What is Yarn Realization?
Yarn realization (YR) is the percentage of fibre that is successfully converted into yarn after the spinning process and largely depends on the waste taken out in the blow room (trash content of the mixing), the waste in cards, the type of cards, the trash in the lap and the waste in combers (nature of fiber length distribution). It indicates the efficiency of fibre utilization in yarn production. It is an operational parameter of yarn manufacturing. Generally it refers to how well a mill has utilized its raw material resource. It is the ratio of output of yarn vs input of mixing. It is the most important factor to assess the profitability and performance of the spinning mill. It is a key performance indicator. Yarn realization is the percentage of raw material converted into yarn. If 100 kg of raw material input in blow room is obtained as yarn in spinning with no waste, then the yarn realization is 100% and it is impossible to achieve as there is lot of waste generation in spinning process. Yarn realization is mainly governed by the level of trash present in the cotton. Higher the trash content, lesser will be the yarn realization and vice versa. The yarn realization varies for carded and combed counts. In combing process, short fibers are removed, and it reduces the yarn realization. The yarn realization for synthetic fibers and its blend will be higher due to less or no trash in the raw material.
Yarn Realization Formula
……………………………………..Yarn production
Yarn realization (%) = ————————————————— x 100
…………………………………. Cotton consumption
Where, Cotton consumption = Cotton issued (kg) + Opening process stock − Closing process stock
Besides, yarn realization is also estimated by the following formulae developed by SITRA (South India Textile Research Association). In this method, all the wastes are expressed as a percentage of raw materials fed to blow room.
1. Yarn realization for mills reusing the entire usable wastes in the same mixing
For carded counts YR% = [100 – (Wbr+ Wk + Wh + Ws + Wg) – I]
For combed counts YR% = [100 – (Wbr+ Wk + Wc + Wh + Ws + Wg) – I]
2. Yarn realization for mills not reusing the entire usable wastes in the same mixing
For carded counts YR% = [100 – (Wbr+ Wk + Wh + Ws + Wg) – I – Wu]
For combed counts YR% = [100 – (Wbr + Wk + Wc + Wh + Ws + Wg) – I -Wu]
Where, Wbr = Blow room waste (%)
Wk = Card waste (%)
Wc = Comber noil (%)
Wh = Yarn waste (%)
Ws = Sweep waste (%)
Wg = Gutter/ filter waste (%)
I = Invisible loss (%)
In another way, the yarn realization is estimated by finding the production of each process and waste generation in each process. The subtraction of wastes of each process from input materials of each process will give the output of each process:
- This final output in spinning after subtracting the invisible loss will give the yarn production quantity in spinning. The ratio between the ring frame production and material fed in the blow room will give the yarn realization percentage.
- The usable waste is not subtracted from production for calculating yarn realization if it is reused in same mixing.
- In the other case, usable waste is subtracted from production for calculating yarn realization if it is not reused in same mixing or if it is sold.
In both methods of estimation of yarn realization, comber waste is added for combed counts manufacturing. The yarn realization percentage is around 74% for combed 40s and 60s Ne counts spun and 88% for carded 40s and 60s Ne counts spun. The yarn realization values are different from each other when the waste (usable) is used in the mixing and when waste (usable) is not reused in the same mixing. It is based on the method followed by the company with respect to managing wastes. It is not a fixed value and yarn realization varies a lot across mills as it is based on various factors. It is required to understand the factors affecting yarn realization and ways to improve it. Here, the factors affecting yarn realization is elaborated.
Factors Affecting Yarn Realization
The factors affecting yarn realization are:
- Customer specification
- Raw material quality
- Process factors
A. Customer specification
The customer would have specified the quality levels to be maintained with respect to yarn imperfections in terms of periodical imperfections/classimat faults, yarn hairiness, yarn unwinding performance, yarn strength and yarn elongation. The yarn imperfections are dependent on waste level at blow room, card, type of machinery/drafting, type of process, cotton fineness, neps in mixing, noil level and type of autoconer used. The yarn strength is dependent on twist level, fiber length, fiber fineness, short fiber content in drawing sliver, relative humidity in departments and drafting quality. The yarn hairiness is dependent on type of spinning, yarn types, ring and traveller type, lift, lappet dia and fiber fineness. The yarn classimat faults are based on type of spinning, fiber opening efficiency, sliver trash content, exhaust quality and overhead traverse clearers performance. All the above factors play a major role in determining the yarn realization percentage.
B. Raw material quality
The raw material quality is another factor which affects yarn realization. The raw material quality is based on 2.5% span length/ mean length, fineness, fiber strength, fiber maturity, trash content and short fiber content count SFC(n).
The impact of trash content and SFC is very important for change in yarn realization. More amount of trash in raw material, improper ginning, poor quality of raw material leads to more waste generation thereby affecting yarn realization. The SFC is another parameter which is neglected by many mills, but which also has a bearing on yarn realization. It is the fibers that are shorter than 12.5 mm with respect to cotton fibers. The SFC varies between 16 to 37% for different counts spun.
C. Process factors
The process parameters, atmospheric condition of blow room and packing, bale management system in mixing and invisible loss also affect yarn realization. The process parameters include type of machinery used, speeds set, draft maintained, etc. Incorrect process parameters lead to poor quality and more waste extraction thereby affecting the yarn realization. The bale management system also plays a role in yarn realization as mixing should be appropriately done in such a way that waste extraction is minimized without quality compromise. The invisible loss caused due to moisture variation, weight variation, incorrect relative humidity and incorrect accounting of waste contribute to reduced yarn realization.
Yarn realization has to be calculated for determining the material cost. Production and waste have to be computed to calculate yarn realization. Hence, the production and waste estimation in spinning is further discussed. It is followed by examples of production, waste calculation and thereby yarn realization estimation is also done.
Conclusion
Yarn realization is a crucial factor in spinning efficiency, directly impacting production costs and profitability. Achieving higher yarn realization depends on multiple factors those are discussed in this article. By minimizing fiber losses, optimizing machine settings, and implementing effective waste control measures, spinning mills can improve yarn realization, reduce material wastage, and enhance overall productivity.
References
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[3] Process control and yarn quality in spinning. (2016). In WPI Publishing eBooks. https://doi.org/10.1201/b18797
[4] Bhatia, S. (2017). Pollution control in textile industry. In WPI Publishing eBooks. https://doi.org/10.1201/9781315148588
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[6] Kiron, M. I. (2023c, December 16). Yarn realization in spinning. Textile Learner. https://textilelearner.net/yarn-realization-in-spinning/
