Influence of infill pattern on tensile strength and material efficiency of fused deposition modelling (FDM)-printed polylactic acid (PLA) parts

This study aims to examine how the infill pattern affects the flexural behaviour of PLA objects that are 3D printed. Fused Deposition Modelling (FDM) was used to build polylactic acid (PLA) pieces at different infill patterns with a 100% infill density. Fourteen distinct infill patterns have been studied (Grid, Lines, Triangles, Tri-Hexagon, Cubic, Cubic Subdivision, Octet, Quarter Cubic, Concentric, Zig-Zag, Cross, Cross 3D, Gyroid, Lightning). Because of the increased strength of the strut connections in this pattern, the results demonstrated that the Tri-Hexagon infill pattern had the highest mechanical qualities, with 1088.24 MPa. Whereas Grid type infill pattern show minimum flexural strength of 296.79 MPa. There is a increase of 266.6% in flexural strength of Tri-Hexagon against Grid type infill pattern. This was due to the pattern's huge air gaps, which caused the pattern to fracture quickly during testing. Surface roughness of Zig-zag pattern shows the minimum value of Rq = 4.94 µm and Rz = 15.96 µm. It can be concluded that the Tri-Hexagon infill pattern is quite promising when considering the construction time and the amount of filament used whereas Zig-zag pattern can be preferred if surface finish is the concern. The results of this study will assist researchers and manufacturing companies in selecting the right infill pattern, enabling the fabrication of FDM parts with high mechanical qualities and low production costs.

Abstract. 3D printing is a revolutionary manufacturing technology that provides previously unheard-of levels of efficiency and design freedom. Fused Deposition Modeling (FDM) is a popular method for creating complicated parts using thermoplastic materials like Polylactic Acid (PLA). Layer height, layup speed, and infill pattern are some of the process variables that have a major impact on the mechanical characteristics of PLA components that are FDM produced. The goal of this study was to maximize the mechanical performance of PLA components made with honeycomb and cubic infill patterns. The best combinations of layer height, layup speed, and infill density were found via Taguchi optimization. The findings showed that in terms of modulus and tensile strength, honeycomb infill designs continuously performed better than cubic patterns. Notably, a 40% infill density with a 0.3 mm layer height and a 60 mm/s layup speed yielded the best mechanical properties for honeycomb-patterned parts. The Taguchi study emphasized how important layer height and infill density are to mechanical performance. These results offer useful recommendations for producers looking to enhance FDM procedures in order to create long-lasting, premium PLA components. Tensile strength and modulus were found to be most significantly impacted by infill density and layer height when the Taguchi method was used to optimize the process parameters.

This study investigates the influence of various printing parameters on the tensile, compressive, and bending stiffness of fused deposition modeling (FDM)-printed polylactic acid (PLA) parts through a comprehensive full factorial design of experiment. Key factors, including infill percentage, infill pattern, number of outer shells, and part orientation, were systematically varied to quantify their impact on mechanical performance. A total of 36 parameter combinations, selected based on a literature review and experimental feasibility, were tested using standardized specimens: beams for bending, cylinders for compression, and dogbones for tensile testing. Mechanical tests were performed according to ISO 5893:2019, employing a 1 kN load cell to determine stiffness and elastic modulus. The results indicate that the number of outer shells and infill density are the most influential parameters, whereas infill pattern and part orientation have a minor effect, depending on the loading condition. This study provides a novel and robust evaluation of the interactions between key printing parameters, offering new insights into optimizing the mechanical properties of FDM-printed parts. These findings establish a foundation for further optimization and material selection in future additive manufacturing research.

Fused Filament Fabrication (FFF) is an additive manufacturing process with wide use.However, the optimization of certain parameters presents some uncertainties in the FFF process.In the present study, the effect of infill density (ID) on the flexural behavior of Polylactic Acid (PLA) parts printed by the FFF process was investigated.The experimental tests were performed on rectangular parts, according to the ISO 178 standard, with a test speed of 5 mm/min.Parts with several IDs in the 20-100% range were 3D printed, analyzed, and tested.Every sample was subjected to dimensional and mass analyses before the experimental tests.After testing, the failure mechanisms were highlighted depending on the ID.It was found that the ID of the printed parts strongly influences the flexural characteristics (elastic, strength, strain, and energy absorption).However, using the specific properties (specific modulus and specific strength), it was noted that 20%-ID is the optimal density for such AM structures.Slight dependencies on IDs were recorded for dimensional accuracy.It was obtained that at low IDs (<40%), the FFF-printed parts show a quasi-brittle fracture, and with its increase (IDs > 60%), a slight plastic deformation was observed.

