Multi-nozzle molten metal droplet jetting

• A novel metal additive manufacturing method is presented in which molten metal droplets are ejected from an array of nozzles to form the 3D part geometry. • High material deposition rates are possible without any compromise in feature size due to the small droplet sizes. • Spacing between concurrently printed tracks of material can be varied by changing the printing skew angle. • Preliminary results with the proposed method are demonstrated with 2D and 3D shapes. Molten metal droplet jetting (MMJ) is an emerging metal additive manufacturing (AM) technology that can use low-cost wire, rod, or even ingot feedstock material. This paper describes the architecture and preliminary implementation of what is believed to be among the first demonstrations of MMJ with a multi-nozzle array that is akin to inkjet printing using molten metal as the ink. A multi-nozzle printhead with a communal reservoir and three piezoelectric actuator pistons is presented. The drive waveforms for each nozzle are independently addressable, thus enabling precise control over drop placement for raster printing of arbitrary layer shapes. A jetting strategy is described in which variable track spacing is achieved by altering the yaw angle of the printhead. This yaw angle method allows printed row pitches that are less than or equal to the nozzle pitch. The printhead and build strategy are applied to demonstrate feasibility of the method with single and multi-layer test sample geometries. The influence of these initial results on future multi-nozzle systems is discussed.