Science and Research 22 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 1 Introduction In modern technical science, the radial shaft seal (RSS) has been developed to match the industrial needs in various aspects. To verify and extend the potential lifetime limit, the function testing environment for RSS has been as well extended in various standards. This work presents a new testing environment for RSS, specifically focusing on the potential application of 3D printed counterpart following from [1]. After different 3D printing processes, different initial materials, and various postprocessing methods, the 3D printed counterparts have been investigated with a reference oil and one specific RSS with various operation conditions. The results show partially comparable results with the standard counterpart, which leads to potential applications of 3D printed counterparts in research field. 2 Test setup and test material In this section, the test procedure, more specifically the applied test setup and test material, will be introduced one after another. Similar like the previous works, the specially designed RSS test rig at the Institute for Machine Elements, Design and Manufacturing has been implemented for the experimental tribological investigations, which provides comparable operation conditions while using simplified minimal lubrication principle [2] [1]. After that, in section 2.2 the test materials are intro- Tribological Investigations of Radial Shaft Seal with Focus on 3D Printed Counter Surface Yongzhen Lin, Matthias Kröger, Jenny Köckritz, Deeksha Lohani, Ringo Nepp* submitted: 26.09.2025 accepted: 19.03.2026 (peer review) Presented at GfT Conference 2025 Tribological performance of radial shaft seals (RSS) has been evaluated among experimental investigations with different metal counter surfaces in the recent decades. The counter surface has been identified as one of the main drivers determining the tribological performance of RSS. In general, the metal counterpart needs to be manufactured specifically to achieve a specific surface structure as well as an optimal surface roughness. The appropriate application of RSS as a dynamic seal element in different types is depending on different boundary conditions. In order to extend the knowledge on the boundary conditions specifically the potential application of RSS on 3D printed counterparts, tribological investigations have been performed and evaluated in this work. More specifically,3D printed counterparts with different materials, various 3D printing processes with or without postprocessing have been examined. The potential operation limits such as temperature and rotation speed have been searched. Correlations between the counter surface properties and the tribological performance have been observed and evaluated from different aspects and in different ways. The results of this work are determined experimentally, particularly focusing on the methodical approach on 3D printed counterparts. A specifically established RSS test rig at the Institute for Machine Elements, Design and Manufacturing is available for the experimental tribological investigations. The aim of this work is to set up a basis for the future researches and potential applications regarding optimization operation conditions of RSS for wear reduction and service life extension. As well as gaining new insights for the possibility of 3D printed counterparts in tribological investigation of RSS. Keywords Radial shaft seal, counterpart, 3D manufacturing, new material, tribological investigation, surface topography analysis Abstract * Yongzhen Lin, M. Sc. (corresponding author) Orcid-ID: https: / / orcid.org/ 0000-0002-0700-0914 Prof. Dr.-Ing. Matthias Kröger Orcid-ID: https: / / orcid.org/ 0000-0002-4132-8323 Dipl.-Ing. Jenny Köckritz Orcid-ID: https: / / orcid.org/ 0009-0000-6042-5367 Dr. Deeksha Lohani Orcid-ID: https: / / orcid.org/ 0009-0003-8455-8473 Dr.-Ing. Ringo Nepp Orcid-ID: https: / / orcid.org/ 0009-0001-7837-258X TU Bergakademie Freiberg Institute for Machine Elements Design and Manufacturing Agricolastraße 1, D-09599 Freiberg duced, especially the applied initial materials for 3D printing processes. Analog from one previous work [1], the 3D printed parts are inserted into tribological investigation to get the tribological properties such as friction torque and temperature. 