## 5 Conclusions  
Nowadays, 3D-printed products are increasingly being used in various areas of industry. One of these technologies is the production technique that uses fused filament fabrication (FFF). With increasing applications and a demand for this technology, there is a need to expand our knowledge about the mechanical properties of materials and about their surface resistance or resistance to various types of wear. Currently, the available studies have addressed the most widespread materials used in experimental investigations of the friction and wear behavior of acrylonitrile butadiene styrene (ABS) specimens. The research on specimens made using the FFF technique has been conducted by considering the normal load, yield speed, and part orientation as parameters in the face-centered central composite design (FCCCD) setup of experiments on a pin-on-disc machine [34] or by studying the friction and wear behavior of parts made of newly developed Nylon6-Fe as compared with the existing acrylonitrile butadiene styrene (ABS) filament of the FFF machine [35]. The PEI material allows the printed products to be used in more demanding applications and this is the reason why we decided to perform experimental measurements of the resistance of this material to abrasive wear. This study is focused on analysis of building orientation and deposition strategy the influence of the FFF additive manufacturing technique on the course of the coefficient of friction and wear of samples (tribological properties of surface and subsurface layers) of ULTEM9085(tm) thermoplastic, as demonstrated by the material weight loss, in compliance with the ASTM G65-16 standard. A total of 10 samples prepared under two different model production orientations were used in the experiment with respect to the orientation of the layers during the testing procedure; five samples were prepared under each orientation, and according to different fiber-laying strategies. The weight loss of the material as a function of the path traveled and the coefficient of friction and wear behavior were observed as the main factors of the experiment. The experimental results show that fiber orientation and the fiber-laying strategy during a model's printing affect its tribological properties. The results show that the influences of different orientations cause differences in weight loss and fluctuations in the coefficient of friction. With respect to the total material losses, the X-orientation appears to be more suitable, where the total material loss is 0.4188 g; with the Z-orientation, the material loss is 0.5315 g, which represents an increase in weight loss of 26.91%. The findings from the comparison of individual deposition strategies show that the strategy of Sample 5 (X-orientation) is the most resistant, where it is a question of alternating the deposition strategy of fibers between 0\({}^{\circ}\) in the even and 90\({}^{\circ}\) in the odd layer with respect to the tested sample wall. Sample 3 (X-orientation) shows the greatest weight loss, where the fiber deposition strategy was parallel to wear direction of 0\({}^{\circ}\) in both the even and the odd layers. The study's findings suggest that printing in a horizontal orientation (X) and a 0\({}^{\circ}\) and 90\({}^{\circ}\) strategy (Sample 5) of layers deposition helps to reduce material wear. In conclusion, it can be stated that if we require higher abrasion resistance from a model made of the ULTEM 9085 material, it is suitable to choose the X-orientation and the strategy of Sample 5. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Numbers of Compared** & **X (g)** & **Z (g)** & **Compared Quantity** \\
**Samples of Type X and Z** & & & \\ \hline
1 vs. 6 & 0.0729 & 0.0933 & \\
2 vs. 7 & 0.0847 & 0.1143 & \\
3 vs. 10 & 0.1340 & 0.0988 & Weight loss \\
4 vs. 8 & 0.0641 & 0.1177 & \\
5 vs. 9 & 0.0631 & 0.1074 & \\ \hline
**Total loss in all samples** & **0.4188** & **0.5315** & Overall difference \\ \hline \hline \end{tabular}
\end{table}