## 1 Introduction
Thus, it is necessary to investigate the effect of the number of parts printed simultaneously (or size of printed part) on local temperature variations and on interlayer adhesion. [PERSON] et al. [14] analyzed PLA tensile specimens (25 mm length, 4 mm width, 2 mm thickness) printed in two scenarios: individual printing of each specimen and simultaneously printing of 15 specimens with three build orientations (5 \(\times\) YXZ, 5 \(\times\) YZX and 5 specimens rotated with 45\({}^{\circ}\) degrees relative to YXZ). The specimens printed simultaneously have a lower weight (approx. \(-\)0.03 g) and the authors consider that the difference may be linked to intermolecular diffusion at the interlayer interface. The ultimate tensile strength (UTS) of individually printed specimens was significantly higher compared to the UTS obtained for simultaneously printed specimens (20% for XYZ specimens, 37% for YZX specimens, 26% for specimens rotated with 45\({}^{\circ}\) relative to YXZ). It should be noted that for the layout chosen by the authors for simultaneous printing, the YZX oriented specimens have more layers compared to the other two orientations. Thus, the time interval between deposition of material on two successive layers in the same area of the YZX specimens is higher for the first 10 layers (2 mm thickness = 10 layers \(\times\) 0.2 mm) compared to the upper layers (printing speed was kept constant). [PERSON] et al. [15] analyzed comparatively the properties of ASTM D638-IV specimens printed simultaneously (batch of five) and individually, using two types of infill (line and gyroid) and two build orientations (rotated 45\({}^{\circ}\) relative to YXZ, respectively to YZX). Two types of PLA filament were used: 3D850 (clear) and 3D870 (white). Individually printed 3D850 PLA specimens showed an increase of UTS compared to simultaneously printed specimens. While for 3D850 PLA specimens rotated at 45\({}^{\circ}\) relative to YZX, the UTS values were about 20% higher for specimens printed individually, for 3D870 PLA specimens rotated at 45\({}^{\circ}\) relative to YXZ the UTS values were not influenced by the printing mode (simultaneous or individual). The two above mentioned studies targeted only the influence of the printing scenario on the tensile strength, without revealing its influence on the specimens' dimensions. No previous studies were found aiming to point out specifically the effect of simultaneous printing on the dimensional accuracy and the mechanical properties of the specimens produced in batches depending on their different positions on the build plate. But when printing finished parts in batches, the problem regarding the predictability of their quality and properties may not be ignored. Although mostly neglected, the color of the PLA should be considered a significant influential variable of the FDM printing process [9; 16]. Color-dependent printing behavior was reported by previous research, with direct influence on the dimensional accuracy [4; 17] and the tensile strength [18; 19] of FDM printed specimens, some of them highlighting particularly the effect of the carbon black in conductive PLA [20; 21]. The reason for the differences determined by the PLA colors was found to be the influence of the coloring additives on the in-process crystallinity and the thermal properties of the PLA filaments [17; 20]. Therefore, when printing different colored PLA filaments under the same conditions, different results in terms of the printed parts properties may be expected. This paper aims to point out if and to what extent the mechanical properties and the dimensional accuracy of PLA tensile specimens are influenced by the printing scenario and if there are notable differences in this respect determined by the position of the specimen on the build plate. Also, considering that the printing scenario has effect on the thermal printing conditions of different specimens, the PLA color was chosen to be an independent parameter as well.