Compulsively constricted WAAM with arc plasma and droplets ejected from a narrow space

Abstract

In order to realize oriented wire and arc additive manufacturing (WAAM) featured by low heat input and small droplets, a novel compulsively constricted WAAM (CC-WAAM) method was proposed and investigated in this paper. The arc burned between a metallic wire and a tungsten electrode in a narrow-space nozzle. The proposed technology could provide compulsive constriction for arc plasma and liquid metal droplets using a cubic boron nitride (CBN) ceramic nozzle. The surrounding arc was ejected out of the nozzle and offered extra heating and a good shielding environment during the whole manufacturing process. The arc and metal transfer behaviors could be improved for better performance and higher quality. The economic and efficient new method is expected to solve the challenges faced by traditional WAAM such as excessive heat input and poor geometrical accuracy. Preliminary experiments showed that the two AM layers produced by the novel method had homogeneous microstructure distribution and fine grains. The geometrical dimensions of each layer can be effectively controlled by regulating the travel speed of the torch. The wide-range adjustable heat input can effectively control the state of the metallic formation, making it possible to realize an accurate control of the microstructure and properties.