# Thermal Layer Design in Fused Filament Fabrication
## 5 Conclusions  
Based on the findings from material testing, it is evident that the layer temperature of PA6-CF plays a key role in the quality of the bonding during FFF. It affects properties such as the ultimate tensile strength, surface roughness, and geometrical tolerances. The results show how the optimal layer temperature range from 166 to 175 \({}^{\circ}\)C provides the highest UTS, and how UTS and dimensional tolerances are affected at different layer temperatures ranging from 147 \({}^{\circ}\)C to 193 \({}^{\circ}\)C only with minor changes in surface roughness. A thermal imaging analysis provided insight into the development of the layer temperature and how it decreases over time, as well as how the temperature is distributed through multiple layers of specimens during manufacturing.  
The component data reveal the extensiveness of the reduction in the expected material properties. The thin-walled sections cool down far below the optimal temperature range before a new layer is applied. By utilizing thermal layer design when creating components, the thermal properties of the layers may be significantly improved. The layer temperatures in the TLD component in this paper are more evenly distributed, leading to more uniform properties throughout the cross-section.  
With the implementation of TLD, significant improvements can be made in DfAM applied to engineering polymers and polymer composites. More knowledge on and research into TLD for engineering polymers are needed to realize the market potential for specialized AM components manufactured with FFF. This will make it possible to tailor a component design to achieve the best possible material properties and produce predictable, high-quality components. By simulating the layer temperature in components based on the input from the process, a future algorithm can implement TLD, increasing both the strength and quality of components. These are crucial steps if FFF of engineering polymers and polymer composites are to be employed for end-use parts.  
The results from the material testing begin to provide insight into how materials must be optimized during the manufacturing process to ensure the highest quality and strength possible while improving the metrology of the process to further improve the process and application of TLD in the future.  
Conceptualization, O.U.B., B.A., S.W.E. and C.W.E.; Data curation, O.U.B., B.A., S.W.E. and C.W.E.; Formal analysis, O.U.B., B.A. and C.W.E.; Investigation, O.U.B., B.A., S.W.E., M.S. and C.W.E.; Methodology, O.U.B., B.A., S.W.E., M.S. and C.W.E.; Project administration, M.S. and C.W.E.; Supervision, S.W.E., M.S. and C.W.E.; Visualization, O.U.B., B.A., S.W.E. and C.W.E.; Writing--original draft, O.U.B., B.A. and S.W.E.; Writing--review & editing, O.U.B., B.A., S.W.E., M.S. and C.W.E. All authors have read and agreed to the published version of the manuscript.  
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.  
Not applicable.  
Data available on request from corresponding author.  
The authors declare no conflict of interest.