The main type of equipment for wrapping pallets in stretch film are pallet wrappers (pallet wrappers, palletizers or pallet macnine). These devices are produced in many countries, but the products of such Italian manufacturers as Robopac, SIAT, Comarme and Siro Technologies, as well as German models of the Cyclop brand, have received the greatest recognition. At present, Asian, or rather Chinese, companies are expanding the production of packaging devices at a rapid pace. Among them, one can especially highlight the Extend company, which supplies to the Russian market not only pallet packers, but also machines for strapping goods with polypropylene and polyethylene straps. Equipment from China is inferior to European equipment in terms of quality and level of technical solutions, however, it is sold at low prices, therefore it quite successfully competes with the products of European manufacturers, especially in Russia.
In our country, the most widespread are pallet wrappers made in Italy. The most popular is the equipment of those manufacturers who have their own dealers, agents, etc. in Russia. For example, Pakman is a Robopac dealer, Packaging Systems supplies SIAT products, Comarme products are represented by Soyuz-Pak.
In general, pallet packers of almost all, with rare exceptions, manufacturers have fundamentally the same design and arrangement of the main components, but significantly differ in details, which usually determines the choice of the buyer in favor of a particular model of a particular company. Almost all pallet wrappers consist of a turntable (table) on which a pallet is placed, and a column with a carriage placed on it with a roll of stretch film. Depending on the size of the pallet, the circle can be of different diameters, most often 1650 mm, optionally 1800 mm.
The column can also be manufactured for pallets of different heights – 2100 (standard), 2600, 3000 mm. The pallet can be placed on the table either with a forklift or with a hydraulic cart, and in this case the machine is supplied with a special ramp for entry. For the convenience of entry, pallet packers are also used, the table of which has a special cutout for the forks of a hydraulic cart. If the weight of the cargo is very small and there is a risk that the pallet will fall apart when pulled together by stretch film, then the pallet wrapper is equipped with a special unit – a pneumatic clamping device. Even before the rotation of the turntable begins, a special disk is lowered onto the pallet from above, which reliably fixes the position of its constituent packages and the shape.
In general, pallet packers, both within the line of models of the same manufacturer, as well as among different manufacturers, differ in the level of automation, productivity, the presence or absence of any functions. However, their main feature should be considered the ability to stretch the film to certain values (its relative elongation during winding can reach 400%).
The simplest pallet wrappers, such as Rotoplat Start, Siat Basic 001, Comarme Ronda 1000, are equipped with carriages capable of stretching the film up to 100%. The principle of operation of this type of carriage is based on simple braking (it can be either mechanical or electronic) of the movement of the stretch film. However, it should be noted that simultaneously with the stretching of the film, its narrowing occurs, and in this case the pallet has to be wrapped with several additional layers of stretch.
Another class of pallet wrappers is pre-stretching machines – the so-called pre-stretch. On such models, carriages are installed, equipped with special friction shafts that rotate at different speeds during machine operation. The film, passing through them, is stretched by the amount that is set from the control panel located on the machine column. Pallet packers, capable of stretching the film by 200% or more, can significantly save packaging material, because in this case, from just 1 meter of film in a roll, 3 meters of stretched are immediately obtained. The savings from using such a machine in enterprises with a large volume of packaging work are quite tangible and can amount to up to 4000 USD per year. It should be emphasized that when working on palletizers with this function, the film, while significantly stretching in length, does not narrow in width, since its stretching occurs due to a decrease in thickness.
There are many varieties of pallet wrappers. For example, on the basis of one of them, a machine is produced for wrapping doors, panels and other similar products simultaneously in two different types of film – air bubble (to prevent mechanical damage) and stretch. For this, four clamps and an additional carriage for air bubble wrap have been added to the machine.
Many companies (for example, Robopac, Siat) produce not only stationary, but also compact mobile palletizers powered by batteries. They are designed for wrapping heavy, bulky cargo or cargo, not
residually stable on the pallet. They are also convenient to use where packaging needs to be done in different parts of the warehouse or there is not enough space to move the pallet using a forklift. The principle of operation of mobile palletizers is as follows: the operator brings the packer to the pallet with the load, fixes the film to the base of the pallet, and then the machine automatically moves around the perimeter of the pallet, packing it in accordance with a given program. Mobile pallet packers are equipped with various film feed carriages, including those with preliminary stretching up to 220%.
Equipment is also manufactured in a special design, resistant to extreme environmental conditions and moisture, which is capable of operating at temperatures from –30 to +30 ° С. All electrical contacts, motors and conductive elements of these machines are protected by special materials, the body is made of stainless steel, and a thermostat is built into the control unit. If necessary, a scale can be built into the pallet wrapper table, in which case the pallet weight control can be carried out directly during the packing process, it will not take additional time.