Welding of thermoplastics printed by fused filament fabrication: A critical review of joining mechanisms and relationships between processing, structure, and properties

Rahmat Azis Nabawi; Dani Harmanto; Febri Prasetya; Yogi Dian Alfana

doi:10.24036/teknomekanik.v9i3.55272

Authors

Rahmat Azis Nabawi Department of Mechanical Engineering, Faculty of Engineering, Universitas Negeri Padang, Indonesia Author https://orcid.org/0000-0003-3082-7060
Dani Harmanto School of Engineering, Infrastructure and Sustainability, Faculty of Computing, Engineering and Media, De Montfort University, United Kingdom Author https://orcid.org/0000-0001-5115-1472
Febri Prasetya Department of Mechanical Engineering, Faculty of Engineering, Universitas Negeri Padang, Indonesia Author https://orcid.org/0000-0002-0871-3350
Yogi Dian Alfana Department of Mechanical Engineering, Faculty of Engineering, Universitas Negeri Padang, Indonesia Author

DOI:

https://doi.org/10.24036/teknomekanik.v9i3.55272

Keywords:

fused filament fabrication, thermoplastic welding, friction stir welding, ultrasonic welding, laser joining, process-structure-property relationship

Abstract

Fused filament fabrication (FFF) technology, also known as fused deposition modeling (FDM), enables the production of thermoplastic components with complex geometries, but remains limited by the printer’s build volume. Welding can join separately printed components. However, layered structures, infill configurations, porosity, and interlayer bonding affect joint formation and strength. This article critically reviews six welding techniques for FFF-printed thermoplastic components: friction stir welding, friction stir spot welding, rotary friction welding, ultrasonic welding, laser joining, and microwave-assisted welding. The review focuses on joining mechanisms, process parameters, material characteristics, mechanical performance, and failure mechanisms. The results indicate that joint quality depends on the interaction among welding parameters, polymer type, infill structure, tool or interface design, and joint configuration. Increasing process energy does not always improve joint strength because excessive heating can cause thermal degradation and deformation, while insufficient material consolidation can limit joint integrity. Direct comparisons between techniques are still limited by differences in materials, specimen geometries, joint configurations, and testing methods. Evidence regarding microwave-assisted welding for joining separately printed components is also still limited. Future research needs to integrate printing and welding parameters, correlate structural characteristics and defects with mechanical performance, and improve the consistency of testing and reporting. Such an approach is necessary to clarify the relationships between process, structure, and properties and to support the development of reliable joints for engineering applications.

References

Mhd. F. M. Putra, S. Syahril, and D. Y. Sari, “Mechanical characteristics and FEA-based non-uniform infill density approaches for Fused Deposition Modelling (FDM)-printed components: A literature review,” Journal of Engineering Researcher and Lecturer, vol. 5, no. 2, 2026, https://doi.org/10.58712/jerel.v5i2.220 DOI: https://doi.org/10.58712/jerel.v5i2.220

M. Q. Hanif, R. Rifelino, F. Prasetya, and Z. Abadi, “Adhesion mechanisms and mechanical performance of single-lap joints in FDM-3D printed: A review,” Journal of Engineering Researcher and Lecturer, vol. 5, no. 1, 2026, https://doi.org/10.58712/jerel.v5i1.214 DOI: https://doi.org/10.58712/jerel.v5i1.214

S. C. Altıparmak, V. A. Yardley, Z. Shi, and J. Lin, “Extrusion-based additive manufacturing technologies: State of the art and future perspectives,” Journal of Manufacturing Processes, vol. 83. 2022. https://doi.org/10.1016/j.jmapro.2022.09.032 DOI: https://doi.org/10.1016/j.jmapro.2022.09.032

Z. Jiang, B. Diggle, M. L. Tan, J. Viktorova, C. W. Bennett, and L. A. Connal, “Extrusion 3D Printing of Polymeric Materials with Advanced Properties,” Advanced Science, vol. 7, no. 17. 2020. https://doi.org/10.1002/advs.202001379 DOI: https://doi.org/10.1002/advs.202001379

D. Anggara, R. Rifelino, Z. Abadi, and A. Arafat, “Exploring how 3D printing parameters affect the flexural strength of ABS materials,” Innovation in Engineering, vol. 1, no. 2, pp. 125–133, Sep. 2024, https://doi.org/10.58712/ie.v1i2.16 DOI: https://doi.org/10.58712/ie.v1i2.16

S. Palaniyappan, N. K. Sivakumar, M. Bodaghi, M. Kumar, and M. Rahaman, “A feasibility study of various joining techniques for three-dimensional printed polylactic acid and wood-reinforced polylactic acid biocomposite,” Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, vol. 238, no. 3, 2024, https://doi.org/10.1177/14644207231189956 DOI: https://doi.org/10.1177/14644207231189956

