Official Answer
Answer
The K-Factor is an empirical correction constant used in the Smalley or standard wave spring formulas to account for the geometry of the wave and the constraints of the material during manufacturing. While the theoretical rate is $k = \frac{E b t^3 N^4}{4 D_m^3 n}$, the inclusion of $K$ adjusts for the ratio of $D_i/D_o$ and the non-ideal curvature of the wave crests. For springs where the ratio of diameter to radial wall is small, the K-factor compensates for the increased stiffness due to tighter curvature, ensuring that the predicted load matches the actual test data within $\pm 10\%$ tolerance.
