How to Measure Film Heat Seal Strength Accurate According to ASTM F2029 and ASTM F88

Why Do We Need to Test Film Heat Seal Strength?

The wide application of films across industries such as food, pharmaceuticals, and electronics highlights their importance in maintaining product safety and integrity. Packaging films rely on strong, consistent seals to prevent contamination, leakage, or product degradation.
Heat seal strength is a critical parameter that determines the durability and reliability of these seals. A weak seal can compromise product quality, while an overly strong seal might lead to unnecessary material waste. Testing film heat seal strength ensures that packaging meets performance and safety standards.

What is the Film Heat Seal Strength Test?

Film heat seal strength measures the force required to break or peel apart a heat-sealed joint. This test evaluates the integrity of the seal and its suitability for real-world conditions.

Applications:

• Ensuring airtight seals for perishable goods.

• Validating seal quality for pharmaceuticals and medical devices.

• Enhancing product development by optimizing sealing parameters.

By assessing seal strength, manufacturers can achieve consistent performance and comply with industry requirements.

Heat Seal Strength Measurement: How to Follow ASTM Standards

1. Film Heat Seal Strength Test Specimen-Making: ASTM F2029

• Purpose: ASTM F2029 provides a standardized method for preparing heat-sealed specimens for testing.

• Equipment and Parameters: Specimens are created using heat sealers under controlled conditions, including specified temperatures, dwell times, and pressures. This ensures repeatable and reliable samples for further testing.

2. Tensile Strength Measurement for Film Heat Seal Specimens: ASTM F88

• Purpose: ASTM F88 outlines methods to measure the tensile strength of heat-sealed joints.

• Test Techniques:

• Unsupported Method: Tests the seal without external support.

• Supported Method: Adds backing for weak films.

• Loop Method: Uses a loop configuration for specific packaging materials.

• Results: Peak force, average force, and failure mode (e.g., cohesive, adhesive) provide insights into seal performance.

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Equipment Used for Heat Seal Strength Testing

1. Heat Seal Tester

• Creates heat seals under controlled conditions.

• Customizable settings for temperature, time, and pressure.

2. Tensile Tester

• Measures the force required to break the seal.

• Provides detailed data on seal integrity and material performance.

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Heat Seal Strength Test Process

Step-by-Step Procedure:

1. Prepare Samples: Cut films to standard dimensions and create seals using the heat seal tester.

2. Set Parameters: Adjust the heat sealer for optimal temperature, dwell time, and pressure based on material specifications.

3. Conduct Heat Seal: Seal the film under controlled conditions.

4. Cool and Test: After cooling, test the tensile strength of the sample using a tensile tester.

Factors Influencing Results:

• Material type and thickness.

• Consistency of sealing conditions.

• Environmental factors such as humidity and temperature.

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Interpreting Test Results

The data obtained includes:

• Maximum Force: Indicates the seal's breaking strength.

• Mode of Failure: Identifies whether failure occurred within the seal or the material itself.

Acceptable Outcomes: Strong seals that meet industry standards.
Unacceptable Outcomes: Weak seals or those with uneven adhesion.

Significance of the Film Heat Seal Strength Test

Testing film heat seal strength offers numerous benefits:

• Ensures product safety by preventing leaks or contamination.

• Helps meet regulatory standards, such as ASTM F2029 and ASTM F88.

• Reduces packaging failures and enhances consumer confidence.

Manufacturers gain valuable insights to optimize materials and processes, ultimately reducing costs and improving product quality.