Yarn formation using Air-Jet Spinners
Yarn spinning with compressed air
The Air-Jet spinning is very sensitive to the fiber length and fiber length distribution(short fiber content) of the material being processed. The amount of wrapping twist varies depending upon the length of the wrapping fibers as only a part of the total extent is utilized to wrap the core fibers. Wrapping the fibers shorter 12.5 mm practically do not make a significant contribution to the strength of the yarn.Air-jet Spinning is suitable for processing medium and long staple comber cotton fibers a
In the process of Card-Spinning, the basic requirement is to be able to cleanly split the web into ribbons of controlled width. Once a ribbon with required fiber density is obtained, the next challenge is to spin all the split ribbons into yarn simultaneously.
The spinning technology should be such that the space required per sinning head is small. This is so because splitting each strip about 2 inches wide results in a total of 10-15 strips for the width of the card web (with both web edges discarded). In order to spin all these ribbons simultaneously, an equal number of spinning heads would be required limiting the available space per spinning head.
In order to make the system more versatile, the technology adopted should allow the spinning at different speeds and different counts of yarn. Also, the complexity of the system should not be very high. The bulkiness of the system can restrict the access to the card web, which is not desirable.This makes air-jet spinning a good candidate for the Card-Spinning system.
A typical carding machine production rate ranges from 80-100 kg/hr. However, newer machines are claimed to have production rates up to 140kg/hr (Card DK 903 by Truetzschler) and 120kg/hr (Card C 51 by Rieter). These speeds for a card web density of 10-15 g/m correspond to web speeds of up to 250m/min. This suggests that even if the split ribbons are spun without any further drafting, spinning speeds should be of the order of 250 m/min. Furthermore, for better fiber orientation in the yarn, some drafting of the ribbons would be required, which increases the required spinning speeds even more.
Therefore, a high-speed spinning technology is best suited for the purpose. Such high speeds can be achieved only by vortex (up to 350 m/min) or air-jet (up to 200 m/min) spinning technology. The other alternative would be to lower the carding speeds, which may not be desirable in the first place, not to lose on carding efficiency. However, for a typical carding machine running at slower speeds (such as the machine being used at 20-40 m/min), Rotor spinning could be a potential candidate, but other constraints, that of, space and system complexity support the use of air-jet spinning.
An air-jet nozzle would occupy the least space as compared to any other technology and is the simplest in terms of handling with least number of moving parts. All these advantages make air jet spinning to be the most suitable for the Card Spinning.
Air-jet spinning is a most gentle spinning method and no revolving parts are used to insert a measurable amount of twist. High friction polyester fibers of regular cut length are more suitable for air jet spinning in the medium and fine count range. It cannot handle short length cotton fibers.
The finer the count, the closer is the strength to that of ringspun yarn. Murata Jet Spinner (MJS) and Murata 851 Vortex Spinner (MVS) are the two major brands of air-jet spinning machines, which are very popular in the U.S.A. MJS can spin polyester, cotton, rayon, acrylic, and blends of each in a count range of Ne10 to Ne60.Air jet yarns are used for the production of synthetic fabrics, print cloth, sheetings, shirting, sewing thread, etc.