As we have discussed in the past, ultrasonic cleaning is used throughout the industrial world to remove a variety of contaminants ranging from dust to metal chips to carbon fibers to oil to baked-on polymers.
There is not a “One Frequency Fits All” out there. Effective cleaning requires choosing the correct ultrasonic cleaning frequency to accomplish any given task.
Ultrasonic sound waves create vacuum bubbles in the cleaning solution. When these bubbles hit a dirty surface, the bubble surface is compromised and the bubble implodes. Implosion is the opposite of explosion. In an explosion, the contents of the blast are pushed out. With an implosion, the contents of the blast are pulled in.
In the first part of our series we talked about 40 and 25kHz. In today’s post we will specifically discuss higher frequencies such as 68 and 170kHz and their place in the cleaning world. These higher frequency bubbles are much smaller and less aggressive than the lower frequencies we have written about previously. Because ultrasound has vast vibrational properties, ultrasonic systems have the most versatile cleaning abilities in the industrial parts cleaning universe.
Intricate cleaning applications such as those found in the medical, wafer fabrication, and computer memory industry to name a few examples, require cavitation bubbles to implode more closely to the substrates being cleaned. These cleaning protocols require a higher or more precision degree of cleanliness. It’s fairly obvious that we want the artificial knee being implanted into our body to be cleaner than the carburetor on our old Harley Davidson touring bike.
Higher frequency applications make up at most five percent (5%) of the market out there. Some interesting characteristics surrounding higher frequency ultrasonics is that not only is the bubble size smaller and less aggressive, but the physical noise produced is much lower. The sound may make your dog howl, but us humans can barely hear it.
Also if you put your hand into a high frequency bath, it actually penetrates deeper into the nerve endings causing more pain than the lower frequencies systems. This has to do with the wavelength being shorter and creating more cycle occurrences in your body thus creating more aggressive sensations.
So remember, 68kHz and above is that sound you rarely hear but really feel.
Don’t forget to read the first two parts of our Ultrasonic Cleaning Frequencies series with our discussions on 40kHz and 25kHz.