Investigation on tribological properties of PETG with integrated PTFE inserts

The parts and components produced from polyethylene terephthalate glycol (PETG) using additive manufacturing techniques require improvements in tribological properties, which represent a significant scientific and technical challenge. The high coefficient of friction and susceptibility to wear of PETG restrict its use in functional parts that operate under sliding conditions. This study, therefore, proposes coaxially integrating cylindrical polytetrafluoroethylene (PTFE) inserts measuring 3 or 6 mm in diameter into 3D printed PETG structures. PETG samples were fabricated using fused deposition modelling and tested under various normal loads (50 – 150 N) at a sliding velocity of 0.2 m/s to evaluate their tribological properties. The experimental results demonstrated that the PTFE inserts reduced the coefficient of friction by up to 68 % (from 0.57 – 0.64 to 0.18 – 0.24) compared to pristine PETG. Samples with a 6 mm insert exhibited the best performance, with a coefficient of friction ranging from 0.18 to 0.24 and up to 75 % wear reduction. PETG serves as a structurally strong matrix, while the PTFE inserts impart excellent anti-friction properties through transfer-film formation. Thermomechanical analysis verified the stability of the materials in the range from 40 to 80 °C. These results highlight the potential of this hybrid material for creating self-lubricating components such as bearings and guides by combining the mechanical strength of PETG with the superior anti-friction properties of PTFE.