Expanding the Possibilities of Multi-Metal Additive Manufacturing with Molten Metal Jetting

Molten Metal Jetting (MMJ) is an emerging Additive Manufacturing (AM) technique that is attracting growing interest due to its ability to directly fabricate complex components with high resolution. MMJ operates by melting bulk metals in crucibles to produce molten droplets, which are deposited at precise locations onto a moving substrate to form three-dimensional objects. These superheated droplets remelt the underlying material upon impact, enabling full consolidation. By using metals in their raw form and eliminating the need for post-processing steps, the technique offers a streamlined and sustainable manufacturing route. MetalJet, an in-house developed MMJ system used in this study, features dual printheads for multi-metal printing in a single operation, representing the first system of its kind. We demonstrate the platform’s capability to deposit microdroplets of tin, indium, silver, and copper onto ceramic, polymer, and metallic substrates. The results highlight the critical influence of substrate temperature on inter-droplet bonding and adhesion to the substrate. Electrical resistivity measurements show values comparable to bulk metals, while X-ray computed tomography revealed part densities up to 99.73% through an optimised deposition strategy. Surface roughness, an important parameter for applications such as radio frequency devices, was reduced to as low as 4 µm. These findings position MMJ as a promising platform for the sustainable fabrication of complex, miniaturised, and high-performance multi-material components.