2.1 Test setup for tribological measurement A specially designed RSS test rig at the Institute for Machine Elements, Design and Manufacturing serves for tribological performance measurements of RSS under minimal lubrication concept. This test rig and the relevant components have been described in Figure 1. In this study the shaft part has been replaced with different 3D printed counterparts. This test rig has been operated for different tribological investigations at the institute to extend the knowledge of tribological behavior of RSS under various influences such as different lubricants, different environment temperature [2]. 2.2 Test material The applied test materials including the RSS, the lubricants as well as the shaft counterparts are introduced in detail in this section. In order to keep the variations of the whole tribological system as simplified, the variations in this study are placed on the shaft counterparts using different materials and potentially the different circumferential velocities. 2.2.1 Radial shaft seal and lubricants In this work, the focus is placed on the potential influence of different counter surfaces. The key parameters of the applied materials are listed in Table 1. In order to keep the focus of this study on potential applications in research of counterparts using different initial materials, the other important components such as RSS and lubricant have been selected as standard ones after the industrial standard [3] [4]. Among all the materials of counterpart, the C45R is selected as a standard reference counterpart, while stainless steel 316L is laser powder [5], Thermoplastic Polyurethane (TPU) is a plastic filament [6] and Copper* filament (Copper*) is indicated as one specific copper filament with over 80 % copper pigment and 20 % Poly Lactic Acid (PLA) [7]. These are initial 3D printing materials with different composites. The states of counterparts are categorized as standard, As-build (AB), Mechanical processing (MP) and Plasma electrolytic polishing (PeP). The process Plasma Electrolytic Polishing (PeP) is an advanced, non-conventional electrochemical surface finishing technique characterized by applying high voltage between the workpiece and an electrolyte, inducing localized micro-discharges at the interface. These micro-discharges facilitate selective anodic dissolution of surface asperities, resulting in substantial surface smoothening while maintaining high dimensional accuracy. The process typically achieves material removal on the order of micrometers, ensuring minimal impact on part geometry. PeP can produce ultra-smooth, mirrorlike finishes across a wide range of metallic materials, including stainless steels, titanium alloys, and aluminumbased substrates. Its non-contact, electrochemical mechanism allows efficient polishing of complex geometries, intricate internal channels, and hard-to-reach features that are challenging for conventional mechanical polishing methods. From an environmental perspective, PeP is a sustainable surface finishing approach, as it employs non-toxic electrolyte soluti- Science and Research 23 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 Figure 1: Applied test rig with necessary components. "#$%#&'&()! *+(',-+.)! +&/ ! 0,#%',(-')! 122! 341! 456*7! 78! 9! : ; ! 9! <=! >: ! 9! <: ! 9! <! ? @A,-B+&(! CD57! E! >F5! G2H! DI! JKK! LG2H! 7>>8M! N'&)-(O! 88>PJQRST$ ! " LJ: QU"M "" ! D-)B#)-(O! VKPK; Q$$ # T)! L>KQU"M! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! JKP>JQ$$ # T)! LJKKQU"M! "#@&(',%+,(! ">: 1! 2(+&/ +,/ =! S,#@&/ ! 7JW? ! 54=! *0=! 0'0! X06! 54! "#%%',Y! 54=! *0! Table 1: Key parameters of the applied materials. FFF process the applied materials are TPU and Copper*. The production processes for different materials also with different 3D printers differ from each other. The important printing parameters from different 3D printing machines are listed in Table 3. The different printing methods influence to a certain extent the material properties from the initial state to the product part. In Figure 2, surface structure differences on the As- Built (AB) parts from different materials can be observed significantly. From 316L and SLM procedure, the AB part has clearly layered structure probably due to the infill scan strategy with 67°. This structure is not clearly visible on the AB TPU part and FFF procedure. Meanwhile