Numerical Simulation and Optimization of Droplet Transition in Bypass-Coupled Twin-Wire Indirect Arc Welding: Insights into Parameter Effects and Process Stability

Abstract

This study develops a numerical model for droplet transition in Bypass-Coupled Twin-Wire Indirect Arc Welding (BC-TWIAW), integrating electromagnetic and hydrodynamic interactions. Experimental validation confirms the model’s reliability with less than 10% error. Analysis reveals that shielding gas flow rate, welding current, and wire feed speed jointly govern droplet transition: gas flow rate exceeding 21 L/min or excessive wire feed speed destabilises the transition, while balanced parameters suppress splashing. The bypass current critically controls the positive droplet stability, evidenced by smaller offset distances at currents between 90-110 A. The main current, optimal in the range of 110-130 A, along with the wire feed speed, regulates droplet size and transition frequency. An unbalanced mix between wire feed speeds—positive speeds between 0.1025 and 0.1225 m/s and negative speeds between 0.14 and 0.16 m/s—optimises droplet growth and detachment. The identified optimal ranges achieve stability by balancing electromagnetic forces and droplet dynamics, providing a transferable framework for multi-wire welding processes. This work advances process control strategies through systematic parameter space exploration, providing new insights into the optimisation of other welding processes and the control of droplet transition.