A Study on Optimal Welding Variables for Horizontal Fillet Welding Using Twin-Flux-Cored-Wires by Taguchi Method Combined with Grey Relational Analysis

The twin-wire welding process consuming the flux-cored wires as the filler material, namely TW-FCAW, was demonstrated to the fillet welding in the horizontal position. To determine the optimal welding variables that are most suitable for the multiple quality characteristics defined by the fillet weld sizes, the Taguchi method combined with the grey relational analysis was introduced into analyzing the experimental results from a test set of orthogonal arrays. Weld sizes, instead of macro-sectional observations, were calculated from the three-dimensional surface model generated from the point cloud survey of the fillet weld by the laser scanning technique. A set of optimal welding variables for TW-FCAW was drawn from the analysis of the signal-to-noise ratio calculated by the Taguchi method combined with the grey relational analysis. Fillet welding in the horizontal position was feasible under faster welding speed and higher welding current by TW-FCAW than the conventional single-wire welding process. A welding test conducted under the optimal condition for TW-FCAW revealed that a nearly equilateral fillet weld with a relevant throat thickness on demand is attainable in good agreement with the predicted quality.