Suppliers of premium brands in particular attach great importance to absolutely high-quality, crease-free containers. The advertising space for the company logo should be as smooth as possible, the fine colour nuances of the print should be brilliant, the foil eyes should be even, the pack should be square and the barcode clearly legible. The new modular tunnel from Krones offers a solution.
The requirements for film packaging for beverages have changed radically over the years. Beverage manufacturers demand the perfect container, „the perfect pack“. Similarly, the demands on shrinking technology have increased significantly over the last few years. Krones is supporting these demands with the new development of a Shrink tunnels in the Variopac Pro packaging machine.
Greater variability
Just a few years ago, film thicknesses of 60 to 80, sometimes even 100 µm were the norm. Transparent LDPE and HDPE material was predominantly used. Today, the process width has increased dramatically, with thicknesses ranging from 25 to 120 µm, and printed material is predominantly produced from LDPE, LLDPE, MDPE and HDPE. The reduction in thickness and therefore costs goes hand in hand with increasing quality requirements for the containers and high processing cycle rates.
What will the perfect container of the future look like? With the Modular principle and the flexible construction Krones is already providing an answer to the more stringent requirements of the coming years to produce an almost crease-free and symmetrical pack with almost any film quality.
Knowing physical limits
The film and film properties, the properties of the containers and packs, the environmental conditions and, of course, the shrink tunnel all have an influence on the shrink process. Depending on the film and container geometry, the degree of demand may reach its physical limits.
The specifications of the various films, the theoretical principles of shrinkage behaviour and the process behaviour of a flexible modular construction were therefore taken into account during development. These aspects are crucial in order to ultimately achieve the perfect result.
Previously, the Krones shrink tunnel offered two different module lengths. The new modular system is reduced to one module length of only 2,250 mm for the standard heating module. This module can be duplicated and a Reheating module can be extended to shrink the film. Instead of the previous four variants, the modular shrink tunnel system now offers five variants, from 2,250 to 6,750 mm in length. This makes it possible to respond to every performance requirement.
Shaft wall technology modified
The shrink tunnel works with the so-called shaft wall technology, which enables an improved shrinking result. The shaft walls are infinitely adjustable to the product width.
The new design of the V-shaped shaft walls offers additional advantages and contributes to further optimisation of the shrinking result. The shaft wall tapers downwards so that the flow around the container is kept homogeneous and an optimum, virtually crease-free shrink result is achieved. But even this further development has been further improved in the new tunnel.
The new V-shaft wall now allows for an even More even jetting of the shrink film. This enables a more homogeneous and process-enhancing heat transfer, which has a direct positive effect on the formation of creases, the shape of the film eyes and the overall shrinking result.
Fully automatic adjustment
The new tunnel also no longer has any external adjustment points. Previously, adjustments were made through the tunnel wall to the outside in order to position the shaft walls manually.
In the new tunnel, a Fully automatic adjustment of the shaft walls at the inlet and outlet. This increases the Reproducibility of the setting after product changeovers and makes it independent of the manual precision of the operator.
The changeover time is also reduced. As a rule, a Variopac-Pro an average of 20 different fittings. Every standstill means dead time. Automatic adjustment minimises this. In addition, the new technology of fully automatic shaft wall adjustment eliminates the thermal bridges that are inevitably caused by every feed-through through the outer wall. The insulation is now continuous.
A new container cooling system was also integrated at the outlet of the tunnel. A powerful, adjustable, flat air curtain ensures that the pack is evenly supplied with air from top to bottom and cools quickly before it is transferred to the pack conveyor. Additional container cooling from below is possible as an option.
Further development and optimisation
In the course of the Variopac tray/shrink packer's success story, Krones has repeatedly adapted the features to the increasing customer expectations and tried to anticipate them. The first machine in the high-performance series was launched in 1995, replaced in 1999 by the introduction of the Variopac generation in single-lane design and later extended by two-, three- and four-lane processing with outputs of up to 500 packs per minute.
Following a redesign in 2004 and 2005, the Variopac was upgraded to the Variopac-Pro in 2007. In 2010, the wrap-around packaging machine Wrapapac was merged with the Variopac-Pro with the introduction of the Variopac-Pro modular one-way packer system.
Today, with the new shrink tunnel, Krones offers the answer to the demand for the container of the future for the highest requirements.
