Influence of Extruder's Nozzle Diameter on the Improvement of Functional Properties of 3D-Printed PLA Products

The dynamic growth of the use of polymer construction parts manufactured individually and in a small series makes it necessary to improve additive methods in the areas of materials, equipment and processes. By observing selected phenomena occurring during the processing of polymer materials in other production technologies (e.g., extrusion and injection molding), it is possible to obtain solutions that positively affect the final performance properties of the products obtained in additive manufacturing technologies using thermoplastic filament. The aim of this research was to determine the effect of the diameter of the print head nozzle on the spatial structure (path width) and selected mechanical properties of samples produced by the FFF method with PLA material. The obtained results were compared to the samples with a solid structure produced using injection molding technology. In the experiment, the RepRap device for additive manufacturing was used, with the use of nozzles with diameters of 0.2 mm, 0.4 mm, 0.8 mm and 1.2 mm. The test objects were produced with a layer height of 0.2 mm, full filling (100%) and with constant remaining printing parameters. The conducted research allowed us to conclude that the use of layer heights lower than the standard ones gives favorable results for selected mechanical properties. The use of an extruder nozzle diameter of 0.8 mm allows one to obtain a macrostructure with a high degree of interconnection of layers and paths and favorable mechanical properties. The test results can be used in the construction of functional elements that are produced by fused deposition modeling (FDM) and fused filament fabrication (FFF) methods in prototype, unit and small-lot production.