Those coils which are free to deflect under load. For compression springs with square ends , total no. of coils minus two is a good approximation of number of active coils.
Angular relationship of ends
The relative position of the plane of the hooks or loops of extension springs to each other.
Heating of Electroplated Springs to relieve hydrogen embrittlement.
Bowing or lateral deflection of compression springs when compressed, related to slenderness ratio (L/D)
Ends of compression springs where pitch of the end coils is reduced so that the end coils touch.
Closed and ground ends
As with closed ends, except that the end is ground to provide a flat plane.
See Solid height.
Coils with adjacent coils touching.
Coils per inch
Motion of spring ends or arms under the application or removal of an external load.
Maximum stress to which a material may be subjected without permanent set.
Maximum stress at which any given material may operate indefinitely without failiure for a given minimum stress.
Angle between the arms of a torsion spring when the spring is not loaded.
The overlall length of a spring in the unloaded position.
The lowest inherent rate of free vibration of a spring itself(usually in cycles per second) with ends restrained.
See Rate (R)
Fixturing a spring at elevated temperature to minimize loss of load at operating temperature.
The spiral form ( open or closed) of compression, extension, and torsion springs.
Load is proportional to displacement.
Open Loops or ends of extension springs.
See Heat setting.
Hydrogen absorbed in electroplating or pickling of carbon steels tending to make the spring material brittle and susceptible to cracking and failure particularly under sustained loads.
The mechanical energy loss that always occurs under cyclical loading and unloading of a spring, proportional to the area between the loading and unloading load deflection curves within the elastic range of a spring.
The force that keeps the coils of an extension springs closed and which must be overcome before the coils start to open
The force applied to a spring that causes a deflection.
Coil like wire shapes at the ends of extension springs that provide for attachment and force application.
Mean coil diameter
Outside spring diameter minus one wire diameter.
Modulus in shear or torsion
Coefficient of stiffness used for extension and compression springs.
Modulus in tension or bending
Coefficient of stiffness used for torsion and flat springs (Young’s Modulus)
Open Ends, Not ground
End of a compression springs with a constant pitch for each coil.
Open and Ground ends
Open ends not ground followed by an end grinding operation.
Acid treatment of stainless steel to remove contaminants and improve corrosion resistance.
A material that is deflected so far that its elastic properties have been exceeded and it does not return to its original condition upon release of load is said to have taken a “permanent set”
The distance from center to center of the wire in adjacent active coils (recommended practice is to specify number of active coils rather than pitch)
See remove set.
Change in load per unit deflection, generally given in Kg/mm.
Full compression of a spring to solid state by manufacturer when needed to prevent length loss in operation.
Stresses induced by set removal, shot peening, cold working, forming or other means.
These stresses may or may not be beneficial, depending on the application.
Length loss in operation due to high stresses and thereby improve fatigue life.
A cold working process in which the material surface is peened to induce compressive stresses and thereby improve fatigue life.
Ratio of spring length to mean coil diameter.
Height of a compression spring when under sufficient load to bring all coils into contact with adjacent coils.
Ratio of the mean coil diameter to wire diameter.
Squared and ground Ends
See Closed and Ground Ends.
See Closed Ends.
The difference in operating stresses at minimum and maximum loads.
To subject springs to low temperature heat treatment so as to relieve residual stresses.
Squareness of ends.
Angular deviation between the axis of a compression springs and a normal to the plane of the ends.
Squareness under load
Same as in squareness of ends, except with the spring under load.
A twisting action in torsion springs which tends to produce rotation, equal to the load multiplied by the distance(or moment arm) from the load to the axis of the spring body.
Total number of coils
Number of active coils plus the coils forming the ends.