Effect of ring and vortex spinning technologies

Ring spinning was invented by Thorp, back in 1828. To date, the concept of ring frames remains same. Ring spinning systems have been refined in order to gain higher production speed combined with adequate quality. By far, ring spinning is the most widely used spinning technique in the world due to its versatility and good quality yarn manufacturing.

Ring spinning has various disadvantages, such as numerous stages of production, yarn breakages, low capacity of cops, high energy cost, low production rate and many more. To overcome these faults, in 1997 Murata came up with the vortex spinning machine (MVS 850) which turned out to be a huge advancement to the conventional ring spinning technology. The production speed of vortex machines is up to 20 times higher than the ring spinning, the stages of production are reduced, labor reduction by 60 %, cost reduction, space reduction by 30 %, power reduction by 30 % etc. [1, 2].

Market trends
While in India 67 % consumed fiber is cotton, which is more than the double of global cotton consumption, trends shows that polyester (PET) is and will be leading the global market. It can be produced with good quality on a vortex machine. Another major reason for the lack of popularity of vortex is the hairiness produced. Hairiness gives comfort to the wearer which is prioritized in Indian market. However, hairiness has various adverse effect on the environment and microfibers pollution accounts for the most [3, 4].

Effect on the yarn and fabric structure
Murata Machinery Ltd., Kyoto/Japan, had studied the effect of ring and vortex spinning technology on yarn and fabric characteristics. The results are:
Hairiness
-           Ring yarn
No untwisted part is present. Some degree of twist is present throughout the yarn, from the center to the surface of the yarn. In uneven yarn thickness areas, the twist will be high in the thinner section and low at the thicker section resulting in high hairiness [5].
-           Vortex yarn
Twist is prominent toward the outside of the yarn, while at the center of the yarn, fibers are parallel.

Table 1: Yarn characteristics of viscose yarn (Source: (DKTES)

Resistance to pilling and abrasion
Fabrics knitted from vortex yarn show more resistance to pilling and abrasion than the fabric knitted from regular ring spun yarn. The effect of pilling on knit fabric after 2 hours and 30 minutes of abrasion testing shows that fabric knitted from vortex yarn shows 3.0 grade while fabric knitted from ring yarn shows 1.5 grade [5].

Lint comparison
Lint refers to suitable long fiber for producing yarn, separated from strand of fibers during spinning or knitting process. Lint is extremely harmful for the machine operators as inhalation of excessive amounts of lint can cause diseases of the lungs, such as byssinosis. From referred data it can be stated that vortex spinning produces less lint as compared to ring spinning [5].

Effect on twist structure of ring and vortex yarn
Ring spinning is a continuous spinning process in which twist is inserted into a yarn by a small circulating traveler. While 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 [5].

Effect on viscose yarn characteristics
To understand the effect on yarn characteristics, 100 % gray viscose 30/1s hosiery grade yarn was manufactured using ring and vortex spinning technologies.
Lot No. Ring Viscose = V130130 and V130140 (29/09/2019)
After spinning both the yarns, they were tested on tensile strength tester. 50 yarn samples each having length of 300 mm were tested and results were calculated as per ASTM D2256.

Fig. 1: Strength of vortex and ring spun yarn (Source: DKTES)

Fig. 1 shows the strength values for both yarns. Vortex yarn has less tensile strength than that of ring spun yarn. This is because in ring spun yarn twist insertion and winding take place simultaneously thus the yarn does not have any wrapper yarns. The strength of ring yarn is almost 20 % more than that of vortex yarn. Twist imparts higher strength to the ring yarn.
Similarly, CSP (Count Strength Product) of both the yarns were calculated and readings were observed.

Fig. 2: CSP of vortex and ring spun yarn (Source: DKTES)

Ring spun yarn has greater CSP value than vortex yarn (Fig. 2). This is because CSP value is directly proportional to the strength of yarn.
Other properties of vortex and ring yarns (Fig. 3) are:
•        The number of imperfections is less in the case of vortex yarn comparatively to ring yarn due to its more uniform structure.
•        Hairiness is less in case of vortex as the structure is uniform and each fiber is guided properly into the fiber body.
•        Moisture absorption is good in vortex yarn than ring yarn due to its positive absorption and diffusion properties.

Fig. 3: Other properties (Source: DKTES)

Effect on other factors

Production speed
Latest MVS 870EX by Murata has a delivery speed of 550 m/min while ring spinning produces a yarn with maximum speed of 27-28 m/min, which means that the production speed of vortex is almost 20 times higher than that of ring spinning machines.

Range of count
Ring spinning is capable of producing yarn of count range from 2-200s Ne, which is the reason for its popularity, while vortex is capable of producing yarn of count range from 10-70s Ne.

Power, labor and space consumption
According to Murata, the power consumed for producing 1 kg of ring yarn is 4.25 kWh while for producing 1 kg of vortex yarn is 2.98 kWh which is almost 30 % less (as of October 2020). Labor requirement for vortex is reduced by 60 % and that of ring spinning machines. Space is reduced by 30 % for vortex.

Costs – productivity
When fiber bundles pass through the nip, they are affected by the vortex and lead to slightly reinforced and folded structure that can later be twisted less by the traveler and the ring. Also, it does not require high-speed rotating mechanical parts, so production increases. One vortex head is equivalent to 20 ring spinning spindles as vortex spinning can achieve the delivery speed of 550 m/min.

Table 2: Cost comparison of vortex and ring spinning

Conclusion
Considering the analytical results, vortex yarns slightly have the upper hand towards hairiness and moisture regain, whereas it is slightly lower in strength, CSP, Rkm.
Uster % is greater whereas elongation was less in vortex yarn than in ring spun yarn. The resistance to pilling and abrasion is better in fabric woven/knitted with vortex yarn. Both ring and vortex spinning technologies have their pros and cons. Which type of technology to is be used depends on the end-use of the yarn. Considering versatility and strength of yarn, it is hard to beat the ring spinning process.
Vortex spinning is a growing technology and has the potential to overcome its drawbacks, while ring spinning is conventional established technology and no other technology has been able to thoroughly replace it.

References
[1]     https://www.muratec-vortex.com/, cited on 17/04/21
[2]     Rameshkumar, C.; Anandkumar, P.; Senthilnathan, P.; Jeevitha, R.; Anbumani, N.: Comparative Studies on Ring Rotor and Vortex Yarn Knitted Fabrics, Autex Research Journal 8 (2008) 4, 100-105
[3]     Market Analysis: Black Horse in The Yarn, Vortex Spinning Human Cotton Yarn Prices Move Up One After Another http://www.sjfzxm.com/global/en/575796.html, cited on 2020/8/25
[4]     Begum, H.A.; Rahman Khan, K.; Rahman, M.: An Overview on Spinning Mechanism, Yarn Structure and Advantageous Characteristics of Vortex Spun Yarn and Fabric, Advances in Applied Sciences 3 (2018) 5, 58-64
[5]     Murata Machinery Ltd., Vortex Yarn Guide, https://www.muratec-vortex.com/vortex01.html, cited on 17/04/21
[6]     Günaydin, G.K.; Soydan, A.S.: Vortex Spinning System and Vortex Yarn Structure, IntechOpen (2017), DOI: 10.5772/67076
[7]     Zeguang Pei; Chongwen Yu: Study on the Principle of Yarn Formation of Murata Vortex Spinning Using Numerical Simulation, Textile Research Journal 79 (2009) 1274-1280