Cotton matching in cotton spinning process (2)
4. Cotton matching method
At present, cotton spinning enterprises generally use the cotton matching method of classification and queuing. The classification and queuing method is based on the characteristics of raw cotton and the different requirements of yarns, which are suitable for spinning. The raw cotton of a certain type of yarn is divided into one category. Queuing means arranging the raw cotton of the same category in a queue based on origin, nature, and color, and then combining it with the cotton allocation schedule to compile a cotton allocation queue list. The advantage of the classification and queuing method is that it can arrange the cotton components of the yarn at one stage in a planned manner, which can ensure the mixing effect. It is a scientific method of cotton matching. a. Classification of raw cotton
The following points should be considered when classifying raw cotton:
First, raw cotton can be classified according to the specifications of spinning products, such as: combed 32-40 count for knitting The yarn uses the same kind of raw cotton.
Second, the ingredients of each cotton category are determined according to the specific technical indicators of raw cotton, but the technical indicators of each batch of raw cotton should not be too different. For example, the control range is as follows: Grade: 1-2 Length: 2- 4mm Impurity content: within 1-2% Moisture content within 1-2% Packaging: tight package with tight package loose package with loose package The weight of the package is close to the origin and is stable, etc.
Third, the cotton spinning process is different, and the packaging Cotton classification should also be handled flexibly. For example, if the same raw cotton has different yarn quality in different seasons, the cotton classification should be adjusted as soon as possible. b. Queuing of raw cotton
On the basis of classification, the same type of raw cotton is arranged into several queues, and raw cotton with relatively close origin and technical indicators is arranged in one queue, so that when the raw cotton of a batch number is used up, , replace it with raw cotton from another batch number in the same team, so that the characteristics of the raw cotton being used do not change significantly, to achieve the purpose of stable production and ensuring the quality of the yarn. To this end, the raw cotton queue should follow the following points:
① Main component:
In order to ensure the stability of the production process and yarn quality, several batches of raw cotton with relatively close technical indicators are generally consciously arranged as the main component in the cotton distribution, and the general origin is the main component. , and some use length as the main body. The main component generally accounts for about 70% of the total cotton, which can avoid excessive mixing of very good or poor quality raw cotton. However, because the properties of raw cotton are very complex, in specific production, if it is difficult to use one team of raw cotton as the main component, you can consider using several batches of raw cotton, but be careful not to have a double-peak batch phenomenon when using it.
② Number of teams and mixing percentage
There is a direct relationship between the number of teams and the mixing ratio. If the number of teams is large, the mixing ratio will be small. If the number of teams is small, the mixing ratio will be large. When there are too many teams, the mixing ratio will be large. Production management is difficult, and it is easy to cause uneven cotton mixing. When the number of teams is too small, the mixing is relatively large, and it is easy to cause large differences in the performance of raw cotton when batches are received.
Therefore, when determining the number of teams, you must first know the cotton mixing processing method. If manual small-batch production is used, the number of teams should be small, no more than 4 teams. When mixing cotton with the cotton picking machine, it can be increased to 6-9 Team, if drawing and strip mixing are used in the post-process, the matching ratio of cotton slivers must also be considered.
Secondly, when determining the number of teams, we must also consider the total amount of raw cotton input. When cotton yarn is produced in small batches, the number of teams will not be too large.
Furthermore, when determining the number of teams, factors such as the origin, variety, and quality indicators of raw cotton must also be considered. There are many ginners and varieties in raw cotton production areas. When the quality difference is large, the number of teams is likely to increase. When determining the number of teams, the variety and requirements of the product must also be considered. For example, when the color requirements of the product are higher, the number of teams is likely to be larger. When the quality of the yarn fluctuates greatly, the number of teams should also be larger.
