## 3 Results  
### Pin Manufacturing Process  
To gain a deeper understanding of the pin extrusion process, especially for non-rotationally symmetrical geometries, to verify the repeatability during extrusion and to investigate the extrusion process in more detail, the force-displacement data of the pin extrusion process were analyzed. Figure 5 shows the punch force-displacement curves averaged from four experiments for each of the pin geometries investigated. Furthermore, the standard deviation of the respective geometries is shown using an error band. Here, it can be seen that the standard deviation with a maximum value of \(\pm\)0.13 kN across all the investigated geometries is very low compared to the maximum forces between 18.23 kN for the elliptical 0\({}^{\circ}\) pins and 21.74 kN for the cylindrical pins. Comparing the maximum standard deviation of the different pin geometries, the cylindrical and polygonal blunt pins show the smallest deviations with \(\pm\)0.08 kN. In contrast, the deviation of the other geometries with \(\pm\)0.12 kN (polygonal sharp), \(\pm\)0.13 kN (elliptical 0\({}^{\circ}\)) and \(\pm\)0.13 kN (elliptical 90\({}^{\circ}\)) are on a slightly higher level. If we compare the force-displacement curves of the geometries formed in different orientations, i.e., the polygonal sharp and blunt as well as the elliptical 0\({}^{\circ}\) and 90\({}^{\circ}\), we see that the rotation of the polygonal geometry has only a very slight influence on the forming and thus the force-displacement curve, and thus the curves are almost identically superimposed. This can be explained by the fact that the general orientation of the geometry in relation to the rolling direction of the sheet does not change and thus similar forming conditions are present. Conversely, a comparison of the elliptical pins at 0\({}^{\circ}\) and 90\({}^{\circ}\) shows a deviation in the force starting at a punch penetration depth of around 0.6 mm. Here, the slope of the force-displacement curve is greater for the elliptical 90\({}^{\circ}\) pins than for the elliptical 0\({}^{\circ}\) pins. In this case, the rolling direction during cold rolling and thus the orientation of the grains of the sheets used for the extrusion of the pin structures is along the long axis of the ellipse in 0\({}^{\circ}\) and therefore along the short axis for the ellipse in 90\({}^{\circ}\). Consequently, it is possible that  
Figure 5: Punch force Fp to punch penetration depth s for the different pin geometries and different orientations. The curves are the average from four tests and the standard deviation is shown using error bands. for the 90\({}^{\circ}\) ellipses along the short side, a greater number of linear dislocations are necessary for the pin extrusion. However, this effect can only be detected as the punch penetration depth increases, as can be seen from Figure 5, since at the beginning of extrusion, the radial flow of material outward into the sheet plane is initially more dominant, and this is directionally independent [19]. The smaller the residual sheet thickness, the more dominant the extrusion into the die, and here the directional dependence due to the pin geometry can be detected. In Table 4, in addition to the force-displacement curves shown in Figures 4 and 5, the corresponding pin height, punch penetration depth, sheet thickness, relative punch penetration depth and residual sheet thickness averaged from a sample of n = 4 pins are listed for the different investigated pin geometries. Looking at the force-displacement curves shown in Figure 5 and the associated standard deviations, as well as the parameters relevant for pin extrusion shown in Table 4 and the respective standard deviations, it can be seen that both the process and the resulting pin structures can be assumed to be repeatable. When considering the pin heights and the required punch penetration depths, it can be seen that, compared to polygonal and cylindrical pins, the elliptical pin structures require a greater penetration depth.