Twist multiple: 4. FIGURE 4.39 Schematic of draw warping process (courtesy of Karl Mayer). A fleece layer offers additional isolation. After these developments, 330 cm weaving machine width and 600 ppm were achieved [13]. FIGURE 6.24 Rotary dobby with electronic control (courtesy of Staubli). The position of the back rest roller is scanned continuously by the sensor and switch flag 2 while © 2001 By Sulzer Textil Limited Switzerland the machine is running, and is transmitted to the control electronics in the switch cabinet. The yarn length in the reserve loop can be roughly considered as a compact body which is available for flight without much resistance. Air-jet machines are also successfully used in terry manufacturing. Complaints are also a good reason to develop new fabric designs or to modify existing ones. The flow of the book follows the flow of the woven fabric manufacturing process. British Patent No. The different counts of the single polyester and polyamide titres are caused by the fact that the softer polyamide with single titres of 0.8 dtex has rather the same textile properties as polyester with single titres of 0.5 dtex. Staggered teeth are used for applications such as multifilament yarns, monofilament yarns, staple yarns including terry, woolen yarns, hard fiber yarns and leno fabrics. It is turbulent because Reynolds number is normally high. In this way, 200 different loose pick distances, and hence the same number of pile heights, can be programmed in any order desired. Factors influencing yarn hairiness include hairiness generated by the winding process, spinning tensions, location of the yarn on the spinning package, yarn balloon shape, yarn twist, spindle speed, yarn size (count), % synthetics in a blend, end spacing at slashing, size add-on, slasher creep speed and bottom squeeze roll cover. The filter systems require close monitoring and in large installations, can add significantly to operating costs through frequent filter replacement and the man-hours required to replace them. Minimal stress on the filling yarn during processing results in good fabric quality and high efficiency. Electronically controlled, highly dynamic yarn brake with programmable braking force and braking duration reduces filling yarn waste and reduces yarn breakage frequency. Consequently, this type of device can only detect thick places in the yarn. Adanur, S., Wellington Sears Handbook of Industrial Textiles, Technomic Publishing Co., Inc., 1995. The taker retracts and brings the filling yarn to the other side. b) Near-parallel packages [Figure 4.17(b)]. Basic woven fabric designs are explained. For example a cotton, nylon and carbon fiber blend yarn can have comfort properties due to cotton, good abrasion resistance due to nylon and flame resistance due to carbon fiber. Figure 14.16 shows a sample window of electronic spare parts catalog. Each set of yarns moves in an opposite direction. Box 3005 Milwaukee, WI 53201 USA Phone: 800–248–1946 http://www.asqc.org American Society of Testing and Materials (ASTM) 100 Barr Harbor Drive West Conshohocken, PA 19428–2959 USA Phone: (610) 832–9585 Fax: (610) 832–9555 http://www.astm.org American Association of Textile Chemists and Colorists (AATCC) P.O. 119 © 2001 By Sulzer Textil Limited Switzerland 120 WEAVING FUNDAMENTALS FIGURE 5.22 Schematic of beat-up process. For example, the basic technology is already available for continuous dyeing of mixed fiber yarns made from cotton and polyester spun fibers in the weft, with suitable dyes. The effect of inertia on yarn velocity compensates for the low initial acceleration resulting in approximately the same velocity irrespective of the yarn count when the change in count is within a small range. Although throwing away textiles before the end of their usable lives is wasteful, it stimulates new developments and business. Picking with Airjet Systems”, Melliand Textilberichte (Eng. the yarn can be controlled by tension, pressure or both. Visualizing the physical characteristics of yarn on the screen before © 2001 By Sulzer Textil Limited Switzerland the yarn is manufactured provides significant advantages in reducing R&D and prototype manufacturing time of fabrics. FIGURE 12.29 Sectional warp beam for monofilament fabrics. Because of the nature of the air-jet filling insertion (i.e. It is driven via gears; the leno device and the stationary gear being attached to the same shaft. Also, the shed timing is important in determining the required energy. Both metric and standard units had to be used in the book. • • parallel creel with reserve packages (magazine creel, for synthetic filaments) parallel creel with unrolling draw-off for polypropylene, monofilaments V-creel with reversible frames V-creel with reversible frames and automatic knotter (for cotton, viscose, polyester/cotton) V-creel with traveling packages Parallel creels are used for sectional warping and direct warping; V-creels are used for direct warping. Lyubovitskii, V.P. Starting at a randomly selected point on the lower left side of the fabric, the interlacing pattern of the warp and filling yarns is determined until a repeat is found in both directions. When does a CD diagram become identical to the X-diagram? The squeezing system