Coaxial wire-based laser material deposition (LMD) is a high-productivity additive manufacturing process for metallic components. Owing to central wire feeding through a hollow beam caustic, it enables direction-independent deposition and is well suited for geometrically complex structures. However, complex geometries involve varying thermal boundary conditions along the deposition path, which affect local melt pool behavior and can cause geometrical deviations such as material accumulation at turning points or poor adaptation to changing wall thicknesses. Physics-based simulation therefore offers strong potential for designing adaptive process strategies.

This work presents a finite element model for the thermal simulation of coaxial wire-based LMD. The model accounts for the annular laser power density distribution characteristic of the coaxial setup and for the cooling effect of the continuously supplied filler wire. Because optical energy is absorbed and thermalized within a very small interaction zone at the material surface, laser-material interaction is represented by a von Neumann boundary condition. To describe material addition consistently, the model combines element activation using the death-and-birth method with continuously deformable finite elements.

The model is validated using single-track, overlapping-track, and multi-pass deposition experiments with 316L stainless steel and then applied to complex deposition scenarios. Results show that the framework can support adaptive parameter strategies to maintain a constant melt volume, particularly in critical regions such as turning points, thereby reducing local overbuild. It also enables tailored parameter adjustment for thin-walled components with varying wall thickness to achieve variable track widths at constant layer height.