**4. Discussion**

The result of the first simulation using a geometry of the flow channel with an area at the outlet of the head of 10 mm (**Figure 20** area in green color) generated high deformations due to the swelling effect of the melt, which means that there was no possiblity to calibrate and manufacture the profile to the required dimensions, as explained above.

Therefore, the model is modified by increasing the length of said area to 60 mm and it is simulated again, obtaining deformation values that are within the

**Figure 20.** *10-mm outlet area flow channel geometry (green area).*

recommended range. This length of the area of the molten profile outside the head is the one that is recommended to use for the extrusion of the same; that is, the distance between the head and the gauge should be of that magnitude to ensure proper calibration and not having clogging when the profile in the molten state enters the calibrator. When a vacuum is applied in the calibration-cooling pan, the molten material in the calibrator increases its cross section by copying the internal dimensions of the same and advancing with a continuous flow by means of the drag force, while it solidifies when immersed in water at 20°C. In addition, the software uses overlock optimization in the said exit zone, which is the one shown in this work, since by increasing the length of the free-flow zone at the exit of the head, the deformation due to the swelling effect of the fade decreases.
