Packaging engineering guides
Longer explanations behind the numbers, each with a worked example computed from the same data as the tools.
Guides
- Right-sizing boxes to cut dimensional weight
- Carriers bill a light, bulky box by its size, not its weight. Right-sizing means choosing the smallest box that still protects the product, and the payoff is usually largest just above a dimensional weight threshold where one inch changes the bill.
- Reading a box maker's certificate
- A box maker's certificate is the round stamp on a box flap in which the maker certifies the box meets a freight classification rule. It tells you which test the board was graded by and the grade it was built to.
- Stacking strength and safety factors
- A box's tested or estimated compression strength is what it holds new, dry and for a short time. Real stacks sit for weeks, absorb humidity and rarely line up corner to corner, so the box needs a margin over the load: the safety factor.
- Unit loads: boxes on a pallet
- A unit load is the box, the pallet and the pattern working together. The box size decides how many fit per layer, the pattern decides how strong the stack is, and the pallet footprint decides whether anything overhangs.
- ECT vs Mullen: two ways to grade board
- ECT grades board by how much load a strip carries on its edge; Mullen grades it by how much pressure it takes to burst. ECT predicts stacking, Mullen predicts puncture and rough handling, and neither converts exactly into the other.
- Choosing a flute
- Choose a coarse flute (C, or A where available) when the box must stack, a fine flute (E or F) when it must print well or save space, B in between for die-cut and dense goods, and a double wall when one wall is not enough.
- How to measure a box
- Box sizes are given as inside length × width × depth. Length is the longer side of the opening, width the shorter, and depth runs from the opening to the floor. Carriers, on the other hand, measure the outside.