This research examines dry sliding of journal bearings made of Polyamide 12 (PA12) using additive technologies, addressing the gap in knowledge related to tribological behaviour in real conditions. In contrast to traditional tribological tests on flat surfaces, in this paper, full-scale journal bearings are tested under radial load. Three different pressure-velocity (PV) regimes were used to determine their effect on the coefficient of friction (COF), contact temperature, and surface morphology change. The results show that after a period of running-in, all tested samples reached a steady state with friction coefficients around 0.1 with insignificant oscillations, which indicates a stable and repeatable friction behaviour. Contact temperatures vary with operating conditions, where they reach their maximum at the most loaded regime, around 90 degrees, but it is still below the PA12 Vicat softening temperature (175°C), which indicates thermal stability. Scanning electron microscopy (SEM) analysis of the surface before and after testing confirms microstructural changes at the contact zone, showing a transition from a particulate to a smoother structure. The intermediate mode used in the test shows an optimal balance between frictional performance and thermal stability. The obtained results demonstrate that SLS-printed PA12 bearings can be applied in conditions without external lubrication, thereby enabling maintenance-free systems with operational parameters suitable for use. This work provides significant insight into industrial applicability and provides a basis for future tests that will deal with long-term tests and comparative evaluation with bearings produced via other additive manufacturing techniques.
Simonović et al. (Wed,) studied this question.