Örgü kumaşlarda nakış problemleri

Abstract

Bu çalışmada, örme kumaşlar üzerinde meydana gelen nakış problemleri araştırılmıştır. Dokuma kumaşlarla karşılaştırıldığında daha elastik bir yapıya sahip olması sebebiyle, örme kumaşlar üzerine işlenen nakışlar, dokuma kumaşlara işlenenlere göre daha fazla problem yaratmaktadır. Çalışma esnasında, farklı gramaj ve yapılardaki kumaşlar üzerine değişik iplik gerginliklerinde ve değişik makina hızlarında aynı tip nakış işlenmiş ve bu nakışlar, kumaşların patlama mukavemetlerinin altında kalan bir kuvvete maruz bırakılarak nakışlar arası açılmalar ölçülmüştür. Ölçülen değerler, makina hızına, iplik gerginliğine ve gramajlara göre incelenmek üzere grafik haline getirilmiştir. Grafiklerin incelenmesiyle beraber, yukarıda bahsedilen parametrelerin nakış açılmalarını ne şekilde etkileyebilecekleri tartışılmıştır.

Embroidery is defined as [ 16 ] "the decoration of textile fabrics by hand or machine achieved by subsequently applying and passing embroidery threads through". The desire to decorate apparel, household and domestic textiles by means of embroidery is as old as the weaving technique itself. At first, plain fabrics were embroidered with very simple and then ever larger and more complicated motifs, taking into account of man's desire for expressing his artistic talent and to be different and unique. The invention of the sewing machine and its modification for embroidery withnessed a growth in the potential for ornamenting and embellishing fabrics and the development of embroidery in terms of "fabric embellishment" can be subdivided into a number of fields, i.e. - standart embroidery - fashion embroidery - high-fashion embroidery - elegant embroidery - domestic textile embroidery. [25] Each of these fields has its own status and market share. - Standart Embroidery: Standart embroidery is used in the decoration of flags, textiles for religious purposes and ethnic clothing. Long term sales, little subject to fashion changes are reckoned here. - Fashion Embroidery: Fashion embroidery which can have a pronounced advertising character is predominantly encountered in product and company advertising. Sportswear articles are embroidered with company or club badges in this respect. This market is always busy. - High-fashion Embroidery: High-fashion embroidery covers monograms, company protected monograms and exclusive clothing manufacturers' emblems together with floral designs, which are used predominantly in domestic textile sector. Well-known companies are increasingly perpetuating the company logos they have created on the clothing they manufacture. This can also be regarded as a growth market. -Elegant Embroidery: The feature of elegant embroidery is the application of fabric components of bathrobes, handkerchiefs, sweaters and blouses, achieving beautiful visual effects. Novel effects are also obtained by embroidering dissimilar textiles, e.g. linen on satin. In this field, creativity is limited only by the garment's care properties. IX - Domestic Textile Embroidery: The greatest demand by far for embroidery has to be in domestic textiles embroidery, involving household and terry fabrics and bed and table linen [25]. However, embroidering on knitted goods, with properties which are not particularly favourable to the embroidery process, have some problems. In contrast to the more stable woven fabrics, with their weft and warp threads being crossed, knitted fabrics often display a great deal of extensibility and elasticity, so that there is the problem of considerable fabric distortion with both small and large embroidery areas. These problems are due to the principle used on embroidery machines which has its origin in sewing field. The embroidery machine puts the embroidery yarn on the ground material under pre-tension conditions, and the ground material here is the knitted fabric. However, whilst the sewing process normally uses the same stitch length through the seam and operates with a steady tension, in the embroidery process the stitch length changes between 0 and 12 mm. And different lengths of stitches also require different amounts of thread tension which are the characteristics of the embroidery work. There is also the danger of damage to the stitches in the knitted fabric often caused by selectingthe wrong embroidery needle, the point of which may cut the fabric stitches as it penetrates the latter [ 1 ]. Obtaining machine embroidery is mainly based on three different techniques. These are as follows: 1- Studio Technique: The wide variety of knitted fabrics makes them particularly suited for embroidery work. As far as stitch length and the position of stitches are concerned as well as the wide range of the colors which are available, embroidery provides an almost unlimited variety of patterning possibilities and can adapt to a particular knitted structure in such a way that the embroidery blends completely into the knitted fabric. Thus many knitted fabrics can be gone over by means of embroidered effects which can be integrated and thus combined in whatever way. The so called "V" stitch which is a good example for what can be done to adapt an embroidery effect to a particular knitted structure. Thus an embroidery thread adapted to the knitting yarn is placed in such a way that it can be absorbed into the stitch structure without any difficulty and can display different shapes and colors. It becomes evident that large embroidery designs, especially with outerwear, are increasingly prevalent and that fashion cannot be imagined without them. 2- The Applique Technique: The most frequent type of applique technique is the one that is combined with embroidery on knitted fabrics. This technique is also used in a similar form with woven terry cloth and permits an application of several layers of various applique materials. Fine stitch and plain knitted fabrics are primarily involved; on the one hand the embroidery work can be applied without difficulty and on the other hand these materials make far fewer demands on the so called applique cutting. Open-meshed fabrics have a tendency to undo after cutting if the embroidery has not been done properly. 