## 2 Materials and Methods
### Cooling Wide  
The DoE for cooling the substrate temperature was quite similar to that of the heating experiment. Instead of infrared heaters, pressurized air was emitted from 1/4-inch flared nozzles. The infrared pyrometers were mounted at the same distance of 150 mm preceding and following the extrusion nozzle, and the air nozzles were placed between them at distances of 100 mm from the extrusion nozzle.  
Again, the full factorial investigation aimed to test experimental setups of different traversing velocities \(v_{TCP}\) (0.080 m/s and 0.160 m/s) and various substrate temperatures \(T_{sub}\). Contrary to the heating experiments, it was not possible to determine the substrate temperature prior to cooling, as the substrate temperature exceeded the melt temperature of 221 \({}^{\circ}\)C [12], and the parts collapsed. Therefore, the target temperature of the leading pyrometer during cooling was chosen as the second independent variable. The actual temperature at deposition had to be determined by additional experiments to capture the effect of the second cooling nozzle, which cools the substrate after the last pyrometer passes and before the new strand is extruded. The target leading temperatures we aimed for spanned the entire process window at 130 \({}^{\circ}\)C, 150 \({}^{\circ}\)C, 170 \({}^{\circ}\)C, and 210 \({}^{\circ}\)C with a tolerance of \(\pm\)2 \({}^{\circ}\)C. At substrate temperatures below 130 \({}^{\circ}\)C, the tensile properties lead to delamination, and for substrate temperatures above 216 \({}^{\circ}\)C, the part simply melts. The dependent variables investigated were, as in the heating experiment, the tensile strength and modulus; however, they were only investigated in the z-direction as the parts manufactured had to be so small in circumference that a sufficiently large longitudinal sample could not be taken.  
The distances were kept constant between the extrusion nozzle and the infrared pyrometers, as well as to the 1/4-inch flared cooling nozzles parallel to the strand. Other control variables included the volume flow of pressurized air at 50% of its maximum volumetric output, the screw speed, which corresponded to the specific traversing velocity, the heat zone temperatures, and the layer height. Due to the short layer times and reduced part size, only two to four transverse samples resulted from a single part. Therefore, each setup was manufactured multiple times until a sufficient number of samples were obtained. To avoid the effect of an altered heat chimney when reducing the part sizes, one of the long sides of the rectangle was positioned over the edge of the assembly bed, allowing the manufacture of a single wall with continuous circular movements.  
During manufacturing, it became apparent that only low temperatures could be realized, as the part would have to be smaller than possible to achieve shorter layer times and higher temperatures. Due to the large distance of 200 mm between the cooling nozzles and 300 mm between the pyrometers, the part size could not be reduced sufficiently. The next section presents a second stage of the cooling experiment with an adapted setup, which allowed all temperatures and velocities to be manufactured.