Sealing technologies in the Schubert Flowpacker

Flowpack sealing systems with guaranteed flexibility

The flow-wrapping machine from Schubert with a flying cross-sealing unit that packs eye drops into flowpacks.

Sealing systems for all flowpack films

Future-proof thanks to flowpack sealing

Manufacturers who pack their products into flowpacks are facing a trend towards more sustainable packaging materials, as is the entire packaging industry. Even if impermeability and other barrier functions of flowpack films cannot be easily achieved with every material, new variants such as mono films or paper-based films are already being used in addition to the classic composite films for heat-sealing and cold-sealing. Due to their material composition, however, the new films usually require extremely gentle sealing. Those who want to ideally position themselves for the future with sustainable packaging materials need appropriate sealing systems for their flowpacks. Optimum flexibility is offered by flow-wrapping machines which are able to seal the proven composite films as well as the latest, more sensitive flowpack films and to switch quickly between the two sealing systems.

This flexibility is already integrated into the Flowpacker, Schubert’s flow-wrapping machine, thanks to its variable sealing system. The technology combines the ultrasonic method for longitudinal sealing with cross-sealing, whose sealing time can be adjusted exactly to a constant value thanks to the flying cross-sealing unit. The advantage is that both longitudinal sealing processes are very gentle, and are not only suitable for heat-sensitive products but also for sustainable flowpack films. This is because with ultrasonic technology, the film is only heated where it is necessary for sealing. Sealing with ceramic heating elements is similarly gentle, because they enable a precise and controlled supply of heat, both in terms of temperature and duration. With cross-sealing, the constant sealing times ensure a consistently high sealing quality, regardless of production fluctuations. The unique sealing system is suitable for all types of heat-sealing films. Manufacturers benefit in several ways: greater freedom in the choice of their flowpack films, higher quality in the finished packaging and enhanced future prospects on the market.  

Advantages of the flowpack sealing systems

Flexible packaging materials and high-quality sealing

A flow-wrapping machine from Schubert with flexible sealing systems in the general view.

The flexibility advantage

  • Heat-sealing by means of ceramic heating elements, cold-sealing and ultrasonic sealing
  • Fast changeover between heat-sealing by means of ceramic heating elements and cold-sealing in a flow-wrapping machine
  • Fast changeover between ultrasonic sealing and cold-sealing in a flow-wrapping machine
  • All flowpack films, including mono films and paper-based films
  • Same forming shoulder for mono films and paper-based films, no change necessary
  • Fast changeover between conventional and sustainable flowpack films
A flowpack made of paper-based film, sealed with a Schubert sealing system.

The quality advantage

  • Specially adapted forming shoulders for all flowpack films
  • High sealing quality thanks to unique sealing systems
  • Precisely selectable, constant sealing times for cross-sealing
  • Consistent sealing quality even with fluctuating product feed
  • Gentle sealing systems for sensitive products

Advantage: Specially developed forming shoulders

Individual forming shoulders for each flowpack film

The two-part forming shoulders in Schubert’s flow-wrapping machines are developed individually for different film types and materials. They form the film strip into a perfect tube without tearing, creasing or wrinkling, therefore enabling optimum sealing. Schubert offers forming shoulders for all proven cold- and heat-sealing films as well as for new, sustainable flowpack films made of mono-material or paper-based material. The simple manual change of forming shoulders, if at all necessary, allows a quick changeover between film types.  

Advantage: The flying cross-sealing unit

Unique cross-sealing thanks to constant sealing times

Schubert’s flying cross-sealing unit is the only one that allows complete control over the duration of the sealing process during cross-sealing. This is because the sealing time for heat-sealing can be selected to the nearest millisecond and always remains constant during sealing. The sealing unit compensates for fluctuating production speeds by moving with or towards each flowpack on the belt as required, and can therefore react to different film speeds. If a cold-sealing film is to be processed in the same flow-wrapping machine, the flying cross-sealing unit is locked in position by selecting the other machine program.  

Advantage: Longitudinal sealing with ultrasound

Gentle flowpack sealing system for sensitive products and films

With ultrasound sealing, heat-sensitive and sensitive products can be packaged extremely gently in the flow-wrapping machine from Schubert. This sealing system in the Flowpacker combines an ultrasonic sealing unit for longitudinal sealing and a flying cross-sealing unit with precisely programmable sealing time. This reliably and continuously reduces the heat development during sealing to a minimum for both sealing seams. The ultrasound sealing system is also an optimal process for sustainable flowpack films such as mono films or paper-based films that are sensitive to excessive heat.  

Advantage: Longitudinal sealing with ceramic heating elements

Precisely controllable sealing technology for sustainable films and sensitive products

As an alternative to the ultrasonic process, which is somewhat sensitive to external conditions during sealing, Schubert uses specially developed ceramic heating elements for longitudinal sealing. The 5 x 5 millimetre ceramic elements can be controlled individually, heat up very quickly and, above all, cool down again within a very short time. This enables the heat input at the seam to be controlled at every point, both in terms of temperature and time. In combination with the flying cross-sealing unit, the Flowpacker therefore offers an extremely flexible and gentle sealing system that is ideal for sustainable films and sensitive products.  

Flowpack sealing systems with Flowpackers from Schubert

Ein modular erweiterbarer 3D-Scanner des Vision-Systems von Schubert im unverbauten Zustand.

Sealing unit for longitudinal sealing

For longitudinal sealing, three sealing methods are possible on Schubert’s flow-wrapping machine: Cold-sealing and the two extremely gentle variants with ceramic heating elements or ultrasound. Four pairs of rollers work in the sealing unit. The first pair provides the necessary tensile force when forming the film into a tube and can be tilted to influence the tube size. The second pair is used for preheating during heat-sealing or, if desired, for slightly heating a cold-sealing film. The third pair performs heat-sealing or remains switched off during cold-sealing, and the fourth pair folds the fin of the sealing seam. If required, the ultrasonic unit is integrated between the second and third pair of rollers. 

Sealing unit for cross-sealing

The cross-sealing unit in the Flowpacker allows two sealing methods. These include cold-sealing with a rigid or fixed sealing unit and the heat-sealing variant with a flying cross-sealing unit and constant sealing times. The flying cross-sealing unit is programmed for a certain sealing time and adapts itself individually to the product flow by short or long counter-travel or travel with each flowpack. This way, the movable sealing unit always ensures constant sealing times and gentle heat-sealing. For longitudinal sealing, the flying cross-sealing unit is combined either with ceramic heating elements or an ultrasonic unit. 

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Stefan Horvath

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