## 5 Conclusions  
The increase in part size and complexity in large-scale additive manufacturing has led to the need for targeted temperature manipulation within the process. With previous research confirming that the fusion bonding process is a largely temperature-controlled phenomenon, the hypothesis was presented that the mechanical properties of additively manufactured polymer parts could be tailored through the use of targeted heating or cooling. These heating and cooling mechanisms and their impact become increasingly relevant in large-scale extrusion additive manufacturing approaches in the automotive or aerospace sector, where large dimensions can only be achieved through systems without envelope heating or ambient temperature control. Through the use of a robot-based system and pelletized feedstock instead of filaments, the throughputs could be significantly increased to reach wall thicknesses comparable to injection molding around 3 mm. With samples manufactured with the FEAM cell at the BMW plant Landshut, tensile tests were chosen as readily available mechanical testing method to allow comparison to other EAM systems. Due to the extrusion unit being robot-based, the heating and cooling equipment had to be compact and easily integrable in a small installation space with flexible positioning. After hot air heating only obtained unsatisfying increases of the substrate temperature, a double infrared emitter system was installed for heating. Effective and robust cooling was achieved through pressurized air supplied 360\({}^{\circ}\) around the deposition nozzle by three separate slit nozzles. The hypothesis that the tensile properties after manipulation from a base temperature to a target substrate temperature would yield comparable results to unmanipulated samples at the specific target temperatures was confirmed for both heating and cooling. For the heating results, it was particularly interesting that the heated tensile samples yielded even significantly higher tensile strengths compared to the unmanipulated samples at the identical target temperature. Furthermore, the impact of the infrared emitters on the tensile strength increased for lower substrate temperatures, especially below the ideal processing window. Overall, the substrate temperature of large parts with long layer times was successfully raised by the infrared heaters, achieving comparable tensile strength and tensile modulus to unheated samples at corresponding temperatures. For future integration of the FEAM process in the automotive prototyping environment, this means that large and complex parts that exceed today's target later times due to increasingly long path lengths can be successfully manufactured without forfeiting the mechanical strength of the resulting part. In similar experimental setups, the cooling potential by pressurized air was investigated. Contrary to the hypothesis, the tensile strength obtained from the cooled samples yielded higher results than the comparable unmanipulated reference samples printed directly at the final substrate temperature. Particularly for tall parts with small cross-sections and thus very short layer paths, such as greenhouse pillars for vehicle prototyping, this is a significant improvement of the process. A now possible increase in traversing velocity reduces the printing time significantly, while ensuring dimensional accuracy, shape retention, and satisfying mechanical properties. It also became apparent that the tensile strength and modulus at lower substrate temperatures did not decline as much as predicted by the reference samples. It is suggested that this should be attributed to the cooling mostly affecting the outer surface of the strand with the core temperature remaining significantly higher than in the colder reference samples. This would lead to increased interface temperatures of the cooled samples and thus higher fusion bonding. To further investigate this thermal behavior, the authors suggest tactile measurements of manipulated and unmanipulated samples at the layer-to-layer interface.