Research on the solidified morphologies of successive pileup metal droplets

Metal micro-droplet 3D printing is an effective additive manufacturing technique to form micro pillar structures. However, the control mechanism of the pillar contour is still unclear. To form a pillar with uniform radius, it is essential to investigate the dependence of processing parameters on pillar contours. In this study, a 3D numerical model was employed to simulate and analyze the successive pileup processes of multiple droplets. The solidification angle of solidified new-coming droplets is defined to characterize the pillar contour. An analytic equation of solidification angle was established. In this case, the solidified morphology of the droplets could be feasibly predicted through thermophysical parameters and initial conditions. This work provides good physical understanding of the complicated mechanisms for fabricating a pillar structure by means of the successive pileup of molten metal droplets, and paves the way for pillar contour control.