Ultrasonic cleaning of 3D printed objects and Cleaning Challenge Devices

We report our experiences in the evaluation of ultrasonic cleaning processes of objects made with additive manufacturing techniques, specifically three-dimensional (3D) printers. These objects need to be cleaned of support material added during the printing process. The support material can be removed by dissolution in liquids with or without ultrasonic cavitation. Distinctive stages in the cleaning processes were found for two different liquids (water and NaOH solutions). The combination of ultrasound and high concentration of NaOH has the best results for support material dissolution in the particular conditions studied. The sonication of cleaning processes in ultrasonic baths is typically a slow process. Here we show the advantages of using an ultrasonic horn to clean the surface of small parts and holes more effectively. We introduce a Cleaning Challenge Device design to be used for the universal evaluation of cleaning performance of different equipment or processes, and specifically for ultrasonic baths. The results and conclusions can be of use for different cleaning situations besides 3D printed parts, such as when deciding which protocol has a better performance or comparing different equipment.