Official Answer
Answer
When a wave spring mates with a component that has gaps, such as a splined shaft or a slotted housing, the peaks of the waves must be supported by a continuous surface. If a wave peak falls into a slot, the spring rate $K$ will drop significantly because that wave is no longer participating in the deflection ($f \rightarrow 0$ at that point). The solution is to use a 'Shim' or 'Bearing Plate' between the spring and the slotted component. This plate distributes the load $P$ evenly across the entire circumference of the spring. In heavy-duty planetary gear sets, failure to provide this support surface leads to localized yielding of the spring and eventual fatigue failure at the transition between the supported and unsupported regions.
