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THE DETERMINATION OF YARN TWIST

Objective



The amount of twist imparted to a yarn during the spinning process determines not only the strength, size etc of the yarn but also its appearance. Thus if the twist in nominally identi-cal yarns varies from bobbin to bobbin when the yarn is woven the eye sees the difference and the material is considered faulty. For this reason both the spinning and weaving sides of the textile industry place great emphasis on the determination of the twist in a yarn by including tolerances in contract conditions.

With regard to written standards it appears that for ring spun yarns there are adequate national and international (ISO) standards. In the case of yarns produced by the so-called open end spinning process (DE) however, there is no approved method. There is therefore a need for prestandardization work in the case of OE yarns to allow a twist measurement method acceptable to all to be agreed.

The participants will test three types of yarn by the so called twist untwist method and will then compare results.

RESULTS

ITF Mulhouse has fabricated and tested 18 batches of threads, including:
1. 3 materials (VIS/CO 67%/33%; PES/CO 67%/33%; PES 100%)
2. 2 titles (20 tex and 50 tex)
3. 3 twist coefficients (115, 125, 135).
The results of the tests indicate important differences in the measured twist values from the actual ones:
a 40-45% for VIS/CO, using the simple twist/untwist method;
b 10-15% for VIS/CO, 15-30% for PES, 20-30% for PES/CO, using the method with double counter try (NF G 07-09).
It was concluded from this preliminary work that no method is as yet sufficiently developed to be proposed as a standard and thus the intercomparison will not be carried out.

Coordinator

Deutsches Institut für Textil- und Verfahrenstechnik
Address
Körschtalstraße 26
73770 Denkendorf
Germany

Participants (10)

Centre de Recherches Textiles de Mulhouse
France
Consiglio Nazionale delle Ricerche (CNR)
Italy
Dansk Beklaednings og Textil Institut
Denmark
ENSITM
France
Instituto dos Texteis
Portugal
International Institute for Cotton
United Kingdom
Laborat. Central du Minist. des Affaires Economiques
Belgium
Laborat. de Ensayos e Investigaciones Textiles del Acondicionamiento Terrasense
Spain
Ministerio de Comercio e Turismo
Portugal
Vezelinstituut TNO
Netherlands