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Die with rotating core

The main novelty of the film blowing die is the rotating core technology where in contradiction with the traditional rotating die only the die’s core is rotated. In this new die we let the self-adjustment of the rotating core resulting in the core’s concentricity caused by the melt and therefore it assures the constant sized slit throughout the discharge area’s whole perimeter. The constant sized discharge slit is the first step to get an even film and furthermore the cooling has a big role as well. It is possible to reach an enormous amount of material saving (~35%) with a film of even wall thickness (thickness tolerance of ±5%) comparing to films produced with traditional methodes where the thickness of the film varied in a wide range (±20%). A further advantage of the rotating core technology is the bioriented, homogenious mash structure. The rotating core enables the forming of this homogenious mesh structure because in the die the melt flow is not distributed into more channels like in the traditional technologies. Owing to the rotation of the core the orientation of the mesh structure is equal in both directions (cross- and longitudonal).

Owing to the rotation, the melt’s temperature distribution will be more even which greatly contributes to the even wall thickness. This even temperature distribution was improved by a ring with good heat conduction capacity placed on the upper cross section of the die. The rotation of the core kneeds the material, and because of this a great amount of heat is generated in it. This heats the melt, and this internal heat generation and the core rotation decrease the probability of burning down. Furthermore, in course of operation this heat-generation of the melt makes the external heating unnecessary resulting in significant energy saving.