The purpose of this study is to analyze the effect of the infill pattern on the mechanical properties of 3D printed PLA parts. Polylactic acid (PLA) parts were fabricated by fused deposition modeling (FDM) at various infill patterns at 30% infill density. Five different infill patterns (stars, 3D honeycomb, honeycomb, gyroid, Hilbert curve) have been investigated. The results have shown that the honeycomb infill pattern exhibited the highest mechanical properties with 29.43 MPa and 2.04 mm elongation due to the improved strength of the strut junctions in this pattern. In the case of the Hilbert curve pattern, compared to the other patterns, though they have the same infill density, tensile strength was lowest because of the presence of large air gaps in the pattern that induced rapid fracture during the test. The optical microscope images of the fracture surfaces were compatible with the tensile strength results. Also considering the build time and the spent filament, it can be said that the honeycomb infill pattern is very promising. Lastly, the results showed that the tensile strength and elongation of 3D printed PLA parts increased 43.4% and 32%, respectively, under optimum infill pattern conditions. The findings of this study will help manufacturing firms and researchers to decide on the appropriate infill pattern, so that FDM parts can be fabricated with minimal production cost and good mechanical properties.

Polylactic acid (PLA) is a widely used biodegradable polymer in fused filament fabrication (FFF) 3D printing, yet its mechanical performance often limits its use in load-bearing applications. Improving the impact strength of PLA components remains a critical challenge in additive manufacturing. This study addresses the question: how can key FFF parameters be optimised to significantly enhance the impact strength of PLA parts? To this end, three influential process parameters – layer height, nozzle temperature and infill density – were systematically varied and analysed using the Taguchi method with an L9 orthogonal array. Impact strength values ranged from 40 kJ/m 2 to 115 kJ/m 2 across different parameter combinations. The optimal settings – layer height of 0.28 mm, nozzle temperature of 215°C and infill density of 30% – achieved a maximum impact strength of 121.23 kJ/m 2 . This represents a 174% improvement over the base case (44.18 kJ/m 2 ) and a 6% increase over the best non-optimised sample. Among the factors, layer height had the greatest influence (68.8%), followed by infill density (24.4%) and nozzle temperature (6.8%). These findings highlight the value of parameter optimisation in improving the mechanical properties of FFF-printed PLA parts and offer practical guidelines for enhancing their structural performance.

Chronic skin wounds pose a global clinical challenge, necessitating effective treatment strategies. This study explores the potential of 3D printed Poly Lactic Acid (PLA) scaffolds, enhanced with Whey Protein Concentrate (WPC) at varying concentrations (25, 35, and 50% wt), for wound healing applications. PLA’s biocompatibility, biodegradability, and thermal stability make it an ideal material for medical applications. The addition of WPC aims to mimic the skin’s extracellular matrix and enhance the bioactivity of the PLA scaffolds. Fourier Transform Infrared Spectroscopy results confirmed the successful loading of WPC into the 3D printed PLA-based scaffolds. Scanning Electron Microscopy (SEM) images revealed no significant differences in pore size between PLA/WPC scaffolds and pure PLA scaffolds. Mechanical strength tests showed similar tensile strength between pure PLA and PLA with 50% WPC scaffolds. However, scaffolds with lower WPC concentrations displayed reduced tensile strength. Notably, all PLA/WPC scaffolds exhibited increased strain at break compared to pure PLA. Swelling capacity was highest in PLA with 25% WPC, approximately 130% higher than pure PLA. Scaffolds with higher WPC concentrations also showed increased swelling and degradation rates. Drug release was found to be prolonged with increasing WPC concentration. After seven days of incubation, cell viability significantly increased in PLA with 50% WPC scaffolds compared to pure PLA scaffolds. This innovative approach could pave the way for personalized wound care strategies, offering tailored treatments and targeted drug delivery. However, further studies are needed to optimize the properties of these scaffolds and validate their effectiveness in clinical settings.

