Yarns are classified structurally
　　They are divided into the following categories.
　　Monofilament: refers to a continuous single yarn of very long length.
　　Compound yarn: A bundle of two or more monofilaments joined together.
　　Twisted yarns: Yarns formed by twisting compound yarns.
　　Compound twisted yarn: Twisted yarn is formed by merging and twisting one or more times.
　　Deformed yarns: Chemical fiber yarns are deformed to give them curls, spirals, loops and other characteristics. The purpose of the process is to increase fluffiness stretchability and elasticity. According to the performance characteristics, there are usually three kinds of elastic yarn, bulky yarn and network yarn.
　　Single yarn: A single, continuous length formed from short fibers by spinning.
　　Strand: Two or more single yarns are combined and twisted to form. If two single yarns are combined, they are called double strands, and three or more are called multiple strands. When the strands are combined and twisted, they become double twisted strands.
　　Fancy yarn: A yarn with special appearance and color made by a special process, including fancy yarn and fancy decorative yarn. It is formed by twisting core yarn, decorative yarn and solid yarn on fancy twisting machine, with special appearance form or color such as fiber knot, bamboo knot, ring, braid, spiral and wave on the surface.
　　Bulky yarn: Bulky yarn is a voluminous yarn with high looseness processed by using the heat shrinkage (thermoplastic) of prolene fiber. The yarn is made by mixing low shrinkage properties with high shrinkage properties of liposomal fibers in a certain ratio and then relaxing to heat set the shape. In this way, the high-shrinkage fibers shrink a lot and form a yarn core, while the low-shrinkage fibers shrink less and are squeezed on the surface, thus making a fluffy yarn.
　　Cored yarn: A yarn formed by wrapping filament or staple fiber yarn as a core with other fibers or yarns.
　　Next, we will focus on fancy yarns, which are used more often in home textiles.
　　Fancy yarn: It is a single-strand yarn with structural and morphological variations. It is spun by using special techniques or devices in the carding, roving and spinning processes to change the structure and form of the yarn, resulting in a "dotted" or "knotted" pattern on the yarn surface. For example, the surface of knotted yarn has granular dots attached to the surface of the yarn; the surface of bamboo yarn has interrupted coarse details; the surface of interrupted AB yarn has one section of single-color yarn and the other section of two-color AB yarn alternately. The length of such coarse details or monochrome and AB yarns can be determined according to the requirements of the later products, which can be long or short, coarse or fine, spacing can be thin or dense, regular or irregular.
　　Spandex corespun yarn
　　The spandex core yarn is formed by feeding a stretched spandex filament (generally 3~4 times stretched) between the middle roller and front roller of a normal spinning machine and converging it with the drafted bearded yarn, and wrapping the original ribbon-like fiber bearded yarn around the outside of the spandex yarn through the front roller.
　　This kind of yarn is generally 12-30tex (33-83 counts), can be used for knitted fabrics or woven fabrics, fabrics are elastic, comfortable to wear. At present, most of the spandex corespun yarn is cotton covered with ammonia, there are also polyester covered with ammonia.
　　Spandex corespun yarn can also be produced on double-roller twisting machine or special covering machine, spandex will be covered with a layer of cotton yarn or nylon filament; some wrapped with silk for silk T-shirt collar, due to the contraction of spandex silk, can make the knitted collar stiff.
　　Polyester corespun yarn
　　Polyester corespun yarn is formed by feeding a high-strength polyester filament yarn between the middle roller and the front roller on an ordinary yarn machine, and then wrapping the original ribbon fiber around the surface of the polyester filament yarn through the front roller.
　　The yarn can be made into high-strength polyester sewing thread by combining strands, which is not only strong, but also has a layer of cotton fiber on the surface, so that it is not easy to heat up when passing through the needle eye of a high-speed sewing machine. This yarn can also be woven into canvas for transportation belt, not only high strength, and the surface of the cotton fibers and rubber bonding performance, to overcome the shortcomings of polyester and rubber affinity. Polyester-cotton corespun yarn can be used as polyester-cotton roving fabric.
　　Stainless steel wire corespun yarn
　　The spinning method is similar to that of polyester corespun yarn, but the process should pay attention to the rewinding of stainless steel wire rolls to use radial positive rewinding method. Woven with this corespun yarn is generally used as weft yarn, and ordinary yarn 1:1 arrangement or 1:2 arrangement.
　　This kind of fabric can be used in the national defense of the radar coverings, can also be used for civilian radiation protection work clothes or aprons, etc., has a wide range of uses.
　　These yarns are made of stainless steel wire drawn into 8,000 to 1,000 bundles (6-8μm in diameter), and then blended with cotton to form yarns by drawing and breaking them into fibers on a drawing machine. Warp and weft with this kind of yarn fabric is very good radiation resistance and shielding effect, can be used for national defense and civilian use. If the cotton fiber is burned off with fire, it is a very thin layer of stainless steel mesh.
　　Bamboo yarn is a device added to the normal yarn machine, so that the front roller changes speed or stops, thus changing the normal draft multiplier and suddenly producing a thick knot in the normal yarn, like a bamboo knot, thus called bamboo yarn. Similarly, the middle and rear rollers can be suddenly overfed, which also changes the draft multiplier and creates bamboo knots.
