Fabrication and evaluation of freeform surfaces in Directed Energy Deposition

Additive Manufacturing (AM) represents a paradigm shift in fabrication methodologies, enabling the creation of intricate geometries through sequential deposition. Among AM processes, Directed Energy Deposition (DED) is a metal-based technique that is particularly relevant for repair and remanufacturing applications, especially for high-value components. When coupled with 5-axis CNC, DED offers the unique ability to construct freeform surfaces, such as those typically found in the aerospace, marine and automotive industries. The focus of this research is to elucidate the interdependencies between the capabilities of a DED system and the achievable dimensional accuracy in freeform structures. To this end, on the basis of a parametrization approach, a comprehensive methodology has been formulated to tailor the design of a sinusoidal freeform to the capabilities and constraints of the specific DED system, taking into account, for example, the deposition head configuration and the number of controlled axes. The dimensional accuracy of the fabricated freeform was evaluated using 3D scanning technologies. The results showed that thermal distortion could significantly affect the geometry and may require thermal compensation. Additionally, acceleration transients may require appropriate path control strategies. The findings of this study offer valuable insights for future research on the influence of critical process parameters and production strategies on the dimensional accuracy of freeform components by DED.