Towards control of liquid-layer deposition over topography in additive manufacturing

A well known additive manufacturing technique, stereolithography, uses a liquid photopolymer selectively solidified by a UV laser. Mechanical properties of the final product as well as dimensional accuracy depend significantly on the quality of the liquid-layer deposition leading up to the irradiation step. Since the building geometry can vary in the direction of recoater movement, the deposition of liquid resin onto the surface of a previously cured layer is not a trivial issue. This study focuses on the understanding how the underlying geometry influences free-surface deformation during the liquid layer application. For this purpose, CFD simulations are used which allow to account for surface tension together with moving objects over varying topography. The problem is modeled assuming a 2D configuration, and the used range of parameters (such as recoater speed and spatial dimensions of topography and recoating system) cover most of the typical values used in modern apparatuses. The results are compared with experiments. We want to use our understanding of the liquid-layer deformation as a function of topography to develop a control system for uniform layer deposition.