High-throughput directed energy deposition process with an optimized scanning nozzle

Abstract

Research on additive manufacturing (AM) is being actively conducted in various fields in order to efficiently manufacture complex three-dimensional structures. In particular, metal powder feedstock and lasers are being used by the manufacturing industry to fabricate mechanical components and parts, such as propellers, fuel nozzles, and vehicle equipment. We developed an approach, scanning- directed energy deposition (S-DED), in which a high-throughput DED method with a scanning nozzle was established that could create metal beads of exceptional quality with high productivity using metal powder. The S-DED nozzle was designed based on a numerical simulation of the particle fluid flow, which was verified through a deposition experiment. Before the simulation, the deposition efficiency and shape of the bead were assumed according to the shape of the nozzle and the distance between the nozzle and the surface of the base material. The optimal inlet supply angle was determined by changing the powder flow inside the nozzle; the optimal number of outlet channels was determined by analyzing the amount of powder deposited by the laser beam irradiated on the base material. It was found that the laser beam improved the productivity by shaping the existing Gaussian beam into an 8 × 3 square flat-top beam. As a result of the simulation, it was proved that the angle of the inlet (that supplied powder to the nozzle) influenced the flow of powder finally captured in the laser beam. Based on the simulation, the angle of inlet was selected as 75°, and the number of outlet and cooling channels was five and three, respectively. A cross section of the specimen was analyzed using a single bead and multiple layers.