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Cost-efficient evaluation of elastomer-lubricant incompatibility under tribological loads equivalent to radial shaft seals
Summary
Incompatibilities between elastomers and lubricants can lead to damages in a sealing system and also to its complete failure. Therefore, there are various test methods to detect these incompatibilities already at the development stage.
The aim of the project FVA 578 III is to develop a standardized test method on a tribometer for elastomer-lubricant compatibility with simple test specimens and a small amount of oil. Furthermore, the applications of various analytical methods for identifying the effects of incompatibility on the elastomer are investigated and rated based on their suitability.
The earlier an incompatibility can be detected, the lower is the resulting loss of investment and working time. A distinction is made between static and dynamic tests, which both have different disadvantages.
In this paper, first results of long-term tests of the project are presented. The tests were carried out using a tribologically equivalent tribometer for RSS. The results obtained so far show that incompatibilities between elastomers and lubricants can be revealed using a steady-state shaft speed. Various criteria are used to evaluate the incompatibility, such as changes of the friction coefficient and wear. Furthermore, results of various analytical methods are presented, which can be used to detect incompatibility effects such as swelling, crosslinking changes or changes in mechanical properties of the elastomer under dynamic tribological load.
Future work includes the definition of standardized test procedures regarding the choice of load collective and test duration and the comparison of various elastomer-lubricant combinations with known (in-)compatibility in benchmark tests.
The new incompatibility test method will allow inexpensive and reliable compatibility tests to be carried out on a tribometer. These tests will be feasible even for small companies and can therefore prevent costly and reputation-damaging early failures of sealing systems due to incompatibility.