the AB Copper* part shows a completely different surface structure, on which there are clearly powdery particles visible. After production, some of the AB metal samples have been processed with two different post-processing methods, which are MP and PeP. Since it’s difficult to apply post-processing on TPU part, the TPU samples are applied in tribological investigation in AB state. Other than that, the 316L and Copper* parts are post-processed. Some 316L samples remain also not post-processed to compare the surface structures under microscopic analyse. Before PeP, the samples were Particle blasted at 9000 rpm for 30 min to ensure uniform surface pre-conditioning. PeP was subsequently carried out at an applied voltage of 350 V and an electrolyte temperature of 80 °C. The treatment was performed in four cycles of 10 min each, with the sample rotated by 90° after every cycle. This procedure resulted in a total polishing duration of 40 min, ensuring complete 360° surface coverage. Science and Research 24 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 ons and generates minimal chemical waste or gaseous emissions. Furthermore, the absence of mechanical contact eliminates tool wear, contributing to process stability and repeatability. Despite these advantages, PeP presents challenges in achieving precise local control of material removal. The stochastic nature of plasma formation and micro-discharge distribution can result in non-uniform polishing at localized regions, which may limit its application for components requiring extremely tight tolerances in specific areas. Continued research is therefore focused on optimizing electrolyte composition, voltage parameters, and process dynamics to enhance local control while retaining the inherent benefits of the technique. To have a short insight on the mechanical characters of 3D printing materials, the physical properties of the standard part and the other initial materials are summarized in Table 2. The Youngs’ modulus of 316L has been measured at the institute according to [8] methodically. The Youngs’ modulus of other materials are from industrial data sheets [6] [7] [9]. As it could be observed that the 316L powder has a much higher Youngs’ modulus than Copper* and TPU materials. Meanwhile, 316L has also a relative higher thermal conductivity in comparison with TPU filament. The thermal conductivity of the Copper* filament remains unknown. 2.2.2 Shaft counter faces Using additive manufacturing methods, multiple components can be produced within hours. The applied methods in this work are Selective Laser Melting (SLM) metal and Fused Filament Fabrication (FFF) plastics. For SLM process the applied material is 316L, while for C45R 316L Copper* TPU Youngs’ modulus [MPa] 210*10 3 180*10 3 4210 40 Thermal conductivity [W/ K*m ] 42.6 15 - 0.19 Table 2: Material properties of the applied counterparts. raw material 316L TPU Copper * 3D printing Machine Farsoon © FS273M Creality Ender 3 S1Pro Bambu Lab © A1 Proceeding SLM FFF FFF Nozzle temp 220 °C 200 °C Print plate temp 100 °C 60 °C 60 °C Layer thinkness 0.041 mm 0.25 mm 0.08 mm First layer thinkness - 0.3 mm 0.1 mm Infill density 100% 100% 100% Infill pattern Scan strategy_X, 67 ° Straight linear Straight linear First layer velocity - 30 mm/ s 50 mm/ s Infill laser velocity 900 mm/ s 30 mm/ s 105 mm/ s Table 3: 3D production processes for different initial materials. ab © A1 near s ab © A1 near s Youngs’ modulus [MP Thermal conductivity [W s’ modulus al conduct In Figure 3, the post-processed 316L parts are shown in comparison with the AB part. As it is directly observed that the MP and PeP processes change the surface structure significantly, while the surface structures changing after MP and PeP differ from each other as well. These optical differences raise the question if the surface roughness ranges and the material properties are sufficient to be applied in tribological investigation of RSS. 2.3 Measuring procedure The mean measuring procedures for this paper are first the surface roughness measurement after the industrial standard [10] [11] [12] and second the tribological investigation. From the topography surface measurement, not only the roughness parameters have been summarized, but also the topographies show the difference in surface structures from different materials and different post-processing. 