Process planning strategy for wire-arc additive manufacturing: Thermal behavior considerations

Wire arc additive manufacturing (WAAM) has become a promising metal 3D printing technology for fabricating large-scale and complex-shaped components. One major problem that limits the application of WAAM is the difficulty in controlling the dimensional accuracy under constantly changing interlayer temperatures. During the deposition process, as the wall height increases, the heat accumulates on the upper layers, which leads to the variation of the layer dimensions. Normal practices such as introducing idle time and actively cooling the workpiece to mitigate such problems lack efficiency and practicality, respectively. A novel process planning strategy is proposed in this paper and aims to achieve a continuous deposition process while ensuring dimensional accuracy. With the aid of a finite element model, the typical thermal transfer cycle of the workpiece was analyzed and then divided into different stages. When depositing material, the interlayer temperature of the subsequent layers can be predicted using the developed algorithm. Hence, the process parameters (e.g., wire feed speed and travel speed) can be varied according to the predicted interlayer temperature using the developed adaptive process model, and this will ensure the uniform layer dimensions. The effectiveness of the proposed technique is verified by a large-scale shell-shaped component with a total of 753 layers. The result shows that such technique succeeds in a continuous fabrication of the component with high accuracy and efficiency.