ASTM D1709-16 pdf free download.Standard Test Methods for Impact Resistance of Plastic Film by the Free-Falling Dart Method.
1.1 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.
1 .2 Two test methods are described:
1.2.1 Test Method A employs a dart with a 38.10 ± 0.13-mm (1.500 ± 0.005-in.) 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 or less to about 6 kg to fracture them.
1.2.2 Test Method B employs a dart with a 50.80 ± 0.13-mm (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.
1 .3 Two testing techniques are described:
1 .3.1 The standard technique is the staircase method. By this technique. the missile weight employed during the test is decreased or increased by uniform increments after the testing of each specimen, depending upon the result (fail or not fail) observed for the specimen.
1 .3.2 The alternative technique provides for testing specimens in successive groups of ten. One missile weight is employed for each group and the missile weight is varied in uniform increments from group to group.
1.3.3 The staircase technique and the alternative technique give equivalent rcsults both as to the values of impact failure weight which are obtained and as to the precisions with which they are deterniined.
4. Significance and Use
4.1 Test Methods A and B are used to establish the weight of the dart when 50 % of the specimens fail under the conditions specified. Data obtained by one test method cannot he compared directly with the other test method nor with those obtained from tests employing different conditions of missile velocity, impinging surface diameter, effective specimen diameter, material construction and finish of the dart head, and film thickness. The values obtained by these test variables are highly dependent on the method of film fabrication.
4.2 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. (see Section 15).
4.3 Test Methods A and B have been found useful for specification purposes.ASTM D1709 pdf download.