The principle of magazine weft insertion (Fig. 27.8) is to supply, for example, 18 or 24 ends of yarn from a stationary creel to an insertion carriage. With a weft insertion speed of 6500m/min, the speed of the weft yarn will be only 320m/min because multiple wefts are simultaneously being laid onto the conveyor to be fed individually to the knitting machine. The carriage traverses across the back of the machine, laying the weft yarns in parallel form onto the receiving pins of two magazine chains, one at each side of the machine.
The chains convey the weft to the weft insertion bits at the rate of one weft per
knitting cycle. As the carriage reverses its traverse, each return weft is placed around a receiving pin 18 or 24 positions further along the chain than the pin that first received it, in order to accommodate all the parallel weft yarns. Once the weft has been inserted into the fabric, the selvedged edges must be trimmed free of the receiving pins as the chains continue their rotation. It is essential in these cut selvedged fabrics to tightly grip the weft within the structure, otherwise wefts may slip or be pulled out; closed rather than open laps tend to be better for this purpose. Patterned effects are achieved by the package arrangement on the creel. Speeds of about 700-800 courses per minute are obtained .
Other methods, such as the use of a propeller for rotating the weft packages on a carousel, have been employed but have been found to be too restrictive.
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