Burst Tests (+Mullen Test) and ECT:
Theses test are essential for evaluating corrugated board performance
Corrugated board is a popular packaging material chosen for its strength, lightweight nature, and recyclability. However, not all corrugated boxes are created equal. They vary in thickness (single, double, triple, etc.), flute type (A, B, C, E, F, etc.), and the variety of paper used. These different components not only determine the strength and mechanical performance of corrugated board but also its economic and environmental impact.
Insufficient mechanical performance can result in the crushing or puncturing of the corrugated board, while excessive performance can lead to costly and sub-optimized overqualification. Therefore, it is important to characterize the performance of corrugated board. Two key tests are used for this purpose: burst tests (including the Mullen test) and the Edge Crush Test (ECT).
The burst test measures the force required to burst a piece of corrugated board. It is useful for evaluating the durability of the board when subjected to handling, which is indirectly related to its ability to withstand external and internal forces and, therefore, contain and protect a product during transportation.
The burst test involves applying hydraulic pressure through a rubber diaphragm onto a circular area of the corrugated board until it bursts. The burst strength is then expressed in kilopascals per square centimeter (kPa/cm2).
Edge Crush Test (ECT)
The ECT is a performance test that directly evaluates the compression resistance of a corrugated box. This measurement is achieved by compressing a sample of the board placed between two plates perpendicular to the direction of the flutes. The result of the ECT is typically expressed in pounds per inch (lb/in).
The ECT is particularly relevant for transport packaging, where boxes are often stacked and thus subjected to significant compression forces. It provides crucial information about the box's ability to resist crushing under load.
Burst Tests and ECT in Quality Control
These tests allow verifying that the technical characteristics of delivered corrugated boards meet the requirements of the purchasing specifications. ECT and burst values help classify corrugated boards into different categories, such as the 4C+E classification system.
However, it is important to note that these tests only characterize the corrugated board material itself. They do not take into account other important factors such as box geometry. Additional tests, such as the Box Compression Test (BCT), are therefore necessary to assess the impact of box geometry on the overall packaging performance.