DOI: https://doi.org/10.32515/2664-262X.2025.12(43).2.79-86
Strength of PLA Products Depending on Fill Density and Layer Orientation in FDM Printing
About the Authors
Olha Musiienko, PhD in Applied Mechanics, Senior Lecturer at the Department of Dynamics and Strength of Machines and Strength of Materials, National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Kyiv, Ukraine, ORCID: https://orcid.org/0000-0001-8255-3909, e-mail: olga.musinko@gmail.com
Oleksandr Bilyi, student in Applied Mechanics, National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Kyiv, Ukraine, ORCID: https://orcid.org/0009-0002-1968-0993, e-mail: oleksandr.bilyi-mp31@lll.kpi.ua
Abstract
The aim of this research is to evaluate the influence of infill density and layer orientation on the mechanical performance of PLA parts produced via Fused Deposition Modeling (FDM) and to create a predictive regression model for parameter optimization. The study is relevant due to the growing use of additive manufacturing in producing functional components where both mechanical strength and material efficiency are critical. Identifying optimal combinations of printing parameters enables manufacturers to achieve desired properties without unnecessary material consumption.
A full factorial experiment with two factors was carried out: infill density (30%, 65%, 100%) and layer orientation (0°, ±45°, 90°). Tensile specimens of type 1 according to ISO 527-2:2018 were printed on an Ender 3 printer with fixed process settings. Mechanical tests were conducted on a TIRATEST 2151 universal testing machine at a crosshead speed of 2.5 mm/min. The results showed that layer orientation had a more pronounced effect on strength than infill density: the 90° orientation produced the highest tensile strength, while 0° yielded the lowest. Increasing infill density from 30% to 65% had little effect, but raising it to 100% improved strength by up to 41%. In the working deformation range (up to 5%), ±45° orientation offered the best balance of stiffness and elasticity.
A linear regression model describing the relationship between elongation at break and the two factors was developed and validated using statistical criteria, with a prediction error not exceeding 7%. Based on the findings, a 65% infill combined with ±45° layer orientation can achieve strength comparable to 100% infill with 90° orientation, while reducing material use by up to 25%. The developed model can guide the selection of FDM printing parameters to reduce production costs and time, making it applicable to the engineering design of functional PLA components intended for moderate mechanical loads.
Keywords
FDM printing, PLA, strength, infill density, layer orientation, regression model
Strength of PLA Products Depending on Fill Density and Layer Orientation in FDM Printing
About the Authors
Olha Musiienko, PhD in Applied Mechanics, Senior Lecturer at the Department of Dynamics and Strength of Machines and Strength of Materials, National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Kyiv, Ukraine, ORCID: https://orcid.org/0000-0001-8255-3909, e-mail: olga.musinko@gmail.com
Oleksandr Bilyi, student in Applied Mechanics, National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Kyiv, Ukraine, ORCID: https://orcid.org/0009-0002-1968-0993, e-mail: oleksandr.bilyi-mp31@lll.kpi.ua
Abstract
Keywords
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Citations
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4. Banerjee S. S., Burbine S., Kodihalli Shivaprakash N., Mead J. 3D-Printable PP/SEBS Thermoplastic Elastomeric Blends: Preparation and Properties. Polymers. 2019. 11(2):347. https://doi.org/10.3390/polym11020347.
5. Fekete I., Ronkay F., Lendvai L. Highly toughened blends of Poly(lactic acid) (PLA) and natural rubber (NR) for FDM-based 3D printing applications: The effect of composition and infill pattern. Polymer Testing. 2021. Vol. 99. 107205. https://doi.org/10.1016/j.polymertesting.2021.107205.
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