Research on lateral instability of the uniform-charged droplet stream during droplet-based freeform fabrication

A droplet initial displacement assumption was made and a dynamic model of the charged droplets was developed to understand the lateral instability of the uniform-charged droplet stream for freeform fabrication. The distribution of charged droplets depending on deposition distance was obtained based on this dynamic model after the droplet charge was calculated by the FEM. Then, a droplet charging and depositing apparatus is set up to generate the uniform-charged droplet stream. The droplet charge was measured and the droplet distributions at different distances were collected in the experiment. The results show that the theoretical radius of droplet distribution area agrees well with the mean experimental value at the deposition distance of 50 cm. The theoretical trend of droplet stream dispersion fits well with experimental result. The maximum accurate deposition distance within which the radius of distribution area is less than one droplet diameter is about 27 cm according to the prediction of droplet distribution, which provides the basis for further accurate metal droplet deposition.