Effect of Infill Density and Raster Angle on the Flexural Properties of FDM-Printed PLA+ Specimens

In this study, the effects of raster angle and infill density on the flexural properties of PLA+ specimens fabricated by the Fused Deposition Modeling (FDM) process were investigated. A three-point bending test was conducted according to the ASTM D790 standard to evaluate the flexural strength and flexural modulus. Two different raster angles (0° and 90°) and three infill densities (20%, 50%, and 100%) were selected to examine the mechanical behavior of the samples under bending loads. The specimen with 100% infill density exhibited the highest flexural strength of 101.82 MPa, which was approximately 30% higher than those of the 20% and 50% infill specimens. This enhancement is attributed to the reduced porosity and improved interlayer bonding, which allowed for more effective stress transfer under bending conditions. The influence of raster angle became more pronounced at higher infill densities. The sample with a 0° raster angle demonstrated approximately 6.9% higher flexural strength and 14% higher flexural modulus compared to the 90° raster angle sample at 100% infill density.