2.3.1 Surface roughness measurement Before the parts are inserted into tribological investigations, the surface topography and surface roughness properties have been measured and evaluated. In Figure 4 and Figure 5 are the topography results of the parts. From the topography figures in Figure 4, clear difference among AB part and post-processed parts can be observed. On AB part there are visible micro particles. PeP process changed the surface character completely. On MP part there are visible polishing traces. In Figure 5 are the topography results of three different materials. Here the different surface structures are clearly visible. The Copper*-MP part shows slight different surface structure than 316L- MP part, mostly due to the initial material and the printing process. Other than that, the TPU part with the layer structure is clearly visible, which is strongly influenced by the filling ratio, the melting temperature as well as the filling velocity. In addition to this, the surface roughness has been measured to reach the surface tolerance according to [12]. As it’s shown in Figure 6, the surface roughness parameters are shown for all the measurements including the AB samples. For all parts, six parameters Science and Research 25 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 AB MP PeP Figure 4: 3D topography figures from the 316L metal samples with and without post-processing. 316L TPU Copper* Figure 2: Surface structure on AB parts from different materials and procedures. Figure 3: Optical observation on AB part and post-processed 316L parts. have been removed. For further analysis in this study, it is focused on R i values. Since the surface structure and the profile valley depth could influence the lubricating film and further the tribological performance, it’s interesting to observe from the diagram in Figure 7 that there is extremely large difference between the TPU part and the metal parts. Other than that, among the metal parts, the Copper* part shows as well higher R z and R v values, which affect the tribological performance significantly. Beside the topography analyses, the concentricity tolerance of the parts has been verified after the industrial standard [15] [12]. This has been investigated with Hexagon Quindos © along the cylinder circumference. 50 sampling points have been taken from each part. The results are listed in Table 4 as follows. The actual diameter D A and the actual roundness R o of the test parts have been measured by 50 measuring points along the circumference. The results are listed in Science and Research 26 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 are shown in diagram, which are specific: Arithmetical mean height (R a ), Maximum height of profile (R z ), Maximum profile valley depth (R v ), Root mean square deviation (R q ), Medium arithmetic height (S a ) and Medium square height (S q ) [13]. All these values describe the surface character from different aspects. In general, R i values describe the measured values along with the sampling length, while S i values stand for the measured values within a defined area range [14]. It’s clearly to observe that the AB parts from three different materials demonstrate higher surface roughness values, especially the R z and R v values. At this point, it needs to be highlighted that the post-processing helps to improve the surface quality significantly. Especially the parts D45-316-PeP have a R a 0.65 μm, R z 3,06 μm while the D45-316L-MP parts have a R a 0.97 μm R z 5.94 μm. Figure 7 shows the surface roughness measurement results of the parts that have been investigated in tribological experiments afterwards. The results of AB parts Figure 5: Topography results of three different initial materials. Figure 6: Surface roughness measurement results from all the parts with and without post-processing. #$$ & #$$ & )& &#) " '' -! )& &#) " '' ! ')& ! "( H * % % Table 4. The industrial Standard [12] and [15] require the shaft diameter tolerance ΔD t should not be exceeding 0.16 mm and the roundness tolerance R ot should not be exceeding 0.02 mm. It can be observed that the D45-316L-MP and D45- 316L-PeP parts have the allowable tolerance on diameter and roundness, while the D38-Copper*-MP part exceeds slightly the roundness tolerance, but has a good fit on diameter tolerance. Nevertheless, the D38-TPU part has exceeded the