Influence of dynamic wire feeding on metal transfer in laser-directed energy deposition (L-DED)

Dynamic wire feeding has recently emerged as a promising strategy to improve control over melt-pool dynamics and energy distribution in wire-laser directed energy deposition (WL-DED). Unlike conventional continuous feeding, where the wire maintains a stable liquid-bridge transfer, dynamic feeding introduces periodic advancement and retraction of the wire, enabling active modulation of local heat input and wetting behavior. In this study, high-speed imaging and quantitative analyses of melt-pool area, contact angle, and bead cross-sections were performed to compare continuous and dynamic feeding conditions. Continuous feeding provided stable melt-pool geometry and uniform bead morphology, while dynamic feeding introduced controlled fluctuations that allowed tailoring of energy density and interfacial stability. Frequency modulation revealed that lower oscillation frequencies favored pool expansion, whereas higher frequencies reduced energy accumulation, defining an operational window between stability and adaptability. Contact angle analysis confirmed that dynamic feeding actively altered wettability, and bead cross-sections showed narrower geometries with increased dilution under dynamic conditions. These results demonstrate that dynamic wire feeding is not a substitute but a complementary strategy to continuous feeding, offering new opportunities for adaptive control of melt-pool dynamics and deposition quality in WL-DED.