Assembly and Warehouse: Before Dispatch
A warehouse turns floor space into time. Between the end of the line and a shut container door, a case passes four accounts: location, stack, rotation and load plan. Each carries a number — square metres taken, layers stacked, days on the shelf, cubic metres paid for and left empty. Get them wrong and freight idles on the dock, or shifts at sea and lands bruised. The figures below are typical ranges from ordinary dispatch weeks, not guarantees, and none of them depend on how many people stand at the assembly benches.
01Four-Part Location Codes: Zone, Row, Bay, Level
Four segments are enough: zone, row, bay, level. A-03-05-2 means zone A, third row, fifth bay, second level. Labels belong at forklift eye height, 1.2 to 1.6 m — high enough to clear a pallet, low enough to read without leaning back. Aisles at 2.8 to 3.2 m suit right-angle stacking; narrower and every entry needs a correction, costing a dozen pallets an hour.
What the code really buys is search time. Without one, tracing a batch takes 5 to 15 minutes; with codes and a location record it falls under a minute. Design turnover at 15 to 45 days, fast movers in the front rows near the dock and slow ones behind. Anything untouched past 60 days gets its own zone, or it will hold prime space indefinitely.
02Three to Five High: The Bottom Case Carries It
Three to five layers is the usual stack, and the ceiling is not the count but the compression strength of the bottom carton. Figure 60 to 120 kg per carton: five high means the lowest one carries four above it, times a safety factor of 1.5 to 2, because humidity alone can strip 30% of board strength. If the arithmetic fails, add a deck or drop to three.
Keep stack height under 2.2 m so the operator can see the top layer. Interlocking the courses is steadier than stacking square, at a cost of 2 to 3 cm. Plastic crates go higher, and the price is a bottom crate that takes a permanent set, so the lid stops sitting flush. Only two honest answers exist here: a layer count from compression, or one from habit.
03FIFO Is a Layout Decision, Not a Discipline
First-in-first-out works best when geometry enforces it: load at one end, pick at the other, and stock ages on its own. Rely on people remembering batch dates and the system breaks at the first shift change. Flow rack does this well and costs aisle space, dropping utilisation to 60% to 70%; double-deep rack stores more but forces the outer pallet out first.
Label two dates, production and receipt. Production alone misleads the moment goods are reworked or transferred. Call a SKU slow after 90 days without movement, list it separately at stocktake, and act once it holds more than 10% of locations. Turnover between 15 and 45 days is healthy: faster means the buffer is thin, slower means cash sits on a shelf.
048–15% Air: What a 40HQ Actually Swallows
A 40HQ measures about 12.03 × 2.35 × 2.39 m inside, roughly 67 m³, and cargo never reaches that figure. Air ratio is one minus cargo volume over internal volume, and 8% to 15% is normal. Four things eat the difference: case sizes that do not divide into the box, staggered courses, the door opening, and a last row nobody planned.
The door opening is 2 to 3 cm narrower than the interior, so a case built to internal width will not pass at the far end. Loading takes 2.5 to 4 hours per container, longer with many pieces or heavy units. Past 15% air, change the stacking pattern before the container type: the first is free, the second forces a new freight rate.
05Wrap and Bracing: The Last Twenty Minutes
Pallet loads take 3 to 5 turns of stretch film, two at the base to lock the pallet, one over the top edge by 5 to 10 cm. Too few and the board takes up moisture in transit, corners crush, and the pallet arrives leaning. A wrapper holds tension at 15 to 25 N — enough to bind the load, slack enough not to fold a corner.
Bracing means air bags or timber, one every 1.5 to 2 m across the box, so freight cannot run forward under braking. Leave 10 to 15 cm behind the doors for bracing rather than filling the space. With 2 to 6 dock positions, fewer than two creates mutual waiting; how fast a position turns matters more than how many exist. Before sealing, reconcile pieces, gross weight and container number.
| Location code segments | 4: zone, row, bay, level |
|---|---|
| Stack height | 3–5 layers |
| Bottom carton load | 60–120 kg |
| Location turnover | 15–45 days |
| 40HQ internal size | 12.03 × 2.35 × 2.39 m |
| Air ratio per container | 8–15% |
| Loading time | 2.5–4 h |
| Dock positions | 2–6 bays |
FAQ
How many segments does a location code need?
Four: zone, row, bay, level. Three loses the level, so high racking cannot be resolved; five is more than anyone remembers at the rack face. Segment count matters less than reading it in one glance, which is why labels sit at 1.2 to 1.6 m.
How high can cases be stacked?
Follow compression, not habit. At 60 to 120 kg per carton, a five-high stack puts four layers on the bottom one, times a 1.5 to 2 safety factor, with humidity taking 30% of strength. If the sum fails, add a deck or go to three, and keep the stack under 2.2 m so the top layer stays visible.
Why does FIFO keep failing?
Usually because it depends on memory, which resets every shift change. Put loading at one end and picking at the other and stock ages by itself. Double-deep racking saves floor space but forces the outer pallet out first, which erodes the rule. Two date labels cover rework and transfers.
Is a half-empty 40HQ a container problem?
Check the stacking first. Eight to fifteen percent air is normal; past 15% the usual causes are case sizes that do not divide into the box, staggered courses, or an unplanned last row — all free to fix. Changing container type means a new freight rate, so it is the last lever, not the first.