Stretch-hood Film

At this moment the stretch wrapping foil is dominating the pallet packaging market. Stretch wrapping foil has to be turned under tension around the pallet. With the help of its memory, the foil tries to get back its original form. By doing this the pallet is being held together strongly. This type of pallet packaging can be done manually either machinally.

Another way of pallet packaging is using a shrink hood. Here a plastic hood with a size a bit larger than the pallet is sliced over the pallet. When done the foil needs to be heated in order to shrink. By shrinking the foil, the goods are strongly kept together onto the pallet. This type of packing can be done manually (but you still need a heater of course) either on fully automated lines.

Since more than 10 years a new type of pallet packaging has been developped. This new packaging technology was possible thanks to narrow cooperation between packaging machine constructors and polyolefin manufacturers. The result is a revolutionary packing way having the pallet packed hermetically, strongly, cheaply and fastly.

Next paragraphs describe principles of Stretch hood wrapping technology, compare with other types of wrapping and offer Bocedi wrapping machines. Era-pack, s.r.o. is exclusive sales representative of company Bocedi for Czech Republic.

Packing principles

Opening
Opening
Winding
Winding
Tension
Tension
Cover
Cover
Packed
Packed

When a pallet of goods is completed, it is moved to the stretch hood installation. This can be done either by roller conveyors or the pallet can be put directly on to the stretch hooder with a fork lift. Note that the pallet is put on a kind of piedestal. Thanks to this piedestal the machine will be able to cover the pallet with stretch hood foil until under the pallet which makes the pallet completely hermetic from the outside world !

Once positionned on the machine an electronic eye is measuring the height of the pallet. Some more sofisticated stretch hood lines are also looking at the dimensions of the pallet. In function of this information the machine will choose which stretch hood foil to use (in that case two foil formats are mounted on the line). Note that with one size of stretch hood foil you can pack several formats of pallets, but when they differ to much you need to use different foil sizes (e.g. for 600x800 mm and 1100x1300 mm pallets you should better use two formats of tubular stretch hood foil).

With all these dimensional informations the machine will roll of the needed length of the correct stretch hood foil. Once the length reached, the foil is sealed together and cut of the roll.

The foil has been rolled of on four mechanical arms. This process is very important because it influences a lot the end result of the packed pallet. When badly positioned on the arms, the stretch hood will show up wrinkles or it will not be put equally over the four sides of the pallet.

The mechanical arms are going down until under the pallet, by doing this the stretch hood is placed nicely over the pallet and from the moment that the stretch hood foil leaves the mechanical arms the foil comes back to its original format helding the pallet together! The smaller the original stretch hood size was, the higher the tension will be on to the pallet. For some applications a maximal tension is desired (eg. stone bricks), but for other applications this has to be avoided (eg too much tension on a tetra pak milk pallet could deform the boxes).

The job is done, the arms are going up again and the pallet can be taken of the stretch hood line, ready to be piled up in the warehouse and to be shipped safely all over the world!

Comparison between different packing systems

Stretch hood packaging technology means improved packaging quality! Pallets packed by stretch hoods are absolutely waterproof: the foil covers the entire pallet and goes until under the pallet. When using a plastic sheet on the pallet before piling up the goods, the pallet will even be waterproof from under to up the pallet!

With stretch wrapping foil you have only horizontal tension to keep the pallet together, with stretch hoods you have tension in both horizontal and vertical directions, this means that the goods are pressed downwards on to the pallet. Moreover the holding force on the goods is higher than with shrink hoods or stretch wrapping foil.

Stretch hood technology doesn't need an oven to be warmed. By consequence energy consumption is very low. This also means more safety on the workfloor and lower insurance fees due to lower fire risk!

The stretch hood foil has the advantage that it follows narrowly the form of the pallet. This is very important when you work with irregular pallets.

Stretch hoods don't stick to the goods piled on the pallet! With shrink hoods you could be confronted with melted plastic on the shrink foil underneath (example cans in shrinkfoil or plastic bags on pallet packed with a shrink hood). With stretch hoods this problem cannot occur!

Stretch hood technology has the opportunity of being very fast. With one single performant line you can easily pack more dan 150 pallets an hour!

With one foil size you can wrap different sizes of pallets! Their are certain limitations but with two dimensions you should be able to cover most of the standard pallet, going from half an europallet (600 x 800 cm) until a double europallet (1200 x 1600 cm).

The optical properties of the stretch hoods are much better. It's possible to produce film with an excellent transparancy and a very high brillance.

Foil consumption is lower with stretch hoods than with shrink hoods. Since stretch hoods are being used thinner and thinner it becomes even more economic as stretch wrapping foil! Using less materials for a same packaging is also more ecological!

Another interesting point of using stretch hoods are the low maintenance costs of the machine due to less moving parts and less heated parts than other packaging systems!

Comparison between different packaging systems

Property Stretch hood Shrink hoods Stretch foil
Holding strength Highest High High
Energy consumption Low High Low
Roll changes Fewest Few Many
Film consumption Low High Low
Optical properties Highest High Low
Manual wrapping No Yes Yes
Automated wrapping Yes Yes Yes
Water proof Yes Yes No
Packaging speed <200 pallets/h <100 pallets/h <100 pallets/h
Safety at packaging High Low High
Ability to recycle foil High High Low
Investment cost Medium High Low
Printability High High Low
Pallet diversity Medium Low High

Bocedi Stretch hood machines

Logo BocediMachine for extension of Stretch hood film. Hood is intended for all types of products, because it doesn't use neither flames nor hot air. This type of machine offers quality of packing by shrink film, protection from weather influences (water and dust) and uses elastic film. Bocedi offers two types of stretch hood machine. It can be modified according to customers needs.

FB1000

FB2000
Machine version with one film reel.

FB2000 Cartesiano

FB2000 Cartesiano
Machine version with one or more film reels.

fb1000.jpg

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