###### Abstract  
In this paper, we are focusing on comparing results obtained for polymer elements manufactured with injection molding and additive manufacturing techniques. The analysis was performed for fused deposition modeling (FDM) and single screw injection molding with regards to the standards used in thermoplastics processing technology. We argue that the cross-section structure of the sample obtained via FDM is the key factor in the fabrication of high-strength components and that the dimensions of the samples have a strong influence on the mechanical properties. Large cross-section samples, 4 \(\times\) 10 mm\({}^{2}\), with three perimeter layers and 50% infill, have lower mechanical strength than injection molded reference samples--less than 60% of the strength. However, if we reduce the cross-section dimensions down to 2 \(\times\) 4 mm\({}^{2}\), the samples will be more durable, reaching up to 110% of the tensile strength observed for the injection molded samples. In the case of large cross-section samples, strength increases with the number of contour layers, leading to an increase of up to 97% of the tensile strength value for 11 perimeter layer samples. The mechanical strength of the printed components can also be improved by using lower values of the thickness of the deposited layers.  
additive manufacturing; fused deposition modeling; injection molding; polymers; tensile strength +
Footnote †: journal: Applied Physics Letters  
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considered in the fabrication of large-scale 3D printed components and the optimization of the additive process.  
From analysis of the literature, we can argue that maximum infill volume is not always recommended. After the infill exceeds 50%, the strength value stabilizes at a certain level [7], and further increase does not affect the strength significantly, while the printing time increases drastically [6]. The types of infill patterns used during the fabrication process in relation to the movement directions of the printing head are presented in the literature [6]. It turns out that the selection of a specific infill type affects the mechanical properties. The most widely discussed problem is related to the orientation of the printed component on the support table. The influence of the sample alignment affecting the direction of the printing on the mechanical properties is evaluated in the literature, and results suggest that the lowest strength values of the formed elements are recorded in the direction of layer growth, which is the \(Z\)-axis for fused deposition modeling process [8; 9].  
What is missing in the literature is detailed studies on the influence of contour layer thickness on the mechanical strength of printed components. Only a handful of studies suggest that increasing the value of perimeter layers improves mechanical strength. Still, no deep analysis of the problem is presented, and no attempt has been made to compare the results of samples printed with different cross sections. In many publications, authors use standard sample shapes without deep analysis of additional geometric factors. For the first time, we compare the difference between the mechanical properties of samples with different cross sections fabricated with the same formation parameters.