Multi-Sensor Correlation of Torch Orientation and Energy Distribution for Tailored Process Manipulation in Arc-Based Directed Energy Deposition

Wire-arc directed energy deposition (WA-DED) using dynamic multi-axis hardware is typically restricted to a neutral position (90°), limiting process flexibility and full exploitation of multi-axis capabilities. To unlock torch positioning and stick-out distance as levers for tailored process manipulation, this study examines energy distribution across 124 samples using ER70S-6 filler wire. A 6 × 6 process window spanning wire feed speed (WFS = 2–7 m/min) and travel speed (v = 400–900 mm/min) was evaluated alongside continuous stick-out ramps (5–35 mm) and ten torch inclinations in push (45°, 60°, 75°), neutral (90°), drag (105°, 120°, 135°), and lateral (L15°, L30°, L45°) orientations. A synchronized multi-sensor framework captured electrical, thermographic, and melt pool dynamics while integrating airborne sound acoustic monitoring of process instabilities. Metallographic cross-sections, microhardness mapping, and EBSD grain analysis indicated microstructural shifts. Across the parameter matrix, volumetric energy density (VED) remained within 19–23 J/mm3 (measured), while thermal tracking revealed progressive heat accumulation. Stick-out extensions reduced heat input by 1.1–1.5%/mm, raising peak hardness in single beads from 290–310 HV to 350–385 HV. Torch orientation redistributed thermal energy at nearly constant heat and mass input. In the walls tested, melt pool length shifted by up to 30% and mean grain size by 11.1%, and penetration depth followed the push to drag sequence. Short-circuit frequency and cycle-period variation mirrored the approach to the humping limit, and acoustic envelope statistics accompanied overmelting. Thus, torch orientation and stick-out provide sensor-observable levers to influence process dynamics and component properties.