GATE (TF) Textile 2013 Question Paper Solution | GATE/2013/TF/11

Core spun yarn spinning is a specialized method of yarn production produced by friction spinning where a core yarn is wrapped or covered with a sheath of fibers to create a composite yarn with specific properties. The core yarn can be made of various materials such as cotton, polyester, or a blend of fibers, and the sheath can be made of different types of fibers or materials depending on the desired characteristics of the final yarn.
The process of core spun yarn spinning typically involves the following steps:
Preparing the core yarn: The core yarn, which acts as the core or central structure of the final yarn, is prepared by spinning or twisting the core fiber material into a continuous strand. The core yarn is typically thicker and stronger than the sheath fibers, and it determines the core strength and stability of the final yarn.
Preparing the sheath fibers: The sheath fibers, which form the outer layer or covering of the core yarn, are prepared by opening, blending, and carding the fibers to create a fluffy and uniform fiber batt. The sheath fibers can be of different lengths, types, or colors, depending on the desired appearance and properties of the final yarn.
Wrapping the sheath fibers around the core yarn: The core yarn is passed through a device known as a “cover roller” or “casing yarn guide” which guides the sheath fibers onto the core yarn. The sheath fibers are wrapped around the core yarn in a helical or spiral pattern, with the tension and twist carefully controlled to achieve the desired level of coverage and uniformity.
Twisting and plying: Once the sheath fibers are wrapped around the core yarn, the resulting composite yarn is then twisted to bind the sheath fibers to the core yarn and create a stable yarn structure. Depending on the desired characteristics of the final yarn, the composite yarn can be twisted in a single direction or plied by twisting multiple strands together in the opposite direction.
Finishing: After twisting and plying, the core spun yarn may go through additional finishing processes such as steaming, washing, or heat-setting to set the twist, improve the yarn’s appearance, and enhance its performance properties.
Core spun yarns are known for their versatility and can be used in a wide range of applications, including apparel, home textiles, and technical textiles, where their unique combination of core strength and sheath softness can offer advantages in terms of comfort, durability, and aesthetics.