**3. Results and Discussion**

#### *3.1. SPIF Process Investigation and Outcomes*

Since the excessive thinning of the sheet is one of the main drawbacks of the SPIF, the focus of the numerical simulation was kept on the resulting thickness distribution of the formed part. Figure 12 shows the calculated distribution of the section thickness (STH) mapped on the prosthesis at the end of the simulation.

‐ **Figure 12.** Numerical thickness map resulting from the FEM analysis of the SPIF process (dimensions: mm). ‐

‐ As expected, the minimum thickness is on the outer edge with a minimum value close to 0.9 mm, whereas the maximum thickness is located in the middle zone, being essentially equal to the initial sheet thickness (1 mm). The final geometry of the prostheses obtained by SPIF, after the cutting and drilling operations, is reported in Figure 13a; Figure 13b shows the cleaned prosthesis ready to be implanted. ‐

Figure 14 shows the obtained thickness map on the prosthesis and the corresponding frequency of the thickness values on the whole surface. The maximum and minimum thickness values, as well as their location and distribution, are close to those predicted by the numerical simulation.

**Figure 14.** (**a**) Thickness map of the prosthesis produced by SPIF and (**b**) frequency of the thickness values.
