Monitoring melt pool asymmetry in gas metal arc-directed energy deposition

Abstract

Cross-sectional asymmetry of melt pools along adjacent tracks results in an uneven build surface in gas metal arc-directed energy deposition. We present here a novel attempt on real-time monitoring of melt pool cross-sectional asymmetry in terms of its lateral and angular deviations from the track centreline using a two-colour quotient thermal camera. The melt pool lateral and angular deviations are found to be 2–3 mm, and 8–12°, respectively, for the range of process conditions. A unique analytical methodology is proposed that shows a hatch spacing of around 72–76% of the width of a deposited track can reduce melt pool asymmetry and layer height variations along adjacent tracks, which is also observed experimentally.