An extrusion line for expanded PET sheets by Union was recently delivered to an Asian processor. The line consists of two extruders in tandem configuration that guarantees high production rates with densities up to 80 kg/cu.m. Union's tandem solution facilitates the achievement of best extrusion quality in a particularly short time, even for a critical material such as PET whose processing temperatures can reach 280°C.
The rheological study of the material has made it possible to build a circular head thanks to which, while varying the thickness and density of the extruded sheet, the operator’s assistance during the die change is no long necessary. A new cooling system keeps the temperatures of the extruders at the set value, which is very important in order to obtain a perfect cellular structure when expansion gases are used. Also important is the cooling-calibrating device with a surface specially designed by Union to avoid any friction and obtain a sheet with high quality appearance and luster.