Open End Sleeve Packaging: Clearance, Substrates and Retention

Overview

An open end sleeve, also called an open-ended tube, belly band or carton sleeve, is a glued tube with both ends open and no closure flaps. Unlike a reverse tuck end carton, it carries no bottom lock and no tuck, which makes it the simplest tube carton to produce and the most economical in board use.

The sleeve usually does one of four jobs:

• Branding overlay: full-colour graphics, ingredient panels or promotional messaging over a plain primary container such as a thermoformed tray, tin or foil dish.
• Multi-pack bundling: banding two or more identical items for club packs, promotions or gift sets.
• Tamper deterrence: glued under slight tension, the sleeve wraps the container tightly, so a clamshell or tub cannot be opened without tearing it.
• Cost control: with no tucks, dust flaps or locks, the blank uses the least board of any tube structure.

Common variations

• Standard four-panel sleeve: glued side lap with four 90 degree corners. Used for ready-meal trays, rectangular tins and software packs.
• Belly band: an unglued blank wrapped by hand and closed with tape, transfer adhesive or interlocking tabs. Used for soap, rolled textiles and book wraps.
• Lock-bottom sleeve: a die-cut tongue into a slot, assembled without glue, for bakery and quick manual packs.
• Curved sleeve: scores follow a tapered or round container, as with salad bowls and yogurt tubs.
• Windowed sleeve: a die-cut aperture on the top or side to expose the product, a logo or a date code.

Anatomy and key dimensions

• Length (L): the dimension along the tube axis, which is the visible band width.
• Width (W) and height (H): the cross-section of the product the sleeve wraps.
• Glue lap: usually 12 to 20 mm (0.5 to 0.75 in), tapered 15 to 30 degrees at both ends so it does not overhang the folded corner.

Clearance and fit

Clearance decides whether the sleeve slides on and stays put. Too loose and the tray slides out; too tight and the sleeve tears or jams the inserter.

• Manual slide-in with a rigid container: add 1.5 to 2.5 mm to width and 1 to 2 mm to height.
• High-speed sleeve cartoner: add 2 to 3 mm to width and 1.5 to 2.5 mm to height.
• Tension fit over a flexible or tapered tray: add 0 to 0.5 mm and rely on board flex to hold.

Blank footprint:

• Blank width = 2 x internal width + 2 x internal height + glue lap + score allowances.
• Blank height = sleeve length.
• Score allowance is roughly half the board caliper per crease.

Substrates

• FBB, 16 to 24 pt (300 to 450 gsm): chilled ready-meal sleeves, confectionery and dairy.
• Kraft board, CUK or SUS, 18 to 28 pt (350 to 500 gsm): frozen meals, where tear resistance and wet strength matter under condensation.
• SBS, 14 to 20 pt (280 to 400 gsm): cosmetics, premium bars and beauty bundles.
• E-flute or F-flute, 0.9 to 1.5 mm: heavier multi-packs of glass jars, ceramics and hardware.

Retention features

With both ends open, heavier products need something more than friction.

• Locking paws: small internal die-cut tabs that deflect as the product slides in and catch behind a tray flange.
• Fugitive glue: a removable hot-melt dot between the sleeve and the base tray, the same idea as a glued credit card letter.
• Flange grooves: narrow scores that snap into the rim of a thermoformed tray.
• Anti-skid varnish: a high-friction aqueous coating on the unprinted inside face.

Production notes

• Run board grain perpendicular to the tube scores, parallel to the length, so the walls do not bow under tension and the corners fold crisply.
• Keep the glue lap free of varnish, coating and ink on both mating surfaces.
• For chilled or frozen use, specify a hard-sized board with a moisture barrier such as PE extrusion, an aqueous grease barrier or a poly coating, so freeze-thaw condensation does not delaminate the sleeve.
• Add a semi-circular thumb notch of R10 to R15 mm at one or both open ends when the fit is snug, so the consumer can pull the product out.

Related specifications

• Reverse tuck end cartons: the same tube with tuck closures when the pack has to seal.
• Straight tuck end cartons: tube cartons that keep the front face free of seams.
• Open top tuck bottom boxes: open-top trays that sleeves are often wrapped around.