A numerical model-based deposition strategy for heat input regulation during plasma arc-based additive manufacturing

Abstract

Heat accumulation in metal additive manufacturing (AM) processes leads to the unstable molten pool size, nonuniform track morphology, excessive dilution, and even structural collapse. Therefore, appropriate heat input management to alleviate heat accumulation is critical for metal AM processes. In order to mitigate heat accumulation and achieve better geometric accuracy, this work develops an innovative 3D numerical model-based deposition strategy to regulate the heat input for the metal AM process. Specifically, the proposed deposition strategy involves two steps: (i) a thermal simulation of the deposition process via an intelligent heat source tracking algorithm, thereby outputting a series of heat source data to ensure a constant molten pool size of the 3D model, and (ii) the output heat source data are utilized to regulate the heat input point-by-point of the deposit in the subsequent AM process. The proposed deposition strategy is demonstrated for plasma arc-based additive manufacturing (PA-AM) of a 20-layer Inconel 625 thin-walled deposit. The surface quality is measured with a profiler and the deviation of the deposits in the building direction is calculated by image processing techniques. The results show that the proposed deposition strategy is superior in geometric accuracy compared with the conventional approaches (i.e., the introduction of interlayer dwell time) from the perspectives of the forming height, surface morphology, and vertical deviation in the building direction. Meanwhile, benefitting from progressive forming and thermal management, PA-AM through the proposed approach can significantly reduce the total deposition time and energy consumption.