Yarn is a continuous strand created by twisting or laying together fibers, which can be used to produce textile fabrics. It can consist of natural or synthetic fibers or filaments, twisted or grouped for applications in weaving, knitting, and other textile construction methods. The choice of yarn depends on the type of fibers used, the desired texture or feel of the fabric, and specific qualities needed, such as warmth, resilience, softness, and durability.
Types of Fibers
Textile fibers are classified based on their length into two main categories: staple fibers and filaments.
Staple Fibers: These fibers have a limited length that varies by type, such as cotton, wool, and jute. Staple fibers can be short or long, with cotton being a notable short-staple fiber, while most other natural fibers are long-staple, except for silk, which is a filament fiber.
Filaments: Filaments have a continuous length, meaning the filament’s length equals the yarn’s length. All man-made fibers are produced as filaments, though they can be used as staple fibers if needed. Filaments can be converted into staple fibers, but staple fibers cannot be used as filaments.
Yarn Classification
Yarns can be categorized by their structure into three types:
Staple Fiber Yarns (Spun Yarns): These are made by mechanically assembling and twisting staple fibers together, a process known as spinning. Machines such as ring spinning, rotor spinning, wrap spinning, and air-jet spinning are used to produce these yarns.
Ply Yarn: Single yarns are typically used in most textile and clothing applications. However, for specialized features, such as increased strength and durability, ply yarns are needed. Ply yarn is made by twisting two or more single yarns together, while cabled yarns are formed by twisting multiple ply yarns or a combination of ply and single yarns. Ply yarns are smoother, more regular, and more durable. The twisting direction is labeled as S or Z, with the folding twist usually in the opposite direction of the single yarn twist.
Filament Yarns: Filament yarns are made from one or more continuous strands, called filaments, that run the entire length of the yarn. Monofilament yarns consist of a single filament, while multifilament yarns contain multiple filaments. In apparel, multifilament yarns may have a few or many filaments, while filament yarns for carpeting can contain hundreds. Most manufactured fibers are produced as filament yarns, with silk being the primary natural filament yarn.
Filament yarns are further classified into flat and bulked yarns based on the shape of the filaments. Flat filament yarns are straight and parallel, resulting in a smooth surface, while bulked yarns, which are crimped or entangled, have greater volume. Texturing is the primary method for creating bulked filament yarns, which have increased air and vapor permeability. Textured yarns are commonly used in stockings, swimwear, sportswear, outerwear, underwear, carpets, and sewing threads, while flat yarns are preferred for applications requiring low air permeability, such as airbags.