ECMA B48.21.00.00

Four-Corner Glued Double-Wall Tray

This premium folding carton tray mimics the clean, rigid feel of a setup box while shipping completely flat. The converter pre-glues the webbed corners, allowing the tray to pop open quickly on the packing line before the inner walls are folded over to lock the tray.

Because it features double-thick walls on all four sides, it provides excellent presentation and vertical strength. The tradeoff is a larger material footprint and the need for specialized four-corner gluing during production.

  • Order custom samples, short runs, or production runs.
  • US-based. Nationwide service.
  • Nationally competitive pricing & delivery costs.
  • Available in a wide variety of configurations.

At a glance

  • Pops open quickly for fast manual packing
  • Four double walls hide raw edges for a premium look
  • Ships flat to reduce transit and storage volume

Common uses

  • Cosmetics and electronics presentation
  • Bakery and confectionery (sift-resistant corners)
  • High-end retail kitting

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Retail and presentation packing

Premium retail and cosmetics

The double-wall construction hides all raw board edges, creating a clean, unbroken interior and exterior. This makes it a strong alternative to rigid setup boxes when warehouse space is limited.

High-speed manual kitting

Because the webbed corners are pre-glued, pulling two opposite walls automatically erects the entire tray. Packers simply fold the inner panels down to lock it, reducing assembly time compared to fully unglued trays.

Bakery and confectionery

The continuous webbed corners bridge the gaps between adjacent walls. While not liquid-tight, this design helps keep powders, crumbs, and small items from sifting out of the bottom corners.

Electronics and component presentation

The double walls provide a stable perimeter for custom inserts, keeping heavy or delicate components aligned during unboxing.

Industry and product fit

Rigid box alternatives

Brands looking to reduce the shipping and storage volume of empty rigid boxes often use this style. It delivers a similar unboxing feel but arrives knocked-down flat.

E-commerce presentation

When used inside a sturdy outer mailer, this tray organizes and presents components cleanly. It cannot ship through mixed-carrier networks on its own and usually needs a fitted outer carton or sleeve.

High-volume manual packing lines

When packing labor is a bottleneck, the pre-glued corners allow the tray to open quickly, shifting the assembly burden away from the packing floor.

When to consider simpler trays

Hand-packed trial programs

If the project is a short run, an unglued self-locking tray shifts the entire assembly burden to the packing line but removes the need for specialized gluing.

Lighter-duty commodity packing

Four double walls consume a large amount of board. If the premium rolled edge is only needed on two sides, dropping to a two-double-wall tray reduces the material footprint.

Board, print, and production choices

Board caliper and fold clearance

The inner panels fold 180 degrees and seat against the base. If the board is too thick, the panels may bind or bow. The exact material thickness helps determine the final cutting template.

Print sidedness

Because the outer walls fold over to become the inner walls, the outside print surface wraps into the tray. If the bottom of the tray interior needs graphics, two-sided printing is usually necessary.

Grain direction

With 180-degree folds on all four sides, the board grain can only run parallel to one set of walls. The board grade and scoring profile should be chosen to minimize cracking on the cross-grain folds.

Insert compatibility

If the tray will hold a thermoformed or die-cut insert, the internal dimensions should account for the thickness of the four rolled walls to ensure a proper fit.

Clearance and structural adjustments

Inner panel height adjustments

The height of the rollover panels is calculated to clear the base fold. This deduction can be adjusted to ensure a tight friction lock without causing the walls to bulge.

Mitered corner clearances

The ends of the inner panels are angled so they meet cleanly in the corners. These angles can be tweaked based on the board thickness to maintain a clean interior presentation.

Webbed corner tension

The diagonal creases in the webbed corners control how the tray opens. The geometry can be adjusted to ensure the tray pops up smoothly without tearing the glued joints.

Board and packing details

Folder-gluer production path

This tray is usually produced on a multi-point folder-gluer equipped for four-corner work and 180-degree fold-overs. This production path should be discussed when planning delivery schedules.

Variants

B48.21.00.00.a

A variant that uses static, hardcoded clearance deductions for the inner panels instead of caliper-based formulas. It needs careful review if the board grade changes.

Additional notes

Board thickness and locking failures

If a thicker board is substituted without updating the template clearances, the inner panels may bind against the base fold and pop back up. Always test a physical sample with the exact production material.

FAQs

Assembly and Packing

Does this tray need a machine to set up?

The tray arrives flat, and packers simply pull the walls up to open it, then fold the four inner panels down to lock it.

Material and Fit

Can this tray be made from corrugated board?

It is very challenging. The 180-degree folds on all four sides create heavy bulk and tension with corrugated fluting. It is typically produced in solid bleached board or similar folding carton grades.

Shipping and Route

Can I ship this tray through the mail?

Not on its own. It is an open-top primary package. To ship through parcel networks, it usually needs an outer shipping box or a secure sleeve.

Structure and Closure

Do the inner walls need tape or glue to stay down?

When the template is sized correctly for the board thickness, the inner panels friction-lock against the base and each other, holding the tray closed.

Print and Finish

How does the double-wall design affect printing?

Because the outer walls fold over to become the inside walls, a single-sided print run will cover the exterior and the inner sides. The interior floor will remain unprinted unless a two-sided print process is used.

Cost and Production

Why does this tray use more material than a standard folding carton?

It uses a larger blank size due to the four double walls, increasing the overall footprint. The webbed corners also add to the material used.

Inserts

Can I use a custom insert with this tray?

The rigid double walls provide a stable perimeter for die-cut or thermoformed inserts. The internal dimensions should be carefully checked to account for the rolled walls.

Samples

Should I test a physical sample before ordering?

Because the 180-degree folds are sensitive to board thickness, testing a physical sample with the exact production material ensures the inner panels lock correctly without bowing.

A refined tray that balances premium presentation with fast packing-line assembly.

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