Origin of deposition errors and layer-wise control strategies during laser additive manufacturing

Abstract

Although additive manufacturing (AM) is a net/near-net forming process, significant deviations may occur between the finally manufactured product and the designed object. This study is inspired by the deposition errors in a typical closed-contour structure manufactured via laser-directed energy deposition (DED). A series of experiments were carried out and a multi-physics mechanistic model was developed to reveal the origins and the spatiotemporal variations of the errors in representative processes. The results demonstrate that the irregularity of the deposition can be initiated by the liquid metal flow in the molten pool driven by forces including the recoil pressure and surface tension. The deviations are subsequently aggravated due to the inheritance between layers. Supported by the revealed underlying mechanisms, solution strategies including layer-wise dynamic compensations are thus proposed. The novel scientific findings can be insightful to researches for other metal AM processes and structures considering the universality of the uncovered mechanisms.

Keywords

• additive manufacturing
• deposition error
• molten pool
• liquid metal flow
• error control
• melting and solidification