Official Answer
Answer
Dish-out is the axial deflection of the ring's inner or outer edge under load, transforming the flat ring into a conical shape. As the ring dishes, the effective contact area with the groove decreases, and the load vector shifts, creating a moment that promotes further deformation. Under dynamic impact (e.g., in pneumatic hammers), dish-out can lead to the ring 'walking' out of the groove. The amount of dish is proportional to $P \cdot R^2 / (E \cdot t^3)$. To counteract this, multi-turn spiral rings (2-turn or 3-turn) are used; they provide significantly higher moment of inertia ($I$) than a single-turn stamped circlip, thereby resisting dish-out and maintaining 360-degree contact even under shock loading.
