## 2 Materials and Methods
The measurements were performed using the following procedure:  
* one measurement for each layer of the individual printed specimen; the thermometer was placed above area 1.1 and the measurements were done when the print head applied the material to area H (Figure 1a). A total of 15 measurements were made for specimen 1.1;
* three measurements for each layer of specimens 3.1, 3.2 and 3.3: the first measurements were done in areas 3.1, 3.2 and 3.3 from Figure 1b, when the print head deposited material on test area H1 of specimen 3.1; the following measurements were done in the same areas when the print head deposited material on areas H2, respectively H3 of specimens 3.2 and 3.3. A total number of 45 measurements were made for each specimen of this type;
* five measurements for each layer deposited on specimens 5.1, 5.2, 5.3, 5.4 and 5.5 (the first measurements were done in areas 5.1, 5.2, 5.3, 5.4 and 5.5 from Figure 1c at the instant when the print head deposited material on area H1 of specimen 5.1; the following measurements were done in the same areas when the print head deposited material on areas H2, H3, H4, and respectively H5 of specimens 5.2, 5.3, 5.4 and 5.5). A total number of 75 measurements were made for each specimen of this type. It should be noted that continuous temperature measurement was also attempted, but the interposition of the print head and printer guide rails between the specimen and \begin{table}
\begin{tabular}{l l l} \hline \hline
**Parameters** & & **Values** \\ \hline Fixed process parameters & Layer thickness, t & 0.2 mm \\  & Printing head temperature, T\({}_{\text{H}}\) & 210 \({}^{\circ}\)C \\  & Build plate temperature, T\({}_{\text{B}}\) & 60 \({}^{\circ}\)C \\  & Printing speed, s\({}_{\text{p}}\) & 50 mm/s \\  & Nozzle diameter, d\({}_{\text{n}}\) & 0.40 mm \\  & Filament diameter, d\({}_{\text{f}}\) & 2.85 mm \\  & Build orientation (acc. to [23]) & YX \\  & Raster angle, \(\theta\) & 45\({}^{\circ}\)/\(-\)45\({}^{\circ}\) \\  & Infill density & 100\% \\  & Number of wall lines, W\({}_{\text{L}}\) (-) & 2 \\ Variable parameters & Number of simultaneously & 1 specimen/build plate \\  & printed specimens & 3 specimens/build plate \\  & Material/Filament color & 5 specimens/build plate \\  & & PLA Black; PLA Natural; \\  & & PLA Grey; PLA Red \\ \hline \hline \end{tabular}
\end{table} 
Table 1: 3D-printing parameters. the thermometer affected the measurements. For the same reason, it was not possible to measure the temperature in the first seconds after the deposition of the material, when the print head was above the measurement area. A detailed analysis of the temperature variation on the deposited layer has been previously presented by the authors in [25]. In this paper, the charts of the temperature variation for the layers 3 to 15 are included (the first two layers have not been included in the graphs, to eliminate disturbances generated by the build plate). Dimensional deviations were evaluated by measuring the width and thickness of the specimens in three sections of the calibrated area (theoretical width--10 mm, theoretical thickness--3 mm). A Mitutoyo 293-240-30 micrometer (Mitutoyo Romania SRL, Otopeni, Romania) with an accuracy of \(\pm\)0.001 mm was used. Width deviations (%), thickness deviations (%), and cross-sectional areas of the specimens were calculated. Subsequently, means and standard deviations were determined for each color and type of specimen. Tensile tests were carried out according to ISO 527-1 [26] and ISO 527-2 [22], using a Mecmesin Multitest 2.5 dV equipment (PPT Group UK Ltd., Slinfold, United Kingdom) with Vector ProMT 6.1.0.0 software for test setup, control, monitoring and data acquisition. Test speed was kept constant \(\mathrm{s_{p}}\) = 10 mm/min. Ultimate tensile stress, mean and standard deviation (according to ISO 2602:1980 [27]) were determined for batches of five tensile samples. The structure of the FDM deposited material was analyzed using a Leica MZ 7.5 stereomicroscope (Leica Microsystems, Wetzlar, Germany).