## 3 Results
### Results for Dimensions and Tensile Strength for the Upper Level of the Working Chamber
#### 3.1.1 Results for Tensile Strength in the Upper Level of the Working Chamber  
Table 3 shows the results of tensile strength at the upper level of the working chamber. One may conclude from the table that the hatch distance and the orientation of the test specimens have an almost equal impact on the tensile strength of the polyamide product. Factors A, B, AB, A\({}^{2}\), B\({}^{2}\), A\({}^{2}\)B, and B\({}^{3}\) are significant. For a factor to affect the change, the value in Table 3 in the last column should be lower than 0.05. The model F-value of 2556.94 implies the model is significant, and the lack of fit F-value of 5.54 implies there is a 9.84% chance that a lack of fit F-value this large could occur due to noise. Although this is still a relatively low value, a non-significant lack of fit means that the parameters are well chosen and there are no major errors in the choice of factors and model.  
\begin{table}
\begin{tabular}{c c c c} \hline \multicolumn{2}{c}{**Hatch Distance—A**} & \multicolumn{2}{c}{**Orientation—B**} \\ \hline
**Actual Values, mm** & **Coded Values** & **Actual Values, \({}^{\circ}\)** & **Coded Values** \\ \hline
0.23 & \(-1\) & 0 & \(-1\) \\
0.32 & \(-0.5\) & \(15\) & \(-0.5\) \\
0.42 & 0 & 30 & 0 \\
0.51 & 0.5 & 45 & 0.5 \\
0.6 & 1 & 60 & 1 \\ \hline \end{tabular}
\end{table}
Table 1: Actual and coded values for experiment factors A and B.  
Figure 4: Test specimen with different hatch distances \(h=0.23\) mm (**left**) and \(h=0.6\) mm (**right**).  
Table 4 shows statistics for tensile strength in the upper part of the working chamber. Apart from the fact that \(R^{2}\) is a sign that the model follows the data very well (the closer it is to 1, the better the model is), at the same time, adeq precision measures the signal-to-noise ratio, and it is important that the difference is greater than 4. In this analysis, the ratio of 168.6247 indicates an adequate signal, and this model can be used to navigate the model design.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Run**} & **Factor A: Hatch** & **Factor B:** & **Tensile Strength** & \multirow{2}{*}{**Length \(l\), mm} & **Thickness _h_**,** & \\  & **Distance HD, mm** & **Orientation \(\mathbf{\alpha}_{s}\)** & \(\mathbf{\sigma}_{\text{m}}\), MPa** & **mm** & **mm** & **Width \(b\), mm** \\ \hline
1 & 0.23 & 0 & 46.27 \(\pm\) 0.138 & 449.81 \(\pm\) 0.  
Tensile strength can be described by an equation with actual parameters:  
\[\begin{split}\sigma_{\text{m}}=23.9+175.7\times HD+1.3\times\alpha-5.3 \times HD\times\alpha-391.2\times HD^{2}-0.013\times\alpha^{2}+6.6\times HD^{2} \times\alpha+0.0085\times HD\times\alpha^{2}\\ +13.9\times HD^{3}+0.00009\times\alpha^{3}\end{split} \tag{4}\]  
where \(\sigma_{\text{m}}\) [N/mm\({}^{2}\)]--tensile strength, \(HD\) [mm]--hat distance, and \(\alpha\) [\({}^{\circ}\)]--orientation.  
Figure 5 shows the dependence of tensile strength on the hatch distance and orientation. The lowest value of tensile strength is 10.79 N/mm\({}^{2}\), which happened at the largest hatch distance and the smallest orientation, while the highest measured value is 42.41 N/mm\({}^{2}\) for the hatch distance of 0.32 mm and the orientation of 15\({}^{\circ}\). However, the values for the tensile strength can be read from the diagram for any combination of input parameters within selected limits.