Knitted technology forms the backbone of countless textiles, from the clothes we wear to advanced industrial materials. This comprehensive guide explores the fundamental principles of knitted technology and fabric structures, delving into the distinct worlds of warp and weft knitting, the innovation of seamless garments, and the unique properties of spacer fabrics. Understanding these techniques is crucial for anyone studying textile engineering or fashion design.
Knitting is a method of producing fabric by creating interlocking loops of yarn. The key distinction lies in how these loops are formed and interconnected, leading to two primary categories: weft knitting and warp knitting. These methods dictate the characteristics, applications, and production processes of knitted textiles.
Understanding Knitted Technology and Fabric Structures
Knitted technology fundamentally differs in how subsequent loops are formed from a single thread. In weft knitting, loops are placed in the same course, creating rows horizontally. Conversely, in warp knitting, subsequent loops from one thread are placed in subsequent courses, creating vertical columns.
Weft Knitting: Loop Formation and Machinery
Weft knitting involves forming loops horizontally across the fabric. A single yarn travels back and forth, creating interlocking loops in a row. This method is highly versatile and allows for easy changes in patterns and designs.
Different types of weft knitting machinery are available, each suited for specific fabric structures. Flat knitting machines, often V-bed types, can create single-faced structures with one needle bed or double-faced structures (like rib or purl) with two needle beds.
Circular knitting machines, on the other hand, utilize either a single cylinder for single-faced structures or a cylinder and dial for double-faced fabrics such as rib and interlock. Large, body, and small diameter machines cater to a wide range of product sizes.
Weft knitted products are incredibly diverse, including various garments, accessories, and home textiles. Examples range from intricate jacquard designs to everyday socks and sweaters, showcasing the adaptability of this knitting method.
Warp Knitting: Machines and Applications
Warp knitting involves multiple yarns, each forming its own set of loops in a vertical direction. Unlike weft knitting, where one yarn creates an entire course, each warp yarn forms a loop in only one wale. This results in fabrics that are generally more stable and less prone to unraveling.
Common warp knitting machines include Raschel machines (single and double needle bar), Tricot machines (using compound or bearded needles, single or double needle bar), and Crochet machines (using carabine or latch needles). These machines are designed for high-speed production and specific fabric characteristics.
Warp knitted fabrics find extensive applications across various industries. They are widely used in garments, underwear, hosiery products, and sportswear due to their elasticity and design versatility. Beyond apparel, they are critical in medical and sanitary textiles, furniture and upholstery, car interiors, and a vast array of technical products, including geotextiles and fishing nets.
The Evolution of Seamless Knitted Technology
Seamless technology is a revolutionary advancement aimed at producing garments with minimal or no seams, enhancing comfort, fit, and production efficiency. Both warp and weft knitting have developed their own approaches to achieving seamless structures.
Warp Knitting Seamless (WKS)Warp Knitting Seamless (WKS) is an innovative approach to creating seamless articles, ranging from t-shirts and lingerie to sportswear and gloves. This technology offers significant commercial and economical advantages.
Key advantages of WKS include freedom of body movement due to the absence of seams, a wider range of fit for diverse body shapes, and inherent softness as there are no bulky or irritating stitches. Furthermore, it significantly reduces labor costs by eliminating cutting and sewing processes.
Machines like the RDPJ and DJ series are ideal for seamless production, capable of creating tubular shapes with variable diameters and functional zones with different stretch values. They can also work seams directly into the garment and produce intricate jacquard designs.
For example, an RDPJ 4/2 machine can produce long-sleeved shirts in a single fabric panel, utilizing core-spun yarns for jacquard patterns and standard yarns for the ground structure. The make-up operation for warp knitted seamless goods involves knitting followed by specialized finishing. Unlike conventional seamless articles that require individual finishing on special frames, continuous finishing is preferred for elastane-containing warp knits due to processing zone limitations and temperature control.
Weft Knitting Seamless
Weft knitting also plays a crucial role in seamless garment production, particularly with advanced circular knitting machines. These machines are designed to produce complete garments or garment components without the need for extensive post-knitting assembly.
Santoni's SM8-TR1, for instance, is a single jersey machine that can produce seamless casual sportswear with eight feeds. It handles various yarns, including natural fibers like wool and cotton, and creates structures like mesh, pointelle, and eyelet areas directly. Another example is the SM-DJ2TS, a double jersey circular machine that produces luxurious women's underwear, men's and women's underwear, and nightwear in seamless form, including true ribs, links-links, and jacquards.
Comparing Warp and Weft Seamless Technologies
When comparing warp and weft seamless technologies, several distinctions emerge. Warp knitting uses warp sheets on beams, while weft knitting uses cones produced on winding machines. Warp knitting allows for varying tubular product diameters limited by the machine's bar width, whereas weft knitting is constrained by the machine's diameter (e.g., 16-20 inches).A significant advantage of warp knitting is its higher loop production rate. Warp knitting also offers greater resistance to laddering compared to weft knitting. While warp knitting requires preparation of bars after warp run-in, weft knitting allows for easier pattern changes and small batch production.
Warp knitting machines, like Karl Mayer's DJ 4/2 EL, can achieve high production rates (e.g., 750 courses/min) and produce finished articles in a single piece. Santoni's SWD 4/2J and SWD 6/2J warp knitting machines are specifically designed for seamless items like pantyhose, underwear, and activewear, offering breathability and non-run fabric structures, often eliminating the need for post-knitting finishing.
Advanced Techniques: Loop Transferring
Transferring loops between needles is a sophisticated technique that enhances design possibilities and fabric structures, particularly in weft knitting. This process allows for intricate patterns and shaping without cutting and sewing.
Weft Knitting Transferring Techniques
On V-bed (flat) weft knitting machines, special needles with a wing in their stem allow for transferring a loop held in one needle to an adjacent needle. This synchronized movement enables the loop to enlarge sufficiently and be transferred in one direction, creating unique design effects.
Historically, creating small holes in fabric involved releasing a loop without feeding new yarn. However, modern techniques allow for transferring a loop from one needle directly to an adjacent needle within the same needle system on circular machines. This enables the creation of small holes without curling and allows for transferring up to three or four loops between adjacent needles in the same course without breaking the yarn.
Exploring Spacer Knitted Fabrics
Spacer fabrics are innovative three-dimensional textile structures, often described as a