Why does Case Export Packaging use three layers instead of one big carton?

One large carton costs more per unit and passes 25 kg, where manual handling stops. Three layers keep each unit under 25 kg and cut handling to a single lift.

How do I judge whether edge crush is enough?

Work back from stack height. The bottom carton carries the two above plus itself, so 12 kg needs 32 lb/in and four tiers need 40 lb/in.

Is thicker film always better?

No. Grip comes from elastic recovery after pre-stretch, so 25 micron at 250 percent holds harder than 30 micron unstretched.

Does every pallet need heat treatment?

Wooden pallets are heat treated or fumigated and marked to the importing country's rules; plastic and paper pallets are exempt.

Which layer fails most often?

The middle one. Stacking is done by hand, and a 50 mm offset starts most collapses.

Case Export Packaging: Carton, Pallet and Stretch Film

Quick answer: Case Export Packaging runs in three layers: a five-wall carton with four 40 by 40 mm corner boards, a 1200 by 1000 mm pallet stacked three high under 1.8 m, and 25 micron film at 250 percent pre-stretch in four wraps plus two straps.

Three Layers of Case Export Packaging
Inner Layer: Carton and Corner Board
Middle Layer: Stacking and Pallet Size
Outer Layer: Film Wraps and Strapping
Drop and Stacking Test Requirements
FAQ

1. Three Layers of Case Export Packaging

Case Export Packaging scales up three times: case into carton, cartons onto a pallet, film and strap around the stack. The carton takes edge impact, the pallet makes one liftable load, the film stops it shifting.

The layers cannot substitute: a stiff carton still leans if stacking is uneven, and six wraps will not save a third tier with short edge crush.

A 40 ft box is 2.35 m wide: two 1200 mm pallets side by side, ten rows, twenty positions. Any remainder that will not divide into the pallet face starts a lean.

2. Inner Layer: Carton and Corner Board

In Case Export Packaging, edge crush comes first: 32 lb/in, near 5.6 kN/m, in 7 mm five-wall AB board, enough for three tiers; four need 40 lb/in.

The cavity runs 10 mm larger per side. Too much and the case slides; too little and it must be forced in, costing a fifth of edge crush.

Four corner boards of 40 by 40 mm and 3 mm, cut to carton height, turn the vertical edge into surface contact; without them it buckles under film tension.

Sealing is 48 mm water tape in an H pattern; below minus 10 C clear tape holds 40 percent of its tack, so cold chain lots take hot melt.

Gross weight	Board	Edge crush	Corner board	Tape
8 to 15 kg	Five-wall AB	32 lb/in	40 by 40 by 3 mm	48 mm water
15 to 25 kg	Five-wall BC	40 lb/in	50 by 50 by 4 mm	60 mm hot melt
Over 25 kg	Seven-wall AAA	48 lb/in	50 by 50 by 5 mm	60 mm hot melt

3. Middle Layer: Stacking and Pallet Size

Case Export Packaging runs on a 1200 by 1000 mm three-runner pallet: 22 mm deck, 100 mm blocks, 1000 kg dynamic, 2500 kg static.

Stacking is interlocked, tiers offset 50 mm; a column stack looks tidy but friction is all that separates tiers.

Three tiers at 550 mm plus a 150 mm pallet gives 1.8 m, where a van side door stops clearing the load.

A centre of gravity 50 mm off centre loads slings unevenly by 30 percent, so overhang stays under 10 mm per side.

Tiers	Tier height	Overall	Equipment	Load limit
2	550 mm	1.25 m	Box van	700 kg
3	550 mm	1.80 m	Van, 40 ft box	1000 kg
4	500 mm	2.15 m	High cube, flatbed	1100 kg

4. Outer Layer: Film Wraps and Strapping

Case Export Packaging uses 25 micron LLDPE at 250 percent pre-stretch, so one metre becomes 3.5 m of wrap; unstretched film tears on the first scrape.

Wraps follow distance: four by road, six by sea, five by air, the bottom two covering 100 mm of pallet top, the top folded 100 mm over the crown. Overlap is 50 percent, and a gap is where rain enters.

Strapping is 16 mm PP at 1600 N, tensioned to 350 N, in two runs 100 mm and 400 mm above the deck, each on a 3 mm pad.

Film carries no compression and strap seals nothing: film alone leans, strap alone lets cartons grind.

5. Drop and Stacking Test Requirements

Drop testing follows GB/T 4857.5: one corner, three edges, six faces, ten drops, a 12 kg carton falling 600 mm onto steel before it is opened and checked.

Stacking follows GB/T 4857.3, the three-tier load held 24 hours on the bottom carton, with height loss under 5 mm and no crushed panels.

Vibration is skipped most often: a 30 minute sweep from 5 to 200 Hz at 0.5 g drops strap tension 15 percent, so straps leave at 400 N to arrive at 340 N.

Conclusion

The three layers are not a material list but three figures that must agree: 32 lb/in edge crush for three tiers, a 1200 by 1000 mm pallet fitting twenty positions in a 40 ft box, and four to six wraps matched to distance. When they line up, the load holds its centre of gravity, which is what makes Case Export Packaging survive the voyage.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.