İplik tüylülüğü ölçümünde farklı yaklaşımlar

Abstract

İplik yüzeyinden dışarı doğru sarkan farklı uzunluk lardaki lif uçları ve gelişigüzel lifler ile halkacıkları ifade eden iplik tüylülüğü, eğirme esnasındaki uçuntu miktarından, üretilen kumaşların tutum ve boncuklanmasına kadar üretimin değişik aşamalarında büyük ölçüde etkili dir. Bu yönden ele alındığında tüylülüğün iplik ile örgü ve dokuma kumaşların kaliteleri açısından en az mukavemet, düzgünsüzlük, büküm, numara ve hatalar (ince-kalın yer, neps) kadar önemli bir parametre olduğu görülmektedir. Son 30 yıldır yapılan çalışmalarda ring ve rotor eğir mede eğirme, çekim elemanları, makina ayarları ile hammad de gibi hususların iplik tüylülüğüne ne şekilde etki etti ği belirlenmiş ve düşük tüylülük değerinde iplikler üret meye yönelik öneriler sunulmuş olmakla beraber, bu öneri ler ya da proses ve klima koşullarıyla bağıntılı olarak işletmeler arası sonuçlar, tüylülük değerleri açısından farklılıklar göstermiştir.. Bu tez, iki değişik poliester/viskon (70/30) harmanı nın, harmanları meydana getiren elyaf ve iplik özellikle rinin iplik tüylülüğüne tesirini mevcut fabrika koşulla rında inceleyen deneysel bir çalışmadır. Harmanlarda kul lanılan viskon elyafın bir kısmı boyanmıştır. Eğrilen Ne 12/1, Ne 24/1, Ne 28/1 ve Ne 40/1 ring ipliklerinin numara, büküm, mukavemet, düzgünsüzlük ve tüylülük ölçüm leri fabrikaların fizik laboratuvarlarında gerçekleştiril miş ve ölçüm sonuçları 1989 Uster istatistikleriyle karşı laştırılmıştır. Ayrıca Zweigle G565 ve Uster Tester 3 tüylülük ölçerlerinde elde edilen nümerik değerler elek tron mikroskobundan (S. E. M) elde edilen fotoğraflarla kar şılaştırılarak aralarındaki ilişki incelenmiştir. Ölçümler neticesinde elde edilen tüylülük değerleriy le büküm, numara ve mukavemet değerleri arasında yapılan ikili regresyon analiz sonuçları da yorumlu olarak veril miştir.

In the quality assurance for textile productions, many characteristics are supervised continuously or on a spot check basis. Based on these results, decisions are made about the product; alterations made to the production machines, faults corrected or maintenance work carried out. There are quite a number of characteristics which come into question for supervision. It is of fundamental importance that only important characteristics be supervi sed. That means, those, which either interfere with the appearance of the finished product or negatively influence further processing steps, e.g. through breaks, dust depo sits and many more. Such disturbances will reduce the efficiency of the following processes. It is therefore the task of the quality control or quality assurance to detect errors at the earliest possible stage of productionf even if they do not take effect or become visible until during weaving or knitting. Hairiness is one of these characteristics. Yarn hairiness is created by the fibre ends and loops protruding from the yarn and the wild fibres existing out side the body of the yarn, thus, imparting it a fuzzy appearance. In certain cases, the hairiness is a favourable fac tor as for instance in overcoat and flannel fabrics. In other words, where a full yarn is needed or where the handle of the end product is important, a certain degree of hairiness is in fact necessary but, in other cases, it is not required. It would be desirable, therefore, if the yarn hairiness were regulated during the spinning process. Hairiness originates in the spinning mill and caused by a whole catalogue of minor details which, when added together, can have a remarkable effect. It generally affects the textile operations following spinning, especi ally weaving and knitting, and the characteristics of the products obtained. During manufacturing operations sub sequent to yarn formation, any increase in hairiness usually leads to increased production of fly. This can be especi ally troublesome in warp knitting. In a warp, increased hairiness increases the probability of entanglement of adjacent ends, which frequently leads to end brekage. Large inter-package differences also are very troublesome. If a package has significantly lower hairiness than the other packages, a weft stripe can occur for instance which reflects light differently. This can occur especi ally in some piece-dyed fabrics. A lot of projecting fib res produce a somewhat darker appearance than few fibres. It may be established that the subjective sensation of sof t handle is related to hairiness, in other words, soft handle with a high number of projecting fibres. Specific confirmation of this has not yet been investigated. Pil ling performance of a fabric also depends on the degree of hairiness of the fabric. It is also known