Official Answer
Answer
Edge-winding (also known as 'No-Tooling-Cost' coiling) involves winding a pre-tempered flat wire on its edge. This process preserves the grain flow of the material along the circumference of the spring, which significantly enhances fatigue life and load consistency. In contrast, stamping involves punching the spring from a sheet, which results in 'cross-grain' orientation at various points around the circle, creating weak spots susceptible to premature failure. Furthermore, edge-winding eliminates the scrap associated with stamping and allows for the easy production of multi-turn Crest-to-Crest springs with shim ends, which provide a $360^∘$ contact surface for more uniform load distribution.
