Casting Unit

 Casting unit is the main constuction part of the film manufacturing.

Casting of the film, and prepare it to orient in two direction in machine direction as well as in transvers direction to the extruded melt coming out from Die is called Casting Unit.

There are many components ans sub parts of casting unit which help to form the film and cast it well.

Name of important parts are-

1)Air knife

2)Water Bath

3)Skin Tank

4)Chill Roll

5)Water removal Unit

6)Guide roll

7)Swivel Roll

8)Drying Unit.

Above shown picture is basic view upper corner angle of casting unit.

lets understand it more deeply by side graphical view of casting unit.

Working Principle-

In the film casting unit the melt film of the melt die is cooled by a water bath and a

chill roll. After the water bath, the cooling water is removed in the water removal

device before the cast film is directed to the next components.

The water removal device dries the cast film after the water bath. The film is first

guided between two press rolls that press the water off of the surface. The remaining

water is blown off by means of two air nozzles that blow air onto the film from both

sides, and two additional air nozzles that dry the edge trim.

The cross cutting device consists of a height-adjustable cutter head that cuts the film

diagonally to the film path on a driven guide block to make it easier to thread the film

into the next component.

The water bath cools the cast film. For a uniform cooling water flow, there are water

nozzles in the water bath.

The water bath is mounted on rails to be able to move the film casting unit for main‐

tenance.

The chill roll is a water-cooled roll that cools the hot melt film.

From directly behind the nozzle, the film pinning device blows an air jet onto the melt

at high pressure. The melt is pressed against the chill roll with this air jet.

The edge pinning blows the film border onto the chill roll using additional air nozzles.

For an even cast film, the surface of the chill roll must be dry. The water removal

device blows the cooling water off the chill roll surface with an air jet before the melt

flows onto the chill roll.

The nip roll at the outlet of the water removal device of the cast film transports the

cast film out of the film casting unit when starting up the line and if there is a film

break, out of the downstream component.

The sedimentation tank is a container beneath the film casting unit. The soiled cooling

water flows via the container overflow of the water bath into the sedimentation tank

where it is cleaned and flows back into the water bath.