When the number of teams is determined, the blending percentage of various raw cottons can be determined according to the quality of raw cotton and yarn quality requirements. In order to reduce fluctuations in yarn quality, the maximum blending ratio is generally about 25%. The factory’s raw material procedure: 1. Feeding procedure: Generally, settlement is based on gross weight (local cotton) or net weight (imported) or quasi-weight (Xinjiang cotton). 2. Material picking in the workshop: Generally, factories calculate based on gross weight, and the production rate depends on the condition of raw cotton: (1) Open-end spinning: with cotton grade: 4 to 6: 1.12 per ton spun. (2) Open-end spinning: When cotton grade 4-6 is added, 1.15-1.2 can be spun per ton, depending on the cotton mix. (3) Ring spinning carded card: When the cotton grade is 3, 1.08-1.1 can be spun per ton. (4) Ring spinning combed: When the cotton grade is 2, 1.34—1.38 is used to spin one ton. (5) When the ring-spun combed long-staple cotton high-count yarn is grade 1-2, the spin rate is 1.38—1.46 per ton, depending on the long-staple ratio. 3. Calculation method:
Cotton collection in the workshop—gross weight weighing–cumulative total weight of monthly inventory
Cotton yarn in the workshop–installed yarn in accordance with national standards– –The accumulated monthly inventory quantity is accumulated.
The weight of semi-finished products in the workshop at the end of the month – the number of semi-finished products in the inventory last month.
Example: A certain factory used 120 tons of raw cotton or usable waste in October. It produced 80 pieces of 10 tons, 40 pieces of 40 tons, and air-end spinning of 50 tons. A total of 100 tons of various types of cotton yarns were put into storage. The inventory of semi-finished products in progress in the workshop this month is 50 tons, and the inventory of semi-finished products last month was 60 tons. Then the production rate of this workshop in October is calculated as: 120-(60-50)/100=1.1, then the workshop is in production this month. The success rate is 1.1. When the usable waste or other waste produced is borrowed from other factories, the accrued raw materials will be reduced.
In order to reduce quality problems such as cloth surface rungs, the difference in micronaire value of cotton and cotton blended fibers in each batch must be controlled within 0.4. Raw cotton transactions in the international market also usually includeThe clone value is one of the reference indicators for price. For raw cotton that exceeds or fails to meet the micronaire parameter of spinnability, the price will be reduced or discounted.
Single fiber strength is also one of the main indicators that determines the strength of the yarn. Cotton fiber has to constantly withstand external forces during the spinning process. A certain strength of the fiber is one of the necessary conditions for the cotton fiber to have spinning performance. 1. Under normal circumstances, if the cotton fiber is strong, the yarn will be strong. The cotton fiber strength is not only related to the fiber thickness, but also to the cotton variety and growth conditions. It is required to achieve the required single yarn strength when spinning different varieties. , special attention should be paid to the single fiber strength of cotton.
Raw cotton defects are substances harmful to spinning caused by poor development or poor rolling during cotton growth. Raw cotton defects are difficult to remove during the spinning process, or are wrapped in the yarn, or attached to the yarn. In the thread, the evenness will deteriorate, end breaks will increase, and the appearance will be very poor, which will directly harm the spinning production and the quality of the final product.
The sugar contained in cotton fiber refers to the general term for soluble sugars, including physiological sugars contained in the fiber itself and exogenous substances attached to the surface. When the sugar content in raw cotton is too high, fiber adhesion will obviously occur during carding, combing, drawing, roving, spinning and other processes, affecting normal production, especially the new domestic equipment that is gradually put into use. Raw cotton with too high sugar content is even more unsuitable. Therefore, no matter how favorable the price is for raw cotton with excessive sugar content, use it with caution, especially when it is used to make high-end knitted fabrics.
Doing a good job in trial spinning of raw cotton can avoid or eliminate the limitations and errors caused by sensory testing and instrument testing. Therefore, before the raw cotton is put into large-scale production, small batch trial spinning of new component raw cotton should be arranged, and then based on the trial spinning The spinning conditions and yarn quality are used to arrange the mixed use of new cotton.
When carrying out new processes and new technologies, small batch trial spinning should also be carried out to confirm the correct use of raw cotton. Doing a good job in trial spinning can reduce yarn quality fluctuations and correctly reflect the use value and economy of the fiber. Value, predicting yarn performance, can ensure that product quality will not fluctuate over time spans. Only then can product quality be recognized by the market.
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