Spring Manufacturing Terminology
Coils which are free to deflect under load.
The relative position of the loops or ends of an extension spring or torsion spring to each other.
Process of heating the material so that it becomes soft.
Heating of electroplated springs to relieve hydrogen embrittlement.
The lateral displacement of a compression spring due to loading. This effect is a function of slenderness ratio L/D.
Generally applies to tension & torsion springs where adjacent coils touch.
The end coils of a compression spring are closed and ground flat square to the axis.
The end coils of compression spring are closed by reducing the coil pitch angle until they are square with the spring axis and touch the adjacent coil.
Compression springs, see solid height.
Number of coils per length, see pitch.
The inactive coils of a compression spring.
The distance moved due to an external load.
The stress point at which the wire material, if subjected to higher stress, will no longer return to its original shape. Applied to a spring, the maximum stress at a given stress ratio at which material will operate in a given environment for a stated number of cycles without failure.
The angle between the legs of a torsion spring when not under load.
The overall length of a compression or extension spring when not under load.
Ratio of load [P] to deflection [mm].
A process to improve spring relaxation when operating at elevated temperatures.
Wire or bar wound to form a helical coil.
The loss of mechanical energy during loading and unloading whilst operating in the elastic range. Ilustrated by the area between deflection curves.
The amount of force that is required to separate the closely wound coils of an extension spring.
The end coil of an extension spring which is lifted to form a loop.
The average diameter of the mass of the spring diameter.
Coefficient of stiffness.
Ratio of Stress/Strain.
Product of the distance (m) and load (N), from the spring axis to the point of load application. The force component is at 90 degrees to the distance line.
Frequency is the ratio of oscillations per unit of time. The natural frequency is the lowest inherent rate of free vibration of a spring oscillating between its own ends.
The length measured from the inside of one loop or hook to the inside of the other on an extension spring.
Heat treatment process where carbon steel is heated above its critical temperature followed by a controlled rate of cooling to produce a fine pearlitic microstructure.
The distance from wire centres of adjacent coils in an open-wound spring.
The ends of a compression spring where the end coils have a constant pitch and not squared.
The same as open ends, except wire ends are ground square to the axis.
Ratio of change of Load (P) / Deflection (mm).
For a compression spring, it is the permanent reduction in length and is a function of material, stress and temperature. The longer the time period a spring is exposed to higher stresses and higher temperature the greater the relaxation. Springs held at a constant stress relax more than if they are cycled between that stress and a lower stress.
Mechanically induced Stress by processes such set removal, shot-peening, cold working, or forming. It may be beneficial or not, depending on the spring application.
Permanent change of length, height or position after a spring is stressed beyond material’s elastic limit.
Stress at which some arbitrarily chosen amount of set (usually 2%) occurs. Set percentage is the set divided by the deflection which produced it.
Blasting the spring wire material surface with steel or glass beads to induce compressive stresses to improve fatigue life.
The ratio of spring length to mean diameter L/D.
When a compression spring is loaded to bring all adjacent coils into contact and no further deflection is possible.
The ratio of mean diameter to wire diameter.
See closed ends.
See closed and ground ends.
The angular measurement of the deviation between the axis in free state and a line at right angles to the end planes of a compression spring.
The difference between the operating stresses at minimum and maximum loads.
The ratio of Minimum stress / Maximum stress.
A low temperature heat treatment process to relieve residual stresses produced when the spring is cold formed.
The sum of active coils and dead coils.