How to reasonably use low grade cotton in yarn thread spinning process

The main physical properties of yarn thread raw cotton, such as length, linear density, strength, maturity and impurity, are closely related to spinning process and yarn thread quality. 

In order to fully and rationally utilize the characteristics of different raw cotton and achieve the goal of guaranteeing quality, reducing cost and stabilizing yarn thread production, cotton yarn thread spinning mills concentrate on different grades. Mixed cotton is composed of cotton, which is called cotton yarn thread blending.

Purpose of yarn thread thread cotton blending

Maintaining the relative stability of production and yarn thread quality, in order to produce with high quality and low consumption, the production process and yarn thread quality should be kept relatively stable, and the relative stability of raw cotton properties is an important condition for production and quality stability.

(2) Reasonable use of raw cotton to meet yarn thread quality requirements; blended cotton spinning to make full use of the characteristics of various cotton, learn from strengths to complement weaknesses, to meet yarn quality requirements.

(3) Save cotton and reduce cost; raw cotton is priced according to quality, and the price difference between raw cotton of different lengths and grades is very large. 

Raw cotton accounts for about 80% of the yarn thread spinning cost. If the grade of raw cotton is higher, although the yarn quality can be guaranteed, the production cost will increase. 

Therefore, the unit price of cotton blending and the amount of cotton used per ton of yarn thread should be controlled in order to save cotton and reduce cost. Increase cotton blending technology and rationally use all levels of cotton yarn thread spinning.

Practice of making full use of low grade cotton yarn thread

1. Strengthen inspection

For low-grade cotton, we must strengthen the inspection work, especially do a good job of package-by-package inspection, according to the color characteristics, the amount of impurities, maturity classification stacking. According to its strength, size and short pile, it can be divided into three categories: upper, middle and lower. The spinning performance is further mastered by single mark trial spinning.

2. Rational allocation

In the light of the long-term development, the use of low-grade cotton should be stable. 

Gradual yarn thread blending should be adopted in large queues by stages, with fewer yarns used first, more yarns used first, and experience used later, and then popularized in large areas.

3. Make full use of the inherent advantages of low-grade cotton 

(1) Making full use of the advantages of low-grade cotton fiber fineness to improve yarn thread strength. 

Fiber yarn thread fineness increases relatively in the cross-section, and it is not easy to slip when the friction force increases. 

When the yarn thread number is fixed, the more fibers in the cross-section, the better evenness of the yarn thread. 

The yarn thread strength is even because the fibers are thin, soft, easy to draw and even winding.

(2) Using the advantage factor of long length of low-grade cotton fibers and long fibers to spin, the overlapping parts of the yarns threads are longer, which will increase the friction and cohesion between the fibers, and the yarn thread strength will be greater. 

In general, the longer the cotton fiber length, the higher the yarn thread spinning count, and vice versa. 

For every 1 mm increase in quality length, yarn thread strength can be increased by 1%-2%, or even higher. 

Generally, the length of low grade cotton is longer, mostly in the range of 28 mm to 29 mm.

The use of colour and lustre can make the cotton yarn thread with cream colour when the amount of low grade cotton is less than 10%, but the cotton yarn thread and cotton cloth will turn yellow if the cotton yarn thread and cotton cloth are mixed too much. 

When used properly, the fabric yarn thread is plump, the cotton miscellaneous is not obvious, and the strip shadow is clear.

4. Appropriate adjustment of process

Quantitative reduction of each process can enhance the yarn thread opening carding and impurity removal. Strengthen the control of planktonic fibers and improve the fiber straightening parallelism.

Cleaning cotton should be as loose as possible and less beaten. 

Cotton box machinery dust rod spacing increases appropriately, reduces recycling, relies on centrifugal force to remove more impurities, reduces cotton box machine oblique curtain spacing, increases angle nail height and length appropriately, in order to facilitate loosening; beater speed is appropriate, not too fast, in order to avoid damage to fibers yarn thread; accelerates uniform cotton roller speed, increases mixing effect, and increases loosening effect. 

It can loosen fibers without damaging them, which is beneficial for stray and short lint removal; properly increasing impurity removal points, appropriately reducing the distance between hitter and dust rod, increasing looseness, more falling objects and more impurities removal; appropriately increasing fan speed at the entrance of each cotton box, making air supply from the upper part or side, reducing recycling and increasing impurities removal.

(2) Carding cotton adopts strong carding process to remove more fine impurities and short fibers yarn thread. 

Increase the speed of cylinder and taker-in properly to increase the puncture combing ability of taker-in roll; 4.5 interval between taker-in roll and small leak bottom, slow air flow, reduce recovery; properly accelerate the speed of cover plate and reduce the distance between cover plate and cylinder, multi-row short pile; slow down the speed of doffer, enhance the combing function, improve the cotton web clarity; reduce the dust remover and shorten the small leak. 

At the bottom, increase the clutter area; the lower yarn thread opening of the back cover plate of Xilin is larger than the distance between Xilin and the bottom of the leak, so that the airflow can smoothly lead to the direction of the small leak without eddy current; and the distance between the large leak bottom and the bottom of Xilin is properly enlarged to ease the airflow. 

The purpose of the above process adjustment is to strengthen carding and remove short fibers yarn thread and impurities as fully as possible, as well as to properly increase the number of needle reading and press the "four fast and one positive" machine to keep the equipment in normal condition.

(3) In the process of coalescence, coarseness and fineness, the roller gauge should be reduced properly and the pressure should be increased so as to effectively control and reduce the free fibers yarn thread, improve the fiber yarn thread straightening parallelism and evenness. 

Yarn thread roving twist coefficient should be properly increased to increase the cohesive force between fibers.

Quality first, overall consideration, is to deal with the relationship between quality and saving cotton. 

The key point of overall arrangement is to find out the trend of yarn thread of cotton and raw cotton quality in time, grasp the information and feedback of product quality at any time, and adjust raw cotton flexibly and carefully. 

In short, rational and scientific use of low-grade cotton is of great significance to rational use of resources and increase the competitiveness of enterprises in the market.