Investigation of the molten droplet deposition offset based on the simple-component pseudopotential model

Abstract

Metal droplet deposition manufacturing is an additive manufacturing technique that relies on the accurate prediction of deposition position, but is influenced by the wetting degree of solidified surface and the substrate. In this paper, a modified solid discriminant function is proposed for the simple-component pseudopotential model in the lattice Boltzmann method. The results show that the wetting degree of the substrate and the pre-solidified droplet causes the post-deposited droplet to deviate from the initial deposition distance Li* under interfacial tension, producing an offset δL*. However, the solidification effect inhibits spreading and rebound motion, thus changing the actual δL*. Under the solidification effect, different wetting degrees show that the horizontal deviation is more influenced by the pre-solidified droplet than the substrate and can be linearly predicted. The deposition can be divided into two stages depending on the attraction and repulsion motions of the droplets. In the attraction stage, the droplets form a three-phase contact line with the solidification surface, generating the pressure drop with the negative horizontal component under capillary expansion. In the repulsion stage, the second contact line is formed on the substrate, generating a smaller pressure drop in the horizontal direction. The essence of the difference effects of the two surfaces lies in the contacting duration and direction. Based on the principle of deposition deviation proposed in this paper, it will help to optimize the process parameters and improve the molding accuracy.