Accelerating heat transfer modeling in material extrusion additive manufacturing: From desktop to big area

Abstract

Thermal modeling informs the understanding of cooling phenomena and structural evolution during material extrusion (MatEx) additive manufacturing to help predict and tune final part properties. For fused filament fabrication (FFF) and big area additive manufacturing (BAAM), in particular, thermal models are well-suited to augment parameter optimization and closed-loop control for high throughput manufacturing of custom parts and products. However, limitations in computational time, speed, and cost pose a challenge to modeling large structures with sufficient multi-dimensional granularity over extended timescales, with many models confined either to high-resolution studies on short length and timescales or low-resolution, lumped approximations for larger timescale simulations. Thus, the goal of this work is to develop a high-fidelity thermal model applicable from desktop to BAAM systems with minimal computational constraint. Here we present a scalable, 2D finite volume “proof-of-concept” model and algorithm to rapidly simulate thermal histories across both FFF and BAAM length and time scales. Our approach implements a two-dimensional implicit numerical strategy that confers reduced computational complexity while offering fine scale granularity in capturing critical inter- and intralayer cooling dynamics and radiative heat transfer. Further, analysis of the effective Biot number (Bi) reveals that, on the BAAM scale, layer width and radiative heat transfer both drive the formation of intralayer temperature gradients, exceeding 51 °C between the layer center and edge. We further simulate the fabrication of single road-width acrylonitrile-butadiene-styrene (ABS) walls at the BAAM scale (50 layers) to demonstrate both the relative speed of the computational approach and its ability to capture the complex dynamics of a multilayer build. The model agrees with published experimental measurements, and results gauge the influence of layer thickness and proximity to print bed on cooling behavior, with larger layers and separation from the print bed lending to longer periods for interlayer welds to form above the ABS glass transition temperature (Tg). Finally, a BAAM case study highlights the model’s utility in design for additive manufacturing (DfAM) and print optimization, demonstrating how changes in bed temperature and layer time can impact interlayer bonding.