Impact of track length, track shape, and track location on thermal distortion in laser powder bed fusion of IN625: Single laser vs. three lasers

Laser powder bed fusion is a popular additive manufacturing process for creating complex metallic components. However, it has limitations in terms of build rate and component size. One potential solution to overcome these limitations is the utilization of multiple lasers for part fabrication. Nevertheless, thermal distortion poses a significant challenge in this approach. While several process parameters can be optimized to minimize distortion, the scan pattern is a critical factor. This study focuses on the design of efficient scan patterns to improve distortion in multi-laser powder bed fusion parts. Previous research has primarily explored default scan patterns like raster, spiral, and Hilbert. In contrast, this paper takes a fundamental approach by introducing customizable variables such as track length, track angle, and track location. The resulting paths are simulated using a commercially available thermo-mechanical solver to systematically evaluate their impact on melt pool dimensions, temperature evolution, stresses, and distortion. The findings indicate that multi-laser simulations consistently exhibit lower thermal distortion compared to single-laser configurations. Longer track lengths result in higher maximum displacement, while straight paths with a 0° track angle reduce distortion. Additionally, boundary conditions significantly affect distortion, and printing farther away from constrained edges proves beneficial in minimizing distortion. In conclusion, the insights derived from this study can be used to design of intelligent scan paths.