ASTM D1781 Peel Plot

ASTM D1781 is a standard test to determine the peel resistance of adhesive bonds on products that have a flexible adherand and a rigid adherand surface. This standard can also be used for testing a sandwich structure and its core by pulling the facing off the sandwich assembly. ASTM D1781 is most often used in A-B comparison testing: to compare the results of two different process conditions for the sake of optimizing a process. A special climbing drum peel fixture is used for this test, where the flexible adherand is pulled up around the drum to create the peel.

Our engineers are familiar with the ASTM D1781 test procedure and can guide you through the process and help you choose the best equipment. We also recommend that you purchase the ASTM D1781 standard and follow it closely to achieve the best results.

Preparing the Specimens

In order to compare results of ASTM D1781, prepare a test for each process condition. This allows you to quantifiably compare each process condition. A test can also be performed on a dummy specimen, which is the same as a test specimen but has no adhesive, in order to quantify the force errors in the test setup. If test results are to be used only for comparative (test to test) purposes, then this error testing is not necessary because the errors are the same in each test and therefore negate each other.

ASTM D1781 Test Procedure

  • First clamp the flexible adherand with the climbing drum fixture.
  • Next, secure the rigid adherand into a manual vice grip.
  • Once the specimen is secured into the fixtures, run your peel tester at 25 mm/minute.
  • Make sure to record force and displacement data for ASTM D1781. The minimum data should be average peel force over six inches. A raw data plot is also useful to view the peel plot data.

ASTM D1781 Advice From Our Engineers

In ASTM D1781, the climbing drum peel force measurement includes two inherent errors: the force to lift the climbing drum, and the force to bend the flexible adherand around the drum. These errors can both be compensated out of the test by running the test on one or more dummy specimens which have the same flexible adherand but no adhesive. The resulting force profile can be subtracted from the actual test data point by point to determine the force generated by the adhesive in the peel.

Due to the errors in the peel force caused by the force to lift the drum and force to bend the flexible adherand around the drum, this standard is less popular than other peel testing standards and is typically used for comparative testing in process control and process optimization situations.

Recommended Test Equipment for ASTM D1781

The peel plot will be an important aspect of data retrieval and therefore we highly recommend our XyPlot software. If you would rather see the data in real-time and study the peel interface at the same time, we would provide you with our XyLive Software. Other test machine options can include the 100 Family, 310 Family and the 220 Family Universal Test Machines. A 100 Series Peel Tester is recommended for ASTM D1781. The 100 series consists of a vertical load frame, an electromechanical actuator, load cell, a tocuhpad test controller, XY test software and a climbing peel drum fixture. For ASTM D1781, we would configure a small capacity load cell (10 or 25 pound) for this low force peel test. Our load cells measure loads accurately (+/- 0.5% of reading) from full scale rating to 1% of FS. A 10 lb load cell can be calibrated to measure 0.1 lb (0.5N) to an accuracy of 0.0005 lb.

ASTM D1781 requires a TestResources GD1781-115 Climbing Peel Drum Fixture. This fixture is made specifically to ASTM D1781 and consists of a flanged drum, flexible loading straps, and specified clamps for holding the test specimen. For this test, our engineers also recommend a G240G manual vice grip.

Give one of our engineers a call today and they can help guide you through the ASTM D1781 test process with the best machine configuration for your requirements.

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