Plastics Technology Laboratories  

Shear Strength
by Punch Tool


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Shear strength testing is used to determine the load at which a plastic or film will yield when sheared between two metal edges. Shear strength results are important to designers of film and sheet products that tend to be subjected to shear loads, or in applications where applied crushing loads are a risk.

Test Procedure:
The test is performed by clamping a test sample attached to a 1-inch punch between two metal fixtures. A male punch is then forced through the hole in the metal fixture causing shear along the edge of the hole. A universal testing machine is used to push the punch until shearing of the specimen occurs.

Specimen size:
The specimens are usually 2-in. diameter discs or 2 in. squared plates, with a thickness ranging between 0.05 and 0.5 in. A 7/16th in. hole is drilled through the center of the specimen to mount it in the fixture.

The results are expressed as shear strength and are given in the units of MPa or psi. The shear strength is calculated by dividing the force required to shear the specimen by the area of the sheared edge. The area of the sheared edge is equal to the circumference of the punch multiplied by the thickness of the specimen.

Equipment Used:
Instron universal testing machine.
Shear fixture

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**Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. For more information please contact a Intertek PTL Technical Representative at . Due to copyright restrictions, we are not able to provide copies of standards. Standards can be obtained from appropriate standards authorities.

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