Sustaining the inter-wire arc in twin-wire indirect arc welding

A study of sustaining or igniting the arc between tips of two wires in twin-wire indirect arc welding (TWIAW) with AC is challenging. In comparison with conventional gas metal arc welding (GMAW) where one of the arc terminals is the base metal which is stationary and large, both arc terminals in TWIAW are wire tips which are small and subject to variations. The alternating of the polarity among the two wires in AC TWIAW further increases the challenge in sustaining the arc between the two wires. To meet the challenges, i.e., sustaining the arc between the small and varying wire tips despite the alternating polarity, the effects on the arc behaviors from different working parameters are observed, measured and analyzed in this study. The inter-wire distance which characterizes the instability of the inter-wire arc between the two wires in TWIAW is found to increase as the AC current frequency, the inter-wire angle and the wire diameter decrease as well as the amperage of the current increases. This definite tendency provides the foundation to control the inter-wire melting and droplet detachment/metal transfer to successfully sustain the inter-wire between the two small wires dynamically such that the AC TWIAW may operate as desired to deliver its desirable properties-low heat input and high deposition rate.