Embedded printing trace planning for aluminum droplets depositing on dissolvable supports with varying section

Droplet-based 3D printing is a promising method to manufacture thin-walled parts with high-quality cavity surfaces of a complex geometry by virtue of dissolvable supports. However, conventional equispaced droplet scanning strategies cannot be used for dissolvable support assisted droplet printing that involves more complex impingement conditions, particularly when the dissolvable supports possess varying sections. This paper investigates the printing strategies for aluminum droplets depositing on dissolvable support that possesses preset dimensions, inclined surfaces and corners. Experimental and numerical results show that: (1) printing orientation on the oblique surfaces of dissolvable supports significantly influences the formation of hole-defects; (2) the printing strategy for corners should be specially adjusted to minimize defects. Moreover, the droplet scanning spacings on the support surfaces with preset shape and dimensions are elaborately regulated according to four different cases. Finally, the fabrication experiments of aluminum horns are performed to further examine the formability of the established droplet scanning strategies. The density of the printed horn is measured to be similar to 98% using the standard Archimedes method, and the corresponding industrial CT scanning results also verify a porosity-free inner structure. The cavity surfaces of the horn are smooth without obvious defects, and the average surface roughness of the inner surface is similar to Ra 4.2 mu m (only 0.53% of the droplet diameter). These measurement results indicate that the proposed strategies can effectively eliminate hole-defects that are commonly seen in equispaced printing.