Open Access

Fast dynamic part profiling during wire arc directed energy deposition (DED-Arc) is required to maintain the dimensional consistency of the fabricated part as it is printed over several overlapped tracks and successive layers. The metrology methods such as laser scanning, though accurate, are costly and less flexible for monitoring of layer-wise deposition. Photogrammetry is an optical measurement technique to reconstruct a 3D geometry using a series of 2D images in different orientations to ensure complete coverage. We propose here a novel attempt for rapid dimensioning of the deposit geometry using smartphone-based photogrammetry for wire arc directed energy deposition (DED-Arc). The recorded images from multiple viewpoints are used for feature extraction and matching and triangulation-based 3D reconstruction of the deposit geometry using open-source software. The reconstructed deposit surface is compared with the original CAD geometry to compare the dimensional consistency of parts during the DED-Arc process. Experimental validation is performed on both simple (cuboid) and complex (hollow cylindrical) aluminum geometries, as well as a steel deposit against laser scanning data. The results demonstrate that the smartphone-based photogrammetry can capture the layer-wise geometry variations with the maximum height deviations well within 15% of the laser scan measurements. Although reconstruction and post-processing times are slightly longer in photogrammetry, the approach provides a flexible, accessible, and cost-effective alternative for part profile monitoring.

Wire arc directed energy deposition (DED-Arc) using a gas metal arc (GMA) welding power source is cited as DED-GMA that fabricates a part by layer-by-layer deposition of molten wire droplets along horizontal and out-of-position inclined trajectories. For the out-of-position trajectories, a smooth deposition of material is impaired by the gravitational force on the molten wire droplets, resulting in uneven and inconsistent deposit profiles. We present here a detailed experimental investigation to realize the effect of the out-of-position inclinations on the quality of the deposited structure for DED-GMA with a steel and an aluminium filler wire. The evolution of the droplet transfer and melt pool during the out-of-position inclined deposition is probed through high-speed videography at different baseplate angles and commonly used scanning strategies. An analytical model is proposed further based on force equilibrium analysis for a prior estimation of the out-of-position inclined deposit profile, which can help design dimensionally consistent and structurally sound parts using DED-GMA.