Effect of Doubling on the Tenacity of Air-Vortex-Spun Yarns

With the open-end (OE) spinning system becoming a commercial proposition in the form of BO-200 machine (based on t,he circumferential assembly system) in 1967, of the remaining OE spinning systems, air-vortex spinning appeared to hold considerable promise for the production of coarse yarns at a low price. It had no moving parts, a feature which was very attractive from the point of view of machine maintenance and power consumption. This system was studied intensively by many researchers who came out with many improv~ments in the original design. However, after the initial enthusiasm it was practically written off because of, among other things, the very low yarn strength, as shown by Iyer et at. I, who collected extensive data on this aspect with different tube designs. Interest in this system has recently been revived with the introduction of a commercial machine known as the Wifama Polmatex System2. The published data show that this system has substantially improved the yarn tenacity, though it is still lower than that of ring-spun yarns. However, practically no work has been reported in the literature on the doubling of these yarns and their tensile behaviour. The aim of the present work was to study these aspects of air-vortexspun yarns .