Technical terms of the film blowing machine

Technical terms of the film blowing machine

Inflation ratio is one of the control points of the blown film production process, is the ratio between the diameter of the vesicle refers Inflation with Inflation tube ring diameter. Inflation than the lateral expansion of multiples of the film is actually a horizontal stretch of the film, the stretch will have plastic molecules to a certain degree of orientation of the role of Inflation ratio, so that the lateral strength of the film. Inflation, however, also can not be too much, otherwise easily lead to vesicle instability, and the film is prone to wrinkles. Inflation than should be the same traction with the appropriate the job, In general, low-density polyethylene (LDPE) film Inflation should be controlled at 2.5 to 3.0 is appropriate.

The speed ratio between the traction extrusion ratio refers to the film speed traction tube ring. Traction than the longitudinal draw ratio, the film has directed in the direction TAKE. Traction ratio, the longitudinal strength will increase as the thinner films, but if traction than the thickness of the film is difficult to control, and even there may be film to pull off, resulting in the phenomenon of broken membrane. Low-density polyethylene (LDPE) films traction than the average control between 4 and 6 is appropriate.

The dew point also known as the frost line, refers to the plastic by the viscous flow state to enter the dividing line of high-elastic state. In the blown film process, low-density polyethylene (LDPE) extrusion from the die mouth was a molten state, the transparency is good. After leaving the die exit, to be cooled by cooling air ring vesicles Inflation District blowing just the nose bubble of plastic film extrusion, high temperature membrane vesicles and cooling air, the cooling air to a certain angle and speed contact with membrane vesicles of the heat the cold air away, its temperature will be decreased below the viscous flow temperature to the low-density polyethylene (LDPE), making it the cooling solidified and become blurred. We can see a transparent and blur the line between taking a dip in the blown film, this is the dew point (or frost line). In the blown film process, the dew point level of the thin films have a certain impact. If the dew point is high, above vesicle Inflation, Inflation of the film is carried out in the liquid state, huff only to make the film thinning, while the molecular orientation by stretching, when the Inflation membrane performance close to cast membrane. On the contrary, if the dew point is relatively low, Inflation in the solid state plastic in high elastic state, blows up as the transverse tensile molecules orientation role, so that the blown film machine blown inflation film performance close to the orientation film.
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