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Gao, Xiangyun (2025) Enabling multi-material Molten Metal Jetting via dual-head MetalJet system. PhD thesis, University of Nottingham.

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Abstract

Multi-material Additive Manufacturing (MMAM) enables the fabrication of integrated components with complex geometries and varied material properties. Among MMAM approaches, multi-metal AM facilitates the direct joining of dissimilar metals during fabrication and has been increasingly adopted in sectors such as aerospace, biomedical engineering, automotive manufacturing, and robotics. Established technologies such as Laser Powder Bed Fusion (LPBF) and Directed Energy Deposition (DED) have demonstrated strong industrial capabilities. However, there remains a need for alternative methods that offer high precision, process stability, and manufacturing efficiency, while avoiding the complexities of powder handling and extensive post-processing.

Molten Metal Jetting (MMJ) is an emerging droplet-based AM process that constructs 3D structures via layer-by-layer deposition of molten metal droplets. Despite its demonstrated potential in producing high-resolution and smooth-surfaced components, MMJ has so far been limited to single-material deposition.

This PhD research aims to establish the feasibility of drop-on-demand multi-metal MMJ for the first time. Key challenges in enabling multi-material MMJ lie in the absence of an available system capable of depositing two metals simultaneously, as well as a limited understanding of interfacial behaviour or process parameter adjustments for depositing metals with different melting points together.



To overcome these challenges, this study presents the development of the world’s first dual-head MMJ system for multi-metal printing. A bespoke control software, implemented in LabVIEW, was designed to coordinate hardware and user interaction, achieving deposition accuracy of within 7 μm. Based on this platform, customised printing strategies were developed to produce parts with densities over 98% and electrical conductivity within 2% gap to the corresponding bulk metal. The dual-head system was subsequently used to investigate interfacial phenomena in dissimilar metal deposition. A droplet coalescence defect was identified at the interface, and novel deposition strategies were proposed and experimentally validated to mitigate this issue. This research not only provides a robust platform for future multi-material MMJ studies but also contributes fundamental insights into interfacial bonding and process optimisation essential for reliable, defect-free multi-metal printing.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Hague, Richard Gilani, Negar East, Mark Simonelli, Marco
Keywords:	Additive manufacturing; Multi-material deposition; Metal printing; Interfacial bonding
Subjects:	T Technology > TS Manufactures
Faculties/Schools:	UK Campuses > Faculty of Engineering > Department of Mechanical, Materials and Manufacturing Engineering
Related URLs:	URL URL Type https://doi.org/10.1016/j.jmapro.2025.07.004 UNSPECIFIED
Item ID:	82682
Depositing User:	GAO, Xiangyun
Date Deposited:	09 Dec 2025 04:40
Last Modified:	09 Dec 2025 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/82682

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