Jacqueline Gerhard

"The use of additive manufacturing, particularly 3D printing, for the production of sealing rings is a promising way to speed up the development cycle of new products. Complex geometries that were previously impossible or difficult to produce could now be realized. In addition, this technology allows for the rapid exploration and implementation of geometric variations in sealing profiles, enabling rapid optimization for individual applications. However, this manufacturing process presents new challenges. In order to guarantee the required sealing function, the sealing material must meet specific requirements. These requirements cannot yet be fully met by 3D printable materials, which is why the use and success of additive manufactured seals is still limited. In addition, there are a number of geometric requirements that have to be considered when printing sealing rings. In this study, a comprehensive analysis is performed focusing on the evaluation of various material properties to identify the most suitable materials for effective sealing functionality. Therefore, several elastic 3D printable materials and their printing settings were analyzed for material properties such as compression set, elongation at break, wear rate and chemical resistance. A liquid crystal display printer was used for all tests. Materials that showed optimal performance in these analyses were further tested for their printability. The geometric accuracy and reproducibility of the printed seals were analyzed and the printing parameters were optimized in order to print an optimum seal geometry. Based on the material property studies, the most suitable materials were selected. The first prototypes of additive manufactured rod seals were tested on a test bench and compared to commercially available rod seals. In this way, the functionality of the printed seals and their materials was tested under real conditions and their performance validated."

Rotary shaft seals are commonly used to seal rotating machine components and prevent the leakage of fluids into the environment. Failures of elastomeric rotary shaft seals are often the result of overheating in the contact area between the sealing edge and the shaft. High temperatures in this contact area occur due to high frictional power and/or inadequate heat dissipation. The surroundig of the seal has a significant impact on the temperatures occurring in the contact area. Studies by Kunstfeld [1] have already demonstrated that additional elements near the seal influence the temperature. Especially rolling-element bearings near the seal strongly influence the contact temperature. The frictional heat generated in the bearings results in an increase in the temperature of the fluid near the seal, consequently raising the contact temperature. Tapered roller bearings pump oil [2] and, depending on the installation situation, can lead to a higher or lower fluid level next to the seal. Tests are conducted on a High-Speed friction torque test bench [3]. This investigation involves four different bearing arrangements, as well as a reference variant without bearings. In these test runs, both the frictional torque and the temperature near the contact area are examined. In addition to the experiments on the test bench, Conjugate Heat Transfer (CHT) simu-lations are conducted with the same installation conditions. The simulated temperatures are compared with the measured temperatures. In most cases, the correlation is good. However, for one bearing arrangement, the correlation is significantly worse [4]. These differences are investigated further.

Rotary shaft seals prevent the exchange of fluid at shaft passages. Their function and service life depend decisively on the temperature in the contact area between the sealing edge and the shaft. Since the temperature depends on both the generation of frictional heat in the contact area and the heat transfer to the surrounding sealing system, the design of the sealing system is crucial. Within the scope of this work, multiphase conjugate heat-transfer analyses were performed considering different assembly situations. The computed results were presented and contrasted to experimental data. This resulted in a valid model for predicting the temperature in the sealing system, which provided insight into the influence of the sealing surroundings on the contact temperature.