Shakehand between Stretching and Shrinking

by Dr.-Ing. Holger Lieberwirth,

Managing Director, Sales and Marketing

BEUMER Maschinenfabrik GmbH & Co. KG

In the field of load securing and protection of palletized goods the stretch hood systems increasingly gain in importance worldwide.

Whereas this technology already has gained a wide spread in Europe and is used for packaging of different product stacks in the meantime - beginning with palletized cement bags and not ending with refrigerators and other products (Fig. 1: Washing machine packed by BEUMER stretch hood®), the use of this technology only is at the beginning of a corresponding spread in many countries of Asia and America.

However, the declaration of intent of the various film manufacturers shows that also in this field it can be reckoned with an increasingly utilization of the stretch hood system.

The stretch hood systems show a large number of fundamental advantages towards other packaging systems such as shrink hoods or stretch wrapping systems. Among other things the following advantages can be mentioned:

• low film consumption,

• low energy consumption and therefore special environmental friendliness (no open flame, no exhaust gas, low noise level and so on),

• tension force acting on five sides by biaxial stretch, both, in horizontal and vertical direction,

• water-proof and dust-proof stacks,

• no lamination between film hood and packaged good,

• excellent display impact by flat surface.

Due to these advantages the system increasingly gains the interest of the different manufacturers. In case of corresponding dimensioning of the parameters „welding seam length“, „biaxial stretch“ and „base stretch“ in relation to the package dimensions and for formatting of the gusseted film tube (please also refer to the patents EP 0 344 815, EP 0 399 540 (Fig. 2: Load securing by base stretch)) and EP 0 633 186 of the BEUMER company, there are optimal packaging results, marked by fold-free packaging, flat cover as well as sufficient vertical tension in the hood for the fixation of the product on the pallet.

However, if the products are rather variable from pallet to pallet with regard to their sizes, it can be reasonable to use a stretch hood machine with a special head which makes it possible to switch over between several gusseted film tubes in a variable way and therefore, the products possessing different sizes can be packaged with the corresponding formatted stretch hoods, in order to achieve a good packaging result.

However, due to the combination of surface tension and formatting of the hood it can also be the case that there are package formats in the transition sizes in the area of the film cover which are not placed at the packaging in a flat way. These areas can possibly lead to problems concerning the products having the possiblity of being put in a highrack warehouse and have to be avoided.

If the possibilities of manufacturing of a flat film cover by means of formatting of the film and the length of the welding seam are completely exhausted, the selective aimed utilization of warmth remains the further option. Corresponding trials have shown that with low utilization of warmth in the problematic zone it is possible to achieve optimal packaging results with formfitting packaging also for these product stacks (Fig. 3: Tiles with stretch hood® packaging).

By means of these basic approaches it should be possible to open the market also for industry branches which up to now dispose of the possibility to use the stretch hood installations only to limited extent for the advantageous utilization of stretch hood installations.

Further investigations concerning the questions resulting from this, especially concerning a possible necessary optimization of the film for comparable cases of application, still have to be effected.

For more information, plase visit:

https://edir.bulk-online.com/oldedirredirect/201732.htm

Fig. 1: Washing machine packed by BEUMER stretch hood®

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