Rieter

Development

Index

The two nozzle air-jet spinning system (refer to section “2.6.2. Two nozzle air-jet spinning”) achieves a fasciated yarn character, i.e. a structure with twistless core and twisted surface or wrapping fibers, through false twist during spinning. However, the false twist limits the percentage of twisted surface fibers to a relative low level of about 5%. Two nozzle air-jet spinning is therefore quite successful in processing man-made fibers and blends with cotton, whereas when spinning 100% cotton, i.e. somewhat shorter fibers, air-jet yarns do not achieve sufficient strength (Fig. 33). For this reason, the USA – with a large market for blended cotton/polyester yarns – has a considerable number of airjet machines in operation. In Europe and Asia, however, where predominantly cotton is processed, air-jet spinning has had no success.

In view of this situation, Murata developed a new spinning process for fasciated yarns. The first patents erase were published in the 1980s. At that time an air vortex was combined with a rotating mechanical element. Since then, Murata has abandoned the rotating element, leaving just the air vortex with no movable mechanical part in the yarn formation zone. Murata presented this new air-jet system under the name of Murata Vortex Spinning (MVS) at the Otemas 97 and then at the ITMA 99 (Fig. 34 a). As in two nozzle air-jet spinning, this system has a drafting unit for processing drawframe slivers and no moving parts in the spinning zone. Air-jet spinning, however, does not make use of false twist for yarn formation.

In 2008 Rieter launched its own Air-jet spinning machine J 10 in the market. A double sided machine with 100 individually driven spinning positions and 4 travelling robots aims at pushing the economy of this spinning system further (Fig. 34 b)).

Between the drafting unit and the point of yarn formation at the entry to a stationary spindle (tube), the fibers are conveyed absolutely parallel to each other (Fig. 35). During this fiber transport, a certain number of fiber ends are separated from the main fiber flow. These fiber ends are then twisted around the non-rotating yarn core at the entry of the hollow spindle by the action of a single air vortex.

Compared to airjet spinning, this spinning process permits a considerable increase in the number of surface fibers, i.e. wrapping fibers, to the range of 15 to 30%. This has a positive effect on yarn strength, particularly when spinning cotton. The air-jet process has thus practically eliminated the main handicap of the two nozzle air-jet spinning principle.

Fig. 33 – Relative yarn strength

Fig. 34 a) – Air-jet spinning principle by Murata (MVS)

Fig. 34 b) – Air-jet spinning principle by Rieter (J 10)

Fig. 35 – Fiber transport from front rollers (Murata MVS)