Answer
Ring dish, or coning, occurs when an axial thrust load is applied to a spiral retaining ring, causing it to pivot within the groove. This is primarily due to the moment arm created by the distance between the point of load application and the groove support. As the ring dishes, the effective contact area with the groove wall decreases, and the radial force components tend to push the ring out of the groove. This phenomenon is quantified by the 'dishing angle' $\alpha$. If $\alpha$ exceeds approximately 7 to 10 degrees, the ring may spontaneously eject. To troubleshoot this, engineers should check for excessive groove radiuses or chamfers on the retained part, as these increase the moment arm and accelerate dishing. Solutions include increasing the ring thickness or using a material with a higher modulus of elasticity.