determines the degree of size pick up to a large extent. Filling cutter 6 cuts the filling yarn. Control of fabric contraction by the temples of the machine is another critical aspect of good weaving performance. Figure 8.8 shows the typical dimensions of profiled reed lamella. Spun yarn quality characteristics that are most important for good weaving performance include short- and long-term weight uniformity, imperfections, tensile properties and hairiness. It is reported that with the M8300 machine, the energy required for the weaving of one meter of fabric is reduced by 30 to 40 %. ISO is important for international trade as well as domestic business. beam in the form of a tow for indigo dyeing (Figure 4.37). SUGGESTED READING • • Marks, R., and Robinson, A., Principles of Weaving, The Textile Institute, 1976. The shedding motion is positively operated via double cams 2. 4. Two modes of operation are possible with the starting gear: © 2001 By Sulzer Textil Limited Switzerland FIGURE 9.2 Schematic principle of filling insertion with projectile. Jamison, H., “Water Successfully Solves Disposal Problem”, Sulzer Technical Review, 3/97. Make the necessary assumptions. They are made with special leno weaving harnesses. The motion of the yarn tip determines the insertion time of the yarn. With the high productivity of today’s weaving machines, the weaving process suffers from the long stoppage times caused by changes of style and warp on the weaving machine. © 2001 By Sulzer Textil Limited Switzerland Filling and Warp Stress Levels Compared to the conditions of single phase weaving, the stresses acting on warp and filling yarns are fundamentally different. Figure 5.5 shows the arrangement for a plain weave which is the most basic weave. 246 © 2001 By Sulzer Textil Limited Switzerland 9.1 Functional Description of Projectile Weaving Machines 247 FIGURE 9.30 Aligned and staggered guide teeth. gripper. Both fabric thickness and internal structure affect absolute void volume. Looks like you’ve clipped this slide to already. 4. © 2001 By Sulzer Textil Limited Switzerland FIGURE 9.31b. However, this is expected to change eventually with increasing market share of 3D fabrics. Phase B: • Pick 1 is beaten up by the reed. 6.3.1 Negative Dobby Shedding In negative dobby shedding, the harnesses are lifted by the dobby and lowered by a spring motion. The face is usually finer and more lustrous on double fabrics. When the shaft is lowered from high to low shed position, the hooks of balance lever 10 are held by control hook 11 of the magnetic assembly. 4.3.3 Film Formers Table 4.4 shows the film forming polymers that are commonly used in sizing; these polymers can be natural materials or synthetic. Figure 12.54 shows the relations between insertion speed, pile density and production rate of a typical rapier carpet weaving machine. Lomax Jr., J.F., “Information Technology and Workplace Privacy”, ATI, February 1997. Several spun yarn properties are positively affected by slashing. © 2001 By Sulzer Textil Limited Switzerland • • • • • Cutter support 3 moves forward with tucking unit cutter 2 and cuts pick 1. For raw cotton and the carded OE (rotor) or ring spun yarns made from it, the quality criteria are as follows: 311 © 2001 By Sulzer Textil Limited Switzerland 312 MANUFACTURING OF SPECIAL FABRICS TABLE 12.1 Parameters that can be chosen/changed to control woven fabric structure. The tubes through which the filling yarn is inserted consist of many small segments as shown in Figure 8.13 (Chapter 8). As the shuttle travels back and forth across the width of the shuttle loom, the filling yarn is unwound from the quill through the eye of the shuttle and laid in the shed. Explain the major characteristics of air flow in air-jet weaving. Besides, there are some good books specifically dedicated to shuttle weaving; therefore, only a basic description of shuttle weaving is given in this section for three primary reasons: • • • For comparison purposes with shuttleless looms. A staple yarn is a lot more flexible than a monofilament yarn of the same count. 148 FIGURE 6.34 Closed shed dobby machine for industrial fabrics (courtesy of Staubli). 3.1.3 The Reed Plan The warp yarns are drawn through the reed dents sequentially. 210 © 2001 By Sulzer Textil Limited Switzerland FIGURE 8.47 Sley movement FIGURE 8.48 Warp stop motion. FIGURE 5.21 Liquid dispenser (courtesy of Savitec). Twist multiplier is determined from the turns per inch and the cotton count: (2.4) where T: turns per inch Typical twist multiplier range for cotton yarns is 2.5–5. There are different test methods to measure impact resistance of fabrics including free falling weights, dropping pendulums and shooting devices [4]. Since yarns are compressible, these forces cause the yarns to deform and take an elliptic shape in the fabric structure rather than a near round shape. 