For many years, Windmöller & Hölscher (W&H) has been known to converters in the flexible packaging market as a supplier of complete blown film lines. Less known may be the fact that the company also utilises its expertise in order to retrofit older W&H blown film lines as well as other makes of blown film equipment with modern components and modules from its current product range. The focus of W&H‘s retrofit program is on increasing output rates, improving film quality, enhancing the efficiency through increased effective up-time, extending the flexibility and reducing waste as well as material usage. Retrofit solutions offered for these purposes range from resin supply to controlled gravimetric metering, plasticising units, different dies, sizing cages and haul-offs and also encompasses the winder and the entire process automation concept.
It does not always take a complete new installation in order to increase the performance capacity of film production. Frequently, it only takes the addition or replacement of individual components that may present a bottleneck inhibiting maximum output. Just by way of example, effective cooling of the bubble is an essential requirement for optimum output rates. Hendrik Steen, Head of Module management at W&H, puts it as follows: “Experience has shown that, depending upon product specifications, incorporating our modern MULTICOOL air ring not only results in an up to 30 per cent increase in output, but also significantly improves film tolerances. And even an only 10 per cent increase in production, considering an average output of in the order of 450 kg/h, would already result in about 330.000 kg of extra film produced per year.”
But there are other positive aspects to a new air ring than just output, including, e.g., significantly improved film tolerances leading to greater consistency and smoothness of running of the downstream converting equipment which, in turn, results in reduced scrap rates. Customers who have opted for output and quality enhancing retrofit solutions are even more amazed seeing a return on their investment within only a few weeks’ time. “Once the retrofit is incorporated, a notably increased profit contribution of the upgraded blown film line will become apparent already during the first months”, says Hendrik Steen.
Improved film quality is attributable to the perfectly homogeneous air distribution achieved by the MULTICOOL ring, which is also a prerequisite for consistent high cooling efficiency and resulting higher outputs. Increased flexibility is another advantage of the MULTICOOL. It just takes a few turns of the hand to replace a single-lip with a duallip or the special HDPE air ring insert. Flexibility also applies to different die diameters and die designs and is a requirement for retrofitting not only W&H systems but also other makes, including rotary dies.
One focus of W&H R&D activities is on the greatest possible modularity of new engineering concepts to allow for individual line configurations not only in case of new installations but also for retrofits. To stay with the example of the MULTICOOL air ring, customers would have the choice of upgrading this retrofit component to a controlled air ring whenever this is desired or needed at a later date“, explains Hendrik Steen. The basis for trouble-free upgrading from a single air ring to a unit with gauge profile control or to a double deck ring for doubling the output is a unique W&H design concept. For gauge profile control, W&H‘s patented OPTIFIL P3 or P3K system is used.
The major advantage derived from retrofitting a single air ring with an OPTIFIL P2K gauge profile controller is that the already improved gauge tolerances provided by the air ring itself can be improved still further. This system, for which W&H is holding a patent, uses heating cartridges in the MULTICOOL air ring, which will heat local gauge bands or thick spots and equalise them as they occur, resulting in the tightest possible gauge tolerances. The system dispenses with any failprone electronics and easily soiled mechanical components, which makes it particularly robust and safe to operate.
The advantages of OPTIFIL P2K are:
– Saleable production shortly after start-up or change-overs.
– Consistently tight gauge tolerances from start to end of production.
– High commercial efficiency through resin savings.
– Significant increase in output.
– Easy to retrofit to all die types (W&H and other makes), including stationary and oscillating.
– Service-friendly technology.
The delivery scope of the MULTICOOL air ring with OPTIFIL P2K encompasses the gauge measurement module, also available as a special design for sticky films, an oscillating assembly, a PROCONTROL TS operator console and the appropriate wiring.