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Establishment of a test method… rssr trIbOMeter 14 RSSR Tribometer … required for rapid assessment of elastomer / lubricant combinations Introduction For the design of dynamic seals with radial shaft sealing rings (RSSR), not only a large number of other influencing factors but also the selection of suitable elastomer / oil combinations plays a decisive role. At present, no standardised test method exists for the purpose of recording the wear and friction of simple material samples, taking into consideration operating conditions such as sealing geometry, contact force, circumferential speed and temperature. For investigations of elastomer / oil combinations on radial shaft sealing rings, it is, due to different shrinkage behaviour, frequently imperative to produce a separate sample tool for each elastomer compound. In order to exclude material combinations which are unsuitable at an early stage, the RSSR tribometer was developed and tested as a dynamic test method within the context of project 664 of DGMK (German Society for Petroleum and <strong>Co</strong>al Science and Technology), enabling a preselection of suitable materials on the basis of easy-to-manufacture elastomer samples. In order to establish this
test method as a standard, we are currently searching for partners who are interested in jointly implementing such a solution. Design and mode of operation The basic design of the RSSR tribometer is depicted in Figure 1. A circular ring-shaped elastomer test specimen is pressed, at a defined force, against a truncated-cone shaft test specimen. The contact area between both test specimens represents the contact between the radial shaft sealing ring and the shaft itself. The shaft test specimen is dri- Figure 1: Mode of operation of the RSSR tribometer ven via a shaft and the moment transferred to the elastomer test specimen is recorded. The contact area is located in a container filled with the test oil. The area below the elastomer test specimen can be filled with air. In addition to selecting the materials for the elastomer test specimen, shaft test specimen and test oil, the parameters oil sump temperature, circumferential speed and contact force can be set. Figure 2 shows the course of the friction moment for different test oils when using a test specimen made of nitril butadiene rubber during the 20-day standard test Figure 2: Tests with RSSR and RSSR tribometer procedure. Furthermore, the influence of the three cycles (see Figure 2) in which the circumferential speed is varied can be clearly seen. results from investigations on radial shaft sealing rings and rssr tribometer in comparison The basic suitability of the RSSR tribometer is examined by investigations of a sample elastomer / oil combination of a nitril butadiene rubber with a conventional mineral oil, and the results of the RSSR tribometer are compared with those of radial shaft sealing rings of the same material. Figure 3 shows the influence of the parameters oil sump temperature and circumferential speed at the sti- RSSR Tribometer 15
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