Abstract
Wire-arc additive manufacturing (WAAM) provides an alternative for the production of various metal products needed in medium to large batch sizes due to its high deposition rates. However, the cyclic heat input in WAAM may cause local overheating. To avoid adverse effects on the performance of the part, interlayer dwelling and active cooling are used, but these measures increase the process time. Alternatively, the temperature during the WAAM process could be controlled by optimizing the welding power. The present work aims at introducing and implementing a novel temperature management approach by adjusting the weld-bead cross-section along with the welding power to reduce the heat accumulation in the WAAM process. The temperature evolution during welding of weld beads of different cross-sections is investigated and a database of the relation between optimal welding power for beads of various sizes and different pre-heating temperatures was established. The numerical results are validated experimentally with a block-shaped geometry. The results show that by the proposed method, the test shape made was welded with lower energy consumption and process time as compared to conventional constant-power WAAM. The proposed approach efficiently manages the thermal input and reduces the need for pausing the process. Hence, the defects related to heat accumulation might be reduced, and the process efficiency increased.
Highlights
Additive manufacturing (AM) processes are flexible manufacturing processes suitable for unit as well as small batch production [1]
The current work introduces and explores the potential of power-controlled wire-arc additive manufacturing (WAAM) to address the problems of heat accumulation
& In multi-layered WAAM parts, welding with the same bead cross-section and input power leads to heat accumulation as the distance of the layers from the substrate increases due to the higher pre-welding surface temperature and less heat conduction to the substrate
Summary
Additive manufacturing (AM) processes are flexible manufacturing processes suitable for unit as well as small batch production [1]. In the field of AM, wire-arc additive manufacturing (WAAM) is categorized as a directed energy deposition (DED) process in which a heat source melts a metal wire and deposits it by a computercontrolled motion layer by layer on the substrate [2, 3]. In comparison to powder-bed fusion AM processes, the cost and manufacturing time of larger components built through WAAM is lower as the deposition rate is much higher, i.e., of the order 2-4 kg/h [6]. The repeated heat input can produce high local temperatures in the work piece, so that a pause time is required before the welding process can be continued. Yang et al [14] described that with the increase in the welding layers, i.e., part height, the heat accumulation becomes more significant. According to Wu et al [15], the heat accumulation with increasing layers is due to the
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