Abstract: Compression Stress Relaxation (CSR) is a test technique used to evaluate materials for their ability to perform acceptably in Static Sealing Applications. Compression Stress Relaxation involves measuring the Sealing Force a Test Specimen projects onto mating surfaces when compressed a defined amounts and exposed to elevated temperatures and fluids with which they might be exposed to in an application. There are two primary ways to measure Sealing Force, 1) Continuous CSR Testing and 2) Discrete CSR Testing. When measured under specific controlled conditions and configurations, they should both provide the same results. The biggest difference is 1) the cost of the test equipment, 2) the kinds of conditions that can be tested, 3) how the Sealing Force is measured 4) the time required for the testing 5) the number of test specimens one can test in a defined volumes and test interval, and 6) the kind of information you can obtain from the test. The primary principle of sealing is that Static Seals will leak when their Sealing Force drops to zero and there is no force being provided to keep the seal in contact with the mating surfaces at a temperature of concern. There are other factors that also contribute to leakage, but this is the main one. Sealing Force is often measured at Room Temperature (23 oC) for uniformity and convenience, but as Sealing Force is lost at Room Temperature, it is also lost over the full temperature range. Seals age at elevated temperatures, but leak at low temperatures. This presentation will discuss the Principles of CSR Testing, along with different methods and equipment used to evaluate it.
Bio: Paul Tuckner is currently the President of Grace Technology and Development. His current business focus is the development and support of test methods useful for measuring and integrating material properties into design. A primary part of this business is promoting and supporting the use of Compression Stress Relaxation Testing.
Prior to starting this business 14 years ago, he had worked at Dyneon/3M for 28 years as a R&D, Application Development and Materials Engineer, specializing in Fluoroelastomers and Fluoroplastics. He has a Bachelor of Arts Degree in Chemistry, with a Master’s Degree in Systems Engineering from the University of St. Thomas. He has written and presented numerous SAE (Society of Automotive Engineers) and ACS (American Chemical Society) Rubber Division papers in the areas of Permeation, Compression Stress Relaxation and Sealing, and has four patents.