6.2 CAM SHEDDING Cams with weave pattern profiles rotate to deliver lifting and/or lowering instructions to harnesses. Some of this is already happening with quick style change and similar processes. The harness board is divided in depth. Patterns, weaves and programs can be exchanged easily. Whichever tension control system is chosen, it must satisfy several conditions. The practical number of warp yarns per dent can be between 2 and 4. Why? The loop is blown by the vertical blowing nozzle not into the shed, but into blowing duct 4. FIGURE 10.25 Diagram of rapier movements during symmetrical rapier travel. When specifying a fabric, the specifications for the entire warp should be given, including © 2001 By Sulzer Textil Limited Switzerland FIGURE 3.8 Examples of reed plans. © 2001 By Sulzer Textil Limited Switzerland 8.2 Water-jet Weaving 221 forces. Therefore, the first nozzle twists the fibers in one direction and the second nozzle twists the fibers in the other direction (Figure 2.6). As a result, a reciprocating movement is obtained in the lever. The schematic of the structure of the FIGURE 12.34 Timbermen wear versatile protective clothing to avoid injuries through cuts. Historical findings suggest that Egyptians made woven fabrics some 6000 years ago. The blades of the weft scissors are diamond coated, which greatly increases their service life. An adjustable tensioning spring regulates the base force exerted by the discs which 118 WEAVING FUNDAMENTALS FIGURE 5.18 Schematic of feed detector to stop the weaving machine (courtesy of Nuova Roj Electrotex). Figure 4.93 shows the configuration of a sizing machine for sizing of filament warps for industrial fabrics made of glass, polyamide, polyester, aramide, carbon, etc. In shuttle looms, there is no need for special selvage; since the yarn is not cut after each filling insertion, the edges of the fabric are smooth and strong (Figure 5.34). The situation is similar in the aircraft industry and in shipbuilding [2]. © 2001 By Sulzer Textil Limited Switzerland 2. Regular machine maintenance is necessary to minimize downtime and keep the throughput high. The main nozzle consumes only a small fraction of the compressed air used in air-jet weaving machines as compared to relay nozzles. The tension device maintains a proper tension in the yarn to achieve a uniform package density. © 2001 By Sulzer Textil Limited Switzerland 34 WOVEN FABRIC DESIGN AND CONSTRUCTION TABLE 3.1 Counters for some satin weaves. The structure of air-jet yarns is in between the open end and ring spun yarns. The sley motion is controlled via sley shaft 1 with clamped reed 2 and supporting teeth 3. However, as the weaving continues and fabric gets away from the reed, the fabric starts narrowing due to several factors (it should be noted that there are certain fabrics which do not get narrower, e.g. A separate fan 5 is fitted to generate the required vacuum for cleaning the two rapiers. Up to 16 different filling yarns can be inserted. Damages due to friction between the bead and the rim during operation as well as when mounting the tire onto the rim are avoided. There is now an opening between each segment through which the warp yarns can pass. This book is concerned only with the weaving process and woven fabrics. © 2001 By Sulzer Textil Limited Switzerland 126 WEAVING FUNDAMENTALS sides of the fabric (Figure 5.34). The total number of weaving machines is decreasing in the textile industry. For example, pneumatic beat-up is being studied to replace the traditional reed in airjet weaving. There are several sheds that exist 308 Multiphase Weaving FIGURE 11.30 Shed retaining in McGinley multiphase system [4]. The teacher discovered a new context for studying the history of the town and its people. The air-jet is started by the electromagnetic relay nozzle valve. Lifting knives 1 move harness cords 2 up via hook 3 and pulley 4 by means of electronic control 5, depending on the weave, down movement is provided by a spring. Referring to Figure 8.27(b), the air valve is turned on but the yarn is still clamped. In the indirect yarn number system, the number of hanks in one pound of yarn is indicated. Due to the support provided by the compressed air, the flow of the tensile load phase is markedly softer and the peak values of the tensile stress are reduced by approximately 50% (Figure 9.22). As a further option, the warp let-off speed can be altered for a pre-set time when weaving with varying weft densities, which assures a smooth transition from one weft density section to the next. REFERENCES 1. Warp beams of 1600 mm maximum diameter can be placed outside the weaving machine (Figure 14.4), overhead (Figure 14.5) or in a cradle underneath the weaving machine. The pattern of lifting the harnesses is called order of lifting. Therefore, in practice more than one yarn is placed in a dent. The electric selvage trimmers can be programmed via the terminal. Trauter, J., “Warp Preparation at ITMA-95”, Melliand International (1), 1996. Table 2.1 shows some synthetic polymers that are used to produce textile fibers. Press roller 2 ensures crease free winding of the fabric. Further discoveries are expected in new polymers and fibers that are even higher performance than the current ones. Weak acids and enzymes are used to break down the starch chain structure without damaging the cotton cellulose (Figure 4.95). This versatility is due to the separate control of each warp end or groups of similarly interlacing warp ends within the pattern repeat across the fabric width. 