Heating and compression of the resin is the process of extrusion, in the event of the melt, at the right temperature, they push it into a mold, so, continuous plastic layer will be formed.
Stretch film.
The thick layer of the blown film squeezes the film, leaving a circular dead and the air blowing in the air. The limit thickness of the material is determined by the volume of the bubble and the original diameter and thickness of the extruded tube.
How big is the vertical bubble? It is very big, I think there may be many feet high, the effect is a can let the film gradually cooled down, because it always can be rolled up the drum, the bursting of the bubble is because it is done, and the thin, flat membrane tube can be controlled by it, can be controlled by it because it is round.
Usually during the upwind, the edge is cut open, the roll is torn open in width, and wound together when the film is extruded.
This is a vertical process, as shown in the figure.
It is estimated that about 20-30% of the stretch film made today has been blown away.
What is cast iron stretch film.
A different process was involved in the production of the film. In this case, the resin is extruded, also through a linear mold, and then it oozes out, in general, to the large diameter cooling roll. It’s worth noting that, in fact, they may not be cold, but compared to semi-molten plastic, it’s much colder. We according to the extrusion of the original thickness, sometimes thin film can be diluted, dilution of the film will be the target, the instrument by winding the film and it is in comparison with the speed of extrusion, by winding the film faster.