What Is the Falling Dart Impact Test? Impact Resistance of Films and Packaging Materials
Impact resistance is one of the most critical performance attributes of plastic films, flexible packaging, and sheet materials. During handling, transportation, and end-use, these materials are subjected to sudden, localized impact forces — from drops, punctures, and mechanical contact. The Falling Dart Impact Test is the standardized method for quantifying a film’s ability to absorb the energy of a sudden impact without failing — and it is a cornerstone test in the qualification of packaging materials across multiple industries.
What Is the Falling Dart Impact Test?
The Falling Dart Impact Test — standardized in ASTM D1709 and ISO 7765 — measures the impact resistance of plastic films and sheeting by determining the minimum weight of a dart (dropped from a fixed height) that causes 50% of test specimens to fail under specified conditions.
The test simulates the sudden impact loads that flexible packaging and film materials experience during manufacturing, filling, sealing, transportation, and consumer handling. It provides a quantitative measure of film toughness — the ability to absorb impact energy without puncture or rupture.
How the Test Works
The test apparatus consists of:
- A drop tower of standardized height
- A dart (hemispherical head, standardized geometry) that is dropped from the fixed height
- A mounting ring that clamps the film specimen horizontally in the path of the falling dart
- A measurement system for dart weight
ASTM D1709 specifies two methods:
Method A — used for films with lower impact resistance. The dart is dropped from a height of 660 mm (26 inches) and a dart mass of 38 mm (1.5 inch) hemispherical head is used.
Method B — used for films with higher impact resistance. The dart is dropped from 1500 mm (60 inches) and a larger 51 mm (2 inch) hemispherical head dart is used.
Test Procedure:
- Film specimens are prepared to standard dimensions and conditioned
- Individual specimens are clamped in the mounting ring at the base of the drop tower
- A dart of specified weight is dropped from the fixed height onto the film
- The specimen is examined for failure (hole or tear) or pass (no failure)
- The dart weight is adjusted using a staircase statistical method until the 50% failure weight (F₅₀) is determined
- The F₅₀ value in grams is reported as the falling dart impact resistance of the film
The dart weight that causes 50% of specimens to fail represents the film’s characteristic impact strength — a higher F₅₀ indicates greater impact toughness.
Key Variables Affecting Results
Film fabrication process — the results of the falling dart impact test are highly sensitive to the film’s manufacturing process (extrusion conditions, orientation, molecular weight, and crystallinity). Biaxially oriented films (such as BOPP) typically exhibit different impact behavior than blown or cast films.
Film thickness — impact resistance generally scales with film thickness; however, the relationship is not always linear and depends on polymer type.
Test temperature — many polymers are tested at room temperature, but low-temperature testing may be specified for films intended for cold-chain or refrigerated applications.
Film orientation — anisotropy from orientation processes can cause directional differences in impact resistance.
Industrial Applications
The Falling Dart Impact Test is applied across packaging and polymer industries:
Flexible packaging — polyethylene (PE), polypropylene (PP), polyester (PET), and multilayer films for food packaging, industrial packaging, and agricultural films are routinely tested.
Agricultural films — greenhouse films, mulch films, and silage wraps must survive mechanical stresses in the field.
Industrial films — construction films, pond liners, geomembranes, and vapor barriers require impact resistance verification.
Medical packaging — flexible packages for sterile medical devices are tested for impact resistance to ensure they survive distribution without puncture.
Protective films — surface protection films for metals, glass, and composites are evaluated for impact resistance during application and removal.
Relevant Standards
- ASTM D1709 — Impact Resistance of Plastic Film by the Free-Falling Dart Method
- ISO 7765-1 — Plastic film and sheeting, free falling dart method (Method A)
- ISO 7765-2 — Plastic film, Instrumented dart impact test
Why Choose Infinita Lab for Falling Dart Impact Test?
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Frequently Asked Questions (FAQs)
What is the Falling Dart Impact Test? It is a standardized test (ASTM D1709, ISO 7765) that measures the impact resistance of plastic films by determining the minimum dart weight dropped from a fixed height that causes 50% of specimens to fail.
What is the F₅₀ value in falling dart testing? F₅₀ is the dart mass (in grams) at which 50% of specimens fail under the test conditions. It is the standard reported measure of falling dart impact resistance.
What is the difference between Method A and Method B in ASTM D1709? Method A uses a lower drop height (660 mm) and smaller dart head, suited for films with lower impact resistance. Method B uses a higher drop height (1500 mm) and larger dart head, suited for tougher films.
Why is impact resistance important for flexible packaging? Packaging films must survive mechanical impacts during handling, filling, sealing, and distribution without puncture or failure. Insufficient impact resistance leads to damaged product, contamination, and packaging failure in the field.
How does film orientation affect falling dart results? Orientation introduces anisotropy — the film is stronger in the orientation direction and weaker transversely. Impact resistance may vary depending on dart position relative to the machine direction; conditioning and testing conditions must match end-use orientation.
