Despite the name, sweep has nothing to do with brooms and dustpans. In the case of ultrasonic cleaners, sweep refers to adjusting the unit’s ultrasonic frequency ±3 kHz during the cleaning cycle. This small, but continuous variation helps to prevent harmonic vibration. Harmonic vibration can occur when a static ultrasonic frequency causes parts submerged in the solution to resonate. Fine wire and other sensitive components can be damaged if allowed to resonate by ultrasonic frequency for any length of time. Further, with sweep, the cleaning power of cavitation is evenly distributed throughout the tank.
Other benefits of sweep are the elimination of hot spots and dead zones. Dead zones are just that, areas within the cleaning solution where there is no cavitation occurring. No cavitation means no cleaning. Hot spots are the opposite. They are areas within the solution with a higher concentration of ultrasonic energy. Hot spots that are too intense can cause etching and other damage to soft, delicate, or thin parts.
Not all ultrasonic cleaners have a sweep function, and not all parts put into an ultrasonic cleaner will be damaged without the sweep feature. If you’re concerned about the parts you’ll be cleaning and don’t know if your sonic cleaner sweeps ±3 kHz from its cycle frequency, then you should contact the manufacturer or buy one that lists “sweep” as a feature. The link below is for an ultrasonic cleaner that will hold any phone’s logic board, does sweep, and the heating element won’t burn out if ran dry.
Okay, so what about de-gassing? De-gassing is basically what it sounds like. It’s the removal of dissolved oxygen from the ultrasonic cleaning solution. To degas the solution, after filling the machine to the appropriate level, run a cycle with no soiled parts. Some machine’s owner’s manuals will have specific instructions on de-gassing and some machines have a “degas” setting. Dissolved oxygen in the ultrasonic cleaning solution will hinder the ability of the machine to clean effectively.