that hairy yarns are appreciably more sensetive to abrasion in subsequent processing. A hairy yarn is more easily roug hened than one having few projecting fibres. The resistance to the air passing through the fabric depends on the yarn hairiness, too. Although numerous tests have shown that the hairiness reduces yarn strength, in this study, a positive correla tion has been found between the hairiness and yarn tenacity. The reason may be either fibre tenacity properties or dif ferent parameters such as yarn count and twist being chan ged at the same time. During recent years, the measurement techniques have been sensibly improved. The relationship between yarn hairiness and the fibre and yarn properties have been studied at various times. The effects of machine parame ters as well as room conditions on yarn hairiness have also been investigated, extensively. A brief summary of the literature on these subjects has been given in PART2. It is still unknown how hairiness occurs or how it can be controlled. What already known is the spinning machine is primarily responsible for yarn hairiness. Some of these are purely mechanical questions of machine design such as the geometry of the spinning zone etc. Drafts also have a significant influence. Depending on the type of fibre and fibre length, a higher overall draft generally leads to increased hairiness. The condi tion of the rollers or the type of the roller coats or aprons are other important factors. Hairiness can be reduced by optimizing the distance between the top and the bottom apron. VI The actual travellers also exert a considerable inf luence. Increasing the traveller weight leads to less yarn hairiness. The thread tension ratios on the ring spinning frame are quite important. This is clear from purely periodic phenomena, the periodicity of which corresponds to the yarn length spun during on lift and lowering cycle of the ring rail. Periodic lengths of 8 cm often occur in hairi ness, caused by dirty front rollers on the ring spinning frame; this periodicity sometimes agrees with the length of spun during on traversing movement of the roving ente ring the drafting system. Less frequently, the causes of yarn hairiness lie in the roving. In this study, only for Ne 28/1 yarns, periodic lenghts of 4 cm which were caused by the varying tension and frictional ratios during the rising and lowering movement of the ring rail, occu- red. In a review of the literature, it is observed that fibre length, breaking strength, and elongation are corre lated negatively and fineness positively with yarn hairi ness parameters, which is the consensus of most researc hers. However, some workers have reported contradictory results on the influence of- iübre fineness' and short fibre percent, probably due to differences in measuring methods. In this study, because of all fibres having the same length the effect of fibre length on yarn hairiness has not been examined. In contrary to the results of the previous studies, breaking strength and elongation ihave beenl found positively correlated to the hairiness. The reason for- this may. be the raw material. Previous experiments have shown that the yarn hairi ness coefficient decreases with increase in twist. When yarn twist is increased, the number of fibre ends on the yarn surface remains constant, the number of looped fib res decreases and the number of wild fibers remains nearly constant or is slightly reduced. It is explained as the result of better binding of the fibers into the body of the yarn as they emerge from the front-roller delivery. It is also known that there is a critical-twist region within which the yarn hairness and diameter increase with increasing twist levels. As twist and yarn count were changed at- the same time, in this study, it became difficult to estimate the exact level of influence of twist on yarn hairiness. For that reason, only two types of yarn, Ne 24/1 and Ne 28/1, ha ve been compared, however, because of the contradiction Vll between the results taken from Uster Tester 3 and Zweigle G 565, it has not been possible to make a decision on the influence of twist on yarn hairiness. It may be caused by the high twist variation of Ne 28/1 yarn or the used apparatus (Uster Tester 3 and Zweigle G 565). As it has been shown in numerous studies, there is a high positive correlation between the yarn count and hairi ness. Correlation coefficient is + 0,99 for Zweigle G 565 and + 0,95 for Uster Tester 3, in the study. The comparative studies have shown that ring-spun yarns are more hairy than rotor-spun yarns, although rotor- spun yarns are bulkier. According to series of experiments reported previously, the ratio of the