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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 7765-1

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.


Testing Equipment and Test Principles

The equipment required for performing the ISO 7765-1 dart drop impact test typically includes:

Dart Impact Tester: Equipped with the function to adjust the dart's height and weight.

Rigid Ring Support Device: Supports the specimen and prevents deformation of the specimen before impact.

Measuring System: Records impact load, rupture point, impact energy, etc.

Auxiliary Tools: Including sample cutting dies, thickness gauges, marking tools, etc.


The test principle is to apply an impact force to the film supported on a rigid ring using a freely falling dart with a known mass. As the dart accelerates downward, the film gradually undergoes impact until rupture. During the test, it is necessary to record the dart's weight, drop height, rupture condition, and calculate the impact energy and the probability of film rupture.


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)


Example of typical plastic film drop dart impact test results:

Material   typeFilm   thickness (μm)Drop   Dart Weight (g)Drop   height (cm)Impact   Energy (J)Number   of ruptures/number of testsRupture   Probability (%)
Polyethylene   (PE)25500500.2451/1010
Polyester   (PET)50500500.2450/100
Polypropylene   (PP)30500500.2452/1020


Related products and device

ISO 7765-1 free-falling impact tester

XJB-30A Falling dart impact tester mainly used to test plastic, film, or sheet thickness below 1mm, impact by falling dart, check the energy when 50% of test specimen broken. Conform with standard: ISO 7765-1, ASTM D1709, GB 9639.

Related Standard

ASTM D1709 Falling Dart Impact Resistance of Plastic Film

ASTM D1709: Standard Test Methods for Impact Resistance of Plastic Film by the Free-Falling Dart Method


ASTM D1709 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.

Main difference of ISO 7765-1 vs ASTM D1709


ItemASTM D1709ISO 7765-1
Standard NameFree-falling dart impact resistance of plastic filmFree-falling dart impact for plastic film & sheet (<1 mm)
Dart A diameter38.0 ± 0.13 mm38 ± 1 mm
Dart B diameter50.80 ± 0.13 mm50 ± 1 mm
Method A drop height0.66 ± 0.01 m0.66 m (no tolerance stated)
Method B drop height1.50 ± 0.05 m1.50 ± 0.01 m
Test methodsStaircase + optional group testStaircase only
Dart well ventRequiredNot specified
Film thicknessAll film thicknessesGenerally ≤ 1 mm


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