Comparison of Various CSR Methods regarding the Static Long-term Sealing Behaviour of AEM, ACM and HNBR Compounds

Abstract

The purpose of this study is to provide a guide to the various methods for compression stress relaxation testing (CSR testing), to assessing the influences of various parameters on the measurement results and to understanding different evaluation variants. It also presents a measuring method developed by ElringKlinger AG together with its various evaluation options. As the experiments in this study show, CSR compression methods developed by Shawbury-Wallace, Wykeham-Farrance and Jamak, which often produce very different static long-term sealing force curves, can be replicated sufficiently accurately by the EK method if the right evaluation variant is chosen. In addition, identical compression stress conditions must be established in the specimen by means of its geometrical design. The CSR methods are surprisingly simple to use and versatile in terms of the choice of test parameters and conditions. The various CSR measuring methods are used to plot the static long-term sealing force curves for AEM, ACM and HNBR compounds in hot air and in SF105G engine test oil. The influences of materials and sealing profiles in CSR testing are also discussed.