Ultrasonic Cleaning
A cleaning process that uses high-frequency sound waves in solvent to remove old oil, dust, and debris from movement parts.
What is Ultrasonic Cleaning?
Ultrasonic cleaning is the standard method for cleaning disassembled watch movement parts. A transducer in the bottom of a cleaning tank vibrates at frequencies of 35,000–45,000 Hz, creating millions of microscopic cavitation bubbles in the cleaning fluid. When these bubbles collapse against the surface of a part, they scrub away dried oil, dirt, oxidation, and debris without any mechanical abrasion.
The Process
Parts are loaded into baskets and run through multiple ultrasonic stages:
- Cleaning stage — an ammoniated or solvent-based solution removes old lubricants and contaminants
- Rinse stages — successive rinses in progressively cleaner fluid remove cleaning solution residue
- Drying — parts are dried in a centrifuge or warm air cabinet before reassembly
What Cannot Be Ultrasonically Cleaned
Not everything goes in the ultrasonic tank. Components with adhesives, certain plated surfaces, and — critically — the balance wheel assembly are kept out. The hairspring is so delicate that ultrasonic vibration can distort it permanently. These parts are cleaned by hand using pegwood sticks and appropriate solvents.