Testing acc. to ISO 178: Plastics - Determination of flexural properties (without method IV - measurement with deflection measuring device)
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Testing methods
Our testing laboratory performs testing according to DIN EN ISO 178 as an accredited test method for determining the flexural properties of plastics. FILK's accredited scope covers the standard except for test type IV – measurement using a deflection measuring device. In the three-point bending test, properties including flexural strength, flexural modulus, flexural stress, flexural strain and deflection are determined under defined static loading.
The method is suitable for rigid and semi-rigid thermoplastic and thermosetting plastics, including unfilled, filled and suitable reinforced compounds as well as plastic sheets. For fibre-reinforced compounds, the standard applies to fibre lengths of up to 7.5 mm before processing. Long-fibre-reinforced materials and laminates with longer fibres are covered by DIN EN ISO 14125. Rigid cellular materials and composite structures containing foamed layers are generally outside the scope of the method.
The test is particularly relevant to the mechanical characterization of Plastics, Elastomers and Foils and plastic semi-finished products and moulded components used in Automotive + Mobility.
Testing according to DIN EN ISO 178
The specimen is supported as a freely resting beam on two supports and loaded centrally by a loading nose. The load is applied in a controlled manner until the specimen breaks or the deformation specified by the standard is reached. Force and deflection are recorded throughout the test. FILK provides further information on the principle under Three-Point Bending Test.
Depending on the material behaviour, flexural strength, flexural stress at break, flexural strain and flexural modulus can be determined from the measured data. For anisotropic materials, specimens may be tested in different material directions. At least five specimens are provided for each test direction.
Applications of the test
Testing according to DIN EN ISO 178 is suitable for thermoplastic and thermosetting moulding compounds, extrusion and casting materials, injection-moulded components, and extruded or cast plastic sheets. Differences between polymer materials, formulations, filler or reinforcement contents and processing conditions can be compared on the basis of their flexural properties.
The results are particularly useful for material comparison, product development, incoming goods inspection and quality control. The standard does not intend the determined values to be used directly as design properties.
Related tests
For long-fibre-reinforced plastics and laminates, FILK performs flexural testing according to DIN EN ISO 14125. Tensile behaviour can additionally be characterized according to DIN EN ISO 527-2, while impact behaviour can be determined according to DIN EN ISO 179-1. For small Dynstat specimens, FILK also offers bending and impact testing according to DIN 53435.
