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Jet spinning process and its product characteristics and applications

October 23,2023

Jet spinning  is a new spinning method developed after rotor spinning and friction spinning. It is a novel and unique spinning method that uses compressed air to generate spiral airflow in the nozzle to falsely twist and wrap the stretched yarn. It consists of two parts: one is the core of parallel fibers, and the other is the wrapped fibers wrapped outside the core. The wrapped fiber applies centripetal stress to the core fiber, providing the necessary polymerization force to the yarn body to withstand external stress. The basic principle is to apply two nozzles with opposite airflow directions. After high-speed drafting, the fiber strip is fed to two series nozzles located between the front roller and the yarn output roller in the drafting area. The first nozzle loosens the fibers and wraps the loose free end fibers around the fiber bundle of the yarn core; The second nozzle plays a twisting role. The surface layer of the yarn leaving the output roller presents fiber wrapping, while the core fibers have no twist. The structure and strength of the yarn vary by adjusting the air pressure of the two nozzles.

Characteristics of Jet Spinning

1.1 High production capacity

Jet spinning uses rotating eddy current false twisting to form yarn, without high-speed rotating machine components (such as spindles and wire rings in ring spinning), which can achieve high-speed spinning. The twisting speed of the yarn can reach 200000 r/min to 300000 r/min, the spinning speed can reach 120 m/min to 300 m/min, generally 140 m/min to 180 m/min, and the ring spinning speed is generally 17 m/min to 20 m/min, which is 10 times that of the ring spinning machine. The output of one head of air jet spinning is about 15 spindles of ring spinning, and the output of three heads of air jet spinning. Therefore, using 10 jet spinning machines (each with 72 heads) is equivalent to the production of 10800 spindles of ring spinning, and the production efficiency is high, reaching 95%.

1.2 Short process flow

Jet spinning omits the two processes of roving and winding compared to ring spinning, thus saving 30% of the factory area, reducing labor by about 60%, reducing machine material consumption by about 30%, and significantly reducing energy costs, maintenance costs, and maintenance workload.

1.3 Wide variety adaptability

Jet spinning can spin yarns ranging from 30tex to 7.4tex (20s to 80s), suitable for pure and blended spinning of chemical fibers and cotton. Because it is a dual structure yarn composed of wrapped fibers and core fibers, it has shown great advantages in both knitting and weaving applications.

1.4 Good product quality and distinctive features

The comprehensive evaluation of the quality of jet spun yarn is good, except that the single yarn strength is about 20% lower than that of ring spun yarn, all other quality indicators are better than ring spun yarn. The most prominent feature is the lack of coarse knots and hairiness above 3mm in air jet yarn, and the lower strength CV value compared to ring spun yarn. It is particularly suitable for weaving new types of looms such as rapier looms and air jet looms, and can improve loom efficiency by 2% to 3%.

1.5 High production rate and good working conditions

The air jet spinning process is reduced, and there is also a self stopping device for breaking ends, which reduces the number of flowers and feet. The production rate is about 2% higher than that of ring spinning. The dust content in the jet spinning workshop is generally only 0.3/m3, and the noise is about 84dB. The labor intensity and working environment of the lathe workers are better than those of ring spinning.

1.6 Convenient variety renovation

When modifying the variety, in addition to adjusting the drafting process normally, the twisting part generally only needs to adjust the air pressure of the nozzle. If the range of spinning numbers does not change much, there is no need to adjust the twisting part.

Performance characteristics of jet spun products

Due to the special spinning mechanism of air jet spinning, the structure and performance of air jet yarn are significantly different from those of ring spinning. Its products have a unique style, and the performance of air jet yarn fabrics is significantly different from that of ring spinning fabrics.

2.1 Good anti pilling performance

The dual structure of jet spun yarn greatly reduces the number of free fibers at the tail and head ends, and significantly reduces the number of hairiness when the yarn is over 3mm. Therefore, the fabric surface is smooth and has good pilling resistance, reaching a level of 3.5 or above.

2.2 Good wear resistance

The outer layer of air jet yarn is wrapped with fibers, with clear fiber orientation and high yarn friction coefficient. The friction and cohesion between the inner yarn and the yarn in the fabric are good, and mutual slip is not easy to occur, resulting in improved wear resistance. The wear resistance of jet spun fabrics is more than 30% higher than that of ring spun fabrics. And due to the surface fiber end wrapping structure of jet spun yarn, the yarn has directionality, and its friction performance also has directionality.

