ISO 776–1

Dart Impact Test

Introduction

In the packaging and plastic film industry, impact resistance is a critical performance parameter. ISO 7765-1 defines a standardized test method for evaluating the impact failure energy of plastic film and sheet materials using a free falling dart impact tester.

Understanding ISO 7765-1 and Its Purpose

ISO 7765-1 is an international standard that specifies two test methods—Method A and Method B—for determining the energy required to cause failure in plastic films and sheets of less than 1 mm in thickness. These methods are designed to simulate conditions under which films may be subjected to mechanical impact during handling, transport, or end use.

Method A: Uses a 38 mm hemispherical dart dropped from 0.66 m.
Method B: Uses a 50 mm hemispherical dart dropped from 1.50 m.

Both methods aim to statistically determine the dart mass that causes failure in 50% of the tested specimens—a value known as the impact failure mass.

Dart Impact Test for Plastic Film: Why It Matters

The dart impact test for plastic film provides essential data for:

Assessing film durability for packaging applications.
Identifying variations in material quality, such as die marks or contaminants.
Comparing the performance of films from different production batches or suppliers.

This test is especially valuable for applications in medical packaging, food protection, pharmaceuticals, and industrial films, where impact resistance translates directly to product safety and consumer satisfaction.

Free Falling Dart Impact Tester: Key Equipment Overview

ISO 7765-1 Dart Impact Test for Plastic Film

Conducting this test accurately requires a reliable free falling dart impact tester that meets ISO 7765-1 specifications. The Cell Instruments FDT-01 is an excellent choice for this purpose. It features:

Precision electromagnetic dart release for repeatable drop height.
Adjustable dart heads and weights for both Method A and B.
Pneumatically controlled clamping system to minimize specimen slippage.
Integrated data acquisition system for automated result calculation.

The FDT-01 enables manufacturers and laboratories to streamline testing, reduce human error, and ensure results align with ISO standards.

ISO 7765-1 Testing Procedure: Step-by-Step

Sample Preparation
Cut at least 30 specimens from the plastic film, ensuring uniform thickness (±10% of nominal). The specimens must be free of wrinkles, pinholes, and folds.
Thickness Measurement
Measure the thickness of each specimen using a micrometer (±0.0025 mm accuracy), in accordance with ISO 4593.
Set Up the Apparatus
- Choose Method A or B based on the expected impact resistance.
- Adjust dart height: 0.66 m for Method A, 1.50 m for Method B.
- Secure the film using annular clamps with cushioning gaskets to prevent slippage.
Conduct the Staircase Method Test
- Start with an estimated dart weight.
- Drop the dart and observe whether the film fails.
- Adjust the weight up or down using fixed increments based on the outcome.
- Continue until at least 20 test points provide failure/no-failure data.
Calculate the Impact Failure Mass
Use the staircase method’s statistical formula to determine the impact failure mass (mass at which 50% of specimens fail).

Factors Affecting Test Accuracy

Material Quality: Uniform gauge, absence of die lines, and lack of contaminants ensure reliable data.
Clamping Pressure: Inadequate pressure can cause slippage, affecting results.
Specimen Condition: Surface defects or inconsistent thickness may skew impact resistance.
Drop Reproducibility: Consistent alignment and drop height are essential for statistical accuracy.

To minimize errors, high-precision instruments like the FDT-01 with automated controls and safety features are highly recommended.

Why Choose the Cell Instruments FDT-01?

The Cell Instruments FDT-01 Free Falling Dart Impact Tester is specifically engineered to meet the strict requirements of ISO 7765-1. Its automated and modular design ensures:

Accurate, reproducible results for both Method A and Method B.
Efficient testing for quality control in packaging, films, and medical materials.
Seamless integration into lab workflows with its user-friendly interface and digital data reporting.

This makes it a reliable choice for R&D labs, quality assurance departments, and third-party testing agencies.

Conclusion

ISO 7765-1 plays a vital role in assessing the impact strength of plastic films through a standardized dart impact test using a free falling dart impact tester. Accurate testing not only improves product safety and performance but also ensures compliance with international quality benchmarks. For precise and efficient testing, professionals should rely on instruments like the Cell Instruments FDT-01, which delivers repeatable and compliant results with ease.

FAQs

1. What is the main goal of ISO 7765-1?
The goal is to determine the energy required to cause failure in 50% of plastic film specimens under standardized impact conditions.

2. What are the differences between Method A and Method B?
Method A uses a 38 mm dart dropped from 0.66 m; Method B uses a 50 mm dart dropped from 1.50 m. Method B is suitable for higher impact ranges.

3. Why is dart impact resistance important for packaging films?
It indicates a film’s ability to withstand mechanical shocks during handling, transportation, and storage, ensuring product protection.

4. Can the dart impact test results from Method A and B be compared?
No. Results from Method A and B cannot be directly compared due to differences in dart size, mass, and drop height.