| Abstract Scope |
Droplet-on-demand molten metal jetting (DOD-MMJ) enables precise molten metal droplet generation for applications like additive manufacturing, electronics, repair, photonics, and powder production. However, the effects of pulsed waveforms on droplet stability, velocity, and size remain underexplored for metals. Using a combined numerical-experimental approach, we analyze pulsed ejection dynamics for Al, Au, Cu, Fe, Li, Sn, Ti, Zn, and Zr. We first show that conventional inkjetting stability diagrams based on dimensionless Weber and Ohnesorge numbers are unsuitable for liquid metals, whose surface tension is the dominant force. Instead, we propose a Weber vs. tdrive/tcapillary framework, where tdrive is the pulsed waveform timescale and tcapillary is the capillary timescale. We then show that diagrams based on tdrive/tcapillary provide deeper insight into DOD-MMJ for different metals and orifice sizes, and when tdrive/tcapillary is ~1, the ability to generate fast, small and satellite-free droplets is improved. Prepared by LLNL under Contract DE-AC52-07NA27344. |