The production of yarn samples was directed and supervised by the leading technical personnel of the Litija Spinning Mill together with the specialists from Suessen and Zinser. Since we wanted to compare the compact and conventional yarns produced on at least two different spinning machines types, the production of yarn samples was carried out at the Suessen and Zinser workshop spinning mills at approximately the same time period. 20 kilograms (20 bobbins with roving) of each yarn type (one compact and one conventional from each ring spinning machine producer) was produced in order to ensure sufficient yarn quantity for testing purposes. The following fibrous material was used for the production of yarn samples: § 100% combed cotton (CO), fibre length 1 3/32 ” – 1 1/8 ”, Micro- naire=4.5, § polyester fibres (PES), fibre length 38 mm, fineness 1.5 dtex, § viscose fibres (CV), fibre length 38 mm, fineness 1.3 dtex. The following fibre blends were proc- essed: § 100% combed CO (noil extraction: 15.5%), § 50% combed CO /50% PES and § 87% combed CO/13% CV. A standard spinning preparation and modern machinery were used to produce the roving with a linear density of 588 tex from each fibre blend at the Litija Spin- ning Mill using the same fibre lots for each blend. After that, conventional and compact yarns with a linear density of 20 tex were produced under comparable technological and kinematical conditions on the Suessen and Zinser ring spinning frames.

Quality Properties of Produced Yarns After production, the quality of yarns was tested in the laboratories of the Sues- sen and Zinser machine producers, where the yarn samples were spun using valid standard methods and procedures that guaranteed the statistical significance of test results. Ten bobbins of each compact and conventional yarn were tested. The information on yarn quality was then sent to the Litija Spinning Mill, where the data was analysed and compared. The following physical, mechanical and mor- phological properties of the compact and conventional yarns produced were tested and compared: real fineness, twist, break- ing force, elongation at break and work to break, Uster properties, hairiness and length distribution of hairs on 100 m of a yarn. An Uster Tester 3 was used for test- ing the hairiness of the produced yarns.

Discussion

 Based on the researched and compared mechanical, physical, morphological and Uster values of the conventional and compact ring yarns spun on the Zinser and Suessen spinning machines, the fol- lowing conclusions can be drawn: Properties of compared yarns made of 100% cotton fibres The breaking force of the compact yarn with a nominal linear density of 20 tex and spun on a Zinser ring spin- ning machine is 18.88% higher than the conventional ring spun yarn, produced on the same machine but without the condenser unit.

 The breaking force of the compact yarn spun on the Suessen ring spinning machine is up to 29.48% higher when compared with the conventional ring spun yarn, produced on the same machine but without the condenser unit. A higher difference in breaking force between the compact and conventional yarns produced on the Suessen ring spin- ning machine can be explained with the construction of the drafting system that enables maximum fibre condensation all the way up to the clamping line, which is not the case in Zinser’s drafting system. Agreater breaking force was measured in the yarn produced on the Zinser spinning machine.

Elongation at break of compact yarns is 7 to 8% higher compared to conven- tional yarns. The tenacity of a compact yarn produced on the Zinser spinning machine surpasses the conventional yarn by 17%, while this value is higher by up to 23.24% in the yarns spun on the Sues- sen spinning machine. A slightly higher value is noted in the yarn produced on the Zinser spinning machine. The work to break of a compact yarn spun on a Zinser spinning machine is 21.82% higher than in conventional yarn. In the compact yarn produced on the Suessen spinning machine, the work to break is 32% higher than that of the conventional yarn. the higher absolute value of work to break was determined in the compact yarns produced on the Zin- ser spinning machine. The physical and mechanical properties of the compact and conventional yarns are represented in Figure 3. No significant changes regarding Uster properties (Uster CV%, number of thin,

 

thick places and neps) in the convention- al and compact yarns were determined. This can be explained by the use of the same three-cylinder drafting equipment, which is proven to be the major influence on these yarn properties. The Uster hairiness (H) of compact yarns is significantly lower when compared with the hairiness of conventional yarns (Figure 4). Conventional ring spun yarn produced on the Suessen spinning ma- chine has an Uster hairiness H=5.80, and the yarn spun on Zinser spinning machine has an Uster hairiness H=5.54. A lower value of Uster hairiness, H=3.80, was determined in compact yarn produced on the Suessen spinning machine, while that spun on the Zinser spinning machine has an Uster hairiness H=4.64. The reason for this is the construction of the drafting equipment, as explained above. The morphology of the yarn, defined as the number of hairs of different length per 100 metres, shows the significantly lower primary hairiness (1 to 3 mm) and secondary hairiness (4 to 12 mm) of com- pact yarns. Better results and significant improvements were achieved with the Suessen spinning machine, which can also be explained by the special construc- tion and elements of the drafting unit.

Properties of compared yarns made of 50% CO/50%PES fibre blend

When comparing the physical and me- chanical properties of conventional and compact yarns produced of 50% CO/50% PES fibre blend, we found no significant differences. This can be explained by the greater bending rigidity of polyester fibre component, which reduces the fibre condensing effect and its contribution to better physical and mechanical properties of compact yarns. The analysed Uster properties of con- ventional and compact yarns are very similar, which confirms the fact that the condensing effect significantly influ- ence neither the yarn irregularity nor the number of yarn faults.

