Effect of arc length on deposition characteristics in rotary tungsten inert gas (TIG) torch

Abstract

A rotary tungsten inert gas (TIG) torch has been developed to enhance the quality and complexity of fabrications in wire and arc additive manufacturing (WAAM). This study explores the influence of arc length on deposition characteristics within a rotary TIG torch by adjusting the wire feed speed, travel speed, and shielding gas type. The findings reveal that the unique vertical wire feeding mechanism of the rotary TIG torch prevents the wire-feeding position shift typically observed in conventional TIG processes. However, extended arc lengths in the rotary TIG setup tend to induce arc deflection and molten metal scattering due to the employment of a tilted electrode. Specifically, at high wire feed and travel speeds, bead continuity is compromised by molten metal scattering. Conversely, at low travel speeds relative to wire feed speeds, defect-free deposition is achievable across a broad arc length spectrum from 4 to 20 mm using rotary TIG. Furthermore, decreasing the wire feed speed in proportion to the current and increasing the heat input per material input minimizes the contact time between the wire and the molten pool, thus mitigating arc deflection. Employing helium-mixed gas as a shielding gas facilitates defect-free deposition over an extensive range of arc lengths, even under conditions that typically induce humping with pure argon.

Keywords

• tungsten inert gas (tig) welding
• wire and arc additive manufacturing (waam)
• wire-arc directed energy deposition
• arc length
• shielding gas