Page 44 - 3D Fibre Reinforced Polymer Composites

Manufacture of 30 Fibre Preforms 33

The formation of the knitted fabric is accomplished through a row of closely spaced
needles (needle bed) which pull loops of yarn through previously formed knit loops
(Figure 2.22). The needle bed can be in a circular or flat configuration and an increase
in the number of needle beds available in the machine for knitting increases the
potential complexity of the fabric knit architecture. For weft knitted fabrics the motion
of the yam carrier as it travels across the width of the needle bed (or around the
circumference for circular machines) draws the yarn into the needles for knitting (Figure
2.23). In much the same way as weaving, warp knitting machines have an individual
supply of yarn feeding each knitting needle.

Figure 2.22 Illustration of knitting process

Figure 2.23 Flat bed knitting machine showing the yarn carrier and needle beds