Why is it so important?
Despite starting out as a slurry of mushy wet paper, the strength of corrugate is incredible. Why corrugate? Because it works! Even with a seemingly weak medium like paper, if you construct it in the right patterns and shapes, it's strength can amaze you.
Corrugate is made up of 3 basic parts, 2 pieces of flat linerboard, with fluted paper sandwiched between. This can be repeated to create double and triple wall boards as well:
The arches between the linerboard are referred to as "flutes" and are on a scale of A-F (based on the number of flutes per foot). "A Flute" has fewer flutes per foot, and "F Flute" has more flutes per foot. Generally B and C flutes are the most common flute sizes and will be utilized in most boxes you see.
The strength of a box, or its corrugate, is tested one of two ways. Either using the Mullen/Burst test, or using an ECT (Edge Crush Test). The Mullen/Burst test is used for corrugate that is comprised of mainly virgin materials. This test involves pressure against the flat side of the corrugate until the board punctures (or burst).
The Edge Crush Test (ECT), is used more often when recycled materials are used. This test puts pressure along the vertical edge of the corrugate.
Factors that go into determining necessary board strength are:
* Nature of the product being packaged
* Total weight of your product
*Size of your product
* How will the box be stacked, stored, and transported