Melt Spinning lines

 1- Design of closed loop process controllers in PLC programming and implementation of Profinet and Profibus communication network between equipment in melt spinning line.

 2- Installation, commissioning and adjustment of drives to control motors in various parts from feeding polyester raw materials to the production of final yarn in the melt spinning line.


Melt Spinning line in the textile industry


At the beginning and before expressing the spinning control process, we examine the importance and growing of this process in the textile industry.

Polyester, scientifically known as “polyethylene terephthalate”, also abbreviated as “PET”, is one of the most important and widely used fibers among all natural and man-made fibers in the world. Of the approximately 83 million tons of annual fiber production in the world, about 43 million tons, or about 50%, is dedicated to polyester. As it is known, now in the world, polyester is the most important raw material of the textile industry and due to advantages such as reasonable price, various production methods, quality of final products and growth rate of consumption, it is several times the average growth of this industry.


Due to the abundance of polyester as a raw material required for the melt spinning industry in Iran, as well as numerous problems in supplying raw materials and producing other yarns needed to produce clothing, carpets and other textiles, textile industry experts believe that in the future, the use of polyester fibers in the textile industry of Iran and the world will grow more.

In general, depending on the type of polymer fluid and the method of coagulation of polymer filaments, there are three different spinning methods:

       1) Melt Spinning

       2) Dry Spinning

       3) Wet Spinning


In general, in the spinning method, the polymer, which is in the form of granules, is melted inside the extruder and after passing through the string makers and becoming polymer filaments, it is coagulated and cooled by cold air. In the dry spinning method, fluidization is done by dissolving the polymer in a special solvent, and after the filaments leave the string maker, evaporation and fiber are obtained by using hot air. In the wet spinning method, the polymer is first inside The solvent is dissolved and then passed through a filament maker, and finally the output filaments pass through a pool of solution called a “coagulation bath” and, upon reaction with the solution, coagulate and turn into a fiber.

In the following, we will specifically deal with the production process of polyester yarn in the melt spinning process.



POY yarn production


In general, POY (Partially Oriented Yarn) yarn production consists of two stages:

Step 1: Crystallization and drying

Step 2: polymerization, extrusion and spinning of yarn


In the first stage, the granules or polyester chips are transferred to the main tank of the melt spinning line and are transferred from the main tank by suction by the pneumatic system with compressed air flow and through the pipes to the “storage hoppers” in the upper part of the line. It is then fed to the crystallizer.


The “crystallizer” does not allow sticking between the chips by hot air and spraying polyester chips, and absorbs a certain amount of moisture in the chips, and the control of the heating section must be done in such a way that the poly chips Do not dry the ester. In fact, in this part, the inner chain of polyesters is crystallized, causing it to turn white and at the same time prevent them from sticking.


After the crystallization stage, the polyester chips enter the “dryer” and in this part, by applying heat, the remaining moisture in the chips reaches about 0.005% and also the polyester material absorbs heat to perform the melting process in the “extrusion” stage. ” they get ready.


In the extrusion part, the chips become molten polyester with a certain viscosity. It should be noted that the melting steps must be done continuously because any stop or occurrence of the slightest problem in this route will cause irreparable damage. The molten material is then subjected to “filtration” to prevent impurities from passing from the previous parts to the next stages of the melt spinning line and the material is ready to be sent to the “spinning head”.



In order to control and prevent temperature drop and solidification of molten material, all paths of the material transfer system in the melt spinning line should be done in double-walled pipes and in case of minor changes in the temperature of the molten polymer, favorable conditions will not be provided for producing high quality yarn.


In the next step, the molten polymer is directed to the pumps. The pumps have a “metering” system and control the exact amount of material passing through. The molten polymer is then fed to the ” spinneret ” part. In this part, the molten material passes through very small holes and yarn strands are produced with special flow, capacity and linear density. After this stage, the strands are cooled and lubrication is done to glaze the yarn. Finally, the threads are directed to the winding and wrapped around the cardboard spindles.


Project Management unit – Novin Control Industrial Group

Novin Control Industrial Group provides a set of technical and engineering services in the field of design, construct and implementation of control systems, industrial automation and instrumentation.

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