yarn tension control during knitting
www.fibre2fashion.com Yarn Tension Control during Knitting
By: Biswajit Saha
Introduction
Control of yarn tension is one of the most important factors in knitting industry. Yarninput tension (YIT) to the knitting zone must be maintained between limits in order toproduce knitted fabric without faults. For preventing faults, however, YIT is not the onlyparameter to control and monitor. The knitting elements and the knitting machine itselfshould be monitored to improve productivity and quality. As far as YIT is concerned,defects may be prevented or quickly detected by using YIT as a means of process control.This has been found to be a valuable approach to accomplish this task, since it reflectsthe general behavior of the knitting machine. There are several ways to control YIT which are being practiced now-a-days or which can be implemented industrially asinnovative means to control the whole process. Monitoring, measurement and control of yarn tension in knitting process have been discussed briefly in this