Compression set is a property that measures how much a rubber part recovers its original thickness after being compressed for a period of time and then having the load removed. For sealing gaskets in particular, this value is a critical performance indicator that determines how long the product can remain effective.
Why Compression Set Matters
When a gasket operates under continuous compression, it can gradually lose its original shape over time. A high compression set value means the gasket loses sealing pressure and the risk of early failure increases. A low compression set ensures long-lasting, reliable sealing performance.
Factors Affecting Compression Set
- Rubber type and compound formulation
- Deflection ratio
- Temperature and exposure duration
- Degree of vulcanization
Which Rubber Types Perform Better?
Generally, silicone and fluorocarbon (FKM) rubbers tend to show lower compression set at high temperatures. Materials such as EPDM and NBR can offer adequate performance for sealing applications with the right formulation; selection should be based on the application’s temperature and duration conditions.
Test Method
The compression set test is performed by holding a standard specimen at a fixed deflection ratio for a specified time and temperature, then measuring how much of the thickness is recovered after the load is removed. The result is expressed as a percentage; a lower percentage indicates better performance.
Alpin Rubber provides customers with technical support in selecting materials suited to the temperature and load conditions of their application.