3- The Tensioning Technique: The nylon stocking is also a fashion article which only rarely carries embroidery adornments and this also applies to nylon tights. There is little doubt that both nylon stockings and tights are amongst the most elegant articles in a lady's wardrobe. Whilst hoisery for sportswear and leisurewear carry embroidery motifs more and more often, there is more reticence when it comes to the use of embroidery on the long, tubular and delicate nylon net stocking or tights. On the one hand there is the need to come to terms with the use of embroidery techniques on very fine gauge knitted fabrics and on the other hand there is an absence of tensioning facilities when embroidering the ankle section. However, it is possible to adom stockings and tights with embroidery motifs. By using the necessary thread tension, it is possible to apply embroidery work in various colors and the so-called bore technique without having to use additional support materials. Normally, these rather elastic and transparent knitted fabrics do not permit the use of such aids. By using their own initiative in such cases embroidery companies have developed special tension aids which permit the adornment of these very fine gauge transparent fabrics Problems in machine embroidery can occur with coarser gauges in single-bed fabrics, with relief structures, with fleecy or hairy yarns or very stretchy knitted constructions. Often the embroidery then sinks down between the knitted stitches even if the wrong side was fixed with a web. A possible solution for this is a film which dissolves in steam, which lies on the right side between the knitted fabric and the embroidery during the embroidering process and can be completely removedd later. Another problem and the reason for complaint is the distortion of the knitted fabric when stretching in the embroidery frame, which can occur due to improper handling when the back has been previously fixed [16]. There is also hand embroidery which is mostly applied to flat knitted fabrics in the most diverse variations is expensive and therefore these articles are produced partly in Italy but primarily in Far East where wage costs are very low. Normally, seperate front pieces or sleeves which have been cut or knitted in the fully fashion technique are embroidered. Only then are the knitgoods made up into a finished article. With hand embroideryone should bear in mind that there is a certain degree of deviation in the workmanship and therefore the most accurate manufacturing spesifications possible should be defined with tolerance values. There are no limits to the creative imagination apart from the cost aspect. Any embroidery yarns can be used, but they should meet the quality requirements of the company with regard to colorfastness, shrinkage and abrassion resistance. In the meantime there are also semi-mechanical possibilities to achieve a hand-embroidered look particularly when fairly thick, wooly/fluffy yarns or lapping techniques are used. Here, unusual yarns such as bast fibres are used succesfully [16]. In these thesis, the factors that can affect the occurance of the spaces between the borders of two embroideries are studied. These spaces affect the fabric appearance negatively. An example for this kind of embroidery appearance is seen in the photograph below. XI Photograph: An Example For An Undesired Embroidery Appearance The knitted fabrics used during the experiments are cotton, two of them consisting elastomeric yarns and one of them consisting %3 cellulosic fiber and all are knitted into different structures. The properties of the fabrics are shown in the table: The fabrics are embroidered under constant yarn tensions and constant embroidery machine speed. Then a force that is under bursting strength of each fabric is exerted on the embroideries to see the behaviour of the embroideries under load and Xll the spaces between the embroideries are measured. According to these measurements, graphs showing the change of the spaces against machine speed, yarn tension and fabric weight are drawn and the results are analyzed statistically. According to the results obtained, it can be said that the spaces between the borders of the embroideries are showing a tendency to decrease as machine speed increases. This may be due to the fact that at higher speeds the embroidery yarn is overfed. So the yarn is relaxed for the next cycle and the tension on the yarn taken into the fabric is less. As the yarn tension increases, the spaces between the borders of the embroideries are showing a tendency to increase. A force exerted on a fabric by a yarn under high tension stretches the fabric and this causes the occurance of the spaces. The parameters affecting the quality of the embroidery design in the fabrics which were studied in this work are: 1- Fabric weight which is an important factor on this matter. It can be said that the spaces between the embroideries are higher on heavy fabrics than on light fabrics. 2- The presence of elastomeric yarns affects the spaces between the embroideries. The elastomeric yarns' extensibility has greater effect on the occurance of the spaces when compared with the extensibility of the fabrics.