Vortex Spinning System
Murata vortex spinning (MVS) is based on the already existing air-jet spinning technology by Murata. It was firstly introduced at Osaka International Textile Machinery Show OTEMAS ’97 by Murata Machinery Ltd. Vortex spinning is another revolutionary system for the production of fasciated yarns, and is gaining greater momentum in the production of yarns from synthetics and cotton in pure form or blends. From the earliest inception of fasciated yarns it was evident that there were limitations, which precluded its wide acceptance. Vortex spinning is 3–5 times higher than rotor spinning and 10–20 times that of ring spinning machine. End users of vortex spun yarn include woven sheets and knitted lightweight shirting.
Murata vortex spinning technology is a modified form of air jet spinning which has attracted a lot of attention because of its advantages over ring spinning, open end and air-jet spinning. It has a high productivity rate, its yarn structure is similar to ring yarn, low hairiness and most important; it is possible to use a wider fiber length range to spin a wider yarn size production rage for 100% cotton. An increasing number of industries are introducing vortex spinning since it’s suitable for spinning rayon yarn that as moderate anti pilling property and softness. Of late, it’s being highly evaluated because it’s capable of producing polyester products requiring luxurious luster.
Vortex spinning systems provide yarn with different structures and properties. Each system has its limitations and advantages in terms of technical feasibility and economic viability. The Murata vortex spinning based on the air jet spinning technology used for a wider range of fiber length. The vortex spun yarn has a two-part structure (core and sheath). In the vortex system, drafted fibers are introduced into a spindle orifice by an air vortex. While entering and passing through the orifice, fibers are twisted by the swirling air. It can deliver yarn at up to 400 mpm.
Vortex spinning, which adopts high speed airflow to insert twist into the yarn, is one of the most promising technological innovations in the textile industry. In vortex spinning, the dynamic behavior of the fiber inside the nozzle, which involves fiber-airflow interaction and fiber-wall contact, plays an important role in the twist insertion process.
Twist Insertion Process of Vortex Spinning
In the twist insertion process of spinning a staple yarn, a strand of fibers is held on one end while the strand length is made to rotate on its axis. The rotation of the strand causes the fibers to adopt helical forms and increase the number of turns of twist. With the insertion of the twist, the fibers are packed together to-form a continuous yarn with special structure and properties. The conventional ring spinning, which uses revolutionary mechanical part to insert twist into the yarn, is currently the most widely used spinning technique. Although ring spinning has the widest spinnable count range, its disadvantages such as low production speed, long processing procedure, and high energy consumption, have limited its productivity and process economy.
Comparatively, the vortex spinning technique utilizes high speed airflow to insert twist into the yarn. This greatly increases the rotational speed of the fiber strand, which can be as high as 200, 000 turns/min. This technique not only increases the production speed and shortens the processing procedure, but also lowers the cost and energy consumption involved in the yarn production. In the global background of energy shortage and manpower cost rising, the vortex spinning technique is one of the most promising technological innovations in the textile industry. In the vortex spinning system, as shown in (Figure-2), the spinning part is composed of an air-jet nozzle and a hollow spindle with a yarn passage through it. The fibers coming from the front rollers are held together and twisted with the action of the high speed airflow inside the nozzle. Fibers that whirl around the hollow spindle tip attach to the core fibers by wrapping onto them and yarn with a similarly real-twisted structure is formed. The formed yarn is then delivered out of the nozzle through the yarn passage of the hollow spindle with the drag of the delivery rollers and fed to the winding part. The most featuring characteristic of the vortex spinning is that it is capable of spinning 100% cotton fibers at very high speed (450m/min) and the produced yarn has a structure much similar to the ring spun yarn.
Principle of Vortex Spinning
Vortex spinning takes drawn cotton sliver and drafts it to the desired yarn count (fineness) via a four-roller apron drafting system. The drafted fibers are then sucked into a nozzle where a high-speed ‘air vortex’ swirls the fibers around the outside of a hollow stationary spindle (see below image). A rotating air vortex twists the free fiber ends around the bridge fibers with true twist, producing a ring yarn type of structure. This makes it possible to process carded yarns also. The twist is inserted as the fibers swirl around the apex of the spindle before being pulled down a shaft that runs through the middle of the spindle. The productivity of the MVS system comes through its delivery speed and the fact that it spins yarn directly from sliver, rather than roving. The resultant yarn is cleared and wound directly onto a package that can be sold readily by the mill.
The finished yarn is wound on a package after its defects have been removed. During the yarn formation, as the twist propagation is prevented by the guide member, most of the fibers do not receive the false twist. Besides, the fiber separation from the bundle occurs everywhere in the entire outer periphery of the bundle. This results in a higher number of wrapper fibers in the yarn. That’s why vortex spun yarns present much more wrapper fibers than air jet spun yarns, and their yarn structure is similar to ring yarns represents an idealized structure of vortex spun yarn.
The following fibers are used in vortex spinning system; staple fibers such as polyester, viscose, cotton and their blends and elastane Sheath: all staple fibers as in core. The characteristics of MVS yarns and fabrics are observed to be comparable to those of ring-spun yarns, i.e., the fabric made from MVS yarn is reported to be as smooth and as soft as that produced from ring-spun yarn. However, MVS requires reasonably good fiber characteristics to achieve these outputs. Fibers must be clean and strong, have a staple length of at least 28 mm and be uniform in length. The production speed is almost independent of yarn count and is in the range of 300–400 m/min. This process is concurrent with rotor spinning and ring spinning in the count range of 12–40 s Ne. Thus with this system, Murata demonstrates a serious alternative to rotor spinning for medium and long staple cotton spinning.
The production cost for 40 s Ne vortex yarn, as compared to equivalent ring and rotor yarns, is approximately 50% and 60%, respectively. The fully automatic process eliminates all rotating mechanical twist-insertion elements. The flexibility of this technology is significantly higher than that of false twist spinning, and will probably take on the latter. Blended yarns can also be produced without any difficulty. MVS has been hailed as a revolutionary new technology for fasciated yarn production. It appears to have a profound scope for spinning of cotton yarns.
Advantages and Disadvantages of Vortex Spinning
Vortex spinning technology was fast introduced by Murata Machinery Ltd in Japan in 1997. This technology is best explained as a development of air jet spinning, making use of air jets for yarn twisting. The main feature of Murata vortex spinning (MVS) is its ability to produce yarn at 400 m/min, which is almost 20 times greater than ring spinning frame production. Other advantages include low maintenance costs, a fully automated piecing system and elimination of roving frame. The yarn and the fabric properties of MVS yarn are claimed by the manufacturer to be comparable to those of ring spun yarn.
One problem with the vortex spinning system is significant fiber loss during yarn formation. This is related to the problem of variations in yarn quality which are not detectable by conventional evenness testers and sometimes only identified by weak points in the finished fabric. The paths followed by the fibers in the currents created by the air jets play a crucial role in yarn quality. Most structural defects are caused by the deflection of fibers in the air jet from their ideal path.
- Technical textile yarns Edited by R. Alagirusamy and A. Das
- Advances in yarn spinning technology Edited by C. A. Lawrence
- Textile Engineering – An Introduction Edited by Yasir Nawab
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Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.