Answer
A snapping sound, often called 'oil canning' or 'buckling,' occurs when a wave spring turn flips or shifts suddenly during compression. This is usually due to a lack of radial guidance or an uneven wave height distribution. When the spring is compressed, the mean diameter expands; if the spring is constrained unevenly, the stress builds up until it is released by a sudden movement. This is detrimental to reliability because the sudden release of energy causes high-frequency stress waves (shocks) that can accelerate fatigue. Furthermore, it results in a non-linear load-deflection curve with significant hysteresis. The solution involves improving the concentricity of the housing and ensuring the spring's waves are uniform within $\pm 2$ degrees of phase.