 The Uster hairiness (H) of compact yarns is significantly lower when compared with the hairiness of conventional yarns. A slightly better hairiness value was de- termined in yarn spun on the Zinser spin- ning machine (H=3.26) when compared with the yarn produced on the Suessen spinning machine (H=3.20). The primary and secondary hairiness of a compact yarn made from this mixture and spun on the Zinser spinning ma- chine are better than in yarn produced on the Suessen ring spinning machine. Both compact yarns have significantly improved primary and secondary hairi- ness when compared with conventional ring yarns. Properties of compared yarns made of 87% CO/13% CV fibre blend The breaking force of the compact yarn with a nominal linear density of 20 tex and spun on a Zinser ring spinning machine is 18.32% higher than the con- ventional ring spun yarn produced on the same machine but without the condenser unit.

The breaking force of the compact yarn spun on the Suessen ring spinning machine is up to 32.30% higher than the conventional ring spun yarn produced on the same machine but without the con- denser unit. Elongation at break of compact yarns is 4 to 11% higher compared to conventional yarns. The tenacity of a compact yarn produced on the Zinser spinning machine surpasses the conventional yarn by 15.90%, while this value is higher at up to 28.87% in yarns spun on the Suessen spinning machine. A higher absolute value of tenacity is determined in yarn produced on the Suessen spinning machine. The work to break of a compact yarn spun on the Zinser spinning machine is 20.87% higher than in conventional yarn. In compact yarn produced on the Suessen spinning machine, the work to break is up to 41.88% higher compared to the conventional yarn.

 A slightly higher absolute value of Work to break was determined in compact yarns produced on the Suessen spinning machine. The analysed Uster properties of conven- tional and compact yarns have very simi- lar values. Conventional ring spun yarn produced on a Suessen spinning machine has an Uster hairiness of H=5.20, and the yarn spun on the Zinser spinning ma- chine has an Uster hairiness of H=4.72. A lower value of Uster hairiness, H=3.40, was determined in compact yarn pro- duced on the Suessen spinning machine, while the yarn spun on the Zinser spin- ning machine has an Uster hairiness of H=3.60, which can be explained by the inability of Zinser’s drafting system to keep thoroughly condensed fibres up to the clamping line. The Uster hairiness (H) of compact yarns is significantly lower when compared with the hairines

of conventional yarns, irrespective of the machine system. Both the primary and secondary hairi- ness of a compact yarn made of this fibre blend and produced on the Zinser ring spinning machine are lower when com- pared with the yarn spun on the Suessen spinning machine. Both primary and secondary hairiness of compact yarns

are significantly lower than in conven- tional yarns, irrespective of the machine system. The improvement is more obvi- ous when comparing conventional and compact yarns spun on the Suessen ring spinning machine, with or without a con- denser unit. n Conclusions The aim of the study presented herein was to analyse and compare the yarns us- ing two different systems for the produc- tion of compact and conventional ring yarns from the producers Suessen and Zinser. The same roving produced by the Litija Spinning Mill with a linear density of 588 tex was used to produce 20 kg of yarns from cotton, cotton/PES and cotton/viscose fibre blends under com- parable technical and kinematical condi- tions. The tests were directed and super- vised by the leading technical personnel of the Litija Spinning Mill together with the specialists of the Suessen and Zinser spinning mills, where the production of yarn samples was carried out over ap- proximately the same time period. Yarn testing was carried out by both machine producers in laboratories using valid standard methods and procedures that

guaranteed the statistical significance of the test results. An analysis of results obtained within the comparative research into the quality properties of conven- tional and compact ring yarns produced at the Suessen and Zinser companies led to the following conclusions: § Compact yarns can be regarded as completely new ring spun yarn types as regards their morphological, physi- cal and mechanical properties. With regard to fibre straightening, light axial tension and condensing of the fi- brous bundle that form compact yarn, the new yarn structure can be defined as near-optimal. § The compact yarns have the follow- ing advantages when compared to the conventional ring yarns: significantly reduced primary and secondary hairi- ness, smooth surface, high gloss, im- proved mechanical and physical prop- erties (with the exception of compact yarn produced from 50% CO/50% PES fibre blend), similar Uster prop- erties, better resistance to rubbing, softer touch, and lower pilling effect in woven and knitted fabrics.

§ It is obvious that in the future compact yarns will be used as referential samples and benchmarks, based on which the quality of different types of spun yarn will be estimated. § Because of the numerous advantages of compact spinning, it can be as- sumed that the new spinning tech- nique represents a promising impulse for ring spinning and spun yarn pro- duction. § If the spinning mills’ customers - pro- ducers of woven and knitted fabrics - require high quality spun yarns and are ready to pay approximately a 10% higher price for them (because of the higher cost of the compact ring spin- ning machine and the slightly higher energy costs), then the compact spin- ning has a promising future because of the higher production and improved quality of compact yarns.