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.

金属微滴3D打印是一种有效的增材制造技术，用于形成微柱结构。但是，支柱轮廓的控制机制仍不清楚。为了形成半径均匀的支柱，必须研究加工参数对支柱轮廓的依赖性。在这项研究中，使用3D数值模型来模拟和分析多个液滴的连续堆积过程。定义凝固的新来的液滴的凝固角度以表征柱轮廓。建立了凝固角解析方程。在这种情况下，可以通过热物理参数和初始条件来预测液滴的凝固形态。