Official Answer
Answer
Dishing is the elastic or plastic deformation where a retaining ring transforms from a flat washer shape into a conical shape under high axial loads. This is caused by a moment $M = P imes _x000c_rac{(L-t)}{2}$ where $P$ is the thrust load, $L$ is the lever arm (distance from the load point to the groove support), and $t$ is the ring thickness. If the dishing angle exceeds a few degrees, the ring may 'walk' out of the groove. To prevent this, the ring must be thick enough to provide sufficient section modulus, or the mating part must have a sharp corner to minimize the lever arm $L$.
