Ultrasonic transducers are the sound-emitting devices which are typically mounted on the bottom of the ultrasonic cleaning tank.  They are designed to work most effectively at a very specific frequency.  If the transducer is powered by a frequency which is different by only 10kHz, power drops more than 50%.  This is the reason why sweep frequency circuits only operate at 2-3kHz outside of the transducer's natural resonance frequency; to ensure that powerful cavitation is still produced at the swept frequency range.  More information on transducers can be found in the Ultrasonic College drop-down menu under "Transducer Types".

By theory, sweeping the output frequency to the transducers causes the standing waves to come closer to one-another, thereby reducing or eliminating standing waves.  However, the reality is that the change is so small that it can barely be called effective for most ultrasonic cleaning applications.  The problem is, a 2-2kHz change produces such a small change in standing wave position that it is invisible to the naked eye.  At 40kHz, standing waves are roughly 1/2" apart, and at 80kHz, standing waves are roughly 1/4" apart.  What kind of a change can possibly be produced by a total 6kHz shift in frequency?  The truth is, barely any change is produced, and any foil test can prove it!

Some customers in the high-technology industry have asked if the sweep frequency circuits minimized the damage on specific sensitive components when cleaned ultrasonically.  The answer to this question would depend upon the nature of the produce being cleaned.  A sweep frequency circuit does create SOME shift in the position of standing waves, albeit not a large amount.  However, this small shift may cause damage to be spread out over a larger area if parts are very sensitive.  In other cases, damage is prevented, since the base material requires continuous cavitational attack in the same area for it to be damaged.

Sweep Frequency Circuits:

• DO NOT Eliminate Standing Waves or "Hotspots" in an Ultrasonic Cleaner
• Do create Small Shifts in Standing Wave Position, but Not Enough to Drastically Change System Performance.
• Do Little to Eliminate Standing Waves, but Can Reduce Damage to Sensitive Parts to Some Degree.

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Zenith Mfg. & Chemical Corp.
85 Oak St.
Norwood, NJ  07648-0412
800-432-SONIC (7664)
FAX: 201-768-6999
sales@zenith-ultrasonics.com