Its main purpose is to strengthen cotton canvas, keep the water repellency of cotton fiber when it swells in water, and make use of the tensile, tear and shrinkage resistance of polyester fiber when it gets wet in the rain. At present, the core-spun yarn has developed into many types, which can be classified into three categories: short fiber and short fiber core-spun yarn, chemical fiber filament and short fiber core-spun yarn, and chemical fiber filament and chemical fiber filament core-spun yarn. At present, many core-spun yarns are generally a kind of core-spun yarn with unique structure, which is made of chemical fiber filaments as the core yarn and wrapped with various short fibers. The common chemical fiber filaments of its core are polyester filament, nylon filament and spandex filament. Outsourcing staple fiber includes cotton, polyester cotton, polyester, nylon, acrylic fiber and wool fiber. Core-spun yarn has many advantages besides its special structure. It can make full use of the excellent physical properties of core-spun chemical fiber filaments and the properties and surface characteristics of coated short fibers, give full play to the advantages of the two fibers and make up for their shortcomings. For example, polyester-cotton core-spun yarn can not only give play to the advantages of refreshing, wrinkle-resistant, easy to wash and quick-drying, but also give play to the advantages of good moisture absorption, less static electricity and less pilling. The woven fabric is easy to dye and arrange, comfortable to wear, easy to wash, bright in color and elegant in appearance. Core-spun yarn can also reduce the weight of fabric, while maintaining and improving the performance of fabric. Based on the different chemical properties of chemical fiber filaments and coated fibers, in the dyeing and finishing of fabrics, some coated fibers were burnt with chemicals to make burnt-out fabrics with three-dimensional pattern effect. Uses of Core-spun Yarn: At present, the core-spun yarn with cotton as the skin and polyester as the core is the most widely used, which can be used to produce student clothes, work clothes, shirts, bathrobe fabrics, skirt fabrics, sheets and decorative fabrics. In recent years, an important development of core-spun yarn is the core-spun yarn with polyester core, cotton silk or cotton wool blended coating in women's fabrics. These products are very popular with people. According to the different uses of core-spun yarn, the main types of core-spun yarn at present are: core-spun yarn for clothing fabric, core-spun yarn for elastic fabric, core-spun yarn for decorative fabric, core-spun yarn for sewing thread and so on. There are also many spinning methods of core-spun yarn: ring spinning, electrostatic spinning, vortex spinning, self-twisting spinning and so on. At present, China's cotton spinning industry mostly uses cotton ring spinning core-spun yarn. 1 Spinning technology At present, there are two processes for spinning core-spun yarn, taking processing polyester-cotton core-spun yarn as an example. Carding system: cotton: carding-roving-spinning (core-covering). Combing system: cotton: blowing, carding, winding, combing and roving, spinning in one (core-covering). In the actual processing process, the selection of core-spun yarn technology depends on the yarn forming requirements and the number of spun yarns. The general principle is that you don't have to comb if you can rough it. If the combing system is adopted, the technological process can be shortened and the production cost can be reduced. For example, some manufacturers have good evenness of combed cotton sliver, good fiber straightness and parallelism, and can meet the coating requirements after stretching once. Then, the processes that can be used are: cotton: blowing, carding, winding, combing, roving and spinning (core-covering).