During packaging, shipping and storage, corrugated boxes are subjected to different types of stresses that can endanger the products inside. Through certain testing methods such as the Edge Crush Test (ECT) and the Burst Strength Test, also known as the Mullen Burst Test, it is possible for companies to foresee these contingencies and design protective packaging according to their needs. In this context, it is common to face the dilemma between Edge Crush Test vs. Burst Strength.
These are two of the most common testing methods for measuring the strength of corrugated material in companies that use corrugated boxes in their packaging. However, they measure different parameters and have different objectives. We analyze the differences between the Edge Crush Test vs Burst Strength Test and when to apply each test, according to the needs of each company.
Edge Crush Test vs Burst Strength Test: analysis
> Edge Crush Test
The Edge Crush Test was created to provide a solution to a common situation in the distribution cycle: the stacking or palletizing of corrugated boxes, which can cause stress and damage to the packaging, causing it to collapse or crumble.
Through the Edge Crush Test it is possible to observe how much force a corrugated material is able to withstand at its edges without crushing and is directly related to the stacking strength of a carton.
For a long time, the Mullen Burst test has been the main standard used by the industry for the testing and classification of corrugated packaging. However, there are now several factors that have made the Edge Crush Test more relevant.
These factors include the use of recycled material in the manufacture of corrugated board, as it was found that recycled board of the same weight did not always perform as well in the Mullen Burst test.
In addition, in modern shipping and storage methods, most products are transported and stored on pallets, with boxes stacked several layers deep. Therefore, it is critical to know if the corrugated box is strong enough to hold the weight of the product inside, as well as having strong enough edges to hold the full weight of the other boxes on top without crushing or warping.
To carry out this test, the compressive strength of the edge of the corrugated board is measured by compressing this area of the material between two rigid plates and in a direction perpendicular to that of the corrugated board flutes. The test ends when the material collapses, so that the company obtains information on the maximum force it can withstand. Besides, it is necessary to have an edge crush test machine such as the Compression Tester system.
> Burst Strength Test
The burst strength test consists of an assessment of the protective capacity of corrugated board, in particular to prevent cases of incorrect and rough handling. In this case, the force required to puncture or break the face of a corrugated board is measured. Thus, instead of applying the compression force on the edge of the board, it is applied on the flat side.
This test is intended to measure the forces that a cardboard box can be subjected to during rough handling, as well as the amount of weight the box can support. It does not measure how much weight can be stacked on top of the box. To understand the stacking force, edge crush test (ECT) ratings should be consulted.
To perform Burst Strength tests, a Mullen Burst Tester is used and the results of the burst test are expressed in pounds per square inch. For example, a box tested by the Mullen Burst Test with a rating of 200# can withstand 200 pounds per square inch of force applied directly to the linerboard on the face of the box.
Unlike the Edge Crush Test, the Mullen Burst Test standards also establish a minimum cardboard weight for the corrugated material. That is, each square foot of the final corrugated material must contain at least the minimum amount of base paper material required by the standard for its burst test rating.
When should you use each test?
Although when comparing the Edge Crush Test vs Burst Strength Test it is determined that both testing methods focus on the testing of corrugated boxes, they are two tests with different objectives and measure different parameters.
The Edge Crush Test is suitable for companies whose distribution cycle includes stacking and palletizing their corrugated boxes. It is also suitable for transporting goods that will not exert lateral forces on the boxes and will not be exposed to multiple shipping modes and the handling that goes with it.
On the other hand, the Burst Strength Test is suitable for companies that use corrugated boxes and are concerned about improper handling. It is also suitable for calculating the resistance force when shipping goods that are likely to move inside the box, exert force on the side walls or pass through multiple transport nodes, as there will be more potential for rough handling to take place.
Unlike Mullen Test ratings, ECT ratings do not require a minimum amount of base paper in the corrugated material. This means that ECT-rated boxes are generally lighter and use less material than a Mullen Test box that is considered equivalent. This can help companies reduce shipping costs and improve environmental metrics, in terms of waste reduction.
The fundamental difference between these two tests is that the Burst Strength Test requires a minimum basis weight of the paperboard. That is, the Burst Test requires that the base papers used to make corrugated fiberboard weigh at least a certain minimum number of pounds per given unit area.
However, the Edge Crush Test eliminated this requirement, allowing the use of lighter materials while still offering high performance.
The importance of corrugated Testing Methods to guarantee packaging quality
As we have already mentioned, corrugated boxes are exposed to various threats that jeopardize their integrity during the distribution cycle: from excessive stacking to the transport of heavy goods or improper handling. Testing methods make it possible to simulate how these threats will affect the material and the product, and the packaging system, so that safer solutions can be designed.
Among the advantages of applying corrugated cardboard testing are the following:
- Ability to carry out quality control processes for corrugated board manufacturers.
- Choice of the appropriate materials to ensure the safety of the transported goods.
- Optimization of the amount of material needed to protect a given commodity, while being economically efficient.
- Increased sustainability. Commitment to the environment in packaging goes beyond choosing sustainable materials. It also means being able to optimize the amount of materials used, reducing the carbon footprint in the production of packaging as well as during the transport of goods.
Test standards for the Edge Crush Test and Burst Strength Test
> Edge Crush Test standards
ISO 3037: Corrugated fibreboard — Determination of edgewise crush resistance (unwaxed edge method)
A test method part of the ISO standards specifies the procedure for determining the crush resistance of corrugated fiberboard with unwaxed edges.
ISO 13821: Corrugated fibreboard — Determination of edgewise crush resistance — Waxed edge method
Determines the crush resistance of corrugated fiberboard with waxed edges by applying the force in the direction of the spline axis.
TAPPI T 811: Edgewise compressive strength of corrugated fiberboard (short column test)
Describes the procedure for determining the compressive strength at the edge of fiberboards, in the direction perpendicular to the spline axis and in single-, double- and triple-walled boards.
> Burst Strength test standards
ISO 2759: Board — Determination of bursting strength
Specifies the method for measuring the breaking strength of cardboard subjected to increasing hydraulic pressure.
TAPPI T810: Bursting strength of corrugated board
Procedure for measuring the tear resistance of single and double wall corrugated cardboard.
Want to know more about the Edge Crush Test vs Burst Strength Test comparison and how to find out which one your company should apply?
At Safe Load Testing Technologies, we’ve been helping businesses create safer, more sustainable packaging solutions for more than two decades with our transportation simulation equipment, including the Compression Tester system for performing the Edge Crush Test. Contact us and let’s talk about how we can help you.