Protrusion Puncture and why

Ensure the durability of your stretch films and food wrap films with our advanced Protrusion Puncture Test solutions. Designed to evaluate the puncture resistance of films, our testers adhere to ASTM D5748 standards for precise and reliable results.

Wrap Film Protrusion Test

Protrusion Puncture Test – Key to Assessing Wrap Film Durability

Puncture resistance is a crucial property for stretch wrap films used in both consumer and industrial applications, particularly in packaging. It measures the film’s ability to absorb energy and resist protrusions, which is essential for ensuring durability during transport and handling. The Protrusion Puncture Test is specifically designed to assess this resistance under biaxial deformation conditions, simulating the stresses films encounter in real-world applications. By using this test, manufacturers can ensure that their films meet the necessary durability and quality standards.

Why Do Wrap Films Need Protrusion Puncture Resistance Testing?

Importance of Protrusion Puncture Resistance in Wrap Films

Wrap films, especially stretch films and food wrap films, are subjected to various mechanical stresses during handling, transport, and storage. 

Puncture resistance is an essential property that ensures the film does not tear, puncture, or lose its integrity when in contact with sharp or abrasive objects. It directly impacts the film’s ability to protect the contents, especially for food packaging or pallets wrapped for shipping.

How Puncture Resistance is Achieved in Wrap Films

Polymer Selection

Films made from LLDPE (linear low-density polyethylene), HDPE (high-density polyethylene), and other polymers have superior strength and elasticity, which provide high puncture resistance.

Thickness

Thicker films tend to offer more puncture resistance, but they must balance flexibility and strength to maintain optimal performance.

Additives

Certain additives are incorporated into the film formulation to improve its impact strength and resistance to punctures, including plasticizers or tackifiers.

This test helps manufacturers verify that their films meet the required puncture resistance to ensure product safety and performance in real-world conditions.

Guiding Standards for Protrusion Puncture Testing

ASTM D5748 – Standard Test Method for Protrusion Puncture Resistance of Stretch Wrap Film

The ASTM D5748 standard provides a reliable method for testing the puncture resistance of films using a probe or dart-like object that is pushed into the film at a controlled rate. This test method measures the force required to puncture the film, which is an indicator of the film’s strength and durability.
Know More About ASTM D5748

BB/T 0024 – Standard for Stretch Wrap Films for Transport Packaging (China)

In addition to ASTM standards, the BB/T 0024 is a relevant standard for puncture testing of films in China. It provides guidelines for determining the protrusion puncture resistance using similar techniques as ASTM D5748, ensuring global compatibility in film testing.

Know More About BB/T 0024

Test Overview

This protrusion puncture test method determines the resistance of a stretch wrap film to the penetration of a probe at a standard low rate, a single test velocity. Performed at standard conditions, the test method imparts a biaxial stress that is representative of the type of stress encountered in many product end-use applications. The maximum force, force at break, penetration and distance are determined.

Step-by-Step Test Procedure

1.Sample Preparation

Test specimens are taken from several rolls of film, and where possible, from several production runs of film. Strong conclusions about a specific property of a film cannot be based on a single roll of film.

Film Cutting: Prepare a sample of the film, ensuring it is cut to a standard size, typically 150mm x 150mm (or a long film strip with width of 150mm for easy test area replacement.).

Test Number: Test a minimum of five specimens for each sample.

Tips: As wrap film has cling and soft features, it’s advised to use two pieces of paper and place sample between to form a “sandwich” style before cutting it.

2.Tester Preparation

Instrument Preparation: The TST-01 Tensile Tester with ASTM D5748 Protrusion Puncture Jig is used for the test. 

Temperature & Humidity Control: Usually 23°C and 50% humidity.

Probe and Clamp. Ensure the testing environment is within recommended conditions (usually 23°C and 50% humidity) to minimize environmental influences.

ASTM D 5748 jig

3.Sample Loading

Clamp the specimen in the holder. Adjust the probe position as close as possible to the specimen without actually touching it. This can reduce the operation waiting time. 

4.Parameter Setting and Start Test

Set the tester crosshead speed at 250 mm/min, Test numbers needed and sample layers.  

Press tester TEST button to initiate the protrusion test.

5.Automatic Process and Data Obtained

After the puncture probe passes completely through the film. The crosshead automatically returns to start position.

In the meantime, the test number, peak force at break, maximum force, and probe penetration distance at break is automatically measured and kept.

6.Finish All the Tests.

Repeat test sequence for the remaining sample specimens.

Puncture Test ASTM D5748 Result

FAQs about ASTM D5748 Protrusion Puncture Resistance Test

What is the Protrusion Puncture Test?

The Protrusion Puncture Test evaluates the puncture resistance of stretch wrap and food wrap films. This test is essential for assessing durability under biaxial deformation, ensuring films can withstand real-world stresses during handling, transport, and storage.

Why is puncture resistance critical for wrap films?

Puncture resistance ensures that wrap films maintain their integrity when exposed to sharp or abrasive objects. It directly impacts their ability to protect packaged goods, especially in applications like food packaging and industrial shipping.

What factors influence puncture resistance in wrap films?

Key factors include:

  • Material Composition: Films made from LLDPE or HDPE offer superior strength and elasticity.
  • Thickness: Thicker films generally provide better puncture resistance while balancing flexibility and durability.
  • Additives: Additives like plasticizers enhance impact strength and resistance to punctures.

What equipment is required to perform the ASTM D5748 test?

The test requires a universal testing machine like Cell Instruments TST-01 Tensile Tester, a pear-shaped probe and a specimen clamping fixture, a template, and a specimen cutter. These ensure accurate and standardized testing.

What are the key performance metrics obtained from the ASTM D5748 test?

The test evaluates:

    • Peak Force at Break: The force required to cause a puncture.
    • Maximum Force: The highest force recorded during the test.
    • Penetration Distance: The depth the probe travels before breaking the film.

How does ASTM D5748 testing simulate real-world conditions?

The test applies biaxial stress, resembling the forces experienced by stretch wraps during use. While it may not replicate every field condition, it provides reliable data for comparing puncture resistance across film samples.

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