Investigation of fused deposition modeling processing parameters of 3D PLA specimens by an experimental design methodology

The main objective of this study is to analyze t he tensile strength of PLA parts manufactured through fused filament fabrication (FEE) using a commercially available 3D printer. This study is primarily focused on the effects of the tensile strength of specimens subjected to the influence of four factors; layer thickness, fill density, raster orientation and sample structuretype. A 2(3)3(1) mixed-level factorial design approach was used, and the individual effects of the four main factors and their interactions determined. This experimental design had been implemented for two different infills: rectilinear and honeycomb. Specimens were printed at raster orientation angles of 30 degrees, 60 degrees and 90 degrees at a fill density of 50% and 100 %. A layer thickness of 0.15 mm and 0.05 mm was chosen for printing the specimens. The samples were tested using a standard tensile testing machine with an extensometer to determine mechanical strength characteristics such as ultimate tensile strength, maximum force and maximum elongation. The data obtained was then analyzed using Minitab 13.20 software. The results showed that 30 degrees raster orientation yields the highest mechanical properties at each individual layer when compared to 60 degrees and 90 degrees. The fill density proves to be the most influential parameter on tensile strength, followed by the sample structure type. The results also found tensile strength to directly proporionate to layer thickness. By improving the material properties through the addition of layers as observed in the results, it will be possible to provide support for software developers, mechanical designers and engineers to reduce manufacturing time, material use and costs.