Study on Yield% Maximization in the Cotton Spinning Industry (Yarn Manufacturing)

Abstract

Yield% shows the performance of any industry; it shows the efficiency of the industry to convert the raw material into the finished goods. The industry management focuses so much on the maximization of yield so that maximum profit can be earned. Yield% directly relates to the profit of the industry; the textile cotton spinning industry usually gives the yield% up to 84, this can be increased up to 1 to 2%, adding a million in the profit of the cotton spinning industry. This article presents the methodology to enhance the yield% of the cotton spinning industry.

Introduction

Raw material consists of impurities up to 4-16% (according to type, region, and the efficiency of the ginning), the yarn manufacturing processes (Blow-room to carding) are especially designed to remove these impurities. While removing the impurities some good fibers are also removed due to inefficient machine setting or improper machine sequence selection and there are many more causes which decrease the yield %. Some of the causes are discussed here which increase / decrease the yield% such as

  • Raw material selection
  • Raw martial process route selection
  • Improper machine setting
  • Maintenance of Machines
  • Inefficient air conditioning plant
  • Improper material handling

Raw material selection

Raw martial costs about 50-70% of the total cost of the product. It is mentioned above that impurities in the cotton raw material in Pakistan ranges between 4 to 16 percent, these impurities must be removed to achieve the required quality product. If the raw material for the yarn is not properly selected than it may cause a decrease in the yield %. Finer yarn requires more cleaning of the material than the coarser yarn because impurities present in the fine yarn create hindrances in further processing and can be more visible and vice versa than coarse yarn. Finer yarn required fine quality raw cotton which has sufficient strength and the fiber length if the cotton selected for the finer yarn is of not sufficient length and strength then the good fibers may be wasted during the processing in result of that yield% is decreased. Another main characteristic of raw material which also contributes to the decrease of yield% is extra moisture in material because if the material has extra moisture present in it then it may difficulty to separate the impurities and good fibers which required more efforts, energy, time etc such material sticks with machine parts which may go into the waste and become the cause in yield% decrease.

[1] Manual of textile technologies by W. Klien volume 1

Raw material process route selection:


Route selection for processing the raw material is also another important task for the management. In cotton spinning industry different lines of processing are installed in the Blow Room, routes have different beating points and according to amount of impurities present in material and quality requirement the processing route is selected. Which reduces the wastage of good fiber, resulting increase in (production) yield%. Processing route selection is based on the type of the material process e.g. natural and synthetic material cannot be processed on the same route even you are required to manufacturing the pc (Polyester cotton with any ration) for blend yarn you have to process both fibers separately and at any particular point blend them with required ratio. Now a days technology facilities process and separate blending machines are available to blend the material with any ratio or you can blend the slivers of the different materials at the draw frame.


Material passage at the draw frame is also pre-decided whether material should be double (Breaker & finisher) or triple passage (breaker, intermediate & finisher). With less passage the production increased by saving the waste % i.e. 0.5 but the quality may be effected or not if the raw material quality is enough then the intermediate process may be omitted otherwise It should be carried to improve the quality so that final product can be sold. If after the processing product is not sold then it means whole material and efforts consumed on it are wasted and yield% becomes 0. Therefore it should be kept in mind that product must be sell out.


Improper machine setting:


Required quality of the product cannot be achieved without the proper setting of machine, any spinning machine setting parameters includes


  • Speed
  • Gauge
  • Top Roller Pressure
  • Air pressure


With the above mentioned setting parameters you can manufacture the required quality of yarn within the required time frame. With the speed you can adjust the draft, production rate, beats per unit time, and many more. With the gauge and pressure (Air and top Roller) setting you can easily process the material without deteriorating its quality and properly removing the impurities to achieve the targeted product and the result of this surely contributes in the increase of yield%. If any above said setting parameter is improperly set then it will deteriorate the quality and ultimately decrease the yield%.

Maintenance of Machines:


There is old saying that machine cannot become older, if properly maintained time to time, if machine is not properly maintained then it will not deliver the required quality and may also waste good fibers and due to this yield% will decrease. E.g. if card machine is not properly overhauled and its taker-in and cylinder wires are out of order, when the material is process on such a machine then the machine is unable to remove the impurities and also unable to properly open the fibers up to individual fiber stage, then the product (sliver) delivered by the card machine is not match with requirement thus for the required quality most of good material may become useless or you have option to reprocess the material in both cases yield% is ultimately decrease and any owner/ management cants bear this, therefore for improving the yield% machine maintenance should be primary objective well maintained machines produces required/ targeted quality and yield.

Inefficient air conditioning plant:


Air-conditioning plant contributes most of its share in increase / decrease of the yield%, due to A.C plant the yield% can be at maximum or minimum level therefore if plant is properly maintained providing proper suctions into transportation pipes, machines, atmospheric conditions with the requirement of each department then surely yield% can be increase. The main objectives of the A.C plant is to maintenance required temperature and RH% into every department, provide proper suction into return ducts so that the fluf and good fibers from the floor properly collected and have sufficient air filters, so that the dust, other impurities and good fibers can be separated. Each machine have also separate suction system e.g. at ring frame pnewmafil is collected by the internal machine suction. Pnemafil 100% good fibers which and be reprocessed with minimum efforts if these are not collected then went into waste hence causing decrease in yield%. Similarly A.C plant performs its job in every machine to prevent the wastage of good/processable fiber.


The objectives of the air-conditioning plants includes


  • Control the RH% & Temperature in every department
  • Collect and Control the fulf
  • Properly separate the collected impurities and good fiber by the help of filters


By achieving the above mentioned objectives we can improve the efficiency of man and machine, Quality of yarn and production of plant in result of that we can achieve our target i.e. yield % maximization


Improper material handling:


Improper handling of material before, during and after process decreases the yield%. E.g. the slivers cans during transporting from the card to draw frame or from draw to comber or simplex if not properly carried and by chance material may be deteriorate by hand touching or due to other reason can fall on floor because of uneven floor or cane wheels will contribute in yield% shortage. Handling of material start when the raw material arrived and you have to plane well where to store it and in which conditions it should me stored considering that when transporting to production floor may not be effected / damage/detoriated. Material handling is also required in each department of cotton spinning staring from blow-room as the material is process through each department e.g. final product of blow-room is lap or final product of chute feed system is sliver of card therefore the lap/slivers are properly transported and stored so that their quality cannot be effected similarly the final product of each department is well stored, material handling also deals with the proper storage and transportation of the finished product.


The author is associated with Textile Engineering Department, Mehran University of Engineering and Technology jamshoro, sindh, Pakistan