How to avoid or reduce the weft, weft shrinkage and looping during the weaving process

Release date: 2018-04-23 14:33:18

Weft-in-weaving is to supply the hank or skein yarn of the weaving section to the spinning section, and the weft winding machine is re-wound into fibers suitable for the shuttle size and for ease of weaving.
General cotton mills, such as the production of low-grade fabrics, use the weft yarns supplied by the factory between the spun yarns without the weft-wrapping process; they are called direct weft yarns; and the weft yarns used in wool, silk, hemp, and yarn-dyed factories have to pass through. Weft-inserting, rewinding and forming, called indirect weft yarns. In recent years, with the continuous development of production, the production of high-grade fabrics has been greatly increased. Therefore, many cotton mills often use indirect weft yarns.
The use of a weft-inserting process can improve the technical performance of the yarn and remove some of the defects, swarf and impurities on the yarn, thereby improving the quality of the weft yarn. At the same time, due to the higher winding density after rewinding, it is approximately 120-150% of the direct weft yarn, which increases the amount of yarn contained in the fiber and reduces the number of looms for looms, which improves the efficiency of the loom, and also increases the efficiency of the loom. Reducing the change of weft yarns; and also reducing weft stoppage caused by weft insertion and fabric weft reduction. In addition, since the winding is tight and well-formed, the weft point on the loom is also reduced.
The disadvantage of using indirect weft is that the winding and weft insertion processes are increased, thereby increasing the area of the factory and the production cost. Whether weaving procedures are used or not depends on the requirements of different products. At present, some looms have been equipped with a front winder, which not only has all the advantages of the weft pick, but also overcomes some of the above shortcomings, but the looms are expensive.
In the weaving process, when the weft yarn tension is too small and the weft yarn twist is large, or when the polyester/cotton yarn is as elastic and anti-tamper as strong, weft, weft shrinkage and looping may occur. In order to avoid or reduce this drawback, in addition to reasonably reducing the weft yarn twist and increasing the tension at the time of unwinding, we often use the method of supplying moisture, heating, or both to stabilize the yarn twist. This process is generally called heat and moisture setting.
Under the effect of heat and humidity, the yarn decreases its rigidity and increases its volume. For example, in the environment where the relative humidity increases from 45% to 100%, the volume of the cotton yarn increases by about 14%. The increase of the volume is the increase of the diameter of the yarn, so that the friction and interaction force between the yarn and the yarn is also increased, thus reducing the possibility of the weft thread being plucked, wefted, and looped.
An appropriate moisture regain can reduce weft removal, but too much water can degrade the physical and mechanical properties of the yarn, and yellow stripes can form on the fabric, which can also cause difficulty in unwinding. Therefore, it is appropriate to give wet treatment, otherwise it will produce short cuts and thinning and other ills. The proper moisture regain of cotton weft is 8-9%. In weft yarns coming from a spinning mill, the moisture regain is usually only 5.6%. Therefore, wetting must be performed before the weaving mill weaving, especially in winter.
In polyester/cotton weft yarns, polyester fibers typically account for 65%, so polyester fibers play a dominant role in determining yarn properties. For polyester fibers with good elasticity and thermoplasticity, heating methods can be used to accelerate the relaxation process of the molecules so as to achieve the goal of stabilizing the yarn twist when it is cooled again. The setting temperature should not exceed 100C so as not to damage the strength of the yarn, and at the same time it must not exceed the setting temperature of the printing and dyeing factory, otherwise it will affect the style of the final product. For polyester/cotton weft yarns, wetting is also used to replace wet set.