Official Answer
Answer
The load $P$ of a wave spring is governed by $P = k \times (H_{free} - H_{work})$. Any variation in the free height ($H_{free}$) or the machined work height ($H_{work}$) leads to a direct linear change in load. In precision assemblies like mechanical seals, the tolerance stack-up of the housing, the mating part, and the spring itself must be analyzed. If the tolerance is too loose, the preload may drop below the required threshold to maintain a seal; if too tight, the spring may be compressed near its solid height, where the spring rate $k$ becomes non-linear and significantly higher due to wave-to-wave contact. Engineers often use 'load-at-height' specifications rather than 'free height' to ensure functional performance.
