Nowadays, polyester fibers are usually produced in two-level and single-level and two-level methods. In Single-level method is usually used to produce thicker fibers. the volume of equipment and ultimately, the cost of energy consumption are less.
In twice-level process, the production of delicate fibers is produced with highly controlled and high-quality physical properties
Polyester single level production technology
In the process of producing polyester fibers, due to the sensitivity of these fibers to moisture, the process of crystallization and then drying is performed first. Raw chips moisture is usually between 500-600 ppm and should be less than 35 ppm for consumption. Otherwise, during melting in the extruder, the hydrolyzing of the polyester will eventually cause the filament to be cut off, which will have a profound negative effect on the spinning efficiency.
After drying, the polyester chips are fed to the extruder by weight To melt, provide the necessary pressure for filtration and transfer in the transit line. At the end of the polymer transfer line through the milling of spinning pumps (volumetric pumps) are pumped into spin pack.
The task of spinning packs is:
1) Polymer uniformization,
2) filter it,
3) In the Spinneret section, converts the molten polymer to the fibers
The output fibers of the pack are melt, so the fiber is cooled down and become solid during the stretching by Queneh Air. The force required to pull the fiber into the spinning part is supplied by the take up section. After cooling and solidification, fibers are dipped into a water and oil solution by finish jet. This action is done to reduce the friction between the fibers and metal and resinous surfaces ,reduce the static electricity effects and stick together the fibers, and then the fibers are sent as a bond to the draw zone.
Due to the fact that the fibers produced in the spinning region are mainly “under the influence of tensile force in molten and ductile conditions, the lack of required orientation for physical properties that are necessary, according to it, they are directed to the stretching area and affected by The heat and mechanical forces applied are drawn by stretch rollers and the required orientation created in the fibers.
Draft in single –level is done in one level, then The fiber is getting warm and passed through the machine to convert the flat fiber to wrinkled fibers. This action is done to increase the fiber interactions in each other in manual processes.
Then, to remove the residual forces in the fibers and to stabilize the properties of the fibers, as well as to control the color of the fiber,
strip is passed through the Heat Setting Oven to give all properties such as strength, elongation, elegance, dye ability and wrinkle and then fixed them . Then the fibers are cut and packed bales.
Twice-level polyester fiber production
The twice-level process is similar to that of the previous spin, except that the fibers are stored after spinning in the spinning can. Then, a number of cans are placed in the tensile region. This method is used to control the spinning parameters when happens trouble , it is possible to correct it in the next process in order to achieve a reliable product. In the twice-level draft system, generally, it is done in three levels and in a step-by-step . so that the fibers do not break, and avoid to produce of thick fibers and unwanted parameters.
Typically, the stretching is carried out in three levels, with ratios of about 2.1, 3.1, 2. The last step of the stretching is on the roller fixing properties of the fibers in the Heat Setting Oven. The fibers are cut and packaged. Elegant fibers are usually produced with a cut length of 32 and 38 mm. In this kind of fiber production, it is usually possible to produce Micro fibers and with 0.1-0.8 decitex.