Falling dart impact is a traditional method for evaluating the impact strength or toughness of a plastic film. There are two main methods for testing, Method A and Method B. These test methods cover the determination of the energy that causes plastic film to fail under specified conditions of impact of a free-falling dart. This energy is expressed in terms of the weight (mass) of the missile falling from a specified height which would result in 50 % failure of specimens tested.
Falling Dart Impact Test Method - ASTM D1709, ISO 7765-1
Falling Dart Impact Test - Method A
Test Method A employs a dart with a 38.10 ±0.13mm (1.500 ±0.005in.) diameter hemispherical head dropped from a height of 0.66 ±0.01 m (26.0 ±0.4 in.). This test method can be used for films whose impact resistances require masses of about 50 g to about 6 kg to fracture them.
Falling Dart Impact Test - Method B
Test Method B employs a dart with a 50.80 ±0.13mm (2.000 ±0.005-in.) diameter hemispherical head dropped from a height of 1.52 ±0.03 m (60.0 + 0.25,−1.70 in.). Its range of applicability is from about 0.3 kg to about 6 kg.
Test Methods A and B are used to establish the weight of the dart when 50 % of the specimens fail under the conditions specified.
The results obtained by Test Methods A and B are greatly influenced by the quality of film under test. The confidence limits of data obtained by this procedure can, therefore, vary significantly, depending on the sample quality, uniformity of film gage, die marks, contaminants, etc.