Rieter

Twist spinning

Index

This is a process that has been known generally for some time but has been rediscovered in recent years. Today it is used mainly in worsted spinning mills. Two systems are available:

  • Duospun, from Ems SA and Huber and Suhner AG; and
  • Sirospun, from Zinser Textilmaschinen GmbH.

The difference, and the only patentable aspect of the process, lies in the procedure adopted when one of the two ends leaving the drafting arrangement breaks. In the Duospin process, the two yarns are recombined almost instantly, whereas the Sirospun system interrupts spinning at this single spinning position.
The mode of operation [4] is shown in Fig. 11 and Fig. 12. Two rovings are passed individually through a slightly modified, but generally conventional drafting arrangement of a normal ring spinning machine. The fiber strands, attenuated by a draft in the normal range, leave the delivery roller separately. At this point, they are each subjected to twist generated by a common spindle (cop); thus, within the spinning triangle, they are twisted into two single yarns, and these are simultaneously bound together to form a composite yarn. Each of the two single strands and the resulting composite yarn contains twist, and the direction of twist is the same for both the single ends and the composite product. This twist-on-twist (ZZ or SS) produces a yarn that is somewhat more compact, with a firmer core, than the usual ply yarn with opposing twist (ZS or SZ). To produce twist-spun yarn, it is only necessary to add several auxiliary components to the ring frame and to provide an enlarged creel to accommodate twice the usual number of packages.
This spinning process, which is already in use in worsted spinning, primarily offers economic advantages, because the production of the ring spinning and winding machines is roughly doubled (two ends instead of one at approximately the same speed). In addition, plying and twisting are eliminated.
In worsted spinning, twist spinning has therefore secured a certain share of the market. However, due to the different twist structure, it cannot completely replace the conventional 2-fold yarn process.

Fig. 11 – Formation of a twist-spun yarn

Fig. 12 – The twist-spinning process