Official Answer
Answer
As a wave spring is compressed toward its solid height, the waves flatten, causing the mean diameter $D_m$ to expand. This radial expansion $\Delta D$ can be approximated by $\Delta D = 0.02 \cdot \frac{(L_0 - L_1)^2}{D_m \cdot Z}$, where $L_0$ is the free height and $L_1$ is the work height. In precision bore installations, this expansion must be accounted for to prevent binding against the housing. If the clearance is insufficient, the resulting radial friction will artificially increase the measured spring rate and may lead to premature fatigue failure due to localized stress concentrations.
