PARAMETRICAL STUDY OF FOIL-BASED DUAL-LASER ADDITIVE MANUFACTURE, MODELING AND APPLICATION Yiyu Shen, Chen Chen, Hai-Lung Tsai ABSTRACT In our recently developed foil−based dual−laser additive manufacturing technology, laser welding of a foil layer to the previous layer (or substrate) plays a critical role in determining the quality and accuracy of the manufactured part. In this paper we conducted experiments to study the effects of laser power and laser scanning speed on weld penetration depth, weld shape, weld surface roughness, and weld stability. A mathematical model is also developed to help understand how the laser parameters affecting the welding process and subsequently the weld quality. The model was validated by comparing with the measured surface bead-width which is in about 6% discrepancy and there is an 8% discrepancy in weld depth. It was found that for welding low carbon foils of 150 µm thickness, a combination of 260 W laser power and 200 mm/s of scanning speed can achieve stable welding and very good weld quality. The model is being used to determine the maximum welding speed while minimizing the generation of surface ripples which is a major source of surface roughness.