Cavitation Erosion

Cavitation erosion is the progressive loss of material from a surface caused by repeated formation and violent collapse of vapor or gas bubbles in a liquid. Each collapse generates localized pressure pulses, micro-jets, and shock waves that pit, crack, and eventually crater the substrate, particularly in high-velocity flow systems. It is a fluid-induced surface damage mechanism, not a chip-forming machining process. It matters wherever parts experience pressure drops, high-velocity liquid flow, or ultrasonic cavitation.

On the shop floor, cavitation erosion typically shows up in CNC-machined pump impellers, housings, valves, and flow passages that see high-velocity liquid. Machining decisions directly influence where bubbles collapse: tight blade geometry, smooth internal finishes, and controlled radii reduce low-pressure zones, while sharp transitions and tolerance drift intensify local pressure recovery and drive pitting near the wall. A machinist holding repeatable flow paths improves hydraulic efficiency and lowers cavitation risk compared with less accurate methods. In ultrasonic processes, the same mechanism becomes a controlled test: specimens are exposed to repeated cavitation and mass loss is measured before and after, with typical changes in the 1–30 mg range. In fabrication, the term is less common unless the part is a wet-service fluid component or spends time in an ultrasonic cleaning bath; soft materials and sharp edges are then most vulnerable to surface loss.