Development of Single Point Exposure Strategy to Suppress Vapour Formation During the Laser Powder Bed Fusion of Zinc and Its Alloys

The conventional scanning strategies based on linear trajectories in Laser Powder Bed Fusion (LPBF) are highly limited for processing novel materials. In order to manage the energy input and exploit a higher feature resolution, novel scan strategies are required, capable of exploiting the flexibility enabled by the fast modulation capabilities of contemporary fiber laser sources. Zinc and its alloys are among these challenging materials for LPBF aimed to be used in customized biodegradable implants. LPBF of Zn is notoriously difficult to process due to excessive vaporisation which generates high porosity. Accordingly, in this study an innovative LPBF processing strategy based on Single Point Exposure (SPE) was developed. The control over the energy input via single spot exposure allowed to suppress excessive vapour and spark formation typical to Zn alloys. The dynamics of the novel process and its parameters were investigated employing open LPBF platforms and high-speed imaging. Fully dense struts with diameters lower than 300 µm were achieved to produce Zn alloy lattice structures, confirming the effectiveness of the innovative SPE strategy for high precision deposition of challenging materials.