Bone Craven mono extrusion line
|Machine||Bone Craven mono extrusion line|
|Machine manufacturer||Bone Craven|
|Type of extruder||Blown|
|Number of layers||1|
|Diameter die||200 mm|
|Lip opening||1 mm|
|Diameter screw(s)||90 mm|
|Material & Min – Max thickness||LDPE
|Max. film width||1100 mm|
|Max. output||100 Kgs/h|
|Rewind type||Back to back,
|Max. rewind reel diameter||600 mm|
|Number & sizes airshafts for winder||4
suitable for 76 mm
|Type of screen changer||Manual|
|Rotating, which part||Die|
|Spare parts||Extruder Gearbox|
Extrusion in the flexible packaging industry can roughly be devided in three kinds of extrusion: blown film extrusion lines, cast film extrusion lines and BOPP extrusion lines.
Blown Film Extrusion
Blown film extrusion is the most common technology to produce plastic film. Blown film extrusion is typically carried out upwards vertically.
Film is made out of polymer material. These polymeres are generally in the form of granulate. This material is melted and then forced or extruded through a die. Air is blwon thourgh a hole in the center of the die. This pressure causes a bubble. This bubble is a thin layer of film. The film is pulled upwards from the die to cool down and winded on the a roll.
Blown film extrusion exists in various layers, the more layers the thicker the film. The process with more layers is called coextrusion.
Cast Film Lines
In the process of cast extrusion polymer travels through a flat die system. For mono-layer extrusion only the die is required. For co-extrusion besides the die you need also aa feedblock.
The extruders melt and mix the material, they filter it and i t will be be fed to the die system. The molten curtain enters the cooling unit directly after leaving the die. A roll cooled by water will freeze the film.
The edges will be trimmed and when required corono treatment is applied. The last stage of the process is winding the film onto rolls.
BOPP Extrusion Lines
BOPP stands for Biaxially Oriente Polypropylene films. BOPP films are widely used since the introduction of the film 35 years ago. BOPP film is streched in two different directions., the direction fot he machine and the direction across the machine. By doing this the film changes: it becomes harder to stretch, the tensile strength will be harder and stiffer. Also the barrier to water and gases improve and the optics of the film are excellent.