Optimization of FDM Printing Parameters for Square Lattice Structures for Enhanced Mechanical Behaviour

Teo, Jin An (2025) Optimization of FDM Printing Parameters for Square Lattice Structures for Enhanced Mechanical Behaviour. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

This study explores the optimization of key Fused Deposition Modelling (FDM) parameters to enhance the mechanical performance of square lattice structures made from polylactic acid (PLA). Due to their high strength-to-weight ratio, these structures are well-suited for aerospace, automotive, biomedical, and protective applications. The research examines how process parameters such as infill density (20%, 40%, 60%, 80%, 100%), layer thickness (0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm), extrusion temperature (190°C, 200°C, 210°C, 220°C, 230°C), printing speed (40mm/s, 50mm/s, 60mm/s, 70mm/s, 80mm/s), and build orientation (flat, upright, on-edge) which affect tensile strength and energy absorption. It also evaluates geometric variables like cell size (1.5mm, 2.5mm, 3.5mm) and wall thickness (0.4mm, 0.5mm, 0.6mm on compressive strength and load dissipation. Mechanical responses under tensile and compressive loads were measured using crosshead speeds of 100 mm/min and 5 mm/min, respectively. Tensile testing showed that increasing infill density from 20% to 100% raised tensile stress from 15.93 MPa to 19.94 MPa, while reducing layer thickness to 0.1 mm yielded 22.34 MPa due to improved interlayer bonding. The optimal extrusion temperature was 220°C, producing 21.79 MPa, and a print speed of 40 mm/s delivered 21.52 MPa. The on-edge orientation achieved the highest tensile strength at 28.79 MPa, while upright orientation only reached 7.50 MPa. Compression tests showed that a 1.5 mm cell size and 0.6 mm wall thickness gave the best results, sustaining 41 kN and absorbing 36 kN·mm. Increasing cell size to 3.5 mm reduced strength to 45.90 N and energy absorption to 2.4 kN·mm. Similarly, increasing wall thickness from 0.4 mm to 0.6 mm improved compressive strength from 7.68 kN to 41 kN and energy absorption from 7.1 kN·mm to 360 kN·mm. Optimal FDM performance was achieved with 80% infill, 0.2 mm layer thickness, 210°C extrusion temperature, 50 mm/s speed, and on-edge build orientation, reaching 28.79 MPa. For energy absorption, a 1.5 mm cell size and 0.6 mm wall thickness yielded 362 kN·mm. This configuration meets realworld application needs. A tensile strength of 28.79 MPa makes it suitable for prosthetic limb sockets, dental implant bases, and medical device casings typically requiring greater than 20 MPa, while 362 kN·mm energy absorption matches demands in automotive bumper cores standard of 300–400 kN·mm. These results confirm the structures are ready for impact-critical, lightweight applications.