## 1 Introduction  
This study relates targeted temperature manipulation in Extrusion Additive Manufacturing (EAM) to deposition parameters, external heating and cooling, and the resulting material behavior. We evaluate the potential of heating and cooling methods for EAM processes while creating a basis for further research efforts and in-depth analysis of the correlating mechanical performance. For the manufacturing of large and complex structural parts, the BMW Group has invested in the development of a custom build Freeform Extrusion Additive Manufacturing (FEAM) facility, which is a robot-based large format deposition system. While this technology aims to move from planar slicing to load path-oriented deposition, its extensive sensor equipment and real-time data acquisition make it well suited for planar parameter variations and investigations into technological enhancements. The use of short carbon fiber-filled thermoplastics in pellet form can further improve the mechanical properties of the polymer and drastically increase the throughput of the system compared to filament-based systems [1; 2]. While industries such as the aerospace, transport, and automotive sector have often used high-volume manufacturing processes, Additive Manufacturing (AM) poses new benefits in terms of individualization, low-volume productions, higher complexities, short lead times, and potential reductions in part costs, especially in prototyping [3]. Due to the vast variety of AM processes, the selection of suitable processes with their corresponding product chain becomes increasingly important [3]. With each different AM process posing new challenges for manufacturing parameters and part optimization, the main detriments and control levers have to be identified and investigated accordingly. The main challenge for most layer-based AM technologies is the directional bias [2; 4], which is particularly evident in tensile testing [5]. The material performance in the longitudinal strand direction depends mainly on the properties of the bulk material within the strand. However, the transverse strength in the z-direction depends on the bond formation across the interface, similar to weld lines, where the morphology is considerably different to that of the bulk [2; 5; 6; 7]. Since incomplete fusion bonding is the result of low molecular entanglement across the interface [6] and strong molecular chain alignment in the flow direction [8], the mechanical performance benefits from the use of polymers with low crystallinity, low coefficient of thermal expansion, and good thermal conductivity [9]. Due to strong crystallization at lower temperatures, this anisotropic morphology is much more problematic for semi-crystalline polymers than for amorphous polymers [10; 11]. Nevertheless, intensive thermal material characterizations and analyses of fusion bonding processes can be used to determine a suitable process window independent of the final extrusion process [11; 12]. Previous studies have shown that the interface temperature of semi-crystalline polymers must rise above the melt temperature of the polymer to enable sufficient molecular diffusion [13; 14]. However, for optimum part quality, good mechanical properties, and geometric integrity, the substrate temperature must be below the melt temperature and above the extrapolated onset of crystallization, while the extrudate temperature generally lies well above the melting point. When using carbon fiber-filled polyamide 6 (nylon), this indicates a process window for substrate temperatures between 166 and 221 \"C, corresponding to a narrow set of layer times [12; 15; 16]. Since FEM technology aims to produce large-scale complex parts, the layer times often exceed those proposed, resulting in insufficient fusion bonding across the interface and reduced mechanical strength [16].