Compression Set Under Constant Deflection ASTM D395
Compression Set Under Constant Deflection ASTM D395 B: Understanding the Test and Its Importance in Evaluating Elastomeric Materials
Compression set testing is a widely used method for assessing the ability of elastomeric materials to maintain their elastic properties after being subjected to prolonged compressive stress. This type of testing is particularly useful in applications where elastomers would be subjected to a constant pressure/release state, such as in gaskets, seals, and other mechanical components.
The test measures the somewhat permanent deformation of the specimen after it has been exposed to compressive stress for a set time period. The result is expressed as a percentage of the original deflection, which is calculated using the original thickness of the specimen (to), the final thickness of the specimen (ti), and the thickness of the spacers used (tn). The compression set (CB) is then calculated as follows: CB = [(to-ti)/(to-tn)] x100.
The test procedure involves measuring the thickness of the original specimen, which comes in two cylindrical disk sizes: Type 1, with a thickness of 12.5mm +/- 0.5mm and a diameter of 29.0mm +/- 0.5mm, and Type 2, with a thickness of 6.0mm +/- 0.2mm and a diameter of 13.0mm +/- 0.2mm. The specimen is then placed between spacers and in the compression device, where it is compressed to 25% of its original height using spacers to accurately measure the compression. Within two hours of assembly, the compression device is placed in an oven at a specified temperature for the suggested time periods of 22 hours and 70 hours. After removing the sample from the oven, the specimen is allowed to cool for 30 minutes before measuring the final thickness.
The ASTM D395 B test is an essential tool for evaluating elastomeric materials in terms of their ability to maintain their elastic properties under prolonged compressive stress. It is widely used in various industries, including automotive, aerospace, construction, and medical, to assess the performance of elastomeric components in various applications.
In our opinion, understanding the compression set under constant deflection ASTM D395 B test and its importance in evaluating elastomeric materials is crucial for ensuring the quality and reliability of elastomeric products. Manufacturers and engineers must conduct this test to determine the compression set of their elastomeric materials accurately, and make necessary adjustments to improve their products' performance and durability.