as closed ends except the ends are ground to have a flat surface.
- Deflection or displacement (\(d_s\)) - The motion of spring ends by adding or removal of an external load.
- Extension hook - The hook is made from the end coil and bent at the center opening extended from the coil.
- Free length (\(h_f\)) - Overall length of a spring which is not under load.
- Initial Tension - A force that keep coils of an extension spring closed and must be overcome before the coils start to open.
- Load (\(P\)) - The force applied to a spring that causes a deflection.
- Mean coil diameter (\(D\)) - The outside diameter minus one wire diameter.
- Number of active coils (\(n_a\)) - Active coils are the open wound coils exerting energy while under a load of compression, extending, or deflection.
- Pitch (\(p\)) - Distance from center to center of wire in adjacent coils.
- Plain end - End coils of a compression spring having a constant pitch and ends not squared.
- Set - Permanent change in height, length, or position after a spring is stressed beyond material's elastic limit.
- Shot peening - Blasting surfaces of spring material with steel or glass pellets to induce compressive stresses that improve fatigue life.
- Side hook - The hook is made from the end coil and bent at the side opening close to the coil.
- Solid height (\(h_s\)) - Length of a compression spring when under sufficient load to bring all adjacent coils into contact.
- Spiral spring - Springs formed on a wound spiral plane from a flat strip or wire.
- Slenderness ratio - The ratio of spring length to mean coil diameter.
- Spring index (\(C\)) - The ratio of mean diameter to wire diameter.
- Spring rate (\(n_s\)) - The change in load per unit of deflection.
- Stress relief - A low temperature heat treatment given to springs to relieve residual stresses produced by prior cold forming.
- Total number of coils (\(n_t\)) - The sum of the number of active and inactive coils in a spring body.
Tags: Equations for Spring