Investigation of a multi-cathode TIG arc process for additive manufacturing applications

Abstract This study investigates a novel tungsten inert gas double-electrode (TIG-DE) welding process with integrated coaxial hot-wire feeding for additive manufacturing applications. By combining arcs generated by multiple cathodes with independent wire preheating, the process aims to overcome the limitations of conventional single-electrode TIG systems, particularly with respect to directional dependence and limited deposition rates. A custom-built demonstrator system was used to systematically analyze the arc behavior, weld bead formation, and process stability under various parameter conditions. Arc pressure measurements confirmed the isotropy of the arc shape under optimized electrode configurations. Blind seam trials in orthogonal directions revealed minimal geometric deviations, verifying the directional independence of the process, which is a major advantage over conventional processes. The integration of an ohmic preheating unit enabled stable wire feeding at high speeds and significantly reduced eccentricities of the weld bead. Compared to the cold-wire TIG process, the hot-wire process exhibited a broader process window and higher productivity, with deposition rates exceeding 1 kg h $$^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:mmultiscripts> </mml:math> and seam height deviations consistently below 1 mm. These findings highlight the capability of the developed process to enable geometrically consistent and directionally independent layer buildup, providing a robust foundation for further development of wire-based additive manufacturing using TIG technology.