Article Contents

1. Introduction
2. What is "Ultrasonics?"
3. Nature of Sound Waves
4. Cavitation and Implosion
5. Benefits of Ultrasonics
6. Ultrasonics Speeds Cleaning
7. Complex Contaminants
8. Ultrasonic Generators
9. Pulse and Frequency Sweep
10. Frequency and Amplitude
11. Magnetostrictive Transducers
12. Piezoelectric Transducers
13. Ultrasonic Cleaning Equipment
14. Maximizing the Cleaning Process
15. Maximizing Cavitation
16. Minimizing Dissolved Gas
17. Maximizing Overall Cleaning Effect (1)
18. Maximizing Overall Cleaning Effect (2)
19. Conclusion

Ultrasonic Cleaning: Fundamental Theory and Application
(p. 17)

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Maximizing Overall Cleaning Effect

Cleaning Chemical selection is extremely important to the overall success of the ultrasonic cleaning process. The selected chemical must be compatible with the base metal being cleaned and have the capability to remove the soils which are present. It must also cavitate well. Most cleaning chemicals can be used satisfactorily with ultrasonics. Some are formulated especially for use with ultrasonics. However, avoid the non-foaming formulations normally used in spray washing applications. Highly wetted formulations are preferred. Many of the new petroleum cleaners, as well as petroleum and terpene based semi-aqueous cleaners, are compatible with ultrasonics. Use of these formulations may require some special equipment considerations, including increased ultrasonic power, to be effective.

Temperature was mentioned earlier as being important to achieving maximum cavitation. The effectiveness of the cleaning chemical is also related to temperature. Although the cavitation effect is maximized in pure water at a temperature of approximately 160°F, optimum cleaning is often seen at higher or lower temperatures because of the effect that temperature has on the cleaning chemical. As a general rule, each chemical will perform best at its recommended process temperature regardless of the temperature effect on the ultrasonics. For example, although the maximum ultrasonic effect is achieved at 160°F, most highly caustic cleaners are used at a temperatures of 180°F to 190°F because the chemical effect is greatly enhanced by the added temperature. Other cleaners may be found to break down and lose their effectiveness if used at temperatures in excess of as low as 140°F. The best practice is to use a chemical at its maximum recommended temperature not exceeding 190°F

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