Ultrasonic cleaning is used across a broad spectrum of manufacturing and service organizations. Correctly breaking in new employees and conducting refresher courses for old hands operating ultrasonic cleaning equipment helps improve productivity within your organization. Here are some suggestions we’ve put together based on our long experience in the business.
Start right. For example, any cleaning liquid in an ultrasonic cleaner bath should be degassed before cleaning begins. You ask why? The liquid contains air bubbles and dissolved air from the atmosphere. See for yourself by dunking a part into a fresh pail of water – you’ll likely see bubbles form on the part. In ultrasonic operations these bubbles absorb acoustic energy, dampen sonication, and inhibit the cavitation process. In actuality, gas in the cleaning liquid migrates into the cavitation bubbles, which keeps them from imploding, which – well, you know, implosion is the crux of ultrasonic cleaning.
The end result: a longer cleaning operation until the gas is the liquid escapes. Wasted time is avoided by degassing the cleaning liquid before starting the cleaning operation. Elma ultrasonic cleaners offer a degas function whereby pulsed ultrasonic energy accelerates the removal of gas by causing the gas bubbles to coalesce, rise to the surface and escape to the atmosphere. The length of the degassing operation depends in part on the amount of gas in the new cleaning liquid, the volume of the liquid, the ultrasonic power employed and how the degassing function operates on a cleaner. Typically it takes 5 to 10 minutes.
“One size fits all” (or more correctly one frequency fits all) does not apply to ultrasonic cleaning. You need equipment that works best with your operation, whether cleaning an engine block or precision optics. We’ve put together a frequency chart that helps you attain maximum productivity depending on what you are cleaning. Here we share some examples:
| Cleaning Job | Frequency |
| Coarse tenacious adhesive contaminants, steel and iron surfaces | 25 kHz |
| General “all purpose” cleaning jobs; laboratory cleaning | 35 – 40 kHz |
| Fine or sensitive cleaning such as light metal alloys | 45 kHz |
| Highly sensitive surfaces – micro electronics, precision optics | 60-130 kHz |
Another good operating practice is to ensure that the ultrasonic effect is evenly distributed throughout the cleaning bath to avoid dead or weak spots and unsatisfactory cleaning. This can be accomplished by using Sweep mode, where the ultrasonic frequency is modulated continuously over a narrow range. Sweep function is a feature of most Elma ultrasonic cleaners and is designed to improve cleaning uniformity. For critical cleaning processes further improvements in cleaning uniformity can be achieved by slowly oscillating the parts basket during cleaning. The Elma X-tra line Flex units included gentle vertical oscillation, achieving exceptionally rapid and thorough cleaning. These models are preferred for cleaning medical implants, precision optics, and other manufactured parts where a very high degree of cleanliness is required.
When heated solutions are employed, maintain the deviation between indicated and measured temperatures within ± 2%. Use ultrasound to keep heated solutions circulating continuously. This helps avoid potential damage from hot spots on the bottom of the tank and evens out the temperature of the solution for more accurate temperature readings.
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What do you do to get the most out of your ultrasonic cleaning operations? Please share any tips you have that increased your efficiency – what you clean and how you do it.
Tags: ultrasonic
