Extrusion Process
How does the extrusion process for plastic strap work?
A PP or PET strap has to go through several stages in the extrusion process before it is finally ready for use as packaging material.
Here is a simple explanation of the steps required.
- Raw material dosing stations
Dosing stations are used to create the desired material mix of granules or PET flakes.
The material mix depends on the desired properties of the strap. - Extrusion
The machine heats and melts the plastic granulate or PET flakes using an extrusion screw. The combination of heat and pressure transforms plastic into a molten mass. The melted plastic is then forced through a specially designed extrusion or moulding die.
- Cooling through a water bath
After exiting the die, the molten plastic enters a cooling section. In this section there is a water bath in which the molten plastic cools and solidifies quickly.
- Stretching units
After cooling, the plastic strap may pass through additional stretching units as rollers or ovens to ensure it has the correct width, thickness, elongation and surface finish. It may also be embossed or waxed, if required.
- Winding units
The continuous strap is then wound on paper cores to finally get the coils with the desired length.
- Quality Control
Throughout the extrusion process, quality control measures are implemented to monitor the strap's properties. This may include checking for thickness, width, and breaking strength. Any inconsistencies are usually identified and addressed during this phase.