The shrink wrapper takes care of creating the bundle and the plasticized package: which usually contains the bottles or cans that are commonly found in the supermarket.
The machine works in two phases: The first deals with creating and enclosing the containers through a shrink film; The second, through an oven, is responsible for heating and consequently making the external plastic adhere to the contents.
How does it work – used Shrink Wrapper equipment for sale:
The shrink wrapper is one of the latest machines encountered in a bottling line: A part that is defined precisely as the end of the line.
It is placed immediately after all the phases that lead to having the product bottled and finished.
Once the bottle is finished, it is transported to a divider that creates two or more rows of bottles; this is in order to make them enter neatly inside the shrink wrapper.
At this point, the shrink wrapper wraps the bottles with a shrink film that can be printed or neutral.
After the wrapping phase, the bundle enters the final part of the shrink wrapper; this consists of an oven which, by means of the heat, makes the film adhere to the bottles. In this way, the classic “shop” packaging is created.
The only thing missing at this point before transporting it on the pallet is the handle; which is used to carry the water crates by hand, however, engaged by another machine, called handle applicator.
Where it is used:
The shrink wrapper is used in all those processes where a container needs to be packaged together, to facilitate transport.
In the collective imagination, the burden is associated with the classic pack of six or twelve bottles of water.
This is partly true, it is generally used to contain all those products that are then found in the store in bulk.
The person in charge of restocking the shelves in a store will unpack the package and place the products inside.
Differences in used shrink wrap equipment:
The main differences are made up of speed, which is defined as strokes or burdens per minute.
The entry into the machine from the last machine before the shrink wrapper, inline or at 90°.
If there is also the tray insert function, the possibility of inserting a cardboard tray inside the bundle.
This is to create support for the internal containers; as jars of mayonnaise, bottles of vinegar or something else.
A shrink wrapper is a machine that is used for the automatic packaging of products; the objects are packed in 'bundles' consisting of a variable number of units.
Generally, a shrink wrapper is equipped with a conveyor belt, along which the product units to be packaged run. The latter are first divided (in the number that will constitute the burden) and then are wrapped in a thin plastic film: That holds them together. In this phase, the bundle can also be made in the presence of rigid support: such as a tray or a flat pad and usually made of cardboard. This will be part of the final product to be delivered.
Some models are also equipped with separation gates – pneumatically or electrically operated: These serve to separate the product units intended to be packed in a single bundle.
Some technical specifications:
Most shrink wrappers work using an LDPE film, which is a low-density polyethene film. This is unwound alternately by two reels, usually placed under the conveyor belt and driven by a motorized unwinder.
When one of the two reels is about to finish, the film will do the following action: Slows down and warns the operator that must intervene: this by cutting the film being processed and then sealing it with the film of the other reel. The junction between the two coils can also take place automatically.
In order for the film to adhere perfectly to the objects, ensuring the integrity of the bundle, everything is done as follows: passed in an oven, to carry out the film 'shrinking' process.
The ovens for the hot air shrinking of the film also called shrink tunnels, have the following function: Shrinking the plastic film coming out of the shrink wrappers makes the film adhere to the product. The ovens are equipped with electrical resistances: these heat the air and fans to cool the film when it has been heat-shrunk.
Once this step has also been completed, the bundle is ready to be sent to a second packaging or to palletization.
The shrink wrappers differ mainly in the production speed:
The shrink wrappers with the lowest production speeds (maximum 25 bundles/min) are those called with sealing bar.
The film is positioned perpendicular to the flow of the package. When the package crosses the film, the sealing bar is activated and seals the film that goes around the package: This, once wrapped in the film, stops to ensure that it can be sealed.
A cutting blade placed between the sealing items separates the film around the pack from the film that will be used for subsequent packs.
The shrink wrappers that reach the highest production speeds are those called film launchers.
One-two-three-lane shrink wrappers with speeds up to 200 packs/minute for every single lane are available.
The film is wrapped around the package, which runs along the conveyor belt without ever stopping, by bars dragged by chains. The film is wrapped around the package with an overlap of 5-8 cm below the package: This is self-glued as it passes through the shrink tunnel.
Therefore, these machines do not require a sealing bar.
To work correctly and continuously, the shrink wrappers must be equipped with antistatic bars.
Which type of materials do these use?
Neutral materials, when processed at high speeds, polarize positively or negatively due to friction, generating an accumulation of electrostatic energy.
Electrostatic charges are the cause of several problems encountered by companies during production:
- interruptions in processing
- electric shocks to operators
- worsening of product quality.
Antistatic bars are devices that neutralize static electricity while the machine works at full capacity and, consequently, eliminate all the problems that their presence causes to the machinery, material and processing.
The procedure is electrochemical: it consists in ionizing the air surrounding the electrically charged point of the machine. Therefore, to eliminate the charges, the ionizing bars must be mounted in the area where they are formed.
The single or coextruded LDPE shrink film is suitable for use on automatic or semi-automatic shrink wrappers.
With the use of flexographic printing systems, it can be printed up to 10 colours, guaranteeing excellent results in terms of graphics and print quality.
The shrink film guarantees a perfect adaptation to the product, ensuring a very stable packaging.
The possibility of working with neutral or printed film, customizing the company logo.
Famous brands of used shrink wrap equipment:
For the shrink wrappers, we can find among the most prestigious brands.
Zmbelli, Dimac, Krones, Ocme, Smi Group.