| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 780442 | International Journal of Machine Tools and Manufacture | 2016 | 8 Pages |
•A novel drop-on-demand generator for ejecting micro metal droplets was proposed.•A rod was used to transfer the impact vibration into the liquid metal.•This proposed generator works in two working modes by changing the rod fixation methods.•The mono-sized metal droplet was ejected on demand in both working modes.•The droplets with a diameter of 0.55±0.07 times the nozzle diameter were obtained.
On-demand metal droplet deposition will be a cornerstone technology in 3D metal printing. However, suitable small nozzles are hardly available, limiting the resolution and surface finish of final products. Here, the ejection of record-small metal droplets with a diameter of only 0.55±0.07 times the nozzle diameter was demonstrated. To this end, a novel metal drop-on-demand (DoD) generator for high-temperature metal processing was designed and manufactured. A metal rod was utilized to transfer a vibration pulse, which was required to eject a liquid droplet, from a low-temperature region to the high-temperature liquid metal close to the nozzle. The influence of the pulse characteristics on the droplet ejection regime was studied experimentally and numerically. A 2D axisymmetric numerical model revealed that the shorter pulses allow reducing the droplet size, with the pulse duration of 13 μs resulting in the smallest feasible droplets. A novel method to create such short pulses, by impacting the metal-ring connected rod with a solid impactor was manufactured and tested, and the benefits of this method over more the spring-type pulse transfer was experimentally confirmed. This research provides a feasible way to achieve ejection of the small metal droplet on-demand.
