Corrugated Box Compression Testing: Is Your Packaging Up to Spec?

Protection is the primary goal of all packaging. For brands shipping from Asia to European and North American Markets, this means withstanding a great deal of external forces in the transport chain (shock, vibration, compression, etc.) as well as environmental factors specific to that part of the world.

Corrugated board is well suited for the job, but only if it’s designed to withstand such forces. Unfortunately, lack of global performance standards can make it difficult for exporting companies to specify their needs when communicating with corrugated manufacturers overseas. Worse, packaging suppliers may sometimes deliver corrugated board that does not meet spec requirements, leaving exporters with sub-par packaging solutions unfit for the demands of their supply chain.

Testing Procedures for Corrugated Boxes

Corrugated boxes fail in many ways and for many reasons, but two very common failures that we see, especially in packaging made overseas, are collapse under a compressive top-load or by rupture due to rough handling. There are several tests that can predict the performance of corrugated boxes under these conditions, including the box compression test (BCT), edge compression test (ECT), short-span compression test (SCT), bending stiffness and the International Safe Transit Association's transportation testing procedures.

Box Compression Test

The box compression test itself is fairly unsophisticated: a fully converted, empty box is placed between two steel plates and compressed at a steady force until the box is crushed. However, when completing the box compression test it’s important that the environmental testing conditions (temperature and humidity) are similar to the actual conditions your packages are exposed to on their way from manufacturers in Asia to distributors and retailers in Europe and North America.

The maximum compressive load of corrugated containers decreases as surrounding temperature and relative humidity increase. Unfortunately, traditional box compression testing doesn’t always take into account the actual transport conditions. This can be extremely problematic (and costly) for global brands with operations in humid environments, particularly Asia. Time is another critical element during box compression testing. The effects of stress and strain are not always immediately revealed, so in addition to complete collapse, boxes should also be held at a predetermined load for a given period to evaluate stacking loads.

Edge Compression Test

ECT is a short column test of the vertical compression load that measures the ability of a sample to sustain top-to-bottom load. After you know the strength of the board, you can use this number to predict the stacking strength of common box designs at various dimensions. It is measured by compressing a segment of board until a peak load is established (pounds per lineal inch of load bearing edge). Boxes built to ECT specifications are designed for stacking strength but may not withstand external or internal forces. Burst testing measures the containment and handling ability of a box (force of pounds per square inch required to rupture the side of corrugated board).