Corrugated packaging glossary

Short definitions of the words box makers, carriers and test labs use, in Packgent's own words.

ASTM International: A standards body whose committee D10 writes packaging test methods such as D642 (compression) and D4169 (distribution testing).
Auto bottom: A box bottom that is die-cut and partly glued at the factory, so it locks closed by itself when the flat box is squared up.

Basis weight: The weight of a fixed area of paper, in the US usually pounds per thousand square feet (lb/MSF).
Billable weight: The weight a carrier actually charges for: the greater of the rounded actual weight and the dimensional weight.
Blank: The flat, cut and scored sheet of board that folds into a box.
Box compression test (BCT): The top-to-bottom load an empty box carries before it fails, measured between two platens in a compression tester.
Box maker's certificate: A printed stamp, usually on a bottom flap, in which the box maker certifies that the box meets a carrier classification rule.
Bursting strength: The pressure a sheet of board withstands before a rubber diaphragm pushes through it.

Caliper: The thickness of a sheet of board, usually given in inches or millimetres.
Center special slotted container (CSSC): A slotted box with inner flaps cut to half the length and outer flaps to half the width, so both pairs meet in the center.
Column stacking: A pallet pattern where boxes sit exactly on top of each other, corners over corners, so the strong vertical edges line up.
Combined board: The finished corrugated sheet: one or more fluted mediums glued between flat liners.
Corrugator: The machine that forms the fluted medium, glues it to liners and cuts the combined board into sheets.
Cube utilization: The share of an available space, such as a pallet load envelope or a trailer, that boxes actually fill.
Cushioning allowance: The space added around a product inside the box for protective material.

Die-cut: Cut and scored by a shaped steel-rule die rather than by the straight slotting knives used for slotted boxes.
Dieline: The flat drawing of a blank, with cut lines and fold (score) lines marked.
Dim divisor: The number a carrier divides cubic inches by to get dimensional weight in pounds.
Dimensional weight: A billing weight that carriers compute from package size: length × width × height divided by a divisor.
Double wall: Combined board with two fluted mediums and three liners.

Edge crush test (ECT): The load per inch of edge that a short column of board carries standing on its edge, flutes vertical.

FEFCO code: A four-digit number naming a box design in the international case code kept by FEFCO, the European federation of corrugated board makers.
Fill-in pad: A loose sheet of board laid between the inner flaps of a slotted box to give a flat, full floor.
Flap: A part of the blank hinged on a score that folds over to close the top or bottom of a box.
Flute: The wave-shaped medium inside corrugated board, and the size class of that wave (A, B, C, E, F).
Freight density: Shipment weight divided by its cubic feet, in pounds per cubic foot.
Full overlap (FOL): A slotted box whose outer flaps are as long as the box is wide, so they overlap completely when closed.

Gaylord: A pallet-sized corrugated bulk bin, usually multi-wall, used for loose parts, resin, produce or recyclables.
Glue tab: The narrow strip on one end of a slotted blank that is glued, taped or stitched to the last panel to make the box a tube.

Half slotted container (HSC): A slotted box with bottom flaps only, closed with a separate cover.

Inner flap: The flap that folds in first. On slotted boxes the inner flaps sit on the width panels.
Inside dimensions: The usable space inside a box, listed length × width × depth. Box sizes are quoted by inside dimension.
Interlocked stacking: A pallet pattern where each layer is turned relative to the one below, tying the load together.
ISTA: The International Safe Transit Association, which publishes pre-shipment test procedures for packaged products.

Manufacturer's joint: The seam where the glue tab joins the first and last panels, made at the box plant.
McKee formula: An equation from McKee, Gander and Wachuta (1963) that estimates box compression strength from edge crush, caliper and perimeter.
Medium: The paper that is fluted on the corrugator and sits between the liners.
MSF: Thousand square feet: the unit board is priced and weighed in.
Mullen test: The common name for the bursting-strength test of board, after the Mullen tester.

NMFC Item 222: The rule in the National Motor Freight Classification that sets construction standards for fibreboard boxes shipped by LTL truck.

Outer flap: The flap that folds last and forms the outside of the closure. On slotted boxes the outer flaps sit on the length panels.
Outside dimensions: The box's outer size, which carriers measure for dimensional weight and which sets pallet patterns.
Overlap slotted container (OSC): A slotted box whose flaps are cut a little longer than half the width so the outer flaps overlap.

Ready-glued: Delivered flat but already glued so it sets up with little extra closing. The FEFCO 07 series.
Regular slotted container (RSC): The standard shipping box: one blank, four panels, all flaps half the box width, outer flaps meeting in the center.
Right-sizing: Choosing or making the smallest box that protects the product, to cut board, void fill and dimensional weight.

Safety factor: The multiple of the expected load that a box's tested or estimated strength must reach to allow for losses in real conditions.
Score line: A crease pressed into board so it folds cleanly along a line.
Sheet plant: A box plant without its own corrugator, which buys combined board sheets and converts them into boxes.
Single wall: Combined board with one fluted medium between two liners.
SIOC: Ships in own container: a product package that goes all the way to the customer without being boxed again.
Slot: The narrow cut between adjacent flaps on a slotted blank, so the flaps can fold independently.
Stacking strength: How much load a box carries in a real stack over time, after losses for storage, humidity and handling.

Take-up factor: How much more medium goes into a length of board than the board's own length, because the medium is fluted.
TAPPI: The Technical Association of the Pulp and Paper Industry, which publishes paper and board test methods such as T 811 (ECT).
Telescope box: A box made of a body and a cover that slides over it.
Triple wall: Combined board with three fluted mediums and four liners, used for bulk bins and heavy loads.

UFC Rule 41: The rail counterpart of NMFC Item 222, in the Uniform Freight Classification.
Unit load: Goods assembled on a pallet and secured so they move as one piece.

Void fill: Loose material that fills empty space in a box so the product cannot move.

Wrap-around case: A case formed by folding a blank tightly around the product on a machine, closing it in the same step.