Tencel® fibres spun by the Com4®twin spintwist method meet the highest standards for exquisite Indian Sarees. It equals or surpasses the benchmark - the traditional saree, woven with 100% silk, in many aspects in the fibric. Considering fibre- and yarn formation costs, it is a most lucrative alternative to silk sarees. The following findings are based on a joint project of the fibre producer Lenzing AG, Austria and Rieter Machine Works Ltd, Switzerland. 

Tencel® - a Cellulosic fibre

Cellulosic fibres like Viscose, Modal, Tencel are good alternatives to natural fibres such as cotton and silk. Generally speaking, cellulosic fibres display very good moisture absorbtion, they dye readily, are antistatic, have a soft handle, are pleasant to the skin and easy care. Compared with other cellulosic fibres, such as Viscose and Modal, Tencel features higher wet strength, has a better dimensional stability and lower washing shrinkage. Tencel is produced with an environmentally friendly solvent spinning process.

Com4®twin – Spintwisting on ComforSpin Machines

The Spintwist method on conventional ringspinning machines has been introduced to the spinning industry many years back. It, however, has never gained a substantial market share for several reasons. The larger spinning triangle of conventional ringspinning leads to higher yarn hairiness and subsequently to lower yarn tenacity. The Com4twin technology combines two important exceptional advantages. The smaller spinning triangle results in lower hairiness and the smaller yarn triangle contributes to better running performance and to reduction in fibre loss.

ComforSpin machines applying a perforated metal cylinder are most suitable for the production of compacted twin yarn. The conversion is simple. Merely roving condensers, suction inserts and air guide elements are to be changed for twin application. 

The creel has to accommodate the double number of roving bobbins. The ComforSpin System facilitates separate drafting and compacting of the two rovings respectively fibre strands. To obtain the desired yarn properties it is essential that the two individual fibre strands reach the last nipping point fully compacted before the fibres are twisted into yarn at the point of the twisting triangle.

Com4®twin – Yarn Properties

The afore mentioned spinning conditions enhance low hairiness and high dynamometric yarn properties.

Yet, despite the excellent quality parameters of Com4twin yarns it cannot be compared visually with classical 2-ply yarns. The difference is to be found in the sense of twisting. Classical two-ply yarns spun with S-twist are usually twisted in Z-direction and vice versa. Where as spin-twisted yarns are spun with one direction of twist only. Thus, the visual yarn structure and consequently also the fabric appearance of compacted Com4twin yarns differ from that of conventional 2-ply yarns.

Com4®twin – Economics

The Com4®twin yarn for this trial was spun of Tencel micro fibre 0.9 dtex, 34 mm. Micro fibres are “compacting friendly” and also accommodate higher numbers of fibres in the cross section for a particular yarn count. Emphasis has been put on technological aspects of Com4twin yarns. However the cost position here is of equal importance and offers a most lucrative alternative in spinning. Taking the yarn count Ne 50 the conversion cost per kg of Com4twin yarn are in fact 45% below the cost of conventionally spun 2-ply yarn

Com4®twin – Exquisite Fabrics

For the fabric for these sarees 100% silk was used for warp and 100% Micro Tencel Com4twin yarn of Ne 75 (150/2) for weft.

The meanwhile widely acknowledged cost savings and the ecological aspects of down-stream processing of Com4 yarns have been reconfirmed in this Com4twin project – namely the savings in sizing, de-sizing, dyeing an finishing. Worth mentioning is the fact that this fabric dyes brighter and thus displays distinctive contours highly appreciated for the ornaments in sarees. It furthemore displays a softer touch compared to 100% silk in warp and weft.

Source:
Bert Rusch/Harald Schwippl, Head Product Management Ringspinning/Head Technology Spun Yarn Systems, Rieter Machine Works Ltd, Switzerland. Email: albert.rusch@rieter.com/harald.schwippl@rieter.com