The Elmendorf Tearing Tester as per ASTM is a pendulum impact tester, used to measure the force required to propagate an existing slit a fixed distance to the edge of the test sample. The usage of these results would be for the specification of material and thickness for plastic film in packaging and also for textile in textile industry. Depending upon the application, a low propagation force or a high propagation force might be more desirable.
The Tearing tester has a heavy sector pendulum mounted on ball bearings. This sector carries a clamp and has a dial graduated from 0 to 100. On the same axis is mounted a pointer which has constant friction, just sufficient to stop at the highest point reached by the swing of the sector. The material is initially cut to certain distance by a fixed cutter and then the weighted sector swings down and tears the sample. The amount of swing is determined by the toughness of the material and pointer notes its maximum point.