Simulating the build shape for a shell structure for wire and arc additive manufacturing using the bead cross-section model

Abstract

Wire and arc additive manufacturing is one of the additive manufacturing processes based on arc welding technology and is particularly useful in fabricating large-sized die and prototype machine parts. In general, a computer-aided manufacturing (CAM) system is required not only to generate the deposition path as a numerical control data but also to estimate the shape of the build structure. Estimating the build structure before the actual fabrication can help determine the optimal process parameters. However, the build structure simulated using the existing CAM system may not be sufficiently accurate, because the bead geometry is influenced by various factors, such as the process parameters, material type, target shape, and the location in which the molten metal is deposited. In this scenario, it is challenging to obtain the optimal process parameters based on the build structure simulation results. Therefore, in this study, a two-dimensional bead cross-section model was established, in which the bead accumulation was considered to fabricate a shell structure, and a build shell structure simulator was developed. The temperature distribution was numerically simulated to obtain the relationship between a process parameter and the bead cross-section geometry without conducting destructive inspection. Furthermore, the accuracy of the simulator was investigated. The results indicated that the accuracy of the simulator was approximately ±1 mm in the area with a low influence of the deposition start and stop processes.