What is D395 ASTM?
The compression set (ASTM D395) of a material is the permanent deformation remaining after removal of a force that was applied to it. The term is normally applied to soft materials such as elastomers. Compression is normally measured in two ways: compression set A and compression set B.
What is a compression set test?
Compression set testing measures the ability of rubber to return to its original thickness after prolonged compressive stresses at a given temperature and deflection. As a rubber material is compressed over time, it loses its ability to return to its original thickness.
What is polymer compression set?
1.3. Compression set is often a property of interest when using elastomers. Compression set is the amount of permanent deformation that occurs when a material is compressed to a specific deformation, for a specified time, at a specific temperature.
What does low compression set mean?
The more indented, the higher the compression set. The less indented, the lower the compression set. An object’s compression set can be measured and is expressed as a percentage of the permanent deformation caused by whatever force was exerted on it.
What is foam compression set?
What is compression set? In the simplest terms, compression set is the measurement of a foam or rubber material’s ability to return to its original thickness after being subjected to a compressive force or load over a given period of time.
How do you calculate rubber compression?
- 720 lb Clamp, Foot Print / Contact Area Foot Size: 3″ x 12″ each. Total Area: 2 x 36in² = 72 in²
- HT-800 Silicone Pad Size: 3″ x 12″ each.
- Mounting Plate.
- Calculation: Load / Area = 720lb / 72 in² = 10 lb/in²
- Compression: From the Compression Force Deflection Curve, HT-800 will compress approximately 30%.
What is good compression set?
Good compression set properties are mostly to do with good rubber choice and fully chemically cross linked and post cured products. The compression set test is a common test in our laboratory. A standard test specimen is measured then compressed in a jig to a certain percentage of its original thickness.
What causes compression set?
Many factors can contribute to compression set failure of an O-ring seal, including: Excessive temperature developed causing the O-ring to harden and lose its elastic properties. (High temperatures may be caused by system fluids, external environmental factors, or frictional heat build-up.)
What is foam compression rate?
Compression (firmness) is an ILD/IFD value represented by how many pounds it takes to compress the foam by 25 percent. A higher number means firmer foam and a lower number means softer foam.
How much can you compress silicone?
The ideal compression percentage is 40, the maximum is 50, and the minimum is between 10 to 15.
Why does compression set happen?
Compression Set Cause: Physical and chemical changes can occur to an elastomer at elevated temperatures that result in set. Cross-link density can increase, this results in the O-ring losing its elasticity and ability to return back to the original shape, this is a permanent chemical change.
Why do O-rings go bad?
The most common causes of O-Ring failures include: Improper gland design, allowing for too much or too little compression, not enough for seal expansion and tolerance stack-up. Incorrect O-Ring size. Incompatibility of O-Ring elastomer and environmental elements.