Longitudinal stretching machines MDO

Longitudinal stretching machines MDO

  DORNIER longitudinal stretching machines (MDOs) are normally used for PA, PP, PET and other special materials. Independent of the material being processed, a longitudinal stretching machine comprises a set of preheating rolls, a set of stretching rolls and a set of cooling rolls. The rolls are heated by thermo oil, hot water or steam. Cooling is done using water or thermo oil whereby, in the case of thermo oil, a water cooler is used to reduce the temperature of the oil.

For polyester film production, longitudinal stretching machines are available with up to three stretching arrangements (multi-gap stretching) to allow stretching films on one or several gaps. For three gap stretching, the film is stretched approx. 20% at the first gap at a temperature of 120°C without module orientation occurring.

For polypropylene production, the preheating and cooling rolls each have a diameter of 650 mm. On longitudinal stretching machines to process polyester or polyamide films, the diameter of each of these rolls is 450 mm. For stretching rolls the diameter depends on the width of the rolls.

All rolls on longitudinal stretching machines are driven independently (preheating, stretching and cooling rolls). These are also gear motors directly coupled. This drive system allows setting the speeds of the rolls according to the heat expansion of the film.

The polyester film production MDOs are equipped with additional infrared heaters in the stretching sections.