3.1.3. Digital Model Repair

Once the detection and categorization of problems derived from the geometry is generated, it is required to correct the errors (overlaps, intersections...) and their subsequent transformation into solid geometry.

In the surface environment of Fusion 360, the stitch tool allows the surface to be sewn, and if it detects that the selection is a closed surface, it will convert it directly into a solid. If it were not a closed element, the interface highlights the perimeter lines of open surfaces in red (see Figure 3). In this case, the thicken tool can be applied to give thickness to the surface and convert it into a solid with the dimension that we have requested.

**Figure 3.** (**a**) Open surface detected through Stitch tool. (**b**) Subassembly 8 plan.

Once this process is completed for each subassembly, it is possible to start the creation of plans for manufacturing. In Figure 4b the planes of the Subassembly 8 are shown. Once all the surfaces are transformed into solids, all the parts (pieces, screws, and nuts) that make up each subassembly of the complete model can be quantified (Table 2).

**Figure 4.** (**a**) Piece without screws in Fusion 360. (**b**) Piece with screws in Fusion 360. (**c**) Piece printed with screws.


**Table 2.** Frequency analysis of pieces that integrate the SO/PHI subassemblies.

3.1.4. Digital Model Restructuration to Optimize Their Manufacturing

It is essential to group geometries to optimize printing times. In particular, the screws and nuts (and other small elements) associated with each subassembly can be grouped in such a way that they can be printed in a single process. Screws and nuts can be embedded in subassembly parts since their mechanical operation is not necessary (i.e., Figure 4).

To shed light on the decrease in printing parts that this process entails, Table 3 presents data on the reduction of parts for Subassembly 8. In this case, the percentage of parts removal is 83. This situation is analyzed for each of the assembly subassemblies.


**Table 3.** Simplification of pieces of Subassembly 8.

In Figure 5, the geometric modeling of Subassembly 8 is exposed graphically, before and after restructuring the model for manufacturing.

**Figure 5.** (**a**) Original subassembly 8 (82 pieces). (**b**) Subassembly 8 prepared for manufacturing (14 pieces).
