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ISO 178: Standard for Plastic Flexural Testing

Testometric > Testing Industries > Plastic Testing Machines > ISO 178: Standard for Plastic Flexural Testing

BS EN ISO 178 specifies the method for determination of flexural properties by the 3-point loading method for rigid and semi-rigid plastics. This method can be used to investigate the flexural behaviour and to determine the flexural strength, flexural modulus and other aspects of the flexural stress/strain relationship. This method is suitable for a large range of plastic materials such as thermoplastic moulding, extrusion and casting materials, including filled and reinforced compounds, thermosetting moulding materials and thermosetting sheets.

A test specimen of rectangular cross-section, resting on two supports is deflected using a
loading nose acting on the test specimen midway between two supports. The specimen
is deflected until rupture occurs on the outer edge of the specimen or until a maximum
flexural strain of 5% is reached, whichever occurs first.

This test standard splits the obtained data into several classes comprising different levels
of complexity and accuracy. All force measurements require class 1 accuracy to ISO 7500-1 but depending on the strain and modulus measurements different classes of deflection measurement are required. Testometric can supply equipment meeting the most stringent
classes of deflection measurement with systems ranging from crosshead displacement with
compliance correction to direct measurement using laser deflectometers. These systems
meet the deflection requirements set out in ISO 9513.

Wintest Analysis EC software is a fully integrated package that supports all industry standards including ISO 178. Testometric can provide software with the necessary test standards preinstalled for ease of customer setup.

 
Common international standards for flexural testing:
  • ASTM D790: Standard Test Methods for Flexural Properties of Unreinforced and Reinforced
    Plastics and Electrical Insulating Materials.
  • BS EN ISO 14125: Fibre-reinforced plastic composites. Determination of flexural properties.
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ISO 178 plastic testing standard

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ISO 178 Plastic Testing FAQs

What is the ISO 178 standard for plastic testing?
ISO 178 is an international standard used to determine the flexural properties of plastics. It outlines the method for measuring the flexural strength, flexural modulus, and strain of plastic materials under a bending load.
What type of materials can be tested using ISO 178?
ISO 178 is primarily used to test rigid and semi-rigid plastic materials. It applies to thermoplastics, thermosetting plastics, and composites, providing key insights into their mechanical properties under flexural stress.
How does Testometric’s equipment support ISO 178 testing?

Testometric’s universal testing machines are fully compatible with ISO 178. They offer precise control over the applied force, and the advanced software accurately records flexural strength, modulus, and strain data as required by the standard.

What specimens are required for ISO 178 testing?

ISO 178 specifies a rectangular test specimen, which is subjected to a three-point bending test. Testometric’s machines are designed to securely hold and test these specimens, providing reliable and repeatable results.

How are flexural properties measured in ISO 178?

During ISO 178 testing, the specimen is placed horizontally on two supports and a force is applied at the midpoint. Testometric’s machines measure the flexural strength, flexural modulus, and the strain at break to provide detailed data on material behaviour.

What grips and fixtures are needed for ISO 178 testing?

Testometric provides a range of fixtures specifically designed for three-point bending tests, ensuring accurate force application and consistent results. These fixtures comply with ISO 178 and are easily integrated into our universal testing machines.

How accurate is ISO 178 testing using Testometric’s machines?

Testometric’s machines are engineered for high accuracy and repeatability. Our equipment ensures that the flexural properties measured during ISO 178 testing meet the required precision standards, making them ideal for both research and quality control applications.

What kind of support does Testometric offer for ISO 178 testing?

Testometric offers full support for ISO 178 testing, including equipment setup, calibration services, and ongoing technical assistance. Our experts ensure that your testing process is efficient, compliant with the standard, and produces reliable results.