Physical washing method for the removal of press oil using the high-speed movement of microbubbles under ultrasonic irradiation

The development of a more environmentally friendly washing technique is of great practical importance. A physical washing method using the high-speed movement of air microbubbles under ultrasonic irradiation was applied to the removal of press oil from a stainless steel plate. The new physical washing method had higher washing efficiency than conventional ultrasonic washing and microbubble washing. The washing method for press-oil removal under the studied conditions achieved a precision washing level, which is sufficient for the method to be used in practice. On the basis of high-speed camera observations, a plausible mechanism of ultrasonic washing with microbubbles was discussed.