## 3 Results
### Effective Curling Height at Profile Sections of 3D Topology  
The evaluation of the generated height maps revealed the quantifiable characteristics of curling at the stages of pre- and post-coating. The analysis of the profile section at the post-coating stage in Figure 15a revealed slight deformation and thus an increase of height values close to the free edges of all build parts. Considering the course of height alongside the \(x\)-axis (b), peaks are visible and measurable at transition points from curled parts to the powder bed surface. For the variations in height, the maximum value of 80 \(\upmu\)m was detected at the left outside edge of the circular part. Figure 14: 3D topology of the powder bed surface (**a**) after laser exposure and related temperature distribution (**b**). A clear development of curling failure can be seen at the height map and the thermal image, even at the uncoated process state. Tagged line (**c**) as horizontal reference point for profile measurements to be discussed in Section 3.4. Figure 15: Height map at the post-coating stage (**a**) of a segment area of the powder bed surface. The corresponding profile section in (**b**) represents the deformation and thus height variation at the defined position on the \(y\)-axis. The visible peaks in the profile section (**b**) are tagged to the related segments at the topological map (**a**). While the analysis of the profile sections at the post-coating stage revealed slightly increased height values and subsequent drops at transition points, the pre-coating stage after powder melting provided completely different results regarding the progression of height values along the \(x\)-axis. Figure 16 shows the 3D topology (a) after laser exposure, which contains segment areas of merged powder resulting in negative values with respect to the powder bed surface, as well as curled peripheral zones at the free edges of all build parts. By analyzing the height values alongside the \(x\)-axis (b), a clear development of curling is demonstrated again, resulting in a curvature progression at the merged segments of the components. However, compared to the profile sections after recoating, strong distortiony peaks in height values are revealed at the transition points from curled parts to the powder bed surface. If the overall process of powder bed fusion is considered in detail, a transition area between merged build parts and the surrounding powder is proven according to the results shown in Figure 16. Within this transition area, non-related powder particles are partially molten and stick to the components due to heat conduction. The resulting area is not part of the actual component and forms a rough surface that must be sandblasted after removal from the powder bed. Another phenomenon called the capillarity effect, proposed by [PERSON] et al. in [51], could also contribute to the present measurement results in Figure 16. Their study examines the influence of surface tension on contour lines in Multi Jet Fusion. The capillarity effect results from the interaction between the detailing agents and the fusing agents during part building and determines a deviation of the upper planar geometries when close to the edges of the molten material and the powder bed. The uniformity of these phenomena is strongly influenced by the geometry of the layer. Although Multi Jet Fusion is a different manufacturing process, it could well be that there are similarities in the sub-processes and that this phenomenon amplifies the measurable curling effect in laser sintering as shown in Figure 16. The derivation of the respective peaks and their impact on the effective curling height (ECH) at non-coated process states is depicted in Figure 17.  
Figure 16: Height map at the pre-coating stage (**a**) of a segment area of the powder bed surface after laser exposure. The corresponding profile section (**b**) reveals strong peaks in height values at the transition points.