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 cyclic loading and unloading of a spring, proportional to the area between the loading and unloading load-deflection curves within the elastic range to a spring.
The force that keeps the coils of an extension spring closed and which must be overcome before the coils start to open.
The force applied to a spring that causes a deflection (F).
Coil-like wire shapes at the end of extension springs that provide for attachment and force application.
Mean Coil Diameter
Outside spring diameter (O.D.) minus one wire diameter.
Modulus in Shear or Torsion
Coefficient of stiffness for extension and compression springs.
Modulus in Tension or Bending
Coefficient of stiffness used for torsion and flat springs (Young's Modulus).
The difference in operating stress at minimum and maximum loads.
To subject springs to low-temperature heat treatment so as to relieve residual stresses.
A cold working process in which the material surface is peened to induce compressive stresses and thereby improve fatigue life.
Squareness of Ends
Angular deviation between the axis of a compression spring and a normal to the plane of the ends.
Squareness Under Load
Same as 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. Usually expressed in inch-oz., inch-pounds or foot-pounds.
Total Number of Coils
Number of active coils (n) plus the coils forming the ends.