Developing high intensity ultrasonic cleaning (HIUC) for post-processing additively manufactured metal components

The high energy phenomenon of cavitation bubble collapses has enabled numerous applications, including cleaning. In ultrasonic cleaning, cavitation intensity is typically lower than in other applications, such as sonochemistry and material processing. However, there has been an emerging application in intense cleaning of metal additively manufactured (AM) components. The presence of partially melted powders on AM surfaces is undesirable, contributing to high surface roughness and posing contamination risks during usage. We designed a high-intensity cavitation cleaning process that has significantly higher inertial cavitation intensity - i.e., erosion potential - than a conventional ultrasonic cleaning tank. Through acoustic signal characterisation, we showed that placing transducer sets on four sides of the tank could effectively focus and generate high-amplitude pressure waves directed towards the central region. Strong subharmonic signals indicate intensely inertial cavitation throughout the tank. Cavitation intensities were measured at various locations to understand the wave transmission characteristics and distribution patterns. Our results show that the cavitation intensity distribution is highly dependent on the height position. Finally, we demonstrated that the high intensity ultrasonic cleaning (HIUC) process could remove partially melted powders from an AM surface - which was not possible through conventional ultrasonic cleaning. HIUC could lead to higher cleaning efficiency and enhanced AM specimen cleanliness.