Metal droplet ejection technology based on water hammer effect for additive manufacturing

Currently, in the field of molten droplet jetting for metal additive manufacturing, existing technologies such as pneumatic, piezoelectric, and magnetohydrodynamic methods face challenges in balancing device complexity, droplet ejection stability, and ejection frequency due to inherent limitations in their driving mechanisms. This study advances the traditional theories and techniques of droplet-based metal additive manufacturing by introducing a novel water hammer-based molten droplet jetting method. Through micron-scale rapid reciprocating motion of the jet tube along its axial direction, pulsed pressure is generated, enabling stable, efficient, and on-demand jetting of molten metal. The investigation systematically analyzed the effects of displacement, nozzle diameter, motion period, and liquid column height on the ejection behavior. The effects of different process parameters on pulsed pressure and jetting behavior were investigated. An increase in jet tube displacement or liquid column height, as well as a decrease in nozzle diameter, results in greater pulsed pressure, leading to higher droplet flight velocity. The additive manufacturing capabilities of this method for two-dimensional and three-dimensional structures have been validated.