Improving the mechanical strength and toughness of 3D printed polymer structures without sacrificing dimensional accuracy and surface finish can be achieved through a combination of material selection, printing parameters optimization, and post-processing techniques. Here are some strategies to consider:1. Material selection: Choose a high-performance polymer with better mechanical properties, such as polycarbonate PC , polyetherimide PEI , or polyamide PA . These materials have higher strength and toughness compared to common materials like PLA and ABS.2. Printing parameters optimization: a. Layer height: Use a smaller layer height to improve the bonding between layers, resulting in better mechanical properties. b. Infill pattern and density: Select a more robust infill pattern e.g., gyroid or honeycomb and increase the infill density to enhance the part's strength and toughness. c. Print orientation: Optimize the print orientation to align the layers and fibers with the primary stress direction in the final part. d. Extrusion temperature: Adjust the extrusion temperature to ensure proper bonding between layers and minimize voids or gaps. e. Print speed: Slower print speeds can lead to better layer adhesion and improved mechanical properties.3. Post-processing techniques: a. Annealing: Heat-treating the printed part at a controlled temperature can improve its crystallinity and molecular alignment, resulting in enhanced mechanical properties. b. Chemical vapor smoothing: Exposing the printed part to a chemical vapor e.g., acetone for ABS can smooth the surface and improve layer adhesion, leading to better mechanical strength and toughness. c. UV curing: For UV-curable resins, ensure proper post-curing to maximize the material's mechanical properties. d. Electroplating: Applying a thin metal coating e.g., nickel or copper can improve the mechanical strength and wear resistance of the printed part.4. Hybrid materials and composite printing: Incorporate reinforcing fibers e.g., carbon or glass fibers into the polymer matrix to create a composite material with improved mechanical properties. This can be achieved using specialized 3D printers capable of printing continuous fibers or by embedding fibers during the printing process.By implementing these strategies, it is possible to improve the mechanical strength and toughness of 3D printed polymer structures without sacrificing their dimensional accuracy and surface finish.