Fundamental Theory of Uniform Metal Droplet Ejection and Deposition

Abstract

Uniform metal droplets will go through a series of physical processes during ejection and deposition, including liquid metal jet breakups, droplet formation, droplet flight, droplet impact on a substrate or pre-deposited droplets, cooling, and solidification, etc. It involves complex metal liquid flow and heat transfer behaviors. Therefore, understanding the underlying theories is essential for controlling the size of metal droplets and printing accuracy. This chapter focuses on a series of fundamental theories concerning metal droplet ejection, flight, and deposition, providing theoretical guidance for metal droplet 3D printing. These theories consist of the theory of continuous uniform droplet ejection and the mechanism of droplet charging and deflection, theories of pneumatic pulse, piezoelectric pulse, and stress wave-driven drop-on-demand metal droplet ejection, the dynamics and thermodynamics coupling behavior of metal droplet flight process, and the fluid-thermal coupling behavior during metal droplet deposition and impact.