What is Covered spandex yarn?

         Covered spandex yarn, also known as spandex-covered yarn, is a type of elastic yarn formed by wrapping spandex filaments with continuous filament or staple fiber yarn in a spiral manner while in a stretched state.

covered spandex yarn

Classification of Covered Spandex Yarn:

  1. Based on the number of coverings, it can be categorized as single-covered yarn and double-covered yarn. Nylon spandex and polyester spandex are commonly single-covered.
  2. Based on the equipment used, there are two types: single-covered yarn (abbreviated as SCY) and air-covered yarn (abbreviated as ACY).

Air covered yarn

         Air-covered yarn (ACY) is created by simultaneously stretching outer filament yarns and spandex filaments through a specific nozzle, forming a rhythmic network of points through high-pressure compressed air. The resulting fabric has a soft and smooth texture.

scy nylon yarn

Spandex covered yarn

Single-covered yarn (SCY) involves continuously rotating outer filament yarn around the stretched core spandex filament. It possesses twist (measured in turns per meter) and offers a fabric with a firm and smooth style.

         In downstream weaving, both ACY and SCY have their advantages and disadvantages.  ACY may require sizing during warp knitting to prevent issues like pilling and breakage, but it can be directly used in weft knitting. Considering cost alone, ACY has higher production capacity, leading to lower prices compared to SCY. However, SCY, despite its lower production, maintains higher prices, increasing the overall cost of using SCY.

Key Processes:

        During the spinning process, the pre-stretch ratio of spandex (spandex stretch) is a crucial parameter affecting the elasticity of covered yarn and fabric. The pre-stretch ratio also influences the tensile strength, evenness, and creep performance of covered yarn. The ratio should be adjusted to balance elasticity and product quality.

        For ACY, the tensile strength increases with the pre-stretch ratio until the spandex filaments start to contract, causing the outer fibers to curl. Adjusting the pre-stretch ratio appropriately can enhance the curling of outer fibers. However, excessive stretching can lead to a decrease in tensile strength.

        Creep, the deformation over time under constant tension, is an important consideration. For conventional covered yarn, the best anti-creep performance is achieved at a spandex pre-stretch ratio of 3.5. Adjustment based on specific applications and downstream fabric styles is necessary.

        For SCY, in addition to the spandex pre-stretch ratio, twist (measured in turns per meter) is a critical parameter affecting yarn quality, tensile strength, and evenness. Proper twist enhances the cohesion between outer fibers and spandex, increasing the strength of covered yarn.

spandex covered yarn machine 1


polylion yarn factory
acy yarn factor machine

       Covered spandex yarn finds its primary applications in weaving, elastic denim, woven belts, socks, underwear, lace, and sports equipment.



           Applications of covered spandex yarn extend across various industries, showcasing its versatility and adaptability. The unique properties of this elastic yarn make it a preferred choice in a range of textile and apparel products. Here are further details on its applications:

  1. Weaving: Covered spandex yarn is widely utilized in weaving processes, contributing to the production of fabrics with enhanced stretch and recovery properties. Its ability to provide elasticity makes it suitable for weaving various types of textiles, from everyday clothing to specialized applications.

  2. Elastic Denim: In the fashion industry, covered spandex yarn plays a crucial role in the production of elastic denim. The yarn’s elasticity ensures comfort and flexibility in denim products, meeting the demand for stretchable and form-fitting jeans and other apparel items.

  3. Woven Belts: Covered spandex yarn is incorporated into the production of woven belts, adding a stretch component to the belts. This feature enhances the fit and comfort of the belts, making them suitable for a diverse range of consumers.

  4. Socks: The yarn finds extensive use in the manufacturing of socks, providing them with stretch and resilience. Whether it’s athletic socks that require extra support or everyday socks for comfort, covered spandex yarn contributes to the overall performance and durability of the final product.

  5. Underwear: Covered spandex yarn is a key ingredient in the production of elastic fibers for underwear and intimate apparel. Its stretch and recovery properties are essential for creating undergarments that offer a snug fit and retain their shape over time.

  6. Lace: In the textile and fashion industry, covered spandex yarn is utilized in the creation of lace fabrics. The yarn’s ability to impart elasticity to lace enhances the comfort and fit of garments incorporating lace elements, such as lingerie and decorative apparel.

  7. Sports Equipment: Covered spandex yarn is applied in the production of various sports-related products. From activewear to specialized sports equipment, the yarn contributes to the flexibility and performance of these items, meeting the demands of athletes and fitness enthusiasts.

           In conclusion, covered spandex yarn proves to be a valuable component in the textile and apparel industry, providing elasticity and stretch capabilities to a diverse array of products. Its applications continue to evolve, driven by the ongoing pursuit of comfort, performance, and innovation in the world of textiles.


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