In wide-format bubble film machines ranging from 1600 mm to 3000 mm, the extruder screw diameter determines the machine’s material conveying capacity and production output. As a central component of the extrusion system, it directly influences how plastic raw materials are transported, melted, and delivered to the die during production.
The screw is responsible for transporting, melting, and metering plastic materials such as LDPE and LLDPE. As the screw diameter increases, the material conveying capacity increases significantly. In general, extrusion output rises in proportion to the square of the screw diameter (D²). This means that even a moderate increase in screw size can greatly improve production capacity and support higher throughput.
For bubble film machines with widths between 1600 mm and 2000 mm, screws with diameters of 70–80 mm can provide stable production. For wider machines, especially those reaching 2500 mm to 3000 mm, larger screws are required to supply sufficient melt flow to the die. A wider die needs a stable and continuous flow of molten material to maintain uniform film thickness across the full width.
Screw diameter also affects melt quality and bubble film structure. When a small screw operates at very high rotation speeds to maintain output, excessive shear heat can occur during extrusion. This may lead to unstable melt flow and inconsistent film structure. A larger screw can operate at lower rotational speeds while maintaining the required output. This allows the material to be heated more evenly and improves melt homogenization.
In addition, a properly sized screw helps maintain stable melt pressure before the T-die. Stable pressure distribution is important for achieving uniform film thickness across wide dies. Consistent melt flow helps reduce thickness variation and supports stable bubble formation during production.
Overall, selecting the appropriate screw diameter helps ensure stable extrusion, uniform melt quality, and consistent bubble film production in wide-format machines.
