Stretch film for machine packaging
Tight fixation of the load on the pallet is achieved by stretching the polymer web on the packer rollers and its subsequent compression. Stretch film for machine packaging is designed to work with a carriage, where the tension is regulated by a friction brake or motor, so the coefficient of tension is stable. As a result, the boxes do not move when the loader accelerates and when braking, and the upper rows do not "float".
Stretch film for machine packaging is selected for the weight of the pallet and the type of product. For bricks or bags with granules, a film with increased thickness and adhesion is used, for boxes with household appliances — an option with controlled return so as not to deform the corners. A mistake that is often made at the start: they put a universal roll on all lines and get overspending and breaks in a cold warehouse.
Where machine packaging is used
In logistics warehouses, the film is fed into an automatic winding machine with a rotary table or a rotating "arm". There, the carriage stretches the canvas by 150-300%, after which the film tends to return to its original length and tightens the load. This mode is necessary when shipping pallets to online retail: the pallet passes through ramps, elevators and long routes, where any backlash leads to displacement.
In the beverage industry, the film fixes the blocks of PET bottles. The speed on the line is high, so a stable thickness and an even edge of the roll are important — otherwise the carriage begins to "cut" the edge, and the web breaks at the start of the cycle. In food warehouses, a purity requirement is added: primary raw materials are used without an odor, so as not to transfer it to the packaging.
A separate scenario is freezers. At temperatures below zero, the usual composition becomes tougher and loses elasticity, so they take a formula with additives that reduce brittleness. If this is not done, the gap occurs at the moment of pre-tension, and the line rises.
Advantages of using stretch film
Savings do not arise "by themselves", but because of controlled pre-attraction. The carriage pulls out the canvas, then it is compressed on the pallet and gives the same holding effect at a lower consumption. With manual winding, a person does not keep a stable force, so the layer is either excessive or weak.
The stability of fixation is explained by the mechanics of return: the higher the elastic recovery after stretching, the more the load is compressed. But there is a limit — if you drag the boxes with soft contents, dents appear. In practice, the carriage setting is selected according to the test: the reference pallet is wrapped, the route inside the warehouse is driven and the offsets are checked.
Another effect is protection from dust and moisture. The canvas forms a continuous barrier,