Fused Deposition Modeling (FDM) has significantly advanced in the additive manufacturing of complex geometrical and customized parts, particularly for thermoplastics like Polylactic Acid (PLA). The present study aimed to optimize FDM process parameters to improve the tensile strength of 3D-printed PLA, a crucial mechanical property for various applications. The Taguchi method was employed to systematically and effectively analyze the effects of six key process parameters: nozzle temperature, printing speed, layer thickness, infill density, infill pattern, and orientation. The analysis revealed that among these parameters, only nozzle temperature and infill density had a significant impact on tensile strength, as demonstrated by the variance analysis. By optimizing these critical parameters, the tensile strength of the printed PLA parts was improved from the previously reported 35 MPa to 40 MPa, representing a notable enhancement. Additionally, a linear regression-based empirical model was developed, achieving an R-squared value of 89.2%, enabling accurate prediction of tensile strength for given process parameter values. These findings provide a vital foundation for enhancing the mechanical performance of FDM-printed PLA components. They are particularly relevant for applications across industries requiring high-strength materials, further solidifying the potential of FDM in advanced manufacturing scenarios.

Fused Filament Fabrication (FFF) is a popular additive manufacturing process for creating prototypes and end-use products. Infill patterns, which fill the interior of hollow FFF-printed objects, play a crucial role in determining the mechanical properties and structural integrity of hollow structures. This study investigates the effects of infill line multipliers and different infill patterns (hexagonal, grid, and triangle) on the mechanical properties of 3D printed hollow structures. Thermoplastic poly lactic acid (PLA) was used as the material for 3D-printed components. Infill densities of 25%, 50%, and 75% were chosen, along with a line multiplier of one. The results indicate that the hexagonal infill pattern consistently demonstrated the highest Ultimate Tensile Strength (UTS) of 1.86 MPa across all infill densities, out-performing the other two patterns. To maintain a sample weight below 10 g, a two-line multiplier was utilised for a 25% infill density sample. Remarkably, this combination exhibited a UTS value of 3.57 MPa, which is comparable to samples printed at 50% infill density, which were 3.83 MPa. This research highlights the importance of line multiplier in combination with infill density and infill pattens to ensuring the achievement of the desired mechanical properties in the final product.

Laser surface polishing of 3D printed polylactic acid (PLA) with different levels of absorption

Fused Deposition Modeling (FDM) based 3D printers are gaining popularity as cost-effective printers that are changing the life of millions with their capability to manufacture products in the fields of engineering, medical and education. This paper examines the variation in the compressive strength of FDM processed Polylactic acid (PLA) parts for different infill design patterns. The work is performed on 6 infill designs i.e., Hilbert curve, honeycomb, line, rectilinear, Archimedean curve and octagram spiral and compressive strengths are compared for infill densities varying from 20 till 80% in step of 20. It is observed that the Hilbert curve design exhibits maximum compressive strength of 121.35 MPa which is much higher than other designs rectilinear (78.88 MPa), line (73.84 MPa), honeycomb (62.56 MPa), Archimedean (70.07 MPa), octagram spiral (60.01 MPa). Also, with increase in infill density, compressive strength increases for all the considered infill design patterns. The fabricated parts are also investigated for surface roughness values for best 3 compression strengths with different combinations of infill densities. The surface roughness increases with increase in infill densities for rectilinear and hilbert curve but decreases for line pattern. Rectilinear pattern exhibits lowest roughness value as compared to hilbert curve and line design patterns.

This study investigates the impact of infill density on the mechanical properties of fused deposition modeling (FDM) 3D-printed polylactic acid (PLA) and PLA reinforced with carbon fiber (PLA+CF) specimens, which hold industrial significance due to their applications in industries where mechanical robustness and durability are critical. Exposure to cooling lubricants is particularly relevant for environments where these materials are frequently subjected to cooling fluids, such as manufacturing plants and machine shops. This research aims to explore insights into the mechanical robustness and durability of these materials under realistic operating conditions, including prolonged exposure to cooling lubricants. Tensile tests were performed on PLA and PLA+CF specimens printed with varying infill densities (40%, 60%, 80%, and 100%). The specimens underwent tensile testing before and after exposure to cooling lubricants for 7 and 30 days, respectively. Mechanical properties such as tensile strength, maximum force, strain, and Young's modulus were measured to evaluate the effects of infill density and lubricant exposure. Higher infill densities significantly increased tensile strength and maximum force for both PLA and PLA+CF specimens. PLA specimens showed an increase in tensile strength from 22.49 MPa at 40% infill density to 45.00 MPa at 100% infill density, representing a 100.09% enhancement. PLA+CF specimens exhibited an increase from 23.09 MPa to 42.54 MPa, marking an 84.27% improvement. After 30 days of lubricant exposure, the tensile strength of PLA specimens decreased by 15.56%, while PLA+CF specimens experienced an 18.60% reduction. Strain values exhibited minor fluctuations, indicating stable elasticity, and Young's modulus improved significantly with higher infill densities, suggesting enhanced material stiffness. Increasing the infill density of FDM 3D-printed PLA and PLA+CF specimens significantly enhance their mechanical properties, even under prolonged exposure to cooling lubricants. These findings have significant implications for industrial applications, indicating that optimizing infill density can enhance the durability and performance of 3D-printed components. This study offers a robust foundation for further research and practical applications, highlighting the critical role of infill density in enhancing structural integrity and load-bearing capacity.

