Physics-Based Nozzle Design Rules for High-Frequency Liquid Metal Jetting

TL;DR

This paper develops physics-based design rules for high-frequency liquid metal jetting in 3D printing, focusing on how nozzle geometry influences meniscus stability and relaxation time, verified through simulations and shape optimization.

Contribution

It introduces scaling laws linking nozzle geometry to meniscus dynamics, enabling optimized design for stable, high-throughput liquid metal jetting.

Findings

Meniscus relaxation time decreases with higher surface area to volume ratio.

Scaling laws are validated by multiphase flow simulations.

Optimized nozzle shapes improve jet stability and performance.

Abstract

We present physics-based nozzle design rules to achieve high-throughput and stable jetting in drop-on-demand liquid metal 3D printing. The design rules are based on scaling laws that capture the change of meniscus oscillation relaxation time with geometric characteristics of the nozzle's inner profile. These characteristics include volume, cross-sectional area, and inner surface area of the nozzle. Using boundary layer theory for a simple geometry, we show that the meniscus settles faster when the ratio of inner surface area to volume is increased. High-fidelity multiphase flow simulations verify this scaling. We use these laws to explore several design concepts with parameterized classes of shapes that reduce the meniscus relaxation time while preserving desired droplet specs. Finally, we show that for various nozzle profile concepts, the optimal performance can be achieved by increasing the ratio of the circumferential surface area to the bulk volume to the extent that is allowable by manufacturing constraints.