Freeform fabrication of aluminum parts by direct deposition of molten aluminum

The use of molten aluminum droplets was investigated for the application of droplet-based manufacturing through the Internet. Three-dimensional parts made of pure aluminum were fabricated by depositing molten aluminum droplets, layer-by-layer, via computer information transferred through the Internet in a real-time mode. By applying a pulse pressure of argon gas, molten droplets were generated through a graphite nozzle with an orifice of 0.3 mm diameter. Typically, droplets were generated at the rate of 1–5 droplets per second. The initial velocity of the droplets, the amount and duration of the pulse pressure, and the pulse interval could be adjusted. In order to shorten the falling time of the droplets, the distance between the orifice and the substrate was set to 15–20 mm. The effect of droplet initial speed on the density of the fabricated 3D structure was investigated and the microstructure of the parts characterized.