This research investigates the drop-on-demand mode of single droplet generation and precise deposition methods for rapid prototyping. As practical examples of rapid prototyping, the behavior of dispensed droplets in continuous deposition modes including columnar deposition and sweep deposition have also been studied.

Major parameters affecting the generation of single molten tin droplet are investigated in the research. The study shows that the opening time of the solenoid valve, nitrogen supply pressure and the vent-hole size are the primary factors to produce a single droplet. The oxidation level plays an important role for the production of uniform spherical tin droplets.

Experimental results on the deposition of 0.6 mm tin droplets on a substrate demonstrate that droplets can be placed in a pattern with an average accuracy of 0.068 mm for a distance of approximately 4 mm between the nozzle and the substrate. In addition, the experimental study on continuous droplet deposition shows that remelting contributes to the fusion of droplets in columnar deposition with the droplet generator temperature of 300°C and the surrounding temperature of 200°C. It also shows that the overlap ratio of droplets deposition has a significant effect on the fusion of droplets in sweep deposition. The droplets tend to fuse with each other better when the overlap is greater. It is also found that the solidification angles for all experimental samples are greater than π/2. As demonstrated by the instability theory for a bead on a solid substrate, the non-uniformity and discontinuity presented in experimental results can be attributed to the instability of droplets in the formation of a smooth bead.