Cavitation in ultrasonic technology

Cavitation is a physical phenomenon that plays a central role in ultrasonic cleaning. It occurs when high-frequency sound waves (typically between 20–80 kHz) are introduced into a liquid. This causes microscopic vapour bubbles to form, which grow rapidly and then collapse. These implosions generate high local temperatures and pressure peaks that remove dirt particles from surfaces – even in the finest structures and hard-to-reach areas.

Advantages of cavitation:
• Thorough cleaning without mechanical action
• Gentle on sensitive materials such as glass, metal and ceramics
• Effective on complex geometries (e.g. medical instruments, watch parts)
• Environmentally friendly, as less chemicals are often required

What is cavitation?
Cavitation refers to the formation and collapse of microscopic vapour bubbles in a liquid, triggered by rapid pressure changes. In ultrasonic technology, this effect is specifically used to clean surfaces effectively – even where brushes or chemicals fail.

The cavitation process
• Generation of ultrasonic waves
• An ultrasonic transducer converts electrical energy into high-frequency sound waves (typically 20–80 kHz).
• These waves propagate in the cleaning fluid and generate alternating high- and low-pressure phases.
• Formation of cavitation bubbles
• During the low-pressure phase, tiny vapour bubbles (microbubbles) form in the liquid.
• These bubbles are unstable and grow over several cycles.
• Collapse of the bubbles
• During the high-pressure phase, the bubbles implode abruptly.

Cleaning effect
• The implosion generates microjets and shock waves.
• These act directly on the surface of the object to be cleaned.
• Dirt, oil, oxidation and particles are mechanically removed – even in crevices, boreholes or rough structures.

Temperature of the liquid:
• Higher temperatures promote bubble formation and improve the cleaning effect.
• Type of cleaning liquid