Underwater drilling of foam-like materials and wax using ultrasound technology

The paper presents the results related to ultrasound machining of several materials as foam-like materials (i.e. Polystyrene and Polyurethane) and wax in underwater conditions. The paper shows also the comparison with in-air ultrasound machining performed on the same materials. The comparison demonstrates an enhancement mainly in terms of surface finish, overcut and heat altered zone. Such enhancements are due to the capability of water to decrease the influence of high temperatures on the tool-surface interface and to facilitate the removal of the machined material. The underwater conditions make it possible to successfully drill and mill wax, too: in air the molten wax tends to refill the manufactured features, while in water wax immediately solidifies and a chip is formed. Another possible machining benefit is given by the cavitation effect which happens underwater and facilitates also chip removal.