Pallet patterns are usually checked for how much they fill and rarely for where the unfilled parts are. A load at 92% utilisation with its gaps along one edge behaves very differently from the same utilisation with the gaps distributed through the middle. The percentage hides the thing that matters.
Why a gap is a structural problem
Boxes in a load hold each other up. Where a gap breaks the chain, the boxes on either side lose their lateral support and can lean into the void. Under braking or cornering that lean becomes a shift, and once the load has shifted the geometry that made it stable no longer applies. Small gaps cause large failures.
Edge gaps versus internal gaps
A gap at the deck edge is usually tolerable if it is small and the wrap closes it. A gap in the middle of a layer is worse, because the boxes around it have free faces and nothing distributes the load. Where a pattern must leave a gap, it should be at the edge and it should be filled – with a smaller box, a filler, or a folded sheet.
The last box in the layer
Part pallets are the normal case in most plants, and the last layer is where damage concentrates. A single box on a wide layer will walk. The practical answers are to strap it, to fill the remainder with empties, or to hold the layer with a pad and wrap drawn tight across the top. All three work; none of them happen unless the packer has been told which to use.
Where cube and stability fight
A pattern that fills a deck perfectly may do so with a shape that is inherently unstable – a long thin box, or one with a high centre of gravity. The gain in cube is real and so is the risk. The honest way to decide is to test the pattern on the actual route rather than to argue about it, which is quicker than most people expect and settles the question with evidence.
What to record after each leg
Photographs of the load on arrival, before it is broken down, and a note of where any damage is. Two or three legs is usually enough to see whether a pattern works. Without the photographs the discussion afterwards is opinion, and opinion tends to favour whatever the last person said.
Filling the gap properly
The cheap fill is a folded piece of corrugated sheet, cut to the thickness of the gap and dropped in. It does not need to carry load, only to stop the neighbouring box from having a free face. Where the gap is at the deck edge, a single sheet folded to an L and placed in the void works and costs very little.
Where the gap is structural – between two units that must not touch – the fill has to carry load and a folded section or a cut block is needed. Distinguishing the two cases is the whole job: one is packaging, the other is structure.
What we can do
We build PP corrugated turnover boxes with bases that tolerate an imperfect deck, and we will say where the pattern needs a filler. Send us the box size and the route, and we will suggest the layout and what to look for on arrival. The stacking side is covered in working out how many layers.