Narrow Web Label Press

Overview

A narrow web label press prints self-adhesive labels and converts them in one pass: it prints the artwork, cures it, die-cuts the label shape, strips the waste, and winds finished label rolls. The base process here is UV flexography, where a relief plate carries ink to the substrate and ultraviolet light cures each color before the next station prints over it. The web is narrow, commonly 330 to 430 mm, and the press runs 60 to 200 metres per minute. Six to ten stations let a job carry several spot colors plus process color, and the converting stations at the end turn the printed web into the rolls a labeling line will use.

The web runs from the Unwind and Infeed through a line of Flexo Print Station units with UV Curing between them, then through the Die-Cutting Station and the Turret Rewind and Slitter. The Web Guide and Tension holds it centered and at tension, the Servo Drive and Register keeps the colors aligned, and the Control and HMI sequences the line. Everything mounts to the Machine Frame.

Print stations

Each color is a self-contained Flexo Print Station. Ink is metered by the Anilox Roll, a ceramic roll engraved with fine cells that pick up a fixed ink film. A Doctor Blade Chamber floods the anilox and a Doctor Blade scrapes off the surplus so only the cell volume carries forward. The anilox transfers that film to the Plate Cylinder, whose Photopolymer Plate is held on a Cylinder Body with compressible Mounting Tape. The raised image areas of the plate touch the web as it passes the Impression Cylinder, printing that color. A Ink Pump circulates UV ink to the chamber, and a Register Motor shifts the cylinder a few microns to hold register against the other stations.

UV curing

UV flexo ink stays liquid until light hits it, so the UV Curing system fires a UV-LED Lamp after each station. These are water-cooled UV-LED heads: a UV-LED Array of UV chips behind a UV Reflector flashes the ink to a hard cure in milliseconds, which lets the next station print over a dry surface. A UV Power Unit drives the LEDs at constant current, a UV Cooling Loop loop carries off their heat, and a UV Shutter blocks the beam whenever the web stops, since a stationary web under a lamp would scorch. UV-LED curing runs cool enough to print thin films that would distort under older mercury-arc lamps.

Materials and die-cutting

The press converts self-adhesive laminate: a face stock, a pressure-sensitive adhesive, and a silicone release liner. Face stock is paper or filmic PP and PE, roughly 50 to 250 micron, fed from the Unwind and Infeed under a Unwind Brake. At the Die-Cutting Station a flexible Rotary Die Cylinder held on a Magnetic Cylinder kiss-cuts the label outline through the face stock and adhesive only, leaving the liner intact, with cut depth set against the Anvil Roller by a Pressure Adjuster adjuster. The surrounding waste, called the matrix, is peeled away and wound by the Matrix Rewind, leaving the labels sitting on the continuous liner.

Lamination, slitting, and rewind

Many labels need a finish, so the Cold Foil and Lamination can add a metallic look by transferring foil from a Foil Unwind over a tacky adhesive, or laminate a clear film from the Film Unwind through a Lamination Roller nip to protect the print. The finished web then reaches the Turret Rewind and Slitter, where the Slitting Section splits it into label lanes with Slitter Knife knives and each lane winds onto a core on a Rewind Shaft. A Turret Head head indexes a full roll out and an empty core in without stopping the press.

Drive, register, and use

The press is gearless: a Servo Drive runs each station servo, all slaved to a Line Encoder master so the cylinders stay in phase. A Register Camera reads register marks and the Control and HMI trims each station to hold color-to-color register tight. The operator sets jobs from the Operator HMI while the Machine PLC runs the line logic and interlocks. The gearless servo drive lets the operator change the repeat length in software rather than by swapping gears, so a job with a different label size loads from the Operator HMI without mechanical setup.

Presses of this kind make the labels on bottles, cans, cosmetics, pharmaceuticals, and food packaging, anywhere a printed pressure-sensitive label is applied at high volume. UV flexo holds its place against digital here because the per-label cost is low once the plates are made, and a single pass prints, cures, laminates, die-cuts, and slits, so the finished rolls come off ready for the labeling line. Setup time is the cost: mounting the Photopolymer Plate on each Plate Cylinder and dialing in register and die pressure takes longer than loading a digital file, which is why short runs increasingly go to digital while medium and long runs stay on flexo. Many modern label presses combine both, adding inkjet heads between flexo stations so variable data and spot color print on the same web.