This study aims to investigate the influence of exposure time and layer thickness on the cavitation erosion resistance of poly lactic acid (PLA) specimens fabricated via additive manufacturing (AM), with the aim of clarifying how these two factors influence erosion behavior and surface degradation.
PLA specimens were fabricated using the material extrusion (MEX) process with layer thicknesses of 0.1 mm, 0.3 mm and 0.5 mm. Cavitation erosion resistance was evaluated using a vibratory erosion test on stationary specimens. Cumulative mass loss and surface roughness were measured at regular intervals during testing. To remove cavitation-induced mass loss from water absorption effects, identical control specimens were used to compensate for weight gain because of water uptake. ANOVA and regression analysis were conducted to determine the significant effects of the contributing parameters on the response.
The results of this study indicated that increasing layer thickness from 0.1 mm to 0.3/0.5 mm markedly enhances cavitation erosion resistance, as evidenced by a longer incubation period and lower cumulative mass loss compared to the thinnest-layer specimens; however, the behavior is not strictly monotonic, as the 0.5 mm specimens exhibited a marginally higher net mass loss than the 0.3 mm specimens at the end of the test, suggesting that 0.3 mm provides a favorable erosion-resistance performance among the investigated three layer thicknesses. During the incubation stage, surface roughness remained nearly constant, corresponding to the initial as-built surface condition. As erosion progressed, surface roughness increased concurrently with mass loss, demonstrating a strong correlation between surface degradation and cavitation activity. Thicker-layer specimens exhibited slower surface deterioration, consistent with their longer incubation period. Statistical analysis of the net mass loss data revealed that both test time (p = 0.011) and layer thickness (p = 0.003) significantly influenced cavitation erosion, with a significant interaction between the two factors (p = 0.01).
The proposed work provides systematic experimental evidence on the role of exposure time and layer thickness in governing cavitation erosion performance of MEX-printed PLA. The findings of this study provide practical guidance for selecting suitable layer thicknesses to improve the cavitation erosion resistance of MEX-fabricated PLA specimens.
