## 4 Discussion  
_Support Structure Design Optimization and Support Removal Strategies_  
Support structure design optimization is the preliminary step in realizing the manufacturing of a filigree structure using the L-PBF method. The integrated experimental optimization approach utilized here was established with the purpose of minimizing three factors: manufacturing time, material consumption, and post-processing time. The benefits of limitless design freedom possible by L-PBF are often sabotaged by the requirement to incorporate additional support structures in order to manufacture overhanging components for various filigree structures. As a result, designing an optimum support structure based on the specific component geometry is required for the cost- and time-effective manufacturing of components utilizing L-PBF. The reduction in manufacturing and post-processing times, as well as the associated costs, leads to a further consensus on the manufacturability of a component after incorporating the appropriate support structure designs. As a conceivable support structure, a variety of geometrical patterns are feasible. Figure 14: Light microscopy images depicting the influence of ECP on the removal of support structures manufactured using strut thickness of (**a–d**) 1 mm and (**e–h**) 0.5 mm; for strut thickness of 1 mm specimens fabricated using (a,b) cross support, (**c,d**) line support; specimens before (**a,c**) and (b,d) after ECP; for strut thickness of 0.5 mm specimens fabricated using (**e,f**) cross support, and (**g,h**) line support; (**e,g**) specimens before and (**f,h**) after ECP. Strut thicknesses are mentioned in each image. In comparison to a complicated design, a simple design that meets the essential criteria is always favored [37]. The support structure optimization followed in the present study was based on a holistic approach combining a stable support structure design and its easy removal. An overview of the performance characteristics of the different support structure designs observed during the optimization procedures is compiled in Table 5.  
Most of the currently available L-PBF systems only allow the incorporation of a single powder handling system during manufacturing. Multiple powder handling systems might provide problems in terms of powder contamination and may not always be the best option [38]. As a result, it is always recommended to utilize the same powder material for both the component and the support structure. The use of the same powder material as the raw material for manufacturing support structures might result in higher material consumption and later in significant additional material wastage. Thus, the discarding of the support material often parallels the disadvantage of material removal in subtractive manufacturing methods such as machining. According to the performance attributes matrix in Table 5, incorporating a line support required the lowest amount of material and the shortest manufacturing time. Furthermore, the breaking load requirements were rather high, and support removal through all post-processing methods seemed straightforward. The improved line support design explored in this study as a combination of two lines connected with an included angle of 145\({}^{\circ}\) offered sufficient stability for the component during manufacturing. The choice of a 145\({}^{\circ}\) angle was made to minimize further material waste in the form of producing another support for the support structure. For any angle < 45\({}^{\circ}\) from the horizontal, the manufacturing of support structures requires the help of additional supports [23]. Thus, for the bottom part of the line support, an angle of 70\({}^{\circ}\) in the counterclockwise direction from the horizontal was chosen and, for the top part, an angle of 75\({}^{\circ}\) in the clockwise direction from the same horizontal. This makes the total included angle 145\({}^{\circ}\).