Surface flatness and height dimensional control of complex structural components with wire arc additive manufacturing

Wire arc additive manufacturing (WAAM) is currently one of the most promising technologies for manufacturing large-scale structures; however, its surface quality and dimensional accuracy urgently need to be addressed. Currently, research on WAAM shape control focuses primarily on single structural parts. Therefore, this study analyzes multiple factors that affect the surface smoothness of complex structural samples using proportional-integral-derivative (PID) control for the dynamic adjustment of wire feed speed to achieve superior surface flatness and establishes corresponding layer height deviation models and parameter self-learning algorithms. By controlling the surface flatness, the surface height difference could be reduced from 8 to 2 mm in the four layers. By the 30th layer, the variation in height was reduced by 88.4% compared with uncontrolled samples. Based on the surface flatness control, a closed-loop height dimensional control system was established. Under closed-loop height dimensional control, the error of the inclined edge of the sample was reduced to 0.87 mm, a decrease of 74.9%, achieving surface smoothness and dimensional precision control for intricate samples. Moreover, the sample exhibited an increase of 48.3% in the maximum available weld bead width and 40.0% in the maximum available area proportion, which significantly reduced the material removal rate.