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ISO 7765-1 Impact resistance by the free-falling dart method

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ISO 7765-1:1988 Plastics film and sheeting — Determination of impact resistance by the free-falling dart method 

Part 1: Staircase methods


ISO 7765-1 and ASTM D1709 specifies methods for the determination of the energy, that causes plastics films and sheet less than 1 mm in thickness to fail under specified conditions of impact of a free falling dart from a specified height, that would result in failure of 50 % of the specimens tested. Two methods are described. Method A employs a dart with 38 mm diameter hemispherical head, dropped from a height of 0,66 m, and method B employs a dart with a 50 mm diameter hemispherical head dropped from a height of 1,50 m. The measurement technique is the staircase method.

Drop Dart Impact Resistance of Plastic Film ASTM D1709, ISO 7765

ISO 7765-1 Impact resistance by the free-falling dart method

Test Scope:

Falling dart impact is a traditional method for evaluating the impact strength or toughness of a plastic film. This test uses a single dart configuration and a single drop height, while varying the weight of the dart. Test results can be used either as a quality control evaluation or for end use comparisons.


Test Procedure:

Depending upon the expected impact strength of the test sample, either Method A or Method B is chosen. The method defines the dart size and the drop height for the dart. A number of test samples are then impacted to determine an appropriate starting point for the weight of the dart.

The test specimen is clamped securely in a pneumatic ring at the base of the drop tower. The mounting bracket is adjusted to the appropriate drop height, and the dart is inserted into the bracket. The dart is released to drop onto the center of the test specimen. The drop weight and the test result (pass / fail) are recorded.

The method to analyze this test data is called the "Bruceton Staircase" method. A series of 20 to 25 impacts are conducted. If a test specimen passes, the drop weight is increased by one unit. If a test specimen fails, the drop weight is decreased by one unit. The results from these impacts are used to calculate the Impact Failure Weight - the point at which 50% of the test specimens will fail under the impact.


MethodDart sizeFalling height
Test method A:38 mm (1.5") diameterdropped from 0.66 m (26")
Test method B:51 mm (2") diameterdropped from 1.5 m (60")


Specimen size:

Film samples that can be cut to 230 mm x 230 mm (9" x 9") specimens

A minimum of 30 specimens are required for the test


Data:

Impact failure weight (grams)

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