## 3 Results and Discussion  
### D Surface Analysis  
Tightness tests against the generated surfaces at various compressive forces were carried out on 42 prepared samples. Among the manufactured parts, six groups were  
Figure 5: Diagram of the stand for testing the tightness of samples. \begin{table}
\begin{tabular}{c c c} \hline
**Range** & **Accuracy** & **Maximum Resolution** \\ \hline
0–50 Pa & \(\pm\)(1.5\% \(\mathrm{\,dP}\;+0.5\mathrm{\,Pa}\)) & 0.01 Pa \\ \hline
0–500 Pa & \(\pm\)(1\% \(\mathrm{\,dP}\;+1\mathrm{\,Pa}\)) & 0.1 Pa \\ \hline
0–5000 Pa & \(\pm\)(1\% \(\mathrm{\,dP}\;+10\mathrm{\,Pa}\)) & 1 Pa \\ \hline \end{tabular}
\end{table} 
Table 5: Ranges of the device for measuring the pressure drop \(\Delta\mathrm{P}\) where \(\mathrm{dP}\) is the measured value of the pressure drop, with permission from Ref [31], 2022, ATEQ. selected using the surface roughness \(Ra\) as a preliminary criterion. The value ranges of the adopted initial classifying feature for individual sets of samples were as follows: 4.24-4.32 \(\upmu\)m, 2.79-2.87 \(\upmu\)m, 1.26-1.34 \(\upmu\)m, 1.34-1.42 \(\upmu\)m, 0.14-0.22 \(\upmu\)m, and 0.06-0.14 \(\upmu\)m. Then, the \(Ra\) parameter, used initially, was replaced by the surface topography parameters. These parameters describe the actual surfaces more reliably, which allows for a more detailed analysis of the influence of the surface topography on the leakage value. Due to the analysis of the surface topography, the pre-selected parameter was changed into groups of parameters describing the generated surfaces--coded A, B, C, D, E, and F. The samples belonging to code group A were characterized by surface parameters with the following values: \(Sq\) = 6.53 \(\upmu\)m, \(Ssk\) = \(-\)0.425 \(\upmu\)m, \(Sku\) = 2.36 \(\upmu\)m, \(Sp\) = 12 \(\upmu\)m, \(Sv\) = 11.7 \(\upmu\)m, \(Sz\) = 23.7 \(\upmu\)m, \(Sq\) = 5.24 \(\upmu\)m, \(Spd\) = 275 1/mm\({}^{2}\), and \(Spc\) = 27,565 1/mm\({}^{2}\). The sample surface was generated by turning on a numerical lathe with the feed parameters \(f\) = 0.3 mm/rev and the cutting speed \(vc\)\(\approx\) 100 m/min. Figure 6 shows the morphology of the generated surface. The code group B was characterized by surface parameters with the following values and measurement errors: \(Sq\) = 3.92 \(\upmu\)m, \(Ssk\) = 0.083 \(\upmu\)m, \(Sku\) = 2.03 \(\upmu\)m, \(Sp\) = 9.1 \(\upmu\)m, \(Sv\) = 5.86 \(\upmu\)m, \(Sz\) = 15 \(\upmu\)m, \(Sa\) = 3.29 \(\upmu\)m, \(Spd\) = 394 1/mm\({}^{2}\), and \(Spc\) = 14,779 1/mm. The sample surface was generated by turning on a numerical lathe with the feed parameters \(f\) = 0.2 mm/rev and the cutting speed \(vc\)\(\approx\) 100 m/min. The samples belonging to code group C were characterized by surface parameters with the following values: \(Sq\) = 2.55 \(\upmu\)m, \(Ssk\) = \(-\)0.112 \(\upmu\)m, \(Sku\) = 2.06 \(\upmu\)m, \(Sp\) = 5.66 \(\upmu\)m, \(Sv\) = 4.06 \(\upmu\)m, \(Sz\) = 9.72 \(\upmu\)m, \(Sa\) = 2.14 \(\upmu\)m, \(Spd\) = 671 1/mm\({}^{2}\), and \(Spc\) = 8351 1/mm. Contrary to the previous parts, the sample surface was generated in the milling process on a numerical milling machine with feed parameters \(f\) = 800 mm/rev, cutting speed \(vc\)\(\approx\) 20.7 m/min, and cutting depth \(ap\) = 0.3 mm. The code group D was characterized by surface parameters with the following values: \(Sq\) = 1.54 \(\upmu\)m, \(Ssk\) = \(-\)0.322 \(\upmu\)m, \(Sku\) = 2.45 \(\upmu\)m, \(Sp\) = 3.96 \(\upmu\)m, \(Sv\) = 2.76 \(\upmu\)m, \(Sz\) = 6.72 \(\upmu\)m, \(Sa\) = 1.25 \(\upmu\)m, \(Spd\) = 331 1/mm\({}^{2}\), and \(Spc\) = 8454 1/mm. The sample surface was generated by turning on a numerical lathe with the feed parameters \(f\) = 0.1 mm/rev and the cutting speed \(vc\)\(\approx\) 100 m/min. For the surface of the samples belonging to the group in question, a contour map, and an isometric view, presented in Figure 7, were created.