tolerance on diameter and the roundness tolerance a lot. 2.3.2 Tribological investigation The tribological performance has been carried out through experimental investigations on the RSS test rig. To explore the potential applications for function tests, a parameter study has been carried out to select the maximum boundary. In Table 5, the applied circumferential velocities have been generated from 1 m/ s to 5 m/ s in various steps. The study [16] has shown that various velocity steps have a significant influence on tribological performance of RSS with specific lubricants. Generally, the tests have been running at a constant circumferential velocity for 1 or 2 hours to reach the stationary states. In addition, multiple repeated tests have been carried out to validate. In Table 5 are the applied circumferential velocities from 1 m/ s to 5 m/ s labeled from E11 to E19. The investigations have been carried out from lower circumferential velocity. The velocity for each test has Science and Research 27 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 Figure 7: Surface roughness measurement results from all parts applied afterwards in tribological investigations. ! "" # &# #! & $$ $&# % ( ' D A [mm] ΔD [mm] ΔD t [mm] R o [mm] R ot [mm] D38-TPU 37.583 0.471 0.16 0.064 0.02 D38-Copper * -MP 37.843 0.157 0.16 0.027 0.02 D38-316L-MP 38.023 0.023 0.16 0.008 0.02 D45-316L-MP 44.942 0.058 0.16 0.01 0.02 D45-316L-PeP 44.901 0.099 0.16 0.02 0.02 Velocity [m/ s] D38, Standard D38-TPU- AB D38- Copper * - MP D38-316L- MP D45-316L- MP D45-316L- PeP E11 1 2h E12 1.2 2h 1h / 2h E13 1.4 1h / 2h 1h / 2h 1h / 2h 2h E14 2 broken 2h 1h / 2h 2h E15 2.1 2h 1h / 2h 2h E16 2.4 broken 1h / 2h 2h 2h E17 2.8 1h / 2h unstable 2h E18 3.5 1h / 2h unstable E19 5 2h unstable Table 4: Actual diameter and actual roundness measurement. Table 5: Applied circumferential velocity profiles and the examined profiles. in comparison with the part D38-Copper*-MP, while the part D38-316L-MP has determined higher torque and temperature values. In addition, the part D38-316L-MP shows that torque and temperature reach slowly stationary state after 30 min, with a temperature about 103 °C near the contact area. Meanwhile the results of part D38- Copper*-MP show a rapid heat up and it reaches an almost stationary state in temperature immediately after 3 min of the velocity application, with a temperature of about 50 °C. Afterwords, the temperature increases slowly till the end of measurement. The torque development shows similarity from both test conditions, yet the absolute values differ from each other. Characteristic results have been marked with three circles in the left diagram in Figure 8, the mean values of the maximal torque at t 0 , the minimal torque at t end and the temperature at t end . These results from each measurement are chosen for the following evaluation. In the very beginning, the maximal torque at t 0 and minimal torque at t end have been presented in Figure 9. These values have been generated from part D38-TPU, D38- Copper*-MP, D38-316L-MP and D45-316L-MP. As it Science and Research 28 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 either been repeated or has been added up to next step. The adding step is stopped when the seal or the counterpart fails. After several repeat tests, the tribological performance could be evaluated based on the measurement results. TPU and Copper* parts are broken after the defined maximal velocities, while the 316L parts remines in good states. In addition, the torque and temperature developments with 316L parts are not stationary with the defined maximal velocities. 3 Results and discussion The measurement results are discussed in this section considering different aspects. First, examples of a whole measurement after 1 hour of two specific tests are shown in Figure 8. Analog to [17] the local tribology of the RSS has been evaluated. On the left, the diagram shows a measurement result from part D38-316L-MP with a constant rotation velocity 3.5 m/ s, while on the right side, the diagram shows a measurement result from D38- Copper*-MP with a constant rotation velocity 1.2 m/ s. From both diagrams, it can be observed that the part D38-316L-MP can stand higher circumferential velocity Figure 8: Torque and temperature measurement of one specific test. Left: D38-316L-MP at 3.5 m/ s, right: D38-Copper*-MP at 1.2 