In warp knitting machines, all needles move together on the needle rails. Warp knit fabrics are often noticed from a vertical thread flow; meanwhile, yarns are mostly fed from warp beams and/or bobbin hangers. The wide range of applications creates a multitude of applications on very different machines, which are very different from each other in order and number, as well as the necessary knitting elements and yarn feeding systems.
Warp knit fabrics,
They are fabrics that are produced by passing the yarns extracted from a warp beam through the perforated needles and on the knitting needles to form loops, showing properties close to woven fabrics in terms of dimensional stability. Warp knit fabrics are more stable than weft knit fabrics, and the appearance of the loops is less obvious. The elasticity of warp knitted fabrics is quite low. Warp knit fabrics can be distinguished from weft knit fabrics by carefully examining the face and reverse. fabric face; It consists of very open, distinct straight loops, the loops run vertically and at a slight angle from one edge to the other. The reverse of the fabric; It has slightly curved horizontal lines. These lines are called top-winding and under-winding threads and are formed by the lateral movement of the warp threads that make up the fabric. Separation of these yarns is the most important feature to distinguish warp knitting. The most important distinguishing feature is that warp knitted fabrics cannot be removed.
Warp knit fabrics are classified by dividing them into 3 parts:
1- Fabrics produced on tricot warp knitting machines 2- Fabrics produced on raschel warp knitting machines 3- Fabrics produced on crochet (accessory) warp knitting machines Both knitwear and raschel warp knitted fabrics are obtained by forming closed loops or open loops and with varying lower feed lengths. Simple structures are achieved by simply forming a closed loop and bottom feed connections from loop to adjacent loop. Open loops can create a similar structure. In this case, the fabric is lighter and has higher elasticity. Two or more underfeeds occur in the vast majority of warp knit fabrics. The fabrics obtained in this way are stronger, heavier and stronger due to their structure. The working place of the two warps is expressed as the front warp and the back warp. The loop underfeed formations of the front warp threads are controlled by the front guide bar, and the rear warps are controlled by the rear guide bar likewise.
1- KNITTED FABRICS WITH KNITWEAR WARP
Fabric structures, which are tricot (warp automat) knitted products, which are accepted as one of the main classes of warp knitting, have approximately the same structure as raschel fabrics as a basic principle. It differs only in the arrangement of the knitting elements, the yarn arrangement and the movement pattern. Simple knitwear structures are knitted from two warps and are called filled knitwear. Both guide rods stretch from one side to the other making two loops. Two guide rods make short bottom feeds from one side of the two mines to the other. These braids are called lock braids. The rear guide bar threads (white) always make the same movement in the full Knitwear. The front guide bar threads (black) run from side to side, three loop lengths, making wide underfeeds. This long bottom feed product fabrics have greater fabric elasticity than full Knitwear.
Fabrics have low elasticity when the front guide bar is short and the rear guide bar is long bottom feeds. Each front guide bar thread (black) makes an open loop through the same ma and if colored threads are used in this warp, longitudinal lines are formed in the fabric. Bottom-feeding with the rear guide bar for three months results in a lighter fabric than that made for four months. Both fabrics are called queen cord.
2-RACHEL WARP KNITTED FABRICS
These fabric types, produced in raschel warp knitting machines, which are one of the main classes of warp knitting, have the same structure as Tricot warp knitting automats products in principle. Therefore, many characteristics are similar to them. The principles of Basic Tricot warp knitting are the same as the basic principles of raschel knitting. The large number of guide rails reveals the wide variety of patterning potential of raschel fabrics. All warp knitted fabrics have open and closed loops. Yarn feeding is also a distinctive feature in raschel fabrics. Two warps are required. The front warp (black) makes a normal open loop and connects with the help of bottom feeds. The back warp creates underfeed only. There is no loop formation. Where there are underfeeds, only the so-called yarn investment is carried out. The advantages of yarn investment are: As there is no loop formation, yarn consumption is low. Therefore, a low weight fabric is obtained. Pattern effects can be created by laying the yarn in thick yarns. Programming a large number of guide rails in raschel machines has a complex structure. The machine preparation of new raschel patterns is slow and expensive if the material is complex or has a single fancy structure. In this case, economical productions are made by working the same (or very similar) fabrics for a long time in a machine.
3-CROCHET WARP KNITTED FABRICS
Accessory-type narrow knitting products, which are an important branch of warp knitting and produced on crochet warp knitting machines, have a wide range of uses, just like narrow weaving products. Although crochet warp knitting machines differ in some details, crochet warp knitting machines, which are actually a versatile raschel warp knitting machine, are generally warp knitting products that can make a wide variety of knitting products with hook needles placed on a needle bar, warp-weft investment, tube yarn guides and other auxiliary knitting elements. knitting machines. Crochet warp knitting machines have gained advantages over narrow woven products thanks to their simple structure, easy band width and motif changing possibilities, use of individual yarn bobbins and beams, and high production speeds. Crochet warp knitting machines have the possibility to produce flat elastic bands, patterned and perforated, elastic or stable narrow laces, wider width plain or patterned fancy fabrics, various tasseled and decorated ribbons used in home decoration and furniture.
General Properties of Warp Knitted Fabrics
Warp knitted fabrics have a wide range of uses in the textile industry and industrial area. Since the loop structure is different from the weft knit loop structures, fabrics with equal stability to woven fabrics can be produced. Thanks to this feature, it enables the production of warp knitted fabrics for suits. It is possible to produce almost any type of fabric according to surface formation and machine properties. They can be used instead of woven and weft knitted fabrics. When we try to disassemble this warp knitted product, it is either not disassembled at all or it comes off a little in the longitudinal direction.
Usage Areas of Warp Knitted Fabrics
Warp knit fabrics are fabrics that are widely used in clothing, home textiles and industrial areas in general. Warp knitted fabrics are used for women's underwear, swimwear fabrics, sportswear, suits, neckerchiefs, lining fabrics, towels and plush fabrics. It is used in home textiles as tulle draperies, tablecloths, upholstery fabrics, plush, lace terry fabrics, dust cloths, bed linens, rugs and umbrella fabrics. In the industrial field, it is used in medical materials, aircraft insulation, fishing nets, shoes and bags.
Comparison of Knitted and Woven Fabrics
Knitted fabrics are textile structures produced by forming a surface by connecting the yarns side by side and on top of each other in the form of loops. Woven fabrics, on the other hand, are structures that form a texture surface by forming a connection as a result of the weft and warp threads intersecting with each other in a straight line at a ninety-degree angle.
When we compare these fabric structures;
1-Knitted fabrics generally have a more flexible structure than woven fabrics.
2-Knitted fabrics are generally more porous than woven fabrics.
3-Knitted fabrics are generally softer than woven fabrics.
4- Knitted fabrics are generally less prone to wrinkling than woven fabrics.
5- Knitted fabrics may have better water absorption ability than woven fabrics in general.
6-Knitted fabrics generally have better insulation properties than woven fabrics.
7-The yarns used in the production of knitted fabrics are less twisted than woven fabrics.
8-While different machines are used for the production of fabrics of different thicknesses and thicknesses in weft knitting machines, different machines are used according to the thickness of the machine, while fabrics of any thickness and thickness can be produced on the same machine in weaving machines.