Polyester fiber:

Polyester is the most important man-made product by producing 22,000,000 tons in 2003 (%58 joined filament, %42premorse fiber) that in some years the amount of its production was even more than cotton. The number of the factories that produce this kind of fiber is more than 500 factories. The other aspect of its noticeable importance, from geographic-economic point of view, is that %75 of its production is placed in Asia. Polyester production has the highest record of synthetic fibers production belonged to polyamide in 1972 and it has %65 of synthetic fibers marketing portions. It was successful because of specific characteristics such as accommodation with various control sections and the amount of raw materials and production costs.

Fiber dimensions:

Denier is the unit of delicacy measurement and it is usually used as a unit for long synthetic fibers (filament). The weight of 9000 meters of each filament in terms of gram (the unit of measurement), specifies its denier. So as the amount of denier yarn or fiber increases, the delicacy decreases. For example, a hundred denier nylon(9000 meters of that weighs 100gr) is more delicate than 150 denier nylon.

General flowchart of spinning process:

The flowchart which is used for various kinds of spinning methods is as it is demonstrated below: Fluid polyester mass (fused or soluble mass) directs through distribution lines and then it reaches measuring pumps (gear system) that provides a constant flow for spinning conditions. It is made of the series of filters that purify the polymer and then distribute it and they are with perforated sheets in various sizes and thicknesses that are usually round shaped and made of a kind of stainless steel (for melt spinning). It can also be made of expensive metals or glass materials (for dilution spinning). According to the type of yarn, the number of the holes on the sheets can be different. They can be 1000 and can have rounded or special cross-sections (shaped or hollow sections). The filaments that come out of the strip maker, after returning to their primary condition (solid polymers), are cut off. Next they will be placed in suitable packs (reels or containers) or they will be carried directly to the next operational sections. In melt spinning condition, if polymer is not generated from polymerization in melted condition, the mass fluid polymer will be manufactured by melting solid polymer granules (polymer chips). This process is done in containers (tubes) that are heated electronically and it is equipped with a net that separates the solid granule from polymer when it is melting. Utilizing this kind of system is now limited to a few users and it is replaced with better and more complete machines (spiral extruder).

Traction:

The polymer that comes out of the string maker is in filament shape that doesn’t have the characteristics of fiber yet and in fact it is the mass of polymer (that is changed to solid legit by chilling or separating) that is placed in an inappropriate section by a mass of molecular chain (in amorphous areas) that in this case a substance with chemical and thermal stability will be produced. The substance that its resistance over time will be low it will have high range of plasticity and deformation capability. So as a result it will have insufficient physical and fiber characteristics. If we consider synthetic fibers as a model, we should place the molecular chain, appropriately and parallel in an arranged form along the fiber direction or we should activate or increase the internal setting of molecular structure (crystal phase). This process can be done by increasing the ratio between removal speed and exit velocity (fiber ratio). But considering high velocity of spinning about joined filaments, this process should be completed with another machinery and mechanical spinning operation.