m/ s. Figure 9: Maximal and minimal torque of all investigations from different parts measured in 1 hour. "%$( " ') & ! '"%$( ' "## % can be observed from the diagram, the TPU and Copper* parts can only endure less than 2 m/ s. Although the parts D38 and D45 have been post-processing with MP, they have different circumferential velocity tolerance and different torque performance, mostly due to the difference in surface structure, which could be summarized from the topography measurement in Figure 7. In Figure 10 the temperature at t end from all the tests has been presented. These points are generated either from different circumferential velocities or from repeat tests. As it can be observed that from one material, the temperature range is relatively large, especially on the part 316L, the temperature range is over 30 °C on velocity difference of 1 m/ s. On the other side, tests with TPU parts have shown higher temperature than Copper* having the same friction torque (see Figure 9). This shows different thermal properties of both these materials. After the evaluation of measurement results of 1 hour, it could be deduced that the testing time is too short to observe any potential long-term changes. Therefore, several tests in 2 hours have been carried out. The testing principle remines to extend the potential maximal velocity, until the counterpart or the seal fails. The evaluation of the tribological performance is based on the minimal torque at t end and temperature at t end . In this batch of tests, the D38-Standard counterpart has been tested to have a reference for the other measured results. All the test results are presented in Figure 11. As it can be observed from the diagram, only the standard counterpart can stand higher velocity of 5 m/ s. The D38-316L-MP parts can stand relatively high velocity till 3.5 m/ s. Between the D45 parts with two different post-processing methods, the PeP part can stand relatively higher velocity till nearly 3 m/ s, while the MP parts stand around 2 m/ s. Last but not less, the TPU part can stand lower than 2 m/ s and the Copper* parts can stand slightly higher than 2 m/ s. In comparison with TPU, the Copper* parts can stand higher velocities, and cause lower temperature. The 316L parts both with D38 and D45 cause higher torque and stranger temperature increase with lower velocities then the reference part C45R. In comparison with TPU and Copper* parts, which cause lower torque and lower thermos effects at lower velocities. All measured temperature results are shown in Figure 12. From this diagram, it can be observed that the TPU, Copper*, D45-316L- MP and D45-316L-PeP parts with lower velocity have caused linear proportionally lower temperature changes. Meanwhile the D45-316L-PeP as well as the D38-316L-MP with higher velocity have caused higher temperature changes. The results of tests with D38-Standard show lower temperature range lower than 100 °C at higher velocities, which could be explained with higher thermal conductivity. Other than that, the friction coefficient μ is calculated with formula μ = 2 * M min / (D * F R ), Science and Research 29 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 Figure 11: Maximal and minimal torque of all investigations from different parts measured in 2 hours. ! $'! ( *+(! - ! #& "*, $ ) ! $' * * ! % &''! ( "%! ( &''! ( "%! ( "%! ( $'&* " ! $ )+ " ( # )$'&* ) $%% ' ) # ' Figure 10: Temperature scattering from adding up circumferential velocities measured in 1 hour. different heating processes with different materials could be observed with more details. Other than that, the rotation speed profile could also to be extended such as inconstant, alternately changing profile to extend different tribological performance testing among different testing environments. References [1] Y. Lin, R. Nepp, J. Gerschler and M. Kröger, “Radial shaft seal with different relative velocities and on a 3D printed counter surface,” Industrial Lubrication and Tribology, pp. 758-764, 75(7) 2023. [2] C. Berndt, Tribologie von Radial-Wellendichtungen, Dissertation, TU Freiberg, 2019. [3] Weber Reference Oils, FVA3A Referenzöl Datenblatt, 2018. [4] Deutsches Institut für Normung e.V. (Hrsg.), DIN 3760: 1996-09: Radial-Wellendichtringe, Berlin: Beuth, 1996. [5] eos, “EOS StainlessSteel 316L-4441,“. Available: https: / / store.eos.info/ de/ products/ eos-stainlesssteel-316l. [accessed on Aug. 26. 