How does 'Gall' or 'Scuffing' on the groove face indicate improper ring selection for an oscillating load?

In applications with reversing or oscillating axial loads, the spiral ring will micro-move within the groove. If the ring's material hardness is too close to the housing hardness, 'Galling' (cold welding) occurs. This is seen as torn metal on the groove face. For an aluminum housing, a steel ring will quickly chew into the groove. This failure is analyzed by looking at the contact surfaces under $20 imes$ magnification. To mitigate this, engineers should either: 1) Increase the preload to eliminate movement, 2) Use a harder groove material (e.g., a steel bushing), or 3) Apply a hard-anodize or plating to the housing.