Jovana Marković

Accurate reciprocating tribological testing depends on the mechanical design, kinematic stability, and load application strategy of the testing apparatus. This paper presents the design, construction, and validation of a custom-built linear reciprocating tribometer developed for controlled laboratory testing. The tribometer provides a programmable stroke of up to 500 mm and a sliding-velocity range of 0.1–50 mm/s. The tribometer was validated through finite element analysis, repeated friction tests, and noise measurements. FEM results showed a maximum displacement of 0.1664 mm and a maximum von Mises stress of 7.47 MPa for the moving plate assembly under a 100 N load, while the loading portal exhibited a maximum localized displacement of 0.017 mm and a maximum stress of approximately 13 MPa under combined loading. These conditions correspond to the maximum design load of the developed tribometer. Repeated tests at 10, 15, and 20 mm/s yielded coefficients of variation of 2.84%, 5.90%, and 14.62%, respectively. Acoustic measurements showed standard deviation values in the range 1.868–3.119 dB. The obtained results confirm stable operation, limited structural deformation, and satisfactory repeatability within the analyzed operating range, indicating that the developed tribometer is suitable for controlled reciprocating tribological experiments under representative laboratory conditions.

Understanding the tribological behavior of additively manufactured polymers is essential for their reliable use in sliding components. Tribological tests were performed on a linear reciprocating tribometer pin-on-plate configuration using a polycarbonate sample (PC–PC). To assess the influence of additive-manufacturing-induced anisotropy, three build orientations (0°, 45°, 90°) were examined. Two normal loads of 39.24 N and 58.86 N, and two sliding velocities of 15 and 20 mm/s were selected to represent typical low-load operating conditions of polymeric components. Tests were conducted in dry contact and with two commercial lubricants exhibiting distinct rheological characteristics. Surface topography was characterized before and after testing to evaluate orientation-dependent roughness evolution, while rheological measurements provided effective viscosities at shear rates corresponding to imposed velocities. Frictional behavior was analyzed through the Stribeck parameter, showing that all configurations operated within boundary or early mixed lubrication regimes. Longitudinal specimen layer orientation (90°) was expected to give the lowest friction. In fact, dominant lowest friction in most of the examination regimes gave the 45° build orientation, whereas the 0° orientation hindered lubricant entrainment and produced the highest boundary interaction. Differences in lubricant viscosity influenced Stribeck positioning and the magnitude of friction reduction, demonstrating strong coupling between layer orientation, roughness evolution, and lubrication performance.