Investigation on optimal temperature conditions for single screw filament extrusion and FDM printing of PLA

The mechanical performance of the Fused Deposition Modeling (FDM) printed polylactic acid (PLA) parts is influenced by the printing and filament extrusion parameters. In this regard, this work focusses on the investigation of the effects of filament extrusion zonal temperatures and printing temperatures on the porosity and mechanical strength of the printed parts. Firstly, the working temperature range of the PLA is estimated as 180°C to 220°C using the Differential Scanning Calorimetry (DSC). Based on this, the filament is extruded using a single screw extruder with varying zonal temperatures in the increments of 5,10 and 15°C. Followed by that, the filaments are printed at various nozzle temperatures between 180°C and 220°C. The results showed that the zonal temperature difference of 10°C and the nozzle temperature of 200°C yields the lowest porosity of 1.2% and highest tensile strength of 49.18 MPa, highest compression strength of 60.89 MPa and flexural strength of 70.19 MPa. This enhanced performance is attributed to the gradual thermal gradient, proper polymer chain alignment and randomized layer bonding in the material. The results provide understandings on the significance of thermal parameters on the structural integrity and mechanical performance of the printed parts.