Influence of Pattern and Infill Density on the Mechanical Strength of PLA and PETG Parts Printed by FDM

The comparative results of the mechanical behavior of printed samples using Fused Deposition Modeling (FDM) on Polylactic Acid (PLA) and Polyester Terephthalate Glycol (PETG) parts are presented. To carry out the experimental procedure, the ASTM D638-14 standard with the standardized dimensions of Type I specimens was taken as a reference. To generate the 3D model and the lamination of the samples were established, specific parameters of extruder temperature, printing speed, and extrusion. Cubic, gyroid and octet filling patterns were used with 100%, 75%, 50% and 25% infill density. For each condition, the G-code was obtained, which was interpreted by the printer for subsequent fabrication. A total of 120 printed specimens were used, which were divided into two groups according to the material. Subsequently, tensile tests were performed to obtain mechanical properties from the Stress-Strain curves for the established conditions. The comparative study revealed that PETG has a greater tensile strength and greater capacity to withstand strain. On the other hand, PLA was more elastic than PETG. Likewise, the filler pattern that withstood the greatest load was the gyroid. PETG also required longer printing time, which implies higher energy consumption.