2025]. Science and Research 30 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004 in which the M min refers minimal torque at t end , D refers the nominal diameter and F R refers radial force which has been measured on new RSS before utilization. The results are shown in Figure 13. As it can be observed from Figure 13, TPU and Copper* parts have caused less friction in the contact area at lower velocities. On the other hand, the 316L parts with MP and PeP post-processing have contributed to higher friction. The standard part shows medium friction coefficient. 4 Summary and conclusion In this work, tribological investigations have been carried out with the focus on different counterparts, especially with 3D printed parts from different materials, different printing processes and different post-processing methods. Before the tribological investigation, surface roughness and other essential measurements have been executed to get more knowledge about the surface structure as well as other mechanical properties. The tribological performance has been tested with different constant circumferential velocity profiles within 1 hour or 2 hours. The constant circumferential velocity varies from 1 m/ s to 5 m/ s. After the experimental investigations, the measured torque and temperature values from all the counterparts have been evaluated in various aspects. The measurement results show significant tendencies of the relevance of the torque temperature depending on the velocity with counterparts of different materials. This study provides a new effective trend at the institute internally by applying additive manufactured parts from new materials as well as new producing processes also in tribological applications. This would help a lot, especially in the first prototype testing phase of products whether for new RSS types, new lubricants, new test procedures or new counterparts. In the future, the thermal properties of different 3D printing initial materials need to be further measured and evaluated. These properties have significant influences on the tribological investigations of RSS. Meanwhile, ! $'! ( *+(! - ! #& "*, $ ) ! $' * &''! ( * % ( ! "%! ( "%! ( ! "%! ( Figure 12: Temperature scattering from adding up circumferential velocities measured in 2 hours. (" *"&% & ! #& "*+ $ ) (" *"&% & ! * &'' ( * % ( Figure 13: Friction coeffient of all investigations from different parts in 2 hours. [6] extrudr, “FLEX Hard CF,”. Available: https: / / www.extrudr.com/ de/ de/ products/ flex-hard-cf/ ? variant=UHJvZHVjdFZhcmlhbnQ6MzYyOQ%3D%3D. [accessed on Aug. 26. 2025]. [7] eins3d, “Kupfer Filament,”. Available: https: / / eins3d.de/ products/ kupfer-filament-2-85mm-500g. [accessed on Aug. 26. 2025]. [8] C.-H. Yu, A. Leicht, R. L. Peng and J. Moverare, “Low cycle fatigue of additively manufactured thin-walled stainless steel 316L,” Materials Science and Engineering: A, p. V. 821, 2021. [9] Deutsche Edelstahlwerke, “Werkstoffdatenblatt C45R,”. Available: https: / / swiss steel-group.com/ content-media/ documents/ Data-Sheets/ Engineering-Steel/ 1.1191_1.1201_de.pdf. [accessed on Aug. 26. 2025]. [10] Deutsches Institut für Normung e.V. (Hrsg.), DIN ISO 25178-2: Geometrical product specifications (GPS) - surface texture: Areal, 2016. [11] W. Tietze, Handbuch Dichtungspraxis. 3.Aufl., Essen: Vulkan-Verl., 2003. [12] Deutsches Institut für Normung e.V. (Hrsg.), DIN3761: Radial-Wellendichtringe für Kraftfahrzeuge, 1984. [13 Keyence, “Introduction to roughness,” Available: https: / / www.keyence.com/ ss/ products/ microscope/ rough ness/ . [accessed on Aug. 20. 2025]. [14] M. Marxer, C. Bach and C. P. Keferstein, Fertigungsmesstechnik. Alles zu Messunsicherheit, konventioneller Messtechnik und Multisensorik. 10. Aufl., Wiesbaden: Springer Vieweg, 2021. [15] Deutsches Institut für Normung e.V. (Hrsg.), DIN EN ISO 1101: Geometrical product specifications (GPS) - Geometrical tolerancing., 2017. [16] M. Kröger, R. Teichert and Y. Lin, “Scaling of radial seals - Safely go into series production,” in JAHRBUCH Dichten. Kleben. Polymer., ISGATEC, 2024, pp. 80-90. [17] M. Kröger, Y. Lin, R. Nepp and S. Haupt, “Observation of local tribology of shaft seals,” in Arnold Tross Colloquium, Hamburg, 2024. Science and Research 31 Tribologie + Schmierungstechnik · volume 73 · issue 1/ 2026 DOI 10.24053/ TuS-73-0004