2.3 Good breathability, easy to wash and dry quickly

Due to the relatively fluffy structure of jet spun yarn, the core fibers are almost in a parallel state, with large gaps between fibers and a loose structure between fibers, the fabric has good breathability, which has been tested to increase by about 10%. Fast drying speed after washing at the same time.

2.4 High stiffness

Due to the wrapped structure of jet spun yarn, it has a higher degree of looseness compared to ring spun yarn at the same number (about 4% coarser). Its yarn has good roundness and high rigidity. Under the same warp and weft density conditions, the arrangement between yarns in the fabric is tight, making it difficult for the yarn to bend in the fabric, resulting in an increase in stiffness.

2.5 Good dyeing performance and low sizing rate

Due to the fluffy structure of jet spun yarn, the fabric has good color absorption during dyeing and finishing, with darker colors but poorer luster, thus saving dyes. The evenness, color fastness, and color difference of jet spun fabrics are better than those of ring spun fabrics, and they have a large suction capacity. The size is easy to penetrate, resulting in a decrease in sizing rate of about 1%.

2.6 Slightly higher tensile strength, lower tear strength

Although the single yarn strength of jet spun yarn is lower than that of ring spun yarn, the tensile strength of its fabric is not low, slightly higher than that of ring spun yarn fabric. This is mainly because the air jet yarn has uniform evenness, low unevenness in strength, and a large coefficient of friction. After weaving into the fabric, the good adhesion between the yarn and the friction resistance during stretching is the reason. The core fibers of jet spun yarn are in a parallel state, and the adhesion between the fibers is poor. When the side of the yarn is subjected to force, it is reflected in the bearing capacity of a single fiber inside the yarn, so the tear strength of jet spun yarn fabric is lower than that of ring spun yarn.

Product application field

Based on the structural characteristics of the above-mentioned jet spun yarn, unique style rear end products can be developed and produced.

3.1 Woven products

Due to the advantages of less hairiness, uniform strength, and fewer defects, air jet yarn precisely meets the yarn standards for shuttleless looms. Therefore, it is also suitable for use on shuttleless looms. Generally, using air jet yarn can improve loom efficiency by 2% to 3%.

The application of jet spun yarn in woven products can also be divided into the following two categories:

Clothing fabric: By utilizing its advantages of crisp, wear-resistant, breathable, and easy to wash and dry, it can be used to produce products such as dyed and ground down shirts, rainproof poplin for outerwear, or summer clothing fabrics resembling linen. It is cool, wear-resistant, comfortable, and breathable to wear, and representative varieties include T/C: 65/35 or 55/45 14.5tex, 13tex, etc.

Home textile products: With their strong breathability, high wear resistance, good moisture absorption, and strong dyeability, they can be used to produce bedding such as bed sheets, duvet covers, bed covers, pillowcases, and decorative items such as curtains and tablecloths. They are suitable for hotel and family room decoration, and representative varieties include T/C50/50 or 40/60 15.5tex, 14.5tex, and T1 00% 36tex~19.5tex (16s~30s).

A. Shirt fabric. Mainly utilizing the advantages of air jet yarn such as good stiffness and strong breathability, the products mainly include thick colored woven ground velvet and thin colored woven poplin.

B. Bedclothes. Mainly utilizing the characteristics of its fabric such as strong breathability, thick and plump, strong moisture absorption, and strong stiffness, the United States and Japan are very popular in weaving bedding with jet yarn. There are mainly dozens of flower patterns such as bleached, dyed, and printed bed sheets, duvet covers, bed covers, and pillowcases.

C. Interior decorative fabrics. Jet spinning can simultaneously feed two different raw materials into the spinning of core-spun yarn, and in recent years, the use of short polyester core-spun yarn in foreign countries has become very popular. The fabric wrapped with pure cotton and short polyester as the core yarn is treated with rotting, resulting in a prominent and plump pattern with a soft luster. The style of making curtains, tablecloths, and other products is very good, and the price of such products is much lower than that of using filament cored yarn.

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