Three-dimensionally printed parts are increasingly used in industry for quick repairs. They are often operated in the presence of grease, oil, and others. This article describes the effect of engine mineral oil on the fatigue life of 3D-printed FDM plastic samples. For this reason, this article aimed to investigate the influence of oil on the fatigue life of materials made using this technology. Samples made of ABA, ASA, PLA, and HIPS materials were printed with 100% fill. Divided into groups, they were stored for 15, 30, and 60 days in an oil bath at a room temperature of 23 °C and an increased temperature of 70 °C. To compare the effect of storage in oil, static tests were performed to determine the tensile strength of the specimens and to determine the load levels for the cyclic tests. Cyclic tests were performed to determine the effect of oil and temperature on the fatigue life. Internal structure studies of the specimens were performed using computed microtomography to determine the changes in the porosity of the specimens under the influence of oil. In the case of ABS, the oil-bathed samples showed a clear increase in the fatigue life, especially at 23 °C. For the ASA specimens, an increase was also evident, especially for the lower stress value. For HIPS and PLA, no clear effect of the oil bath on the fatigue life value of the samples was determined. Porosity studies using computed microtomography showed a clear decrease in the porosity of the samples as a result of the oil bath for all of them.
Keywords: 3D print; cyclic test; micro-CT; mineral oil; oil bath; polymers.