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Assessing the Flexural Properties of Heat-Treated 3D Printed PLA Luggage Handles: Impacts of Intricate Designs and Thermal Processing on Structural Performance.
No full textThis study investigates enhancing flexural strength in 3D-printed Polylactic Acid (PLA) specimens, focusing on mechanical bending testing. Prior to experimentation, several parameters were identified to have an impact on flexural strength. These were divided into printing parameters (printing speed, specimen orientation, infill pattern and percentage, layer thickness) and heat treatment factors (time, temperature, cooling rate, heating container). Three factors were selected to be varied: printing layer thickness (0.1 mm, 0.15 mm, 0.25 mm), heat treatment duration (20, 30, 40 minutes), and rubberized coating application (none, Clear FLEX SEAL��, Black FLEX SEAL��). Using the Taguchi method, 9 combinations were selected from 27 possibilities. A total of 135 PLA specimens were prepared according to the ISO-178-19 standard, implementing randomization to ensure statistical reliability. Results showed that the strongest specimens were those with the thinnest layers (0.1 mm), attributed to increased layer fusion enhancing material cohesion. The optimal duration for heat treatment was identified as 30 minutes, balancing effective thermal fusion against the risk of thermal degradation. The application of FLEX SEAL�� coating significantly diminished flexural strength, primarily due to solvent volatilization and induced stress concentrations from handling the specimens, with the highest strength achieved with no coating. These optimal conditions resulted in a flexural strength of 197 MPa, a 33.3% increase from the baseline strength. A three-way ANOVA analysis indicated that the null hypothesis was not rejected, revealing no statistically significant variation in flexural strength across different factor levels. Signal-to-noise ratio analysis complemented these findings, allowing for an evaluation of the robustness of the flexural strength against variability in experimental conditions. This analysis reinforced the importance of layer thickness and heat treatment duration in achieving optimal flexural strength. Regression analysis predicts the optimal combination for maximum flexural strength (205.73 MPa) as 40 minutes of heat treatment, 0.1 mm layer thickness, and no coating. According to this predictive model, this combination is expected to improve flexural strength by 39.2%. Dimensional analysis revealed that temperature has the biggest impact on warping due to thermal expansion and uneven cooling rates, with the most optimal heat treatment decreasing the length of the specimens by 4.99%. Microscopy analysis revealed areas of unfused layers after heat treatment, and voids between the top layer of the specimen and the coating layer due to solvent volatilization. Subjecting a case study to the optimal conditions revealed a 55% increase in flexural strength but diminished tensile strength by 6.2%. The findings highlight the intricate balance between material properties and processing conditions in 3D printing. Further research is recommended to explore varied printing parameters and validate the predictive model, contributing to an innovative and environmentally conscious manufacturing landscape in alignment with Qatar���s��2030��Vision
