Yarn Realization in Spinning

What is Yarn Realization?
Yarn realization (YR) is a term used to represent the quantity of yarn produced from a given weight of raw material expressed as a percentage. A high yarn realization is a matter of paramount importance in the production economics of a spinning mill. Yarn Realization (YR) is largely governed by the level of trash in cotton, expected yarn quality and type of machinery. Yarn realisation governs to improve yarn quality, productivity and waste reduction in process. The control of raw material cost is mainly influenced by yarn realization. The yarn realization normally ranges from 85% to 90% for carded cotton yarn and from 67% to 75% for combed cotton yarn, depending on the trash% in cotton and quantity of waste extracted during fiber to yarn conversion.

yarn realisation

The cotton accounts for nearly 65–70% of the yarn cost. It is therefore essential to convert cotton into yarn as fully as possible. However, due to the presence of micro dusts, trash and short fibers, all cotton cannot be converted into yarn. The percentage of cotton realized as yarn is termed as yarn realization. If we feed 100 kg of cotton and get 87 kg of yarn, then the yarn realisation is 87%.

Yarn realization plays a significant role in production economics of a spinning mill. One per cent reduction in yarn realization would cause almost the same economic impact on the mill’s profit as 1% increase in the raw material cost would make. This is because resale value of waste is much less than the actual price of cotton till it reaches yarn stage. To illustrate, in the prevailing cotton cost and yarn selling price, even a 1% improvement in yarn realization would lead to a saving of 20 lakhs Taka per year for a 30000 spindle mill manufacturing 40s yarn. Hence control of yarn realization is important to a mill as the control of cotton and mixing costs. Yarn realization from various textile manufacturing operations is shown in below Fig.

Yarn realization from various textile manufacturing operations
Fig: Yarn realization from various textile manufacturing operations

Impact of Cotton Characteristics on Yarn Realization:
Yarn realization is affected by following cotton characteristics.

Trash % in cotton purchased: Higher the trash % content in bale, higher will be need to remove waste in blowroom and lower is the yarn realization. Material handling storing of material in ginning process is more responsible for trash % in cotton.

Moisture content in cotton: As amount of moisture in cotton goes up, the yarn realisation goes down.

Short fiber content in material: Higher the short fiber content, higher is the removing efficiency of short fiber at comber stage because of that yarn realisation become lower.

Departments for yarn realization:

  1. For carded yarn: Blow room, carding and ring frame.
  2. For combed yarn: Blow room, carding, comber and ring frame.

The control over the yarn realization can be done by owner of organization, manager of organization, Head of Department (HOD) of each department, supervisors, workers, etc.

Effect of Fiber Parameters on Yarn Realization:
The fiber parameters which can affect the yarn realization are:

a) Trash% in mixing: If the trash percentage is higher in mixing, more waste in blow room and card be removed to get the required quality compared to the cotton having less trash% in mixing, which in turn affects the yarn realization.

b) Short fiber content (SFC) in mixing: Higher SFC in mixing resulted in more waste in blow room. Improper control of short fibers leads to fluff liberation in the departments which in turn higher invisible loss and affects the yarn realisation.

c) Moisture content in mixing: If there is more moisture content in cotton, the amount of invisible loss will be higher.

d) Micronaire: In less Micronaire cotton, the amount of immaturity is higher, so that due to fiber rupture in blow room and card the waste will be higher.

e) Maturity Ratio: In more immaturity cotton, due to fiber rupture in blow room and card the waste will be higher.

f) Stickiness of cotton / Honey dew content: Higher honey dew content in cotton leads to more white waste and higher micro dust/fluff accumulation on the machine components and leads to higher invisible loss or micro dust which in turn affects the yarn realisation.

Method of Yarn Realization Calculation:
The estimation of yarn realisation has to be done accurately by maintaining proper recording of bale weights, wastes and yarn produced. Because the estimation of quantities such as moisture content in cotton and yarn, tare weights, allowances for twist contraction and idle spindles and invisible loss are subjected to a number of assumptions as well as possible sources of error.

Generally most of the mills use the following formula:

……………………………………..Yarn production
Yarn realization (%) = ————————————————— x 100
………………………………….Cotton consumption

Where, Cotton consumption = Cotton issued (kg) + Opening process stock − Closing process stock

The percentage of yarn realization from any mixing depends upon the magnitude of two types of wastes:

  1. Process waste: Wastes taken out in blow room, cards and combers, which together form about 80% of the total waste. These wastes are extracted for the purpose of cleaning, so there should be a direct measurement and control of process wastes.
  2. Product waste: Wastes which are incurred at each stage of processing. The product wastes can be controlled through proper supervision.

How to Improve Yarn Realization:
Yarn realisation is associated mainly with cotton feed, yarn produce and waste generation. To improve yarn realization % we have to concentrate on reduction in waste generation. Better way to control over the yarn realization is by means of better practical way to control over the waste generation. The percentage yarn realization depends primarily on process waste taken out at blow room, card and comber. Waste taken out in blow room depends on trash content of the mixing. The waste in cards depends on type of card and also to some extent, on trash in lap. The waste in comber, depends on nature if fiber length distribution in feed.

Measures to improve yarn realization:

  1. It should be ensured that the overall lint in waste is no more than 40% in cottons with high amount of trash and 50% for cottons with a low level of trash.
  2. Bale weight variation due to moisture loss should be prevented. Variation between invoice weight and actual weight of cotton bale should be controlled.
  3. Contamination content in the cotton bale should be at a very low level.
  4. Addition of soft waste in mixing should be at a minimum level.
  5. Control fly liberation in blow room department by maintaining recommended R.H%.
  6. Sand liberated from the trash removed also should be taken into account for realization calculation.
  7. Fitting of automatic waste evacuation system in blow room and carding to control effective waste management.
  8. Addition of right amount of water and mixing oil during stack mixing in order to control fly liberation and invisible loss.
  9. Weighing of waste during every shift wise should be proper, and there should not be any manipulation under any circumstances.
  10. Weighing balance used for bale weighment, waste weighment, and cone bag weighment must be calibrated as per recommendation.
  11. Standard procedure must be adopted while taking process stock and the person responsible for process stock should be trained properly.
  12. The incidence of yarn waste should be below 0.4%. Cop rejection in the automatic cone winding should be checked regularly, ring frame wise, and it should be ensured that it does not exceed 6%.
  13. Appropriate roving empties and ring tubes with microgrooves should be used to avoid frequent slough-off of roving and yarn, respectively.
  14. Ring frame doffers should properly follow simultaneous doffing and donning method with which the starting breaks could be reduced.
  15. R.H% to be maintained in each and every department to control fly liberation that increases the invisible loss.
  16. Yarn conditioning plant improves the yarn realisation to some extent by increasing the moisture in final package.
  17. R.H% should be maintained properly in cone packing area to prevent any weight loss.

References:

  1. Pollution Control in Textile Industry By S. C. Bhatia
  2. Process Management in Spinning by R. Senthil Kumar
  3. Process Control and Yarn Quality in Spinning By G. Thilagavathi, and T. Karthik
  4. Handbook on Cotton Spinning Industry by Purushothama

You may also like:

  1. Waste Management in Spinning Mill
  2. Types of Waste in Spinning Mill
  3. Process of Controlling Waste in Comber
  4. Cotton Yarn Spinning Process Step by Step

Share this Article!

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.