To date, some 12,000 ASTM standards are used around the world with 143 technical standard writing committees. The latter are usually academics and consultants.ĪSTM develops and publishes technical standards that are arrived at through consensus and used on a voluntary basis for a wide variety of products, materials, systems and services. The association has more than 30,000 members, classified as users, producers, consumers and general interest. Originally called the “American Society for Testing and Materials”, it changed its name to “ASTM International” in 2001. It was founded in 1898 by a group of Pennsylvania Railroad engineers and scientists, led by chemist Charles Benjamin Dudley, to address the frequent rail breaks in the fast growing railroad industry. Here’s a brief rundown on ASTM International’s history and operations.ĪSTM is an international standards and testing organization with headquarters in West Conshohocken, PA and offices in Belgium, Canada, China, Mexico and Washington, D.C. These tests are standardized so that they can be reproduced by labs around the world. “ASTM” followed by numbers or letters is used on data sheets to indicate the test used to develop the data. Please read the official specification for more information on the calculation values.Have you ever been reading a material data sheet and wondered what ASTM means? Well, you’re not alone. Thus, if a sample only returns to 80% of its original height, the compression set is given as 20%. The calculation is specified in such a way that it describes the amount of height that was permanently lost. Essentially, the test is run and sample height is measured to find out how much it has bounced back since the compression. Sample calculations for ASTM D395 are given as a percentage. Testing at low temperatures is specified in ASTM D1229. The compression fixture for Method B is quite simple and can be placed in an Environmental Chamber for proper conditioning and testing. The specimen is compressed evenly for an extended period of time. The compression jig for Method A uses a spring and two guide rods to evenly load a rubber sample. The fixture ships with 2 sets of 6 spacers with height of 4.5mm and 9.5mm Custom fixtures for different sized thicknesses and numbers of cavities can be selected. Universal Grip stocks standard sized Method B fixtures. The fixture translates a compression deflection of about 25% onto the sample. 49" thick, or smaller specimens that are. The Universal Grip fixture accepts samples that are either 1.14" in diameter and. Test Method B uses a compression fixture which is held together by large diameter screws. A calibrated spring is used to apply constant force to the sample over the designated time period. The procedure requires circular rubber disks to be used according to the official ASTM D395 specification. Test Method A uses a specially designed fixture which is referenced in our PDF. In some cases, a shortened test period can be used such as 30 minutes. Most test periods last between 8-24 hours. The fixtures for Method B is usually inserted into an Environmental chamber for 1-3 days at elevated temperature. Test Method B uses screws to tighten down on the sample and maintain constant deflection. Method A uses a spring to push down on the sample and maintain constant force. Test Method A governs the compression set under constant force while Test Method B governs the compression set under a constant deflection. ASTM D395 - Standard Test Methods for Rubber Property-Compression Set Theory:ĪSTM D395 specifies two test methods for testing the compressive properties of rubber.
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