Flexography: How a Rubber Plate Prints a Web

Flexography is the method behind much of the packaging a person handles in a week. Corrugated boxes, labels, flexible film, cartons and paper bags are all likely to be flexo work. It prints from a raised image on a soft plate, and it runs on a roll of material rather than a stack of sheets. That pairing is what makes it quick and forgiving on rough surfaces.

A raised image on a flexible plate

The image sits above the plate surface, the way a rubber stamp sits above its base. Ink is metered onto the raised areas by a roller, and the plate is pressed against the moving web. The soft plate deforms slightly under pressure, which lets it reach into the texture of a board that a hard metal plate would miss.

Ink metering starts with the anilox

Inside the press, a ceramic anilox roller carries a measured film of ink in millions of tiny cells. A doctor blade wipes the surface clean so only the cells hold ink. The volume of those cells decides how much ink reaches the plate, which is why a change of anilox is one of the first moves when a colour runs too heavy or too light.

Why the web runs, not a sheet

Flexo presses feed a continuous roll through the units, so printing, drying and often die-cutting happen in one pass. Registration is held by tension on the web, and each colour unit adds its layer as the material travels. For labels and flexible packaging, this keeps the cost of a long run low and the speed high.

Where it suits the job

Flexo is at its best on large areas of solid colour, on uncoated brown board, and on film that has to stretch or seal. Very fine photographic detail is better served by offset or digital, where the image is formed differently. The decision is rarely about one method being superior. It is about matching the plate, the ink and the substrate.

What a buyer can expect

A flexo job is planned around the substrate and the number of colours. Artwork that keeps fine reverse text a little heavier, and keeps the smallest type clear of the trim, prints more cleanly. Once the plates are made, a long run of packaging holds its look from the first metre to the last.