Dielines explained: how a carton goes from artwork to die

What a dieline is

A dieline is a flat, precise outline of the carton with every panel, flap and fold laid out in one plane. It shows exactly where the board will be cut and where it will be creased to fold. Designers place artwork onto the dieline; the die maker builds the cutting tool from it; the press and the die cutter both work to it.

The dieline lives on its own layer in the artwork file, drawn in colours that will never print. It is a set of instructions, not a graphic.

Reading the lines

Two line types do most of the work. Cut lines, conventionally solid, mark where the blade will separate the carton from the sheet. Crease lines, conventionally dashed, mark where a rounded rule will press a fold channel into the board without cutting it.

Around the outside sits the bleed: artwork extended a few millimetres past every cut line so no white sliver appears if the cut drifts fractionally. Inside sits the safety margin, keeping text and logos away from cuts and folds. The dieline also shows the glue flap, the dust flaps, and the lock or tuck that closes the box.

From artwork to approved dieline

The dieline should come first, before design begins, built from the product's real dimensions and the chosen board thickness. Thicker board needs slightly larger panels to fold around itself, which is why a dieline drawn for 250gsm cannot simply be reused on 350gsm.

Before anything is made, ask for a physical mockup: the dieline cut and folded from the actual board, unprinted. Ten minutes with a sample in hand catches sizing errors that no PDF ever reveals. Only after the mockup is approved should the die be made.

Making the steel rule die

The cutting tool itself is a steel rule die: a wooden board with the dieline's paths cut into it, into which the die maker bends and sets strips of hardened steel. Sharp-edged rules follow the cut lines. Rounded creasing rules follow the fold lines. Blocks of rubber sit beside the blades to push the sheet free after each strike.

The die is a physical asset. Once made, it is stored and reused for every repeat order of that carton, which is why a repeat run is cheaper and faster than the first: the die cost is already paid.

Die cutting and breaking

On the die cutting machine, each printed sheet is pressed against the die, cutting and creasing the whole carton in one strike, hundreds of times an hour. The sheets come off with cartons still held in place by small uncut nicks.

Breaking, also called stripping, then separates the cartons from the waste skeleton around them. What remains is a flat, creased carton blank ready for folding and pasting. At PrintVision this whole chain runs in-house, from dieline to die to cut blank, which keeps responsibility for fit in one place.

What buyers should ask for

Three requests keep dieline projects clean. Ask the printer to supply the dieline before your designer starts. Ask for an unprinted mockup on the production board before the die is made. And confirm in writing who stores the die and that it will be used for your repeat orders. None of the three costs money at the enquiry stage, and together they remove almost every structural surprise a carton project can spring.