ASTM D732 Shear Strength Testing of Plastics

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ASTM D732 Shear Strength Testing of Plastics

ASTM D732 is a test used to measure the shear strength of a plastic to determine if it will withstand the necessary stress without distortion or cracking.

What Is ASTM D732?

ASTM D732 standardizes the shear punch test that is used to determine shear strength of sheet and molded disk plastic specimens ranging from 1.27 to 12.7 mm (0.050 to 0.500 in) thick.

Why Perform Shear Tests on Plastic?

The test helps compare shear performance between materials and also to obtain engineering design data.

Important Considerations When Testing to ASTM D732

For end-use applications there may be many factors not taken into account in this simple test method, such as stress-concentrating geometries and rates of shear, which can affect shear strength. Also, shear strength is calculated by dividing the load by the area of the sheared edge (circumference X thickness) and should not be interpreted as indicating that the shear strength value so obtained is solely a material property, independent of thickness.

ASTM D732 Test Specimens

The specimen consists of a 50 mm (2 in) square or a 50 mm (2 in) diameter disk cut from sheet material or molded into the form. The thickness of the specimen may be from 1.27 to 12.7 mm (0.050 to 0.500 in). The upper and lower surfaces are parallel to each other and reasonably flat. A hole approximately 11 mm (7⁄16 in) in diameter is drilled through the specimen at its center.

Test Machines for Plastics

Our universal test machines serve multiple plastic testing applications and are capable of performing all quasi static tension/compression tests, such as tensile, peel, adhesion, and flexural testing. The machine force capacity should be chosen by taking into account the highest force needed over the lifetime of the equipment. Our machines feature a uniform constant rate of extension (CRE), or constant velocity control mode, with a speed range between 1 and 500 mm per minute (0.04 to 20 in/min). Force measurement complies with ASTM E4 (ISO 7500-1).

The majority of rigid plastics tests can be performed at loads under 25 kN (5500 lbf).

What Shear Tool is Recommended for ASTM D732?

Our model GD732-712 is an application specific test fixture designed exclusively for ASTM D732. The specimen is rigidly clamped both to the stationary block and movable block so that it cannot be deflected during the test.

What Other Accessories Are Available?

A digital micrometer is used to measure and capture the thickness of the test specimen to an incremental discrimination better than 0.025 mm (0.001 in.).