Rubber is often used in areas where it must withstand stress. In order to assure rubber will do its job correctly, tests are always helpful. Compression set tests determine the ability of rubber compounds to keep their elastic qualities after being subjected to stress for an extended amount of time. ASTM D395-18: Standard Test Methods For Rubber Property—Compression Set covers information on the test methods that can determine elastic qualities in rubber.
Compression set tests, like the ones described in ASTM D395-18, measure how well a specimen retains its elastic characteristics after being subjected to continued amounts of stress. These tests allow the user to understand the deformation of a rubber device after the stress has been removed.
Why is a Compression Set Important?
Knowing how much rubber change due to stress allows the user to understand how useful the rubber product will be in certain situations. For example, if the rubber is used as a sealant and is unable to recover to an appropriate form after compression set testing, it may be prone to leaks.
How are Compression Set Results Measured?
The results of a compression set test are conveyed as a percentage. The better a rubber is able to resist permanent deformation, the lower this percentage will be.
What is the Standard Test Methods for Rubber Property – Compression Set?
The test methods in ASTM D395-18 cover the testing of rubber meant to be used in applications in which the rubber will be exposed to compressive stresses in air or liquid media. These tests are especially useful for rubber that will be used in vibration dampers, seals, and machinery mountings.
There are three tests covered in ASTM D395-18. They are:
Test Method A – Compression Set Under Constant Force in Air
Test Method B – Compression Set Under Constant Deflection in Air
Test Method C – Compression Set Under Constant Deflection in Air Considering Material Hardness
It is important to consider which test best aligns with the operation of the rubber. As stated in ASTM D395-18 , “Test Method B is not suitable for vulcanizates harder than 90 IRHD.”
ASTM D395-18: Standard Test Methods For Rubber Property—Compression Set is available on the ANSI Webstore.