ASTM D638, “Standard Test Method for Tensile Properties of Plastics,” has just been updated and the new 2014 Edition is available now at Document Center Inc. Although the document was approved in 2014, it has just been made publicly available (published). This is one of the most commonly used test methods for determining the strength of plastic. It tells you how to test the strength of a plastic specimen in the shape of a dumbbell or dogbone in specific conditions, including temperature, humidity, and testing machine speed.
The test is basically executed by putting your specimen into a test machine that basically pulls the sample apart. It’s held in place by grips and measurements are made as this process is taking place. You then use your data to determine your results.
One thing to realize with a standard like this is that those results can vary depending on a number of factors. So ASTM is clear in pointing out where these variations can occur and what you must do if your application requires more precise results. The committee has also provided caveats for those who want to use the test for engineering design.
You’ll want to note that if your material is thinner than 1.0 mm (0.04 inches), you’ll need to use the ASTM D882. And if the specimen is thicker than 14mm (.55 inches), you’ll have to reduce the thickness by machining.
Since ISO 527-1 is a similar standard, there is the question of interchangability. The answer? They are not. ASTM D638 and ISO 527-1 cover the same subject matter, but they are different in the technical content. This divergence occurred when the ISO 527-1 was updated in 2012.
Now to take a look at where the changes are in this new 2014 Edition, since it cancels and replaces the previous 2010 issue. The authoring committee, ASTM D20, has put a list of updates at the end of the document. You’ll see that:
- Note 1 has been revised, since ISO 527-1 is no longer equivalent (the changes that happened when the 2nd Edition of ISO 527-1 was released).
- Updates have happened in some areas of the standard to eliminate permissive language
- Editorial changes have also been made
- Tables 2, 3, 4, and 5 have been moved to Section 13 (Precision and Bias)
- And of course, the summary of changes has been changed!
If you use this standard, you’ll need to get a copy of the new D638-14! Order online at the Document Center Inc. webstore, www.document-center.com. You’ll have the option of ordering a paper copy or getting a pdf download. Want multi-user access? Check in with our staff about our Standards Online subscription service. You can reach them by phone (650-591-7600), fax (650-591-7617) or email (info@document-center.com). Document Center has been an authorized distributor of ASTM standards since the 1980’s. You’ll notice the difference when you take a look at the revision history of the standards you’re interested in. So make us your Standards Experts!
