Forming characteristics of additive manufacturing process by twin electrode gas tungsten arc

Traditional gas tungsten arc-based additive manufacturing (GTA-AM) system normally applies high-level deposition current to achieve a high deposition rate. Due to the induced high arc pressure, defects (e.g., humps) may always happen, which made the deposited beads unsuitable for additive manufacturing (AM) purposes. To solve this issue, a twin electrode approach has been applied in an implemented GTA-AM system, which achieved high deposition rate while kept the arc pressure with a relatively small value. The objective of this paper is to investigate the principles of using the twin electrode GTAW approach in an AM context. This paper first explored the maximum allowable wire feed speed (MAWFS) with regard to the deposition currents ranging from 200 to 450 A. A piecewise linear model was established to represent the relationship between the MAWFS and the current, which formed a basis for defining the feasible range of travel speed at a given deposition current. To validate the proposed principles, a case study was conducted, in which a set of deposition parameters were determined for fabricating a cube part. The deposition rate of twin electrodes GTA-AM is up to 2.7 kg/h, which is almost twice as much as that of traditional GTA-AM.