The word sonic quite often brings with it the idea of vibration. If you have never used an ultrasonic cleaner, you might assume that the way it works is by using vibration to shake off dirt and debris from the part being cleaned. This could not be further from the truth. Let’s take a look at the difference between using an agitating action and ultrasonic.
What is Cavitation?
Ultrasonic cleaners use a physical effect called cavitation to clean. Cavitation is an effect that happens when small bubbles or voids are created inside a liquid. We’re not talking about large soap bubbles, but very tiny bubbles. As the bubbles are created they collapse very quickly.
When they collapse, a large amount of force and temperature are created at a very small point. Since the application of the force is so small, it does not damage the part. Instead, it works to break free dirt and debris that are stuck to a solid part.
How Does an Ultrasonic Cleaner Generate Cavitation?
Ultrasonic cleaners work by using an electronic device called a transducer. The transducer produces sound waves at very high frequencies. These vibrations create pressure waves in a solution that make small voids. These are the bubbles that collapse and cause the cavitation action.
To picture this, think about dropping a stone into a calm pond. Disturbing the water like this creates waves that ripple out. There is a peak to the wave, this is where the pressure is highest, and there is a trough to the wave where the pressure is low. Now, if you fully submerge that action the troughs are where air pockets develop and collapse.
The higher the frequency used to by the transducer the smaller the bubbles are that are created in the solution. This effect can be used to clean very small parts; the bubbles can make their way inside any corner or opening on your part as long as the frequency is set high enough.
How is Cavitation Different than Agitation?
A good example of cleaning using agitation is to think of a clothes washing machine. Your clothes are placed into a solution. The solution and the clothes are then moved by the large armature on the inside. The motion of the fluid rubbing against the material is what frees the dirt from the clothes. This process can be harsh and cause damage to more intricate parts. It is also less effective than using the forces generated by cavitation.
Ultrasonic cleaners can be used for a wide variety of applications, such as cleaning intricate machining parts or for precise biomedical applications. The wide usage is due to the ability of the ultrasonic cleaner to not only clean parts more thoroughly, but get to areas that other cleaning methods cannot reach.