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Mixed-SKU palletizing has no pattern to repeat.
Single-SKU palletizing is solved once per product: find the tie-and-layer pattern, print it, reuse it. A mixed-SKU B2B order is a new problem every time — twenty SKUs, twenty footprints, twenty weights, and one stack that has to survive a truck. These are the rules that decide it.
Why the single-SKU answer does not transfer
- The pattern changes per order. There is no “best pattern” to look up: the set of cases is different every time.
- Weight is no longer uniform. With one SKU every case weighs the same, so stacking order does not matter. Mix two densities and it decides whether something gets crushed.
- Heights differ. Cases of different heights in one layer means the layer above sits on high corners only.
- The last layer is always partial. A mixed order rarely ends on a full layer, and a partial top layer is where towers appear.
Six rules, and what each one is defending
Numbers below are the engine’s defaults; the app lets you change most of them per company.
| Rule | Default | Defends against |
|---|---|---|
| Heavy on the bottom | upper layer average ≤ +15% of the layer below | Crushed cartons and a top-heavy pallet. |
| One layer, one height band | cases within 0.75 in of each other | The next layer resting on corners instead of a flat surface. |
| Partial layer threshold | below 80% fill a layer counts as partial | Treating a half-empty layer as if it could carry load. |
| Base support | ≥ 75% of each case base supported | Overhang. This is a hard rule: the plan is rejected, not warned. |
| Crush limit | product limit, else 8 × case weight | Load above a case exceeding what the case can carry. |
| No towers | max 2 cases of one product, top block ≤ 24 in | A narrow column of identical cases on top of a finished pallet. |
A worked example — arithmetic, not a customer result
We have no customer results to show yet, so this is computed from the rules above. Nothing here is a claim about anyone’s savings.
Take two products on a 48 × 40 in pallet: 40 cases of a 24 lb detergent carton and 60 cases of a 4 lb plastic bottle pack. Weight alone says the pallet can hold 40 × 24 + 60 × 4 = 1,200 lb, well under the 3,000 lb cap, so a naive tool loads all of it.
The rules disagree. Put the bottle packs down first and the detergent layer above averages six times the weight below — the +15% band refuses it. Put the detergent down and the 4 lb packs may sit on top, but only two of them per column and only up to 24 in, so the leftovers start a second pallet instead of a tower. And if the bottle pack carries a measured crush limit of, say, 60 lb, the planner uses that number instead of the 8 × 4 = 32 lb fallback — which changes the answer in the other direction. The point is not the total; it is that weight capacity alone never decided anything.
Where mixed-SKU plans go wrong in practice
- Crush limits nobody entered. The fallback is a rule of thumb. If a product is fragile and has no limit on file, the plan can be geometrically perfect and still arrive damaged.
- Overhang that “worked last time”. A case hanging a quarter off the edge is carried by air.
- Centre of gravity, not just total weight. A pallet can be inside every cap and still be top-heavy, which is why the plan warns on drift as well as on weight.
- The partial layer at the top. This is where the tower rule earns its place.