The usage of fabrics and the number of spinning branches determine the size of fibers and the number of individual fibers. The finer the single filament and the more the number of strands, the softer and smoother the fabric with the same fiber size; On the contrary, the fewer the pieces, the harder and more straight the fabric. For laminated products, without considering the luster of the core wire, smooth core wire can be used to reduce production costs; For exposed products, the luster of the core wire should be considered, and the bare core wire should be avoided as much as possible to produce aurora and affect the use effect of the product. If producing 11.8tex (50s) polyester cotton core-spun yarn, when choosing 5.56tex (50D)/24F polyester semi gloss filament as shirt or skirt fabric, 5.56tex (50D)/24F ordinary low tensile strength fibers should be selected. Generally, polyester core-spun yarn with high light length, high elongation, and a single filament count of 7.78tex (70D)/36F or above is used for sewing. Made of polyester fibers below 7.56tex (68D)/36F, used as a tattered coat. However, as a core spun yarn used for worn-out fabric, the core yarn has a larger size and is generally made of 7.22-8.33tex (65-75D)/36F polyester filament. Light or semi light should not be used to avoid the worn-out area being too thin or thin, causing aurora. Elastic fabrics use core spun yarn, and the size of the core yarn can be selected according to the usage situation. Ordinary polyester 7.78 tex (70D) spandex has a stretching ratio of approximately 3.8 times that of polyester fibers. When the size of the spandex core yarn is moderate (medium to low count), the strength of the spandex core yarn is higher, up to 3.8-4.0 times, ensuring greater elasticity in stretching pants, buttocks, and knees. 2、 Selection of outsourcing fibers.

If cotton fibers are used for outsourcing cotton, theoretically, long count raw cotton should be used with high maturity. However, if high-speed sewing thread is not used, but is used to make shirt fabric or skirt material, or other fancy decorative fabrics, there is no need to use high-quality raw cotton because it does not require strong friction and high-temperature melting like high-speed sewing thread, and there will be no "peeling" phenomenon. 30mm long raw cotton can meet the requirements. However, due to the fact that cotton fiber is a core spun yarn of worn-out fabric, there are fewer neps and impurities. If it is outsourced cotton, the strength is low, the dyeing property is good, and there are fewer impurities and neps.