Warp knitting spacer structures

To this end, the machine building and textile industries have together developed what is known as the Caliweb process in which a warp-knitted spacer nonwoven Multiknit is used instead of the layer of foam. The nonwoven is clearly three-dimensional and is available from 3 mm to 8 mm thick. Fibres are mainly orientated in the third dimension and are integrated into both the meshed surfaces of the nonwoven (Fig. 3.3). Above this, their position is fixed by means of thermosensitive bonding fibres. This structure is as good as the foam which has been replaced. Composite formation between the decorative material and the nonwoven... 

Warp knitting technology is the most commonly used technology for the production of spacer fabrics. Warp-knitted spacer fabrics have attracted great attention due to their low cost, high productivity and wide structure variations compared to other kinds of spacer fabrics. The critical characteristic distinguishing warp-knitted spacer fabrics... 

Figure 6.31 Effect of different structural parameters on cushioning properties of warp-knitted spacer fabrics (a) spacer yam inclination (b) spacer yam diameter (c) fabric thickness and (d) outer layer structure (L, locknit Cl, chain plus inlay RM, smaU-size rhombic mesb HM, large-size hexagonal mesh).

D knitted textiles have already been widely used as technical textiles in different fields. The future work should be on the development of new 3D knitted structures with more extra functions to meet the requirements of new application fields. For example, warp-knitted spacer fabrics have great structural variations. By using different structures and fibre materials, they have been developed to have various physical functions to be used in different fields, such as cushioning, sound absorption, smart textiles and thermal collection. New potential application fields should be identified first in the future, and then fabric stmctures can be designed to better match the specific applicatimis. 

Liu, Y.P., Hu, H., Au, W.M., 2014b. Protective properties of warp-knitted spacer fabrics under impact in hemispherical form. Part II effects of structural parameters and lamination. Text. Res. J. 84, 312-322. 

In most load-bearing medical applications, however, warp-knitted structures, which include both weaving and knitting features, will generally be preferred. Specially constructed Raschel machines that have two needle bars and several guide bars are commonly used. The two needle bars, working alternately, contribute to the versatility of the products. The basic principle is that each needle bar produces a flat fabric the two fabrics are simultaneously connected to each other to form a three-dimensional structure. Examples of structures that can be produced are a double-sided, double thickness structure two separate fabrics with different structures and yarns, joined as needed tubular structure, straight or tapered, and with branches and a sandwich or a spacer fabric with filler yarns. 

Spacer structures have a 3D construction consisting of two separate outer fabric layers joined together but kept apart by spacer yams or fabric layers (Liu, 2013). This kind of fabric can be manufactured by weft and warp knitting. 

Figure 14.5 similar to Figure 14.4, a spacer structure having hemispherical spacers. However, the warp-knitted fabric consists of warp-knitted threads or warp-knitted filaments, which are brought into this shape and solidified by a thermal process or by impregnation with synthetic resin (Bier et al., 2008). 

Spacer brics are three-dimensional structures that can be engineered to incorporate a wide range of attributes and hence fulfil specific pre-determined requirements. Knitted spacra fabrics can be produced on both weft and warp kiutting machines. Each of the fabric faces can be designed independently, as well as the middle layer (spacer layer), in terms of yams and structures and this will determine the unique individud properties of each fabric [1,2]. Spacer fabrics have been studied and developed for a few years now but the number of variables that can possibly be input in their constmetion gives such a wide range of possibilities that many are still to be developed and exploited commercially. 

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