The use of clips and chains in the transverse stretching sections of BIAX Film Stretching Lines (BIAX Lines) is an almost 50 years old concept. It has been created at a time wher BIAX Lines were slow and narrow and so where their TDO ovens. Over the decades output, speed and width of Biax Lines has changed dramatically, now reaching speeds of about 500 m/min and widths of more than 10 meters.

Still the concept is the same using chains and clips guided by rails. This evolution has come to an end, the known chain track systems are able to run around 500 m/min, but at a price of high cost, intensive maintenance  and high risk of damage and even breaks.

(State of the art TDO System)

The basic problem is, that such high speed systems get very long, exposing them especially in the preheating zones to heat. This and the own friction created by their own mass results in all kind of mechanical problems.

(State of the art sliding chain track system)

Amongst other problems, the suppliers of chain track systems do not talk much about the so-called unwanted longitudinal stretching effect at the change of the track direction to stretch the film. Here the film already stretched in the longitudinal direction is stretched again in MD as shown in this picture, creating lots of problems like film breaks and damaging the chain track system.

The new patented system changes the concept of chains,clips and rails totally and is simpler in all aspects.

The chain and the clips are replaced by guided ropes made of steel and plastic components. The ropes are used for transportation as well as clipping the film. They are guided guided by special giiding systems and roller bearings and special magnet systems in the stretching areas to press the ropes towards each other and so generating the necessary clipping force.

Here an example can be seen for a solution consisting of 2 ropes in top view at the beginning of the stretching section.

Here an example for a 2 rope guiding element front view:

This system allows much higher transport speed for TDO Systems and is much cheaper and simpler in maintenance.

Please see some videos of the existing test stand to measure gripping forces.

 RST the perfect way of TD Stretching film for existing lines as well as new biax lines.

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