Film Stretching Machines - up-to-date with custom-made systems Photo and X-ray films, graphic films, electric insulation, special film for technical applications, condenser films, packaging films and audio and video as well as computer tapes … All these materials represent DORNIER technology.
DORNIER has supplied about a third of all film stretching machines installed around the world. The Lindauer DORNIER GmbH has developed and manufactured film stretching machines since 1955. These machines, usually built to customers’ requirements, are integrated into film production lines.
DORNIER also supplies complete production lines. The manufacturing program includes chill roll units, longitudinal stretching machines, transverse stretching and heat setting machines, post stretchers, take-up devices and transfer sections as well as extrusion systems and nowadays more and more complete lines. Other components for completion of production lines, such as winders and slitters, are procured from other suppliers. Most DORNIER film stretching machines are supplied for the production of polyester and polypropylene film. Other applications include the processing of PA, PVC, PE, PS, cross-linked material, PETG and PEN plus other thermoplastic materials. For the manufacture of geotextiles and biaxially oriented nets as used for road or rail construction, DORNIER stretching equipment is also in operation. The individual layout of the production ranges changes with application, and machine specifi-cations can vary considerably. However, all the machines without exception have one thing in common: a high quality standard combined with an outstanding reliability. DORNIER extrusion systems are available as single extruder with melt pump or as cascade extrusion system and all of those extruders are very constant with respect to output and temperature uniformity. The extruders to be combined with filters, melt pump, melt pipes and a die plus control equipment, etc. to form an extrusion system.
From the extrusion system the hot melt is cast on the chill roll to form a sheet. In case of polypropylene production the casting drum normally is arranged in a water bath. For polyester film production, however, no water bath is used. After controlled cooling the primary film passes through the longitudinal stretching machine, where the film is stretched in machine direction by several groups of driven rollers, which are running at different speeds.
In the following transverse stretching machine the film is gripped with clips at both edges and stretched in width at a given temperature. Cross loads up to 3500 N per clip can occur. Material and mechanism have to withstand temperatures in the range of 100 to 280 °C at production speeds between 100 and 500 m/min according to output and film thickness. After the film has been oriented in both directions, the stretched film is guided from the TDO by a take-up system to the winder. In this area the film temperature will be lowered and the edges are cut off. At the same time the thickness uniformity is checked and the results of this measurement control the die in front of the casting system. The film finally will be wound on cores with a length up to 50 km, which later on is slit in a rewind and slitting machine.
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