What causes 'Ring Flutter' and how does it lead to groove erosion?

Ring flutter is a high-frequency axial vibration of the retaining ring within its groove, typically occurring in reciprocating applications like piston pins or high-speed valves. If the axial clearance between the ring and the groove is too large, the ring will impact the groove walls repeatedly. This leads to 'pounding' or 'erosion' of the groove, eventually widening it until the ring can no longer stay seated. To solve this, the groove width should be held to a tighter tolerance, or a wave-shaped 'WaveRing' can be used, which provides a constant axial preload to dampen any vibration.