What is the difference between tensile strength and bursting strength?

What is bursting strength?

Burst strength refers to a material's ability to withstand pressure in all directions before breaking. This is particularly important for materials such as paper, cardboard, fabric, and packaging film, which may be subjected to multi-directional stresses during transportation or use.

A bursting strength tester is used to measure this property. In this test, the material is clamped and gradually increased hydraulic or pneumatic pressure is applied through a rubber diaphragm until it breaks. The maximum pressure at which the material breaks is the bursting strength.

Differences Between Bursting Strength Testing of Corrugated and Plain Paper

The test methods for corrugated and plain paper are the same; the only differences are the sample material and the test standard.

Traditional Paper Testing

This test uses thinner materials (such as printer, kraft, or writing paper) as samples and follows ISO 2758 or TAPPI T403 standards. For traditional paper testing, testers use samples less than 1 mm thick and apply pressures of 100–500 kPa.

Corrugated Boxes

These materials are thicker and consist of multiple layers, such as liner and corrugation. These materials are tested according to ISO 2759 and TAPPI T810. These standards measure the bursting strength of multi-layered items and materials that require high pressure to tear.

For corrugated box testing, testers use samples thicker than 3 mm and apply pressures between 500 and 1200 kPa.

Using a Carton Bursting Strength Tester to Improve Packaging Durability

Corrugated boxes protect goods during storage and transportation. A carton bursting strength tester is used to test a box's strength, indicating its ability to withstand internal loads and external pressure.

Single-wall boxes require a bursting strength of 12–14 kg/cm², while double-wall boxes require a bursting strength of 20 kg/cm² or higher. The required box strength depends on the product weight and logistics requirements.

The Importance of Carton Breakage Testers in Logistics

During logistics, cartons are subjected to various stresses during storage and transportation, including stacking, pulling, vibration, and rough handling. Therefore, cartons with low breakage strength may break during transportation, resulting in damage to the products inside and financial losses.

Fast-moving consumer goods, electronics, and pharmaceuticals require strong cartons. This strength helps ensure the safety of products during transportation.

Applications:

Corrugated boxes

Paperboard

Textiles and fabrics

Packaging film

Leather and synthetic materials

What is tensile strength?

Tensile strength refers to the strength of a material when stretched. It indicates the maximum amount of force a material can withstand before breaking. This test is crucial for items that are subject to stretching during use. A tensile strength tester (also known as a tensile testing machine) tests the strength of a material by clamping its ends and slowly stretching it until it breaks. This instrument measures the force required to break the material—the tensile strength.

Applications:

Tensile strength has a wide range of real-world applications, including plastic films, wires and rods, fabrics, rubber, and other composite materials. Here, we focus on its application in fabrics.

Tensile strength is the breaking strength of a textile. It measures the force required to break a material when stretched. It is an indicator of the absolute value of the tensile force, with the legal unit being Newtons (N). A textile's breaking strength refers to the peak force required to tear a specimen. This is measured during a tensile test under specific conditions. The breaking strength index measures the effects of sunlight exposure, washing, abrasion, and finishing on fabric quality. Therefore, testing is necessary for textiles with anisotropic strength and low stretchability.

Textiles are subject to various types of damage during daily use. Stretching, compression, bending, and friction are the most common types of damage. These forces can cause cracks, tears, and breaks in the fabric. Therefore, the tensile strength, tear strength, and breaking strength of a textile directly affect the durability of the product and determine its quality.

Tensile Strength vs. Burst Strength Comparison Table

Mullen & G229P Pneumatic Bursting Strength Tester

FAQ

What materials are suitable for tensile strength and breaking strength testing?

Both test methods are suitable for a wide range of materials, including metals, plastics, composites, textiles, and some ceramics. Universal testing machines (UTMs) are currently recognized as one of the most versatile testing machines, capable of meeting all of these material testing needs.

Is breaking strength the most critical factor in material selection?

While breaking strength is an important specification, it is not the only consideration. The specific application of a material determines the priority of its various properties. The key is to achieve the optimal balance between these properties to ensure safety and performance.

Can a material have high tensile strength but low breaking strength?

Yes, there are such cases. Some materials can withstand high tensile stresses but have relatively low breaking strength, meaning they may break before reaching their maximum tensile load.

What is the ideal burst strength standard for corrugated boxes?

The ideal burst strength for corrugated boxes depends on the application, but a typical range is between 16 and 32 kg/cm². For heavy-duty packaging, a higher burst strength standard is recommended.

Can tensile testing replace burst testing?

No. Tensile testing and burst testing measure different material properties. Using one instead of the other—especially in packaging material evaluation—would result in inaccurate performance assessments, so their use is not recommended.

Is burst strength testing suitable for plastics?

Unless the plastic is in sheet form and subjected to multi-axial stress, burst strength testing is generally not suitable for most plastic materials. For plastics, tensile testing is more recommended for relevant property assessments.

How often should packaging companies schedule burst and tensile testing?

It is recommended that each incoming batch of packaging materials be tested. In applications where safety is paramount, it is best to conduct daily quality checks using laboratory equipment to ensure consistent quality.