This study focuses on the investigation of infill patterns and their influence on the mechanical behavior of sandwich structures fabricated using the Fused Deposition Modeling (FDM) technique. Polylactic Acid (PLA) was chosen as the primary material, known for its favorable mechanical properties and biodegradability. Six different infill patterns, including Cubic, Line, Triangular, Trihexagonal, Octet, and Gyroid, were employed to fabricate sandwich structures with varying infill densities (20%, 30%, and 40%). The samples were subjected to edgewise compressive strength tests, and the force-displacement curves were analyzed to evaluate the performance of the structures. The results revealed that the Cubic infill pattern exhibited superior strength in all infill densities, while other patterns showed variations in performance. Moreover, the analysis of damage types indicated different failure modes, such as core shear and facesheet buckling, depending on the infill pattern and density. These findings contribute to understanding the role of infill patterns in enhancing the mechanical properties of sandwich structures fabricated via FDM.

In the realm of additive manufacturing, the quality and mechanical performance of 3D-printed structures are heavily influenced by the parametric settings used during the printing process. Some of these conditions include layer thickness, printing speed, infill density, filling pattern, printing substance, and so on. This research investigates the effect of printing factors on the strength characteristics of 3D-printed acrylonitrile butadiene styrene (ABS) as well as polylactic acid (PLA) structures. The parameters considered for the proposed study include material type, infill direction, infill density, and infill pattern. These four conditions are optimized using the machine-learning algorithm to obtain maximum strength in the resulting structures. The breaking load, extension, tensile strain, and tensile strength are the strength factors determined by the experiments. Furthermore, a deep neural network integrated with a walrus optimization algorithm (DNN-WOA)-based hybrid machine learning method is used in the experimental data to discover the optimal parametric conditions for constructing the structures with maximum strength. Based on the findings, infill density is a significant component in increasing both the tensile strength and elastic modulus of printed samples. Line and triangular-type infill patterns exerted the range of tensile strength with 10–20 MPa of deviations. In terms of tensile strain, the line pattern produced significantly more tensile strain than the triangle pattern. The highest breaking stress is observed at a [Formula: see text] raster angle, regardless of infill density. When compared to the strengths of ABS and PLA, the PLA with a triangle infill pattern outperformed the ABS structure printed with a line-type infill pattern. The optimum printing settings for a PLA structure with a line-type infill pattern are [Formula: see text] and 25% for raster angle and infill density, respectively. This parameter resulted in enhanced strength performance, with 45.81[Formula: see text]MPa of tensile strength, 12.13% of tensile strain, 359.34[Formula: see text]kgf of breaking load, 7.21[Formula: see text]mm of extension, and 24.12[Formula: see text]min of printing time.

This study purposed to develop conductivity 3D printed (3DP) fingertips and confirm their potential for use in a pressure sensor. Index fingertips were 3D printed using thermoplastic polyurethane filament with three types of infill patterns (Zigzag (ZG), Triangles (TR), Honeycomb (HN)) and densities (20%, 50%, 80%). Hence, the 3DP index fingertip was dip-coated with 8 wt% graphene/waterborne polyurethane composite solution. The coated 3DP index fingertips were analyzed by appearance property, weight changes, compressive property, and electrical property. As results, the weight increased from 1.8 g to 2.9 g as infill density increased. By infill pattern, ZG was the largest, and the pick-up rate decreased from 18.9% for 20% infill density to 4.5% for 80% infill density. Compressive properties were confirmed. Compressive strength increased as infill density increased. In addition, the compressive strength after coating was improved more than 1000 times. Especially, TR had excellent compressive toughness as 13.9 J for 20%, 17.2 J for 50%, and 27.9 J for 80%. In the case of electrical properties, the current become excellent at 20% infill density. By infill patterns at 20% infill density, TR has 0.22 mA as the best conductivity. Therefore, we confirmed the conductivity of 3DP fingertips, and the infill pattern of TR at 20% was most suitable.