hairiness of ring spun yarns to that of rotor-spun yarns is about 2.5 for the same yarn linear density and equivalent twist multip liers. The hairiness range is greater for ring-spun yarns than for rotor-spun yarns. Number of protruding ends is less for open-end-spun yarns than for ring-spun yarns, but the number of loops is larger for open-end-spun yarns than that for ring-spun yarns, as expected from the structural differences of the two types of yarn. The mean length of the protruding ends is less for open-end spun yarns than for ring-spun yarns. Previous studies show that hairiness is more irregu larly distributed in open-end-spun yarns than in ring-spun yarns. In the experimental studies, it has been observed that the type and the geometry of the rotor have seem to influence hairiness to a significant extent. The fric tion between the surface of the yarn and the rotor elements has seem to be the determining factor for hairiness. As in ring yarns, the linear density influences the hairiness of rotor-spun yarns, coarser yarns tend to be more hairy. In rotor-spun yarns from man-made fibers, the effect of twist on hairiness is of little importance and, of cour§e, smaller than that for ring-spun yarns. vxn In this study, yarn hairiness values have been taken from both Zweigle G565 and Uster Tester 3 Hairinessmeter. Zweigle G565 hairinessmeter uses an electronic hardware and accompanying software, time-proven mechanical yarn- feed system and an innovative optical sensor array. A single-pass, multi-sensor optical system simultaneously measures 12 individual hair-length zone. An adjustable guide positions the yarn surface on to the reference plane. A simplified control panel designed to store and recall up to different test classifications, edit test parameters and enter alpha-numeric characters. The hairines index of a yarn can be evaluated considering distribution of the various hair lengths, fiber number, maximum theoretical hair length, and longest and shortest measured hair lengths. Because a mathematical relationship exists between these variables, with a. computer, a nume rical value known as the hairiness index "H" can be driven. Generally, the numerical value of the hairiness index and the yarn hairiness are in a direct relationship. The presence of longer hair lengths surrounding the yarn will result in a higher hairiness index number despite a. larger number of shorter hair lengths. The number of hair lengths longer than 3mm is know as S3. These longer lengths contribute to poorer running conditions. The hairiness testing module of the Uster Tester 3 enables reproducable results to be obtained because it does not count the projecting fibers, but rather senses the total fiber length in cm of all fibers projecting from the body of the yarn within a test zone 1 cm long. This hairiness index is called "H" again and its variation CVft. As it is reproducible, it is also possible to calculate and publish comparison values, in the form of "Uster Statistics" for example. In this experimental study which is focussed on different problems in plants, the yarn hairiness for two different polyester/viscose (70/30) blends are examined from the fibrograph values of fibres to the winding process and the results for 4 different yarn counts (Ne 12/1. Ne24/1, Ne28/1, Ne40/1) and twists are compared and explained by means of barcharts and graphics. In addition hairiness values and the photographs which are taken by SEM are compared and the relationship between them, is investigated. The first blend consists of 1.65 dtex viscose, 2.75 dtex polyester (20%) and 2.5 dtex dyed- poliyester (50%). The second one is consists of 1.65 dtex viscose j 2.75 dtex polyester (20%) and 1.65 dtex dyed-poly ester (50%). The blend rates are the same. Fiber lengths are also the same and 38mm. xx The important conclusions driven from the experi ments can be summarized as follows. 1- There is a significant positive correlation between hairiness and the yarn count*. 2- Because yarn count and twist have been changed at the same time, they have not been independent. For that reason,' the -exact influence of twist on hairiness has not been determined. On the other hand, although there is no correlation between twist multiplier and hairiness, twist as turn/inch shows significant positive correlation by avoiding the yarn count and the twist multiplier. 3- Although there are differences between the results which are taken from Zweigle G 565 and Uster Tester 3, a sufficient positive correlation exists between the results. 4- The comparison of the hairiness values and the photographs shows that hairiness can be seen visually but can not be classified exactly enough.