The Box Compression Test (BCT) is used to evaluate the structural strength of a cardboard box. This test is typically performed by compressing an empty box (or one with dividers) between the platens of a compression testing machine. The vertical load is distributed to the sidewalls, causing lateral deformation of the box, commonly referred to as buckling.
BCT depends on several factors:
Carton Type: The type of cardboard used (single, double, or triple wall) plays a significant role in BCT. Generally, the more walls the cardboard has, the higher its compression strength.Corrugated Flute Type: A, B, C, E flutes, etc., each have their unique properties and can influence BCT.Packaging Geometry: The shape and size of the box can impact its compression strength.Corrugated Structure: The structure of the corrugated material can also affect BCT.
It is important to note that BCT values obtained from this test cannot be used to determine the stacking strength of the box, i.e., the total load it can support. Other factors need to be considered.
Factors influencing performance:
Humidity: An increase in relative humidity from 50% to 95% can lead to dimensional changes and increased gross weight of the box, loss of strength properties, and decreased compression performance, resulting in reduced BCT.Storage Duration: Prolonged storage can cause packaging "fatigue," resulting in decreased stacking performance.Storage and Stacking Pattern: The type of pallets used and the stacking method can impact BCT.Handling: Rough handling, such as drops, can significantly weaken boxes.
There are several testing standards available to evaluate BCT. The most commonly used ones include ASTM D642, TAPPI T804, and ISO 12048. These standards provide detailed procedures for appropriate testing methods to determine the compression strength of cardboard boxes, ensuring consistent and comparable results.
Compression tests on material samples of cardboard are referred to as Edge Crush Tests (ECT).