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Impact test on plastics - ISO 179, ISO 180, ASTM D256

Purpose of the test

Impact testing is used to determine material behavior at higher deformation speeds. Classical pendulum impact testers determine the impact energy absorbed by a standardized specimen up to break by measuring the height of rise of the pendulum hammer after impact.

Principal impact test methods and standards

4 standardized pendulum impact test methods are recognized:

Charpy test (ISO 179-1, ASTM D 6110) Izod test (ISO 180, ASTM D256, ASTM D4508) impact tensile tests (ISO 8256 and ASTM D1822) Dynstat impact test (DIN 53435)
Charpy test to ISO 179, ASTM D6110
Izod test to ISO 180, ASTM D256
impact tensile test to ISO 8256
Dynstat impact test to DIN 53435
Charpy impact test (ISO 179, ASTM D6110)
Charpy impact test (ISO 179, ASTM D6110)

Charpy impact test (ISO 179, ASTM D6110)

In the context of the standard for single-point data, ISO 10350-1, Charpy as per ISO 179-1 is the preferred test method. The test is normally performed on unnotched specimens, with edgewise impact (1eU). If the specimen does not break in this configuration, the test is performed with notched specimens, although the test results are not directly comparable. If specimen break is still not achieved the impact tensile method is employed.

Advantages of the Charpy impact test

The Charpy method has a broader range of applications and is better suited to tests on materials displaying interlaminar shear fractures or surface effects. The Charpy method also offers advantages when testing at low temperatures as the specimen support is farther away from the notch, so that rapid heat transfer to the critical areas of the specimen is avoided.

Izod impact test (ISO 180, ASTM D256, ASTM D4508)
Izod impact test (ISO 180, ASTM D256, ASTM D4508)

Izod impact test (ISO 180, ASTM D256, ASTM D4508, ASTM D4812)

For ASTM Standards the Izod test method to ASTM D256 is usually employed. Here notched specimens are always used for testing. A method used less frequently is the 'Unnotched cantilever beam impact' described in ASTM D4812, which is similar to the Izod method, but is performed with unnotched specimens. If it is only possible to produce small specimens, the 'Chip impact' method to ASTM D4508 can be used.

Dynstat impact test (DIN 53435)
Dynstat impact test (DIN 53435)

Dynstat impact test (DIN 53435)

Some German automobile manufacturers use the Dynstat bending and impact method to test small specimens. This method is only described in DIN.

Differences between ISO and ASTM impact tests

In ISO tests, each pendulum hammer may be used in the range from 10 % to 80 % of its nominal initial potential energy. ASTM permits use up to 85%.

A fundamental difference between ISO and ASTM concerns the choice of pendulum size. According to ISO the largest possible pendulum hammer must be used, although the overlaps between pendulum sizes are often very small. This requirement is based on the consideration that speed decay during specimen penetration should be kept as low as possible. With ASTM the standard pendulum hammer has a rated initial potential energy of 2.7 joules and all further sizes are arrived at by doubling. Here the smallest possible hammer in the range is to be used for the test.

Testing equipment and accessories for impact tests on plastics

Zwick pendulum impact testers are constructed strictly in accordance with DIN, ISO and ASTM standards. Completing Zwick's product range for impact tests on plastics are our drop-weight testers.

HIT pendulum impact tester up to 50 joules 

HIT pendulum impact testers up to 50 joules

Zwick Roell is the leading European manufacturer of instruments and systems for mechanical materials testing. Our HIT pendulum impact testers are benchmark instruments for plastics manufacturers and processors.



230-joule drop weight tester

The HIT230F drop weight tester was developed in close collaboration with our customers, allowing all the relevant requirements of research and development and quality assurance to be met. It is available in two versions.




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