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The film stretching lines

Built for the times and the customer

Lindauer DORNIER GmbH has been developing and producing film stretching lines since 1955. Today, they represent about a third of all film stretching lines installed worldwide. Film stretching lines are designed for specific applications, so the machinery equipment can sometimes vary widely. But all DORNIER machines and systems have two features in common: exceptional quality and reliability.

DORNIER polyester systems

Function of a film stretching line and product examples

In order to produce film, plastic granules (polymers) must first be melted. A die dispenses the molten plastic onto a chill roll, where it cools to form the raw film. This film is then stretched lengthwise, and also transversely to the film web by clips which grasp and guide it. The film must be heated and cooled again for the stretching process.

DORNIER film stretching lines are mostly used to manufacture polyester and polypropylene films, but also for stretching polyamide, polystyrene, PVC, crosslinked polyethylene, PEN and other thermoplastic materials.

DORNIER polypropylene systems

Examples of film products produced on lines by DORNIER: Films for mobile phone, tablet and flat-screen displays, photographic  and X-ray films, graphic films, electro-insulation and special films for technical applications, capacitor and battery films, packaging films for foodstuffs and hygiene products as well as geogrids and biaxially oriented meshes for road and rail construction.




Lindauer DORNIER GmbH
Rickenbacher Str. 119
88131 Lindau, Germany

Telephone:   +49 8382 703 1225
Telefax:        +49 8382 703 17225


Telephone:   +49 8382 703 1932
Telefax:        +49 8382 703 17932


Download the Film stretching lines brochure here.

Film stretching lines brochure

"Made in Germany": Film stretching lines by DORNIER

All DORNIER film stretching lines and their components are produced and preassembled at the Esseratsweiler production site on the shores of Lake Constance, with a 90 % vertical range of production.

The production program includes not only complete lines but also components thereof such as extruders, casting units, longitudinal and transverse stretching machines and heat setting machines, post-stretching longitudinal stretching machines, transfer and take-up devices. Downstream equipment like winders, cutters and drive and control systems are purchased from well-known machine producers.


Extrusion Systems

DORNIER supplies extruders for producing polyester, polypropylene and polyamide films in various sizes. The extruders can be configured as single or cascade extrusion system and all are notable for constant polymer throughput and excellent temperature uniformity of the polymer.

The extruders are available with electro or oil heating as single extruders or complete systems combined with melt pumps, melt pipes, dies and filter systems.Melt filters are available as single, double or continuous filters in electrically or oil-heated variants. The filter inserts for filter cartridges or filter discs are also available in various sizes and throughputs.

For high production outputs and fast product changes for the film outer layers, DORNIER also offers twin screw extruders as main or co-extruders.

Casting systems

DORNIER casting systems are built extremely rigid and designed correspondingly very robust. For optimized film production, they can be displaced horizontally and vertically. They will be equipped with a water bath for producing polypropylene films.

The drive system is notable for excellent accuracy. Flexible options such as a second chill roll or additional take-up and deflection rolls are also possible. After the casting system, the first film thickness gauge for checking and controlling the profile is arranged.

To prevent any vibration or oscillation of the casting system from being transferred to the pinning system or the extrusion die, those machine parts are placed on individual stands. The following pinning systems are available as air knives, wire or band pinning systems.

Longitudinal Stretching Machines

A longitudinal stretching machine typically consists of preheating, stretching and cooling rolls. In the preheating area, the film is heated up to the desired temperature by rolls, which are heated with thermo oil, hot water or steam. Infrared radiators are installed in the stretching area for polyester as an additional heat source.

A variety of stretching gaps is possible depending on the final film application. Single gap, multi-gap stretching, hot stretching and omega stretching gaps are available.

All DORNIER longitudinal stretching machines are designed to be hard-wearing and easy to maintain. The rolls can be replaced quickly; they do not need to be aligned again. All rolls are driven separately and the film stretching can be controlled extremely precisely.

Upon request, longitudinal stretching machines can also be supplied with a housing.

Transverse Stretching and Crystallizing Machines

Transverse stretching and crystallizing machines from DORNIER are well known for solid, maintenance-friendly construction and are designed with an excellent airing system. They are requested as single components and are ideal for producing films with productions speeds up to 600 m/min.

All DORNIER transverse stretching and crystallizing machines are equipped with a monorail clip guiding system. This system guides the film from the inlet to the outlet of the TDO with an endless clip chain. A range of clip chain systems is available depending on the application. The returning of the clip chain can be arranged inside or outside the oven. The DORNIER clips with ball bearings can be provided for the thin, medium and thick film and thicknesses ranging from 0.8 to 450 µm. The consumption of lubricating oil is reduced to a minimum, which is about 40 cm³ per day for each machine – roughly the capacity of a small glass.

The ovens are mounted on rollers and equipped with floor insulation. This ensures that thermal expansion is controlled, avoiding heat stresses in and outside the oven. The ovens are divided into various zones where the length of the zones are be made as per need of the application. For uniform air exchange and optimized temperature management, each zone is equipped with a ventilation system consisting of a heater and a circulation fan.

In case of required access inside the oven, the oven can be entered within a few minutes via the maintenance access. By using the patented quick ventilation flaps arranged above the Penthouse, hot air can escape within minutes and the zone can be entered.

The ovens are available in widths up to 12 m. They can be heated with thermo oil, steam, electrically or with a combination of these systems. Gas-heated ovens are also possible for producing polypropylene films.

Take-up Systems

The DORNIER take-up and transfer section is designed for guiding the film from the transverse stretching machine (TDO), for further cooling down the film temperature, for cutting the edges and to adjust film surface properties. The TUT section can also be called pull roll stand (PRS).

The take-up systems are vibrationless, and are designed to allow easy removal of the rolls from above.
Each roll is driven separately and the first rolls can be cooled individually. All installed nip rollers are guided on linear bearings and have rubberized surfaces. For surface treatment of the films, the take-up systems can be equipped with corona and flame treatment stations. The DORNIER take-up system includes a thickness gauge to measure the final film thickness.<o:p></o:p>

DORNIER supplies take-up systems for final film widths up to 10.6 m.

Drive and Control Systems

DORNIER produces customized integrated PLC controllers for complete systems and for components such as casting systems or longitudinal stretching machines based on the Siemens SIMATIC S7 standard.

The Windows-based Siemens WinCC system is used for the control of the machine (HMI). Upon request, a higher level process control system can also be supplied.