Thermal Layer Design in Fused Filament Fabrication

Abstract

The current limitations of design for additive manufacturing (DfAM) are the state of knowledge on materials and the effects of production parameters. As more engineering-grade polymers become available for fused filament fabrication (FFF), the designs and processes must be adapted to fully utilize the structural properties of such materials. By studying and comparing the production parameters of a material test specimen and a component, the effects of layer temperature on the strength, surface roughness, and dimensional accuracy of PA6-CF were found. As the cross-section increases in component manufacturing, maintaining the layer temperature becomes a major challenge. From the findings, the concept of thermal layer design (TLD) was introduced as a way of increasing strength via temperature in selected regions after presenting the effect of layer temperature. TLD proved to have a major effect on layer temperature and heat distribution. Depending on the investigated layer temperature, from 147 °C to 193 °C the UTS of PA6-CF increased from 42 MPa to 73 MPa. Implementing TLD in DfAM represents a big leap for designing high-performance polymer components.

Sensing in-Situ Temperatures by Coordinates in Fused Filament Fabrication for Identifying Interlayer Anisotropic Mechanical Properties and Enabling Post-Fem Analysis

“…FFF components are inherently anisotropic due to different mechanical properties parallel or normal to the layer orientation and raster angle (Koch et al, 2017). Therefore, the experiment uses hardware and custom GCode to map previous layer temperature to identify interlayer bonding and mechanical anisotropy based on results by Bjørken et al (2022). Voron printers are known for their build quality, customizability, precision at high speeds, and ability to print engineering materials at high flow.…”

“…A complete thermal map of the component yields full process control of how bed temperature, nozzle temperature, print speed, chamber temperature, humidity, and layer area impacts the actual layer bonding. By measuring the temperature in situ, the Δt within each layer can be used to determine the mechanical properties, as demonstrated by Bjørken et al (2022). The Δt within each layer will also wary depending on size and geometry, and change as layers change during the component print.…”

“…An experimental, in -process way of thermal mapping instead of complex heat equations for the FEA mesh used for bonding calculations would make it possible to document the calculated layer adhesion for individual components. Calculating bonding strength is possible because a printed part's UTS results from layer temperature (Bjørken et al, 2022) and parameters like chamber temperature (Zawaski and Williams, 2020). With enough experimental data, FEA could predict the bonding strength based on layer area, layer time, bed temperature, and chamber temperature for any printer or component, which could then be experimentally validated by continuous monitoring of the layer temperature during printing.…”

“…If provided with experimental mechanical properties, calculating thermal evolution between layers and predicting bonding strength is possible with transient heat equations and finite element analysis modeling (FEA) of a single line component (Khanafer et al, 2022). FEA computations for more complex geometries can optimize a part for stronger layer adhesion by altering the design of specific component sections to retain more heat between layers in a thermal layer design process (Bjørken et al, 2022). Thermal evolution inside complex geometries is hard to predict.…”

Creating an Open-Source, Low-Cost Composite Feeder Design to Improve Filament Quality of High-Performance Materials to Be Used in Fused Filament Fabrication (Fff)

“…Filaments with long fibres are hard to obtain commercially, as the fibre length often wary between 80µm and 300µm due to compatibility with standard nozzle sizes. By creating their own filament, researchers may be able to develop and test new materials for high-performance AM parts (Bjørken et al, 2022). Fibre length beyond 1mm has proven to enhance the strength of injection moulded components (Botelho et al, 2003;Calignano et al, 2020) and could be compatible with AM by increasing nozzle size.…”