Ultrasonic cleaner manufacturing is experiencing sustained growth according to a recent report by industry research publisher IBISWorld. While the report focuses on ultrasound as the dominant method used for cleaning medical and dental equipment, a takeaway is that companies in many industries are looking at the technology as an environmentally friendly way to remove contamination from surfaces that can be safely wetted in a biodegradable water-based ultrasonic cleaning solution.
When you select an ultrasonic cleaner, whether tabletop or industrial-sized, you must make decisions in addition to cleaning solution capacity. Two have to do with ultrasonic frequency and ultrasonic power.
How to Specify Ultrasonic Frequency
Ultrasonic frequency is measured in thousands of cycles per second (kilohertz or kHz). Frequencies are generated by ultrasound transducers affixed to the bottom, and in some cases also the sides, of the ultrasonic cleaning solution tank. The transducers are excited by the unit’s ultrasonic generator to produce millions of microscopic bubbles in the solution that implode on contact with parts being cleaned. The implosion, called cavitation, removes contamination faster and more thoroughly than mechanical scrubbing using wash tanks or aerosol sprays.
Ultrasonic frequency also determines cavitation bubble size. Low frequencies such as 25 kHz produce relatively large bubbles that implode more violently than those created at higher frequencies that produce comparatively gentle cleaning action. Visually the size is virtually impossible to distinguish. For example a 25 kHz bubble has about 3 times the approximately 40 micron radius of 80 kHz.
So, what does this mean? If you are removing gross contaminants from robust parts such as fabricated or cast metals specify a lower frequency ultrasonic cleaner. Softer metals, plastics, and products with polished surfaces should be cleaned at higher frequencies. The smaller bubbles are less likely to cause surface damage. They are also better able to penetrate tight areas such as seams, crevices and blind holes.
If you are cleaning a variety of products consider a dual-frequency ultrasonic cleaner. An example is the Elmasonic TI-H line available from Tovatech offered in either 25/45 or 35/130 kHz frequencies. Another is the Elmasonic P series that operates at 37 or 80 kHz.
The Role of Ultrasonic Power
Power has several definitions when discussing ultrasonic cleaning and is described in different ways by equipment manufacturers. In terms of cleaning power it is calculated as the power delivered to the transducers and expressed as watts per gallon (or liter) of cleaning solution. Most cleaners operate at 50 to 100 watts per gallon.
As power increases so does the number of bubbles, so increased power yields faster cleaning action but only up to a point. Beyond that you are not only wasting energy you also risk damaging parts being cleaned.
Another definition is total power or the amount needed to drive everything in the unit including ultrasonic generators and heaters (if supplied). It should not be confused with ultrasonic power.
Peak power is defined as the ultrasonic power generated at the peak of the sound wave and can equal 2, 4 or 8 times the average power.
Variable ultrasonic power is offered on certain units such as the Elmasonic TI-H and P series mentioned above. Another useful feature on the P series is a pulse mode that provides bursts of power to remove tenacious contaminants.
This post does not answer all questions on ultrasonic frequency and power but should give you an idea of the importance of these features when purchasing an ultrasonic cleaner. The professionals at Tovatech are available to guide you through the process and to recommend the correct equipment for your requirements.