Official Answer
Answer
Parallelism is critical for uniform load distribution. If the mating surfaces are not parallel, one side of the wave spring will be compressed further than the other. This creates a non-uniform stress distribution where specific waves exceed the calculated design stress $\sigma = _x000c_rac{3 imes _x000d_ho imes P imes D_m}{2 imes n^2 imes b imes t^2}$. The waves on the 'tight' side may enter the plastic deformation zone or reach the fatigue limit prematurely. This often manifests as localized 'settling' or cracking on only one sector of the spring. For high-cycle applications, mating surfaces should be held to a parallelism within $0.05$mm to ensure that the cyclic stress range $ riangle au$ remains within the S-N curve limits.