2 Overview of Polymers, Fibers and Yarns Used in Woven Fabrics The purpose of this chapter is to give an overview of polymers, fibers and yarns that are used in woven fabrics, as a convenience to the reader who may not be familiar with these areas. In this system, the spool does not rotate. Development of 3D weaving machines so far has been confined to universities and research centers such as NASA. 2.2 TEXTILE FIBERS 2.2.1 Fiber Classification and Spinning Fibers that are used in textiles can be classified under two main categories: natural fibers and man-made 9 © 2001 By Sulzer Textil Limited Switzerland 10 OVERVIEW OF POLYMERS, FIBERS AND YARNS USED IN WOVEN FABRICS TABLE 2.1 Examples of polymers used to make textile fibers [3]. Smith, W.C. and McCurry, J.W., “Industrial Textiles Thrive Through Technology”, Textile World, February 1999. The force needed to move the hooks is not supplied by feelers. Ishida, T., “Historical Developments in Weaving Machinery”, JTN, No. The conventional protection of the lower extremities consisted of 28 layers of polyamide yarn knittings that were fixed to the trouser legs as cushionshaped bags. A variation of twill weave is called broken twill. Therefore, the buckling of the filling yarn is neglected. Instead of a mechanical guiding shaft, an electronic guiding shaft, without moving parts, is used. A mechanical clearer may be as simple as two parallel blades (Figure 4.10). In basket weaves, warp and filling yarns are grouped and they interlace together. Rotary Dobby for Double Pile Weaving Machines Figure 6.36 shows a positive dobby machine with electronic control for double pile weaving machines. Until a few years © 2001 By Sulzer Textil Limited Switzerland ago, shuttle was the only insertion method used in those machines. Figure 1.3 shows the major steps in manufacturing of finished woven fabrics. Then, The Coriolis acceleration is (8.12) (8.18) which is normal to the yarn path (eN: unit vector normal to the yarn but not the principal normal) [32]. There are two types of chain structures in starch granules: linear and branched. However, most of those designs are based on the six basic designs that are explained in the chapter. Their main purpose is to supply filling yarn to the weaving machine smoothly and at a constant and proper tension. Multiple nozzles with profiled reed Figure 8.7 shows schematics of these three yarn insertion systems. Figure 8.2 shows a modern air-jet weaving machine. Figure 6.10 shows the schematic of a basic double lift, negative dobby mechanism in which a baulk and pairs of feelers, pegs, hooks and knives are used for © 2001 By Sulzer Textil Limited Switzerland each harness (single lift dobbies, which have become obsolete, had only one knife per harness). In direct sizing, yarns are fed to the size box from a single creel beam or warper’s beam. Draw the typical velocity and acceleration curves of a double flexible rapier head against the machine width. However, it is reasonable to state that there may be not much room for speed improvement in single phase machines due to physical limitations. The data can be retrieved from the machine with an interface. 13. For air-jet weaving, a minimum of 75% open space on the dry cans is recommended for any type of yarn. Its purpose is to develop and promote common standards worldwide. 4.3 SLASHING (SIZING) 4.3.1 The Need for Slashing Although the quality and characteristics of the warp yarns coming out of the winding and warping processes are quite good, they are still not good enough for the weaving process for most of the yarns. Residual size contamination can also affect permanent press, soil release and other finishes. High weaving tensions, especially in the warp yarns, cause fabric to shrink. By the nature of the fiber spinning process, the fiber lengths are very long. and Brady, P.H., Fiber Forming Polymers in Wellington Sears Handbook of Industrial Textiles, Technomic Publishing Co., Inc., 1995. See our User Agreement and Privacy Policy. 3. A conveyor takes expelled projectile 1 and carries it outside the shed back to the picking position. The yarn is guided onto a vibration sensitive beam by an entrance and exit eyelet. There is a wide variety of dry can designs that are used for efficient drying of the yarns. Air-jet weaving is the subject of Chapter 8. Warp density is 24 ends/cm and weft density is 11 picks/cm. A 600 needle machine has 1200 hooks; each needle controlling two hooks. The filling end grippers with the clamped yarn ends move forward with it at the same time. The lifting units work on the patented rotary principle. Several sets of warp yarns may be beamed to make several narrow fabrics, side by side, on the same weaving machine. Warp Let-off (Figure 8.34) The power warp let-off can handle a wide weft density range. Nevertheless, the shuttle loom is still used as a reference point for the modern shuttleless weaving machines. Kawabata developed an equation that gives a weighing to each of the measured properties and called the resultant summation Total Hand Value. “Zero defects” is literally a must in these fabrics; geometrically, the weft and warp have to be accurately positioned in the fabric in all three dimensions. In Phase A, the left-hand rapier takes the pick with accelerated and decelerated speed into the middle of the weaving machine.