V. K. Tiwary, A. P․, and V. R. Malik, “Investigations on the effect of Spin Friction Welding parameters on joint strength and cylindricity of similar/dissimilar Material Extrusion (MEX) 3D printed parts,” Journal of Advanced Joining Processes, vol. 9, 2024, https://doi.org/10.1016/j.jajp.2024.100208 DOI: https://doi.org/10.1016/j.jajp.2024.100208

S. M. Senthil and M. B. Kumar, “Effect of tool rotational speed and traverse speed on friction stir welding of 3d-printed polylactic acid material,” Applied Science and Engineering Progress, vol. 15, no. 1, 2022, https://doi.org/10.14416/j.asep.2021.09.002 DOI: https://doi.org/10.14416/j.asep.2021.09.002

V. K. Tiwary, A. P, and V. R. Malik, “An overview on joining/welding as post-processing technique to circumvent the build volume limitation of an FDM-3D printer,” Rapid Prototyping Journal, vol. 27, no. 4. 2021. https://doi.org/10.1108/RPJ-10-2020-0265 DOI: https://doi.org/10.1108/RPJ-10-2020-0265

J. A. Almazán, M. Á. Almazán, M. M. Marín, A. García-Domínguez, and E. M. Rubio, “Mechanical Performance of FDM-Printed PLA Joined by Portable Friction Stir Welding: Influence of Infill Density and Tool Pin Geometry,” Polymers (Basel)., vol. 18, no. 9, 2026, https://doi.org/10.3390/polym18091013 DOI: https://doi.org/10.3390/polym18091013

M. Panico, S. Genna, A. Langella, and I. Papa, “Laser joining of FDM-printed PLA components: feasibility and thermo-mechanical analysis,” International Journal of Advanced Manufacturing Technology, vol. 139, no. 5–6, 2025, https://doi.org/10.1007/s00170-025-16036-2 DOI: https://doi.org/10.1007/s00170-025-16036-2

E. Baysal, “Investigation of the weldability of 3D printed dissimilar materials (PLA Plus and PLA CF) using ultrasonic assisted friction stir spot welding,” Mater. Today Commun., vol. 51, 2026, https://doi.org/10.1016/j.mtcomm.2026.114707 DOI: https://doi.org/10.1016/j.mtcomm.2026.114707

V. K. Tiwary, A. P․, and V. R. Malik, “Investigations on microwave-assisted welding of MEX additive manufactured parts to overcome the bed size limitation,” Journal of Advanced Joining Processes, vol. 7, 2023, https://doi.org/10.1016/j.jajp.2023.100141 DOI: https://doi.org/10.1016/j.jajp.2023.100141

N. Vidakis, M. Petousis, A. Korlos, N. Mountakis, and J. D. Kechagias, “Friction Stir Welding Optimization of 3D-Printed Acrylonitrile Butadiene Styrene in Hybrid Additive Manufacturing,” Polymers (Basel)., vol. 14, no. 12, 2022, https://doi.org/10.3390/polym14122474 DOI: https://doi.org/10.3390/polym14122474

O. Koçar, N. Anaç, and E. Baysal, “A New Approach in Part Design for Friction Stir Welding of 3D-Printed Parts with Different Infill Ratios and Colors,” Polymers (Basel)., vol. 16, no. 13, 2024, https://doi.org/10.3390/polym16131790 DOI: https://doi.org/10.3390/polym16131790

S. F. Raza, M. Umair Furqan, S. A. Khan, K. H. Mughal, E. U. Haq, and A. M. Mehdi, “Comprehensive Insights into Friction Stir Butt Welding (FSBW) of 3D-Printed Novel Nano Chromium (Cr) Particles-Reinforced PLA Composites,” Journal of Composites Science, vol. 10, no. 2, 2026, https://doi.org/10.3390/jcs10020072 DOI: https://doi.org/10.3390/jcs10020072

G. Şahin, N. Anaç, and O. Koçar, “Investigation of the Weldability of 3D-Printed Multi-Material Materials (PLA and PLA Wood) Using Friction Stir Welding,” Polymers (Basel)., vol. 16, no. 23, 2024, https://doi.org/10.3390/polym16233249 DOI: https://doi.org/10.3390/polym16233249

M. Petousis, N. Mountakis, and N. Vidakis, “Optimization of hybrid friction stir welding of PMMA: 3D-printed parts and conventional sheets welding efficiency in single- and two-axis welding traces,” International Journal of Advanced Manufacturing Technology, vol. 127, no. 5–6, 2023, https://doi.org/10.1007/s00170-023-11632-6 DOI: https://doi.org/10.1007/s00170-023-11632-6

P. Rendas, L. Figueiredo, P. Melo, C. Galhano, C. Vidal, and B. A. R. Soares, “Investigation of Friction Stir Welding of Additively Manufactured Biocompatible Thermoplastics Using Stationary Shoulder and Assisted Heating,” Polymers (Basel)., vol. 16, no. 13, 2024, https://doi.org/10.3390/polym16131897 DOI: https://doi.org/10.3390/polym16131897

