New high-performance 7-layer line for barrier films in KUHNE laboratory

There is an increasing demand on the plastics market for machinery which can produce barrier films. The packaging produced – particularly in the food industry – enables the achievement of a considerably longer shelf life (i.e. the period of time in which the product can be sold as fresh). A continually growing area is the use of coffee and tea capsules, a segment in which KUHNE has sold numerous lines in recent years, and the same applies to meat and cheese packaging.

KUHNE Maschinenbau has been providing an optimum and, simultaneously, continually improving line solution in this segment for almost two decades. A new 7-layer barrier line is now demonstrated to enthusiastic customers in company's own laboratory

KU7 lamella feedblock

The following are a few of its special features:
•    A gravimetric dosing system enables precision weighing / dosing in even the smallest quantities, particularly where expensive raw materials such as EVOH are involved.
•    A PP output of more than 1,200 kg/h is achieved with a total of 5 extruders. The two high-speed main extruders with diameters of 70 and 60 take on the lion‘s share of the work in this respect. Both of these are equipped with water-cooled torque drives which have in the meantime proven their effectiveness hundreds of times over. It goes without saying that only familiar types from partners such as Oswald, Elin, Siemens or Baumüller are used here. The extruder cylinders are bimetallic, while the screws (in-house products) are specially hardened. A further model with a diameter of 60 and two smaller extruders round off the range.
•    The equipping of all extruders with melt pumps is a further highlight. The constant speed of the pumps ensures uniform application of the respective layer at all times. This leads to improvements in the production process and, consequently, a reduction in reject quotas. Furthermore, raw materials can be saved and layer thicknesses adapted to suit respective requirements.
•    The patented KU7 feedblock has proven its value many times over. It ensures the optimum distribution of layers over the complete working width. Expensive EVOH is applied in exactly the desired thickness, and an option is also available to apply less EVOH to the edges of the film where cutting or deep drawing is planned by closing the lamellas. This achieves clear financial savings.
•    The thickness measurement and control unit supplied by SBI works capacitively. The system reacts automatically through an attachment on the KUHNE flat sheet die to deviations from the specified thickness tolerance. The desired tolerance can be achieved rapidly again through temperature application or removal (i.e. heating or cooling) on the affected position. A further new innovation is the ability of the unit to now also identify and measure the EVOH layer independently in the case of translucent films (i.e. films with very little or no colouring).
•    The KUHNE Smart Sheets® roll stack has an overall width of 1,200 mm and a roll diameter of 300 mm. This means that net film widths of up to 800 mm can be produced for thermoforming applications. However, what really makes this design a high-performance film cooling line are the 9 additional cooling rollers downstream of the actual roll stack. Four of these are positioned on top, the other five on the bottom. With a diameter of 150 mm each and individual water cooling, the film can be uniformly treated on both sides. All post-cooling rollers are, naturally enough, motor powered. Five heating and cooling units are employed for a total of 12 rollers.
•    In addition to equipment such as an edge cutting unit and associated grinder and a conveyor, KUHNE also unveils its new FP 508 winder in this line. The winder, which is a completely in-house development and construction, can be operated in contact, gap or central mode and enables the achievement of a line speed of up to 150 m/min. Simultaneously, an accumulator can be dispensed with. Thin films in particularly such as those used for lids can be wound rapidly without any problems in this manner, and space is also saved. Several of these winders have been successfully installed recently for European customers.