Compression set reflects the ability of silicone rubber to return to its original shape after prolonged exposure to pressure and temperature. It is not an isolated material property, but rather the result of the combined effects of the material, structure, temperature, and assembly.
1. What Do the Metrics Indicate?
A lower value generally indicates better rebound retention, but results from different test conditions cannot be directly compared.
- Confirm the test temperature, compression ratio, and holding time
- Distinguishing Between Data from Material Test Specimens and the Actual Performance of the Finished Product
- Focus on the measurement conditions for cooling recovery after high temperatures
2. Material Selection
Hardness, formulation, and the vulcanization system can affect long-term rebound performance.
- Select materials based on their actual temperature range rather than just their hardness at room temperature.
- Prioritize verifying the performance of components that have been under prolonged stress following thermal aging
- Avoid equating temperature resistance with low compression set
3. Effects of Structure and Assembly
Excessive compression, overfilling of grooves, or uneven local stress distribution can all accelerate deformation.
- Keep the compression within the design window
- Ensure that the sealing surface is flat and that the force is distributed evenly
- Prevent persistent misalignment or distortion after assembly
4. Improvement and Validation
The validation combination should be selected based on leakage risk and service life requirements.
- Conduct a test to verify the interaction between compression set and seal retention
- Add high- and low-temperature cycling and immersion in various media
- Inspect failed parts for permanent flattening, cracking, and assembly marks
FAQ
1. Does higher hardness necessarily mean greater resistance to compression?
Not necessarily. Hardness affects the initial load, but long-term deformation is also influenced by the formulation, temperature, and compression ratio.
2. Why is there still a leak even though the compression set test results are within specifications?
It is also necessary to check the groove tolerances, defects on the sealing surfaces, assembly torque, and the actual medium pressure.