Magrupak — Corrugated Box Flute Guide | magrupak.com
An ordered procedure from product weight to a signed-off box specification, closing with a moisture check.
Step one: state the product weight and the stack load the box will carry in storage. These two numbers set everything that follows, because a box rated for a light product and a light stack needs a different strength value than one carrying a heavy load three high.
Step two: pick the flute by thickness and by print needs. Fine E flute at 1.6 mm or F flute at 0.8 mm suits retail print where detail has to hold; deeper A flute at 4.8 mm, B at 3.2 mm or C at 4.0 mm suits shipping protection where cushioning matters more than the printed surface.
Step three: specify the bursting or edge crush value. This is the strength figure the box is rated to, and it is written into the specification alongside the size and weight limits rather than implied by the flute name.
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Step four: add the size limit as length plus width plus depth, and the gross weight limit. The size limit caps how large the box may be at that strength; the gross weight limit is the packed weight the box is rated to carry.
Step five: check board moisture stays in 6.5 to 9.5 percent before packing. Board outside this range loses edge crush strength or cracks at the score lines, which invalidates the figures written in steps three and four.
The common failure mode is choosing on flute thickness alone. A thick A flute box with no edge crush value, no size limit and no gross weight limit is an untested box: the flute says how it is built, not how much it holds.
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