　　At present, the density of bamboo yarn is 12-83ex (12-83 counts), raw materials are cotton, chemical fiber blends, etc., mainly staple fiber, but also medium-length and wool fiber. The length of the bamboo knot generally can not be less than the length of the fiber, the length of the bamboo knot of the cotton fiber is longer than the length of the bamboo knot of the short thousand type fiber.
　　The thickness of bamboo knot depends on the variety, the smallest bamboo knot is about 1 times thicker than the base yarn, with this bamboo knot yarn and a normal yarn with the same number of special combined to make clothing fabrics, the surface of the fabric can show irregular patterns.
　　Bamboo yarn with 4~5 times thicker than the base yarn is often wrapped with a finer yarn or filament because the difference between the thickness of the thick section and the base yarn is too great and the twist at the thick section is very small, which makes the yarn easy to hairy and low strength, and this shortcoming can be overcome by wrapping a yarn.
　　The fabric woven with this yarn has a rough surface and unique style; it is also used to make wave yarn on a fancy twisting machine, which is also called popcorn yarn because the wave shape at the thick section is very large and resembles corn.
　　There are single-color and two-color bamboo yarns, and the two-color bamboo yarn is also spun on a modified spinning machine. Two different colored rovings, one from the back roller is fed into the groove of the rubber roller of the middle roller into the front roller to form a drafting area with the front roller, and the other roving is fed from the back of the middle roller to form a drafting area with the front roller, and the two-color bamboo yarn is produced by overfeeding on the basis of spinning two-color yarn.
　　This kind of yarn spinning method is in the middle roller and the back roller each feed a different color (can also be different dyeing properties) of the roving, the middle roller and the back roller are separate drive, such as the middle roller and the front roller spinning A yarn, the back roller intermittently send out B yarn, this section is formed AB yarn, when sending B yarn A yarn should be slowed down, in order to ensure that the dry uniform.
　　The spinning principle is the same as double-color bamboo yarn, which is also spun on the modified spinning machine. The middle roller and the back roller each send out a different color roving, and the two pairs of rollers alternate in sending out the yarn. If the middle roller sends out A color roving, by the front roller draw spinning out a section of A yarn; when A yarn stop, the back roller began to send B color roving spun into a section of B yarn. The length of each color yarn can be set by the program.
　　The main difference between this yarn and the bamboo yarn is that the thicker and longer knots and the shorter details. Generally, bamboo yarn has fewer bamboo knots, only about two knots in 1m, and they are very short, so bamboo yarn is mainly the base yarn, and bamboo knots play a role in embellishment. And big belly yarn with thick section mainly, highlighting the big belly, and the length of the thick details vary greatly. At present, the commonly used yarn is 100 ~ 1000 (1-10 counts), using raw materials such as wool and acrylic and other wool-type long fibers.
　　The yarn with dots of various colors attached to the surface of the yarn is called colored dot yarn. There are light-colored dots on dark-colored base yarns and dark-colored dots on light-colored base yarns. This kind of colored dots generally use various kinds of short fiber first rolled into particles, after dyeing in spinning added. Whether cotton spinning equipment or rough comb wool spinning equipment can be rolled into colored wool particles.
　　Because of the addition of short fiber particles, so the yarn is generally spun thicker, its line density of 100 ~ 250tex (4 ~ 10 male), this type of yarn in the rough combing tweed with more, such as coarse tweed in the fire of the Muzi Ben (steel tweed), etc., are woven with colored dot yarn. Also use polyester staple fiber rolled into particles, mixed in the cotton yarn, woven into cloth after dyeing with room temperature.
　　Because polyester to high temperature and high pressure disperse dyes to color, so the surface of the fabric to generate a star-like white dots, unique style. There are also dark-colored particles added to light-colored fabrics to make colorful dots on the surface of the fabric, which has a unique style.
　　This kind of yarn is similar to the color dot yarn, but it only uses one color of dots, such as spinning polyester yarn with particles made of cotton or viscose fiber. If this yarn is dyed with disperse dyestuff after weaving polyester, the cotton is not colored, and it shows white stars. With this kind of yarn and ordinary yarn in the warp direction at a certain spacing, dyeing will generate stripes, and if added to the weft spacing will generate lattice.
　　Unlike segmental dyeing, this yarn is first dyed with a lighter color, such as peach red, light blue, light green, goose yellow, etc., and then printed with darker colored knots, usually with a length of about 10mm per knot and a larger spacing.
　　Dyeing multiple colors on the same yarn is called segmental dyeing, generally 4-6 colors for one yarn. Its application in the fancy yarn, can be used for big belly yarn, coarse special hair yarn, coarse knot and waveform yarn composite fancy yarn, also use the segment-dyed yarn and then processed fancy yarn for decorative yarn, made of colorful circle line (Figure 3), and also used as a solid yarn to make colorful. Most of these fancy yarns are used for knitted products, which is a major product that has been developing rapidly in recent years. Segment dyeing is also very effective on regular flat yarns.
　　This is a traditional method of dyeing fancy yarns in China, which is to divide a twisted yarn into two or three sections and tie them tightly with cotton yarn rope (the rope thickness is usually 5mm), the length of which depends on the variety, usually about 30mm. Because each section of white knot is not equal in length, the fabric made has a natural and casual style.