ASTM D1004-13 Tear Resistance (Graves Tear) of Plastic Film or Sheeting
ASTM D1004 measures the tear resistance of flexible plastic film and sheeting. Raw materials manufacturers are constantly challenged to identify the ideal formula that minimizes material cost and waste while retaining the necessary strength. Tear resistance is only one of the properties that comprise a plastic film's overall strength, but it can prove to be crucial if the material is subjected to tear events over its life. The packaging industry is an example of a business that relies heavily on the integrity of its plastic film suppliers.
ASTM D1004-13 reports the maximum tear resistance in units of force (lbf or N) and the maximum extension in units of length (in or mm). The specimen must be die-cut to specifications found in the standard. Specimens are formed with a 90° notch to create a stress concentration in a specific area which will initiate a tear. The specimen is then subjected to a tensile test at 2 in/min (51 mm/min) until complete failure. The specimen geometry and test speed are not intended to simulate real world tear conditions; instead, ASTM D1004 is intended to create a controlled tear of to analyze force versus displacement data for quality control or material comparison purposes. ASTM D1004 is not applicable for plastic material where brittle failure occurs or where elongation greater than 200% occurs. Material between those two extremes has been shown to reliably use ASTM D1004 to compare tear resistance between materials.Materials Testing System
Due to the low forces involved in ASTM D1004 testing, we recommend a single column test frame such as Instron’s 68TM-5 or 34TM-5. Labs performing multiple test types on a single testing machine may prefer a dual column system with an increased force capacity.
|ASTM D1004 Test Setup|
3400 Series Universal Testing System
Bluehill Universal Software
2519 Series Load Cell
|2712-041 Pneumatic Side-Action Grips|
The preferred set of grips for ease of use and clamping repeatability is Instron’s 1 kN pneumatic side-action grips (2712-041). If manual grips are preferred, we suggest using a self-tightening grip to ensure the specimen doesn’t slip during the test. As maximum forces of an ASTM D1004 test are almost always under 1 kN (225 lbf), the 1 kN (2713-007) or 2 kN (2713-004) self-tightening roller grips would be suitable.
- Non-repeatability of results – ASTM D1004 requires the operator to exclude results that deviate markedly from the mean value. Bluehill Universal software offers visual pass/fail indicators to alert users when test results are out of specification. Bluehill Universal also offers a TestCam module to record a video of the test, enabling users to replay videos to ensure a test performed as expected.
- Preventing specimen slippage – When testing thin films, specimen undergo thinning as they are stretched. Instron’s pneumatic side-action grips or manual self-tightening grips are designed for the testing of films and other flexible materials exhibiting a large reduction in cross-sectional area under load.