Upcoming Solid Freeform Fabrication Symposium 2021 (August 2-4, virtual)

We present a novel wire-fed AM technique that achieves direct printing of metal microdroplets from a fine wire feedstock. The process involves a wire feed mechanism that advances a wire at a controlled speed and a desired trajectory, and the modulated laser heating applied near the wire tip to liquefy the moving wire and generate a stream of molten droplets. We demonstrate the stable feeding of a Φ 50 μm 304L stainless steel wire at a controlled speed ranging from 0.5 to 1.5 m/s, and continuous breakup into molten droplets with a corresponding diameter of 120-180 μm, at a frequency of ~1 kHz. Via experiments and numerical modeling, we analyze the mechanism of breakup and the factors influencing the stability of the droplet stream. Further, we investigate how to direct the droplet trajectory, and present preliminary results where the droplets are printed onto moving substrates.