Summary of Test
ASTM D1414 is used to measure the mechanical properties of vulcanized rubber o-rings. Multiple different tests are utilized to determine these properties, such as tension, compression set, low temperature, density, fluid aging, heat aging and hardness. Here we address the tension testing portion of the specification only. In order to perform the tension test, a universal testing machine is required.
Recommended Equipment
ASTM D1414 requires special grips. These grips have interchangeable spools with various diameters for a wide variety of o-rings. The spools rotate freely on a pin extending from the grip. If using the motorized version, the bottom grip and spool is connected to a small variable speed electric motor to enable rotation during the test to minimize stresses. Other more primitive and costly systems have been employed that generate rotation from the upward movement of the crosshead. However, the optional motorized version is easier to use and is usually less expensive.
If the motorized fixture is not an option, the specification allows for a lubricated spool instead. In this case, the test would be run with two upper grips, one being inverted.
Testing Procedure
- Prior to testing, store the o-ring specimens at 23+/-2C for at least 30 minutes.
- Load the o-ring onto the ball-bearing spool grips by bringing the grips in close proximity to each other so as not to stretch the sample during loading.
- Apply a small preload (<1lbf) to the o-ring. Once the preload force is achieved, zero the position.
- Conduct the test by loading the sample at a spool grip separation rate of 20 inches per minute until specimen failure. If a motorized spool grip is used, the spool needs to rotate through one revolution per six inches of travel. For non-motorized grips, lubricate the contact surfaces of the spools with castor oil.
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Questions about running ASTM D1414 on your system?
