Summary of Knitted Technology and Textile Machinery

## Introduction Warp knitting is a family of knitting techniques in which yarns run longitudinally (warp-wise) along the machine rather than circumferentially. It enables production of tubular and shaped fabrics with built-in zones and minimal seams, commonly used for seamless garments, technical textiles, and fashion items. This guide focuses on warp knitting principles, seamless warp-knitting (WKS) applications, key machine types, and finishing considerations. > **Definition:** Warp knitting is a knitting process where each needle is fed by its own yarn or yarn guide so that loops are formed in a longitudinal direction rather than a transverse direction. ## Core concepts of warp knitting ### How warp knitting works - Yarn arrangement: yarns are supplied longitudinally from beams or cones and guided to needle hooks by guide bars. - Loop formation: loops are formed across wales by coordinated motions of guide bars and needle hooks. - Machine types: raschel, tricot and specialty warp knitting machines differ by sinker/guide and bar arrangements. > **Definition:** Raschel machines are a class of warp knitting machines with latch or compound needles and multiple guide bars, used for openwork, jacquard and technical warp-knitted fabrics. ### Key machine features relevant to seamless production - Multi-bar raschel (e.g., RDPJ, DJ series) enables: tubular shapes of variable diameter, built-in functional zones, integrated seams, and jacquard/open-work designs. - Gauge and working width affect fabric fineness and maximum panel size (example: RDPJ 4/2 with gauge E 24 and 138" working width produced multiple shirts from one panel). ## Seamless warp knitting (WKS) – advantages and examples ### Advantages - Freedom of movement: no conventional seams removes restrictions caused by seam elasticity differences. - Wider fit range: garments can accommodate a broader range of body shapes due to continuous geometry and elastic behaviour. - Inherent softness: absence of bulky stitches at shoulders, underarms and neck reduces irritation and improves comfort. - Reduced labour cost: cutting and sewing steps are largely eliminated, reducing manual labour and margin for error. Fun fact: Seamless warp-knitted garments can include seams worked directly into the fabric structure, eliminating many post-knitting joining steps. ### Practical examples and real-world applications - Apparel: t-shirts, lingerie, gloves, tights, and sportswear where stretch, fit and comfort are priorities. - Technical textiles: areas requiring variable stretch zones, contour shaping, or integrated functional features (e.g., compression zones in medical hosiery). - Prototype case: three long-sleeved shirts produced on an RDPJ 4/2 using a core-spun yarn in the jacquard bar and standard yarn in ground guide bars (fabric composition 81% PA 6.6, 19% elastane). > **Definition:** Core-spun yarns have an elastic or high-strength core wrapped by a sheath yarn to combine elasticity and surface properties. ## Make-up operations (production steps) ### Step 1: Warp knitting production - Machine selection: RDPJ and DJ series raschel machines are suited for seamless garments requiring little further make-up. - Capabilities: produce tubular shapes, variable diameters, integrated seams, open-work patterns and different front/back patterns. - Yarn placement: use of different yarns in jacquard bars (e.g., core-spun) and ground guide bars (standard yarn) to achieve functional zones and aesthetics. ### Step 2: Finishing - Typical finishing for tubular items: relaxation and heat-setting are often done on each tube or stocking individually using small units composed of a dryer, steam chamber and hot-air tunnel. - Limitations: conventional tubular finishing can be suboptimal for elastane-containing fabrics due to processing zone size, peak temperatures, and process reliability. - Continuous finishing options: developments exist for continuous finishing of seamless warp knits to improve thro