Effect of print orientation and recycling on the mechanical and tribological properties of 3D-printed PLA polymer materials

ALTINSOY Ş.

Journal of Mechanical Science and Technology, vol.39, no.10, pp.5897-5912, 2025 (SCI-Expanded, Scopus) identifier

  • Publication Type: Article / Article
  • Volume: 39 Issue: 10
  • Publication Date: 2025
  • Doi Number: 10.1007/s12206-025-0926-6
  • Journal Name: Journal of Mechanical Science and Technology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Page Numbers: pp.5897-5912
  • Keywords: 3D printing, Mechanical properties, Polylactic acid (PLA), Recycled filaments, Wear
  • İstanbul Yeni Yüzyıl University Affiliated: Yes

Abstract

Polylactic acid (PLA) and recycled PLA (Re-PLA) samples were produced using a 3D printer with 50 % fill rate, vertical and horizontal truss orientation, and layer thickness of 0.10, 0.15, and 0.20 mm. Mechanical, wear, and SEM analyses were performed. Results show that printing orientation has a stronger influence on tensile, bending, and compression strength than layer thickness. Vertically printed PLA and Re-PLA samples exhibited higher strength and ductility, while Re-PLA horizontal samples lacked a clear yield point. The highest hardness (76 shore D) was measured in PLA-V at 0.20 mm thickness. Surface roughness increased with layer thickness and was greater in horizontal and Re-PLA samples. Friction behavior varied by filament type and thickness, with 0.1 V samples showing the highest values. SEM images revealed brittle fractures in PLA and more ductile but structurally irregular fractures in Re-PLA, with more cracks and gaps-factors contributing to its reduced mechanical performance.