A Physical Comprehensive Model for Studying Temperature Evolution in FDM 3D Printing

Abstract

Abstract Along with emerging engineering requirements in multiple fields, how to fully realize the three-dimensional (3D) design has become a critical manufacturing challenge. To tackle this challenge, there is continuous research in recent years for development of additive manufacturing processes, that is 3D printing techniques. Fused deposition modeling (FDM) is one among the most extensively studied 3D printing techniques that generate 3D models, prototypes and especially end products from polymers. FDM printer uses a continuous filament of thermoplastic polymer or its nanocomposite, which is fed to the heated printer extruder head and then deposited onto the growing work. This technology offers multiple advantages over existing techniques, including fabricating complex designs, multi-material printing, rapid prototyping, high spatial resolution, on-site and on-demand production, as well as efficient material utilization with little or no waste. For example, according to existing literatures related to the FDM technique, various polymers, and their composites, such as ABS, PLA, PE, PEEK, Nylon, etc., have been designed and applied to build functional structures. In spite of current research and advancement, there are still limitations and disadvantages reported regarding FDM, e.g.., the lower strength exhibited in FDM parts compared to those by injection molding or compression molding techniques. Reasons could be explained by the insufficient bonding between the adjacent layers and the distorted shape of extruded polymers while printing, which hence needs to be improved by controlling the temperature related parameters, such as the speed of printing, temperatures of nozzle and bed. Therefore, validated by the videos from thermal camera, we here propose a new physical comprehensible model to simulate the temperature evolution during FDM 3D printing. In specific, we use finite element method (FEM) to build a heat transfer model with element activation function in ANSYS. Each element simulation is activated for multiple layers with over 1000 elements each layer at the bottom, middle and top of the sample to simulate the drop-by-drop and layer-by-layer extrudate “printing” behavior. The mesh temperature and element initial temperature are set as the same values to the bed and nozzle temperature, while the time interval of adjacent elements is set according to the printing speed in experiments. Thermal videos are generated by FLIR A320 Tempscreen from Teledyne FLIR. To further prove the accuracy of the FEM model, we collect and compare the temperature plots of the same area in thermal video and simulation. This work not only introduces a new physical comprehensive FEM model for FDM 3D printing process but also shed light on the printing process optimization and potential new future process development.