The effect of wire-feeding direction on quality and accuracy of unsupported wire arc additive manufacturing

The low accuracy of wire arc additive manufacturing (WAAM) is one of the main factors limiting its development, and is detrimental to the mechanical properties of WAAM structures. This study primarily investigated the effects of wire-feeding directions and positions of the molten pool on the quality and accuracy of unsupported WAAM. First, the three-dimensional (3D) morphology and volume of unsupported rods manufactured with different wire-feeding directions were quantitatively evaluated using a 3D scanning method. The effects of the wire-feeding direction and arc length on the volume and standard deviation of the unsupported rods are then discussed in detail. Finally, the influence of the wire-feeding direction on the quality and accuracy of unsupported WAAM is discussed and revealed by combining the temperature gradients, surface tension, and contact angles. The research revealed that feeding a wire into the high-temperature zone of the molten pool could reduce material spatter and achieve higher precision. The volume of the sample fed into the high-temperature zone was 120 % of that fed into the low-temperature zone. This reduced not only the material waste but also the standard deviation of the diameter of the same group of samples. This research is of great significance and value for high-quality unsupported WAAM.