Polyester (PETP) is manufactured using a process called extrusion.
The extrusion process is similar too squeezing toothpaste out of a tube. The Ertalyte extrusion process produces continuous shapes like, sheet, rod and tube. During the process of extrusion, granular polymer resin is placed in a hopper and then fed through a heated, rotating screw and die. The die and the take off line shape the material as it cools and controls the final dimensions of the cross sections of the material. Extruders are designed and controlled to produce melted plastic at a very uniform temperature and pressure. This in turn controls the size and quality of the extruded product.