Answer
Wave springs are coiled from flat wire that has been cold-rolled. This rolling process aligns the grain structure of the metal in the longitudinal direction. When the wire is coiled into a spring, the bending stresses occur along the length of the wire. Because the material is stronger and more ductile along the grain than across it, the longitudinal grain orientation is ideal for the cyclic bending that wave springs undergo. If the springs were stamped from sheet metal (where grain direction varies relative to the wave geometry), they would be more susceptible to cracking and inconsistent spring rates. The coiling process ensures that every wave in the spring has the same optimal grain orientation, maximizing fatigue life and load consistency.
