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How to Choose the Right Stretch Film for Packaging?

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  • How to Choose the Right Stretch Film for Packaging?

    Stretch film is an essential packaging thanks to its versatility: it is used to film pallets and cartons to keep them in place and protect them for shipping but also to film food to preserve them. as long as possible. Of course, there are two different types of stretch film: the first being particularly strong and the second being treated for safe contact with food.

    SUMMARY

    The different models of stretch film
    Two different manufacturing processes
    1) Blown extrusion
    2) Cast extrusion
    Manual stretch film or film machine?
    1) Manual stretch film
    2) The machine stretch film
    3) How to know which stretch film to choose?
    For which thickness to choose?
    1) The weight
    2) The salient angles
    3) The homogeneity of the load


    The different models of stretch film
    There are several models of stretch film to satisfy all the requirements:

    the transparent film , the classic model for film pallets;
    the black opaque stretch film to hide the contents of the pallet and thus to avoid it being stolen;
    the opaque white plastic wrap , perfect to protect sensitive products in the light;
    the pallet cap , specially designed to cover the top of the pallet and thus prevent dust and moisture infiltration.
    However, the stretch film is also used in the agri-food sector, especially to cover foods that need to be kept cool. Generally called " food film ", this model is specially designed for food contact (no plastic particles come into contact with the food covered).

    Two different manufacturing processes
    There are two different manufacturing processes for stretch film: blown extrusion and cast extrusion. What is the difference ?

    1) Blown extrusion
    This method uses blowing to obtain a tubular shape : the plastic granules, usually made of polyethylene just like ethafoam wellpackeurope.com/ethafoam-stratocell-white-planks-grey-foam-polyethylene-closed-cell-foam, are placed in the machine and are heated. Then, the hot air produces a tubular shape that is cut and coiled after cooling.

    The main advantage of this method is that the stretch film is bi-oriented , its mechanical strength has been worked in the direction of the length and transversely. Therefore, it is very strong and resistant especially with regard to sharp edges (it resists very well to tears).

    In addition, the blown stretch film marks a big difference between its tacky face and its slippery face . You can not go wrong with palletizing! It is particularly effective for conditioning in cold and dusty conditions . It is also suitable for long-term storage.

    2) Cast extrusion
    This extrusion method uses polyethylene granulates: they are first melted then they are cast in line before being rolled on a flat die. The main advantage of stretch film "cast" is that it is very pre-stretch : up to 300%! It is also multilayer and has several thicknesses ranging from 10 to 80 μ (microns) . It is to be used for the conditioning of loads with angles not or not very prominent whatever their weight.


    Manual stretch film or film machine?
    The first question one can ask when choosing stretch film is: Will I film manually or with a machine? This question is important because it allows you to identify your equipment needs. In addition, manual stretch film and machine stretch film do not have the same characteristics.

    1) Manual stretch film
    The manual stretch film is recommended for relatively low use : less than 15 pallets or packages to be filmed per day. In addition, these packages and pallets must be relatively light .

    2) The machine stretch film
    The stretch film machine is preferable if you have to film all types of loads all day long : the wrapping machines will help you stretch the film and place it on the pallet or package. These machines are also very useful for conditioning very heavy loads .

    3) How to know which stretch film to choose?
    Well, simply by calculating the number of shipments you make each day:

    if you make less than 15 pallets a day , you can use manual stretch film ;
    if you make more than 15 pallets a day , it is strongly recommended to use machine stretch film ;
    and if you go beyond 50 pallets a day , maybe it makes more sense to use pre-stretch machine film .
    transparent stretch film

    For which thickness to choose?
    To choose the thickness of the stretch film, three criteria must be taken into account:

    the weight of the pallet,
    the presence of salient angles or not,
    the fact that the load is homogeneous or not.
    1) The weight
    The heavier the load, the greater the thickness of the stretch film. So for a palette of:

    - 250 kg: you need stretch film of 15 microns ;
    250 to 400 kg: you need stretch film of 17 microns ;
    400 to 600 kg: you need 20 micron stretch film ;
    + 600 kg: You need stretch film 23 microns or 30 microns .
    2) The salient angles
    As it was written above, it is best to use stretch wrap when a load has sharp angles. And so, the more this load has very sharp angles that are likely to pierce the stretch film, the thicker it is necessary for this film to cope with this risk of tearing.

    3) The homogeneity of the load
    As before, it is recommended to use blown stretch film to maintain a non-homogeneous load. You must also pay attention to its thickness which must be greater if the load is not at all homogeneous.
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