E. Kanlı, O. Koçar, and N. Anaç, “An Investigation into the Friction Stir Spot Welding Behavior of 3D-Printed Glass Fiber-Reinforced Polylactic Acid,” Polymers (Basel)., vol. 18, no. 9, 2026, https://doi.org/10.3390/polym18091041 DOI: https://doi.org/10.3390/polym18091041

R. Singh, J. Singh, G. Singh, and R. Kumar, “Friction Stir Spot Welding of PLA-PEKK-HAp-CS Based 3D Printed Scaffolds for Minor Repair,” Journal of the Chinese Society of Mechanical Engineers, vol. 41, no. 5, pp. 639–646, 2020, [Online]. Available: https://journal.csme.org.tw/download/Friction-Stir-Spot-Welding-of-PLA-PEKK-HAp-CS-Based-3D-Printed-Scaffolds-for-Minor-Repair.pdf

C. C. Kuo, H. X. Liang, S. H. Huang, and S. F. Tseng, “Enhancing the Weld Quality of Polylactic Acid Biomedical Materials Using Rotary Friction Welding,” Polymers (Basel)., vol. 16, no. 7, 2024, https://doi.org/10.3390/polym16070991 DOI: https://doi.org/10.3390/polym16070991

C. C. Kuo, H. W. Chen, and S. H. Huang, “Rotary Friction Welding of Dissimilar Polymer Rods Containing Metal Powder,” Polymers (Basel)., vol. 15, no. 22, 2023, https://doi.org/10.3390/polym15224354 DOI: https://doi.org/10.3390/polym15224354

C. C. Kuo, H. W. Chen, J. Y. Xu, C. H. Lee, and S. H. Hunag, “Effects of Rotational Speed on Joint Characteristics of Green Joining Technique of Dissimilar Polymeric Rods Fabricated by Additive Manufacturing Technology,” Polymers (Basel)., vol. 14, no. 22, 2022, https://doi.org/10.3390/polym14224822 DOI: https://doi.org/10.3390/polym14224822

C. C. Kuo, N. Gurumurthy, and S. H. Hunag, “Fatigue Behavior of Rotary Friction Welding of Acrylonitrile Butadiene Styrene and Polycarbonate Dissimilar Materials,” Polymers (Basel)., vol. 15, no. 16, 2023, https://doi.org/10.3390/polym15163424 DOI: https://doi.org/10.3390/polym15163424

C. C. Kuo, N. Gurumurthy, H. W. Chen, and S. H. Hunag, “Mechanical Performance and Microstructural Evolution of Rotary Friction Welding of Acrylonitrile Butadiene Styrene and Polycarbonate Rods,” Materials, vol. 16, no. 9, 2023, https://doi.org/10.3390/ma16093295 DOI: https://doi.org/10.3390/ma16093295

F. Al Fathurrahman, F. R. N. Santoso, Erwin, D. Sugiyanto, and J. Pratama, “Limitations of Interlocking Features in Rotary Friction Welding (RFW) of 3D-printed PLA,” Jurnal Rekayasa Mesin, vol. 21, no. 1, 2026, https://doi.org/10.32497/jrm.v21i1.7419 DOI: https://doi.org/10.32497/jrm.v21i1.7419

B. Khatri, M. F. Roth, and F. Balle, “Ultrasonic Welding of Additively Manufactured PEEK and Carbon-Fiber-Reinforced PEEK with Integrated Energy Directors,” Journal of Manufacturing and Materials Processing, vol. 7, no. 1, 2023, https://doi.org/10.3390/jmmp7010002 DOI: https://doi.org/10.3390/jmmp7010002

R. S. Rana, I. Singh, and A. K. Sharma, “Ultrasonic welding of printed/molded sustainable polymer specimens with energy directors,” Ultrasonics, vol. 134, p. 107078, Sep. 2023, https://doi.org/10.1016/j.ultras.2023.107078 DOI: https://doi.org/10.1016/j.ultras.2023.107078

V. K. Tiwary, P. Arunkumar, and V. R. Malik, “Ultrasonic Welding of Similar/Dissimilar MEX-3D Printed Parts Considering Energy Director Shape, Infill, Welding Time and Amplitude,” Computers, Materials and Continua, vol. 84, no. 3, 2025, https://doi.org/10.32604/cmc.2025.066129 DOI: https://doi.org/10.32604/cmc.2025.066129

J. M. Vazquez-Martinez, D. Piñero, J. Salguero, and M. Batista, “Evaluation of the joining response of biodegradable polylactic acid (PLA) from fused deposition modeling by infrared laser irradiation,” Polymers (Basel)., vol. 12, no. 11, 2020, https://doi.org/10.3390/polym12112479 DOI: https://doi.org/10.3390/polym12112479