Circular weft knitting

Figure 6.1 A single-jersey circular weft knitting machine.

Both weft and warp knitting machines are able to construct tubular structures. Although circular weft knitting machines can only be used in producing single tubes, flat weft knitting machines with two needle beds and double-needle bar Raschel machines are able to produce single, bifurcated and multibranched tubes. 

The key feature of circular weft knitting is to produce fabric structures in a tubular form. Figure 6.5 shows a tubular weft-knitted fabric developed for vascular stent application on a circular weft knitting machine with a small-diameter cylinder. The diameter and stitch density of a tube can be adjusted by varying the cylinder diameter and machine gauge, respectively. 

Compared to circular weft knitting, flat weft knitting is more flexible in producing tubular structures due to the capabilities of individual needle selection, loop transfer and multiple system knitting and the use of stitch presser and holding down sinkers... 

Figure 6.5 A tubular weft-knitted fabric by circular weft knitting.

Figure 6.15 Producing a spacer fabric on a circular weft knitting machine (a) a Terrot double-jersey circular machine and (b) knitting a spacer fabric on the circular machine.

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