Abstract: An ultrasonic cleaning tank with an ultrasonic vibrator mounted on its bottom is supplied with an aqueous cleaning solution which has been deaerated to a predetermined dissolved oxygen content ranging from 0.01 to 5 ppm. A workpiece to be ultrasonically cleaned is then immersed in the cleaning solution. Thereafter, the ultrasonic vibrator radiates ultrasonic energy into the cleaning solution to remove foreign matter and burrs off the workpiece.

Abstract: Disclosed is an improvement of ultrasonic washing apparatus comprising at least one washing vessel, an ultrasonic vibrator for radiating ultrasonic wave into the washing bath, an oscillator for operating the ultrasonic vibrator and degassing means for removing dissolved air and other gases from the washing liquid, thereby enhancing cavitation in the washing bath when the ultrasonic wave is radiated therein, said degassing means including gas separating means and barrier means for preventing surrounding air from dissolving into the washing liquid while it is degassed. Thanks to deaeration in the washing bath cavitation can be used to its full extent in removing soil from a soiled object in the washing bath.

Abstract: Disclosed is an improvement of ultrasonic cleaning system equipped with degassing means or boiling vessel to remove gases from cleaning liquid for activating the formation of cavitation in the cleaning bath. The ultrasonic cleaning system is improved according to the present invention in that the boiling vessel is used to supply the degassed liquid to the cleaning vessel to form a high-temperature zone on the cleaning bath, and that a circulation conduit is provided to supply the cleaning liquid from the high-temperature zone to the bottom of the cleaning vessel. The improved structure permits the creation of a high-temperature zone and a low-temperature or cleaning zone in one cleaning vessel, thereby preventing the dissolution of surrounding gases into the cleaning liquid, and at the same time, subjecting objects to ultrasonic-cleaning at a controlled temperature which is appropriate for ultrasonic cleaning, thereby improving the cleaning effect, and hence the cleaning efficiency.