Article Contents

1. Introduction
2. FM: Sweep and Dual Sweep
3. Ultrasonic Power Into a Tank
4. FM: Upsweep
5. Multiple Frequencies (1)
6. Multiple Frequencies (2)
7. Cavitation
8. Transducer Impedence (1)
9. Transducer Impedence (2)
10. Transducer Impedence (3)
11. Universal Transducer
12. Applying the Technology (1)
13. Applying the Technology (2)
14. Applying the Technology (3)
15. Conclusion

Designer Waveforms: Ultrasonic Technologies to Improve Cleaning and Eliminate Damage
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Cavitation

Controlling the energy in each cavitation implosion is important to prevent pitting or craters in the part being cleaned. The energy in each cavitation implosion is reduced if the temperature of the liquid is increased, if the surface tension of the liquid is decreased and if the frequency of the ultrasound is increased. Figure 6 gives a pictorial description of these change effects. Changing the ultrasonic frequency is the most commonly used technique to control the energy in each cavitation implosion.

Cavitation density is the number of cavitation implosions per unit volume per unit of time. If the input energy to the tank is kept constant, the cavitation density increases as the energy in each cavitation implosion decreases. Therefore, higher ultrasonic frequencies are typically associated with higher cavitation density. This high cavitation density is a significant factor in the higher percent particle removal rates at higher ultrasonic frequencies. Figure 6 also gives a pictorial description of cavitation density.

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