Ultrasonic cavitation is a proven cleaning technique used throughout industry to quickly and safely remove grit, grime, grease, and other contaminants on products ranging from delicate laboratory glassware and surgical instruments to steel and iron castings and forgings. Performed in an ultrasonic cleaner such as the Elmasonic series available from Tovatech, cavitation occurs in a cleaning solution when generator-powered ultrasonic transducers create billions of minute bubbles that implode with tremendous force upon contact with objects being cleaned.
While there are many ways you can improve ultrasonic cleaning performance here are some examples.
A. Ultrasonic Frequency
The frequency of ultrasonic cleaning is measured in kilohertz and generally ranges upwards from 25,000 (25 kHz) cycles per second. Low frequencies create relatively large cavitation bubbles and more vigorous cleaning action. As frequencies increase to 37, 40, 45, 130 kHz and higher, cavitation bubbles become smaller, cleaning action gentler and the ability to penetrate cracks, crevices and blind holes increases.
This suggests that one way to improve ultrasonic cleaner performance is to select the ultrasonic frequency best matching your cleaning task. Some models of ultrasonic cleaners such as Elma’s TI-H series operate at user-selected 25/45 or 35/130 kHz dual frequencies. The ultrasonic cleaning professionals at Tovatech will work with you to select ultrasonic cleaner frequencies that best match your requirements.
B. Ultrasonic Solution Temperature
The temperature of the ultrasonic cleaning bath also affects efficiency. Generally cleaning becomes more efficient as the bath temperature increases but there are exceptions. One manufacturer states that the best temperature for ultrasonic cleaning is approximately 65% of the boiling point of the cleaning solution.
The best way to address bath temperature is to match it to the particular cleaning solution formulation and what is being cleaned. Again, the scientists at Tovatech should be consulted for expert advice. If you consider a cleaner with a built-in heater keep in mind that cavitation causes bath temperatures to rise.
C. Ultrasonic Cleaning Solution Maintenance
Dirt and contamination removed during ultrasonic cleaning remain in the cleaning solution and will eventually impact cleaning performance. Cleaning solution maintenance helps extend efficiency. A good practice is skimming off oils and other contaminants that rise to the surface. This also helps avoid contaminants adhering to cleaned products as they are removed from the bath. Some industrial-sized ultrasonic cleaners are equipped with skimmers; otherwise it is a manual process. Solution filters are also available to remove suspended solids in industrial sized equipment.
When it is time to change the solution it must be drained and disposed of according to local regulations. Take the time to thoroughly clean the bottom of the tank. This removes settled solids that will eventually cause serious damage. Follow the manufacturers’ tank cleaning procedures.
D. “Sweep” and “Pulse” Functions and Ultrasonic Cleaning Performance
Ultrasonic cavitation creates what are called “standing waves” of ultrasonic energy. Otherwise explained these are areas of relatively high and low cavitation action in the cleaning solution. This can cause streaking on delicate or highly finished parts. The sweep function causes a continuous slight shifting of the ultrasonic frequencies so that the ultrasonic cleaning action is distributed more evenly throughout the cleaning bath.
A pulse mode, available on some ultrasonic cleaners, produces intermittent high intensity bursts of ultrasonic power and is generally engaged to remove stubborn deposits from parts being cleaned.
In summary there’s no question that ultrasonic cavitation is an effective cleaning technology. Operators of ultrasonic cleaning equipment can contribute to effectiveness by following proven procedures to improve ultrasonic cleaner performance. Rely on the scientists at Tovatech for unbiased advice on equipment, solution formulations and operating suggestions to help you get the most out of your investment.