Palletising

Palletising means placing packs layer by layer on a load carrier to a defined pattern. In Europe the most common carrier is the Euro pallet at 1200 by 800 millimetres. The layer pattern defines how the packs lie within a layer.

There are two stacking methods. In column stacking each pack sits exactly above the one below – this makes the best use of the compression strength of cartons, but the stack holds together less well. In interlocked stacking the pattern changes from layer to layer and the packs bridge the joints like bricks. The stack is more stable; the cartons carry less.

The first layer is set down just above the floor, the last often above shoulder height. In between comes the reach across the depth of the pallet, frequently with a twist of the trunk from conveyor to pallet. This combination of weight, frequency and unfavourable posture makes the task one of the most strenuous in production and despatch.

In Germany there is no statutory weight limit for it. The Manual Handling of Loads Ordinance requires the task to be assessed as a whole; the key indicator method for lifting, holding and carrying is commonly used.

A hand-guided lifting aid takes the weight off the operator and compensates for the height. The operator guides the pack from the conveyor to its place in the layer pattern and decides where it belongs. Nobody has to program the pattern.

Sizing depends on the gripper – suction cups for cartons and sacks, an under-gripping fork for soft or porous packs – and on the lifting stroke: it has to reach from the bottom layer to above the top one, including the height of the pack itself. A rail system across two pallet positions allows the full pallet to be exchanged without interrupting work.

A palletising robot or layer palletiser pays off when few pack types occur in large quantities, the conveyor delivers the packs aligned and the line runs in several shifts. It needs floor space for the safeguarding and someone to set up new layer patterns.

With many formats, small batches or lines that run only part of the time, the hand-guided solution keeps the advantage. The most common mistake is to compare only the two ends and overlook the level in between.