This study examines the effect of elevated printing speeds (100–600 mm/s) on the dimensional accuracy and tensile strength of PLA components fabricated via fused deposition modeling (FDM). To isolate the influence of printing speed, all other parameters were kept constant, and two filament variants—natural (unpigmented) and black PLA—were analyzed. ISO 527-2 type 1A specimens were produced and tested for dimensional deviations and ultimate tensile strength (UTS). The results indicate that printing speed has a marked impact on both geometric precision and mechanical performance. The optimal speed of 300 mm/s provided the best compromise between dimensional accuracy and tensile strength for both filaments. At speeds below 300 mm/s, under-extrusion caused weak layer bonding and air gaps, while speeds above 300 mm/s led to over-extrusion and structural defects due to thermal stress and rapid cooling. Black PLA yielded better dimensional accuracy at higher speeds, with cross-sectional deviations between 2.76% and 5.33%, while natural PLA showed larger deviations of up to 8.63%. However, natural PLA exhibited superior tensile strength, reaching up to 46.59 MPa, with black PLA showing up to 13.16% lower UTS values. The findings emphasize the importance of speed tuning and material selection for achieving high-quality, reliable, and efficient FDM prints.

This study examines how manufacturer-specific additive formulations used to obtain nominally identical black PLA filaments influence the thermal, mechanical, and tribological performance of FDM-printed parts. Five commercial filaments were analyzed under identical processing conditions using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile testing, pin-on-disc measurements, and stereomicroscopy. The filaments exhibited substantial compositional variability, with total additive contents ranging from 2.08 wt.% to 27.82 wt.%. One filament (M5) contained a significant fraction of inorganic fillers, confirmed by SEM/EDX as Ca-, Na- and Mg-based oxides and silicates, identifying it as a PLA-based composite despite being marketed as standard PLA. These differences strongly affected thermal behavior (Tg, Tcc, Tm) and translated directly into the performance of the printed parts. Ultimate tensile strength varied by 88.91% across all filaments (19.38–36.61 MPa), but only by 13% among the four conventional PLA filaments (M1–M4). Tribological performance differed markedly: mean coefficients of friction ranged from 0.246 (M3) to 0.368 (M2), a spread of approximately 50%, with wear-track morphologies reflecting the frictional response. Overall, the results show that PLA filaments cannot be treated as interchangeable materials. Greater transparency and standardized reporting of filament composition are needed to ensure reproducibility and support informed material selection in FDM applications.