PACKAGING TECHNOLOGY

Packaging technology

The main packaging formats, what each one is made from, how it is converted, and the production problems that come with each structure.

The formats

Format	Typical structure	Usual process	Where it goes wrong
Flexible packaging	Single film, or two and three layer laminates	Flexo, gravure, digital	Lamination bond, seal integrity, colour on metallised substrates
Labels	Facestock, adhesive, liner	Flexo, digital, offset	Die cutting, matrix stripping, adhesive bleed, repeat accuracy
Folding cartons	Folding boxboard, often coated one side	Offset, flexo, digital	Creasing and cracking, fibre direction, board tolerance
Corrugated	Liner and fluting	Flexo post-print, or litho lamination	Washboarding, crush, print contrast on brown liner
Paper cups	Cup board with a barrier coating	Flexo, offset	Seal in the coating, curl, print registration around the blank
Paper bags	Kraft or machine glazed paper	Flexo	Absorbency variation, ink strike-through, tension on the web

The pattern across the table is worth noticing. Almost every recurring problem in packaging production is a substrate and converting problem before it is a printing problem, which is why fixing them at press rarely holds.

Substrate decides more than anything else

Substrate is the first thing to establish and the one most often left vague on a job sheet. It governs ink choice, drying, colour appearance, achievable tolerance and every converting step after printing.

Absorbent materials such as uncoated paper, kraft and cup board take ink into the surface. Density drops, dot gain rises, and the printed result looks duller than the proof unless the proof was made on the right stock.
Non-absorbent films hold ink on the surface. Drying or curing has to do the work, surface treatment level matters, and adhesion becomes a measurable property rather than an assumption.
Metallised and transparent films change appearance entirely because of what sits behind the ink. A white ink layer is part of the colour result, not a separate item, and measuring over an inconsistent white gives inconsistent numbers.
Board brings fibre direction, caliper tolerance and moisture content into the picture, all of which show up at creasing rather than at print.

Surface energy on film is worth treating as a routine check rather than a troubleshooting step. Treatment decays over time in storage, and a roll that was fine when it arrived may not be fine when it runs.

Converting is where jobs are lost

Printing is one step in a chain. In flexible packaging the chain usually runs printing, lamination, slitting, pouching or delivery to a filling line. In cartons it runs printing, coating, die cutting, stripping, folding, gluing. Each step can undo the one before it.

Two habits prevent most of the damage. Define the specification for every step, not just for print, so lamination bond strength and seal integrity have target values the same way colour does. And test the finished structure, not the printed sheet, because a laminate that passed at print can still fail at the seal.

Planning material before you start

Material is usually the largest single cost in a packaging job, and most of the overspend happens during planning rather than during production. Working the numbers before the order is placed is the cheapest possible intervention.

Question	Tool
How many metres do I need for this quantity?	Running meter calculator
How do kilograms and metres relate for this film?	Kg to meter calculator
How many labels fit across the web?	Label repeat calculator
How well does this carton fit the sheet?	Sheet utilisation calculator
Roughly how much ink will this consume?	Ink coverage calculator

Each one states its formula and its assumptions on the page, so the output can be checked rather than trusted.

Structure design and the dieline

A packaging structure starts as a dieline: the flat layout with cut lines, crease lines, glue flaps and panel dimensions. Everything downstream depends on it being right, and an error here is expensive because it is usually discovered after tooling has been made.

The keyline and dieline planning tool generates a dimensioned layout for straightforward structures so panel arithmetic can be checked quickly. It is a planning aid. Production tooling should still come from a structural designer or the die maker, and the page says so plainly rather than implying otherwise.

Frequently asked questions

What is the difference between flexible packaging and folding cartons?

Flexible packaging is printed and converted on a web of film, paper or foil and stays flexible in use, for example pouches and wrappers. Folding cartons are printed on board, then die cut, creased and glued into a rigid box. They use different substrates, different converting equipment and different quality controls.

Why does print look different on metallised film?

Because the reflective surface behind the ink changes the appearance of every colour on top of it, and the white ink layer underneath becomes part of the colour result. Variation in the white layer shows up directly as colour variation, so the white has to be controlled as carefully as the process colours.

What causes cracking at the crease on a folding carton?

Usually fibre direction relative to the crease, crease depth or rule selection, coating thickness, or low moisture content in the board. It is a board and tooling problem far more often than a printing problem, so the investigation should start at the creasing station.

How much material should I order for a packaging run?

Calculate the theoretical requirement from the repeat, the number across and the quantity, then add setup waste and running waste based on your own plant records rather than a generic percentage. The running meter and kg to meter calculators on this site do the first part and show the formula.