Explain the phenomenon of 'Wave Shifting' in multi-turn springs and its impact on load consistency.

Wave shifting occurs when the peaks of one turn do not stay aligned with the valleys of the adjacent turn. In a Crest-to-Crest spring, if the turns shift, they may 'nest' (peak-to-valley), causing a sudden drop in the spring's effective height and an increase in the spring rate (since the number of active turns $n$ effectively decreases). This is usually caused by lack of radial constraint or high-frequency lateral vibrations. To prevent wave shifting, many engineers specify 'interlocking' waves or use a 'Wavo' spring (a round-wire wave spring) which has higher lateral stiffness. Alternatively, a tight-fitting pilot shaft can help maintain the axial alignment of the turns.