Palletising Patterns And Layer Planning

The Pattern Is A Stability Decision

A pallet pattern is not a packing puzzle, it is a structural design. Bags are soft, they settle and they slide. The pattern is what stops the load walking apart in a container over three weeks at sea.

The Three Basic Patterns

Column stacking places every layer identically. It gives the highest bag count per layer and the worst stability, because there is no interlock between layers at all. It is acceptable when every load is stretch wrapped and travels short distances.

Interlocked or back stacking rotates alternate layers so bags bridge the joints below. Stability improves dramatically at the cost of a bag or two per layer.

Five-flower stacking, published as one of our standard options, places four bags around one central bag. It is a strong interlock for square-ish bags and it is common on fertiliser and building material loads.

How Many Bags Per Layer

Published configurations on our palletising line are 6 to 8 layers with 4, 5, 6 or 8 bags per layer, in combinations such as 3+2, 2+3, 3+3 and 3+3.

The number follows from the bag footprint and the pallet size. The published tray size is 1400 x 1200 x 150 mm, and a bag flattened to a known width and length either fits five per layer or it does not.

Flatten The Bag First

The single most effective thing you can do for load stability costs almost nothing: run the filled bag through a flattener before it reaches the palletiser. A flattened bag has a predictable footprint, stacks square and settles evenly. An unflattened bag is a pillow and it will roll.

Robot Reach And Payload Set The Envelope

Published robot data is a 180 kg bearing capacity, IP67 protection, 0.1 mm repeat positioning accuracy, 0.3 mm repeat cycle accuracy and a 3.15 m maximum reach, at 600 to 1000 bags an hour on 25 kg to 50 kg bags.

Reach is what usually constrains a cell layout, not payload. Two pallet positions either side of the robot must both sit inside the working envelope, along with the pallet magazine.

The Gripper Decides What You Can Pick

The published fork type grab is a stainless welded fork with pneumatics, mounting bracket and a vacuum pipeline system, picking by photoelectric detection. Fork grippers suit bags. Vacuum suits cartons and slip sheets. Clamps suit rigid cases.

A cell that has to handle both bags and cartons needs either a combination tool or a tool change, and that is a decision to make at layout stage rather than later.

Practical Layout Advice

• Give the pallet magazine 10 to 15 pallets of capacity so a pallet change is not a line stop.
• Leave the forklift a clear straight run to the discharge position, not a turn inside the cell.
• Put the stretch wrapper immediately after the palletiser and before any storage, so no load is ever moved unwrapped.
• Make the pattern adjustable on the touch screen so your own shift leader can add a size without a programmer.