September 21, 2021
When ultrasonic cleaning doesn’t deliver the expected rapid and complete cleaning performance, it’s usually because the cleaning system is not configured to match the cleaning task. Characteristics such as frequency and power have to be specified correctly for the system to work properly. If the ultrasonic cleaner does not match the cleaning application, cleaning can be spotty, take a long time or even damage the parts to be cleaned. With the help of an experienced ultrasonic cleaning system manufacturer, the cleaners can be configured and set up correctly. Such systems can clean more quickly and completely than traditional cleaning methods.
How Ultrasonic Cleaning Works
Ultrasonic cleaning systems work by producing microscopic cavitation bubbles in the cleaning solution. An ultrasonic generator sends a high-frequency electrical signal to an ultrasonic transducer immersed in the cleaning solution. The transducer converts the signal to sound waves that travel through the cleaning solution and create cavitation bubbles in time with the frequency. The creation and collapse of the bubbles produces a scrubbing effect that removes contaminants from the parts to be cleaned.
Why an Ultrasonic Cleaning System May Not Work
High ultrasonic frequencies create small, less energetic bubbles while low frequencies produce larger bubbles with an intensive cleaning action. To work properly, the bubbles have to be distributed evenly throughout the cleaning solution and there have to be enough bubbles for rapid cleaning. A wrongly configured system may have too few or the wrong size of bubbles and it therefore can’t clean properly.
Not Using the Correct Ultrasonic Frequency
Heavily contaminated parts with hard surfaces such as those made of steel are best cleaned with low frequencies. Softer materials such as plastic require higher frequencies. Delicate components such as electronics or fragile medical equipment can be cleaned safely with a high frequency ultrasonic cleaner. Choosing the right ultrasonic frequency based on the material of the part or device being cleaned is critical.
In addition to choosing the right frequency, the system needs to have enough power to fill the tank with ultrasonic sound waves. If the system is not powerful enough, there will be dead spots where cleaning doesn’t take place and contaminants will not be completely removed.
For parts with several different types of contaminants, the best cleaning performance may require two frequencies so that both contaminants are removed completely. Other measures to improve cleaning include adding a mild detergent or a weak solvent designed to remove a particular material. To remove oil or grease, heating the liquid in the cleaning tank softens the contaminants and speeds up cleaning.
Uneven Distribution of Ultrasonic Waves
Sometimes the set frequency creates a resonance in the cleaning tank so that the sound waves are concentrated in some areas and lacking in others. Ultrasonic systems can be programmed to vary the frequency slightly on a continuous basis to avoid resonant hot and dead spots.
An even distribution of bubbles may need more than one transducer. When cleaning large parts, transducers may have to be placed at several locations around the tank to ensure even cleaning. It takes experience with ultrasonic technology to configure these systems so they deliver optimal cleaning performance.
Kaijo is Your Experienced Partner for Ultrasonic Cleaning
With so many characteristics, features and practices to keep in mind for effective ultrasonic cleaning, a trial attempt can easily go wrong. By using both in-house experts and experience in designing ultrasonic products, Kaijo can ensure that installed systems will perform as expected. Kaijo’s experts can advise customers on the appropriate frequencies to use and how much power will be required for a system to function well. For special cleaning applications, Kaijo can design custom ultrasonic cleaning systems to meet specific requirements. Additional process features such as detergents, solvents and tank heating can be put in place as needed. When customers work with Kaijo, they can be confident that their use of ultrasonic cleaners will be successful. Contact Kaijo for a free consultation with an in-house expert to discuss your cleaning application requirements.