Shrink Sleeve Applicator Product

Overview

A shrink sleeve applicator dresses containers in full-body printed labels. The label arrives as a continuous tube of shrink film, printed on the inside surface and wound flat on a roll; the machine opens the tube, cuts it into individual sleeves, drops one over each passing container, and a steam tunnel shrinks it tight to the contour. Because the film can shrink up to 75% in the transverse direction, a sleeve can follow waisted bottles, yogurt cups and aerosol cans that pressure-sensitive labels cannot, and the same pass can add a tamper-evident neck band.

How it works

The printed film tube pays off the roll on the Unwind Shaft, its tension held at a gentle 30–80 N by the Dancer Arm — shrink film is 35–50 µm thick and stretches or curls if over-tensioned, ruining registration. The web runs over low-inertia Idler Roller up the Applicator Tower; roll changes are taped up on the Splice Table when the End-of-Film Sensor calls one.

The core trick of the machine is the Mandrel Body: a polished bullet-shaped former that floats inside the film tube with no mechanical connection to the frame. Opposed Mandrel Drive Rollers pinch the film against the mandrel from outside, simultaneously suspending it in space and driving the film down over it. The flat tube enters at the top, is spread open by the mandrel's profile, and travels down as a round tube ready to cut.

Feed is servo-registered. The Feed Roller Pair advance one sleeve length per cycle while the Registration Sensor reads the printed eye-mark, correcting the Servo Motor so the Rotary Knife cuts within ±0.3 mm of the intended line every time. The knife orbits the tube against the Anvil Ring, making a square cut at up to 600 cuts per minute; dulling blades swap as pre-set Blade Cartridge units. An optional Perforation Wheel adds tear perforations for tamper bands.

Below the cut, the Shooting Wheels grab the freed sleeve and fire it downward at several metres per second onto the container passing beneath — timed by the Bottle Trigger Sensor, spaced by the Timing Screw, and arrested at the right height by the Positioning Brush. Light empty bottles would bounce or tip under the impact, so the Stabilizer Belt presses gently on their caps through the application zone. The Sleeve Detection Sensor confirms each sleeve actually left and landed.

Shrinking

Sleeved containers ride the Conveyor Belt straight into the Steam Shrink Tunnel. Steam is the preferred medium for full-body sleeves because condensing vapor delivers heat evenly to every surface at a self-limiting 85–95 °C, just above the film's shrink onset and far below temperatures that distort the print or scorch the film. Inside the insulated Tunnel Shell, several Steam Manifold banks aim at different heights, each metered by its own Steam Control Valve under feedback from Zone Temperature Probe RTDs. Zoning matters: the sleeve must shrink onto the container from the bottom up (or grip a waist first), or trapped air bubbles and a sleeve that rides up result. Condensate drains to the Condensate Tray and the Vapor Extraction Blower captures escaping vapor at the tunnel mouths. Hot-air tunnels replace steam where water on the pack is unacceptable — multipacks, electronics — at the cost of less uniform shrink and 20–40 kW of electric heat.

Materials and operation

PETG is the dominant film: high shrink ratio, no chlorine, good clarity. PVC is cheaper with easier shrink behaviour but faces recycling objections; OPS gives low shrink force for thin-wall containers that would crush; crystallizable PET and PLA films answer bottle-recycling requirements by floating or separating in the recycling stream. Because the print is on the tube's inner surface, it is protected from scuffing for the product's whole life — one reason sleeves took over the energy-drink and dairy aisles.

The PLC Controller stores a recipe per SKU: sleeve length, mark offset, shoot timing, mandrel height on the Height Adjustment, and tunnel zone setpoints. Changeover between bottle formats means a different mandrel and timing screw plus the recipe, typically 20–40 minutes. At 200–400 containers per minute the applicator is usually paced by the filler upstream, and its reject rate — sleeves cut off-mark, missed shots, smiles and wrinkles from bad tunnel zoning — is the line's working quality metric, held below a fraction of a percent on a tuned machine.