Official Answer
Answer
A wave spring, especially a multi-turn Crest-to-Crest type, can behave like a slender column and buckle if not properly guided. Guidance is typically provided by either a bore (internal) or a shaft (external). The pilot diameter should provide a clearance of approximately 0.25 mm to 0.50 mm. If the spring is bore-guided, the outside diameter $OD_{max}$ of the spring under full compression must be calculated: $OD_{max} = OD_{free} + 0.02 \cdot (f^2 / D_m)$. If the bore is too tight, the spring will frictionally lock against the walls, leading to 'hysteresis' in the load-deflection curve. If the clearance is too large, the spring may shift off-center, causing uneven stress distribution and potential interference with other moving parts.
