Heat-sealing film is often a more appropriate solution than cold-sealing – if only the processing aspect were less demanding. For an airtight flowpack with a high-quality seal seam, three factors need to remain constant during the sealing process: temperature, pressure and time. Furthermore, not every product can withstand the heat, which significantly limits flexibility in the packaging process. This is a clear case for new creative ideas from Schubert.
Heat-sealing has a number of advantages: heat-sealing film is cost-effective, can be stored for long periods of time and leaves no unpleasant adhesive residue behind when the packaging is opened. But how can Schubert customers benefit from these advantages? This was our incentive to produce a new heat-sealing technology.
The first challenge – heat-sensitive products such as chocolate, which can be damaged on the longitudinal sealing unit – was solved by Schubert using ultrasonic sealing technology. This means that unlike standard heat-sealing technology, the heat is generated in the heat-sealing film itself and does not dissipate into the tools and machine parts. The product therefore remains flawless during longitudinal sealing. Ultrasonic technology also ensures that the seal quality remains the same at differing machine speeds. The fixed-mounted cross-sealing unit presents a greater obstacle: the faster the products are channelled into the cross-sealing unit, the shorter the sealing time, and vice versa. Markus Riek, Flowmodul Team Leader, explains: “The challenge was clear: the speed of the chain is variable. How can we keep the sealing time constant?”
The key was to break the rigid mechanical link between the chain and the cross-sealing unit, and to design a mobile unit. When the speed of the chain changes, the unit moves either in the running direction or in the opposite direction, allowing each individual flowpack to have the same sealing time. Company founder Gerhard Schubert was immediately impressed and brought in his own ideas: “This needs to be made into a robot.” The flying cross-sealing unit was born.
The new technology makes it possible to program sealing to the millisecond and ensures constant sealing times. This is because, for each flowpack, the cross-sealing unit immediately adapts to the variable speed of our upstream pick & place robots. Like all of Schubert’s sealing technologies, the flying cross-sealing unit can be integrated into every Flowmodul and combined with other sealing technologies.
- There are 36 Flowmodul units in use, of which four feature flying cross-sealing technology and eight have ultrasonic sealing technology. Three more have been ordered.
- They are used to package biscuits, chocolate, marzipan, pancakes and French toast, as well as BFS products from the pharmaceutical industry and many other products.
- The output is up to 500 packs per minute with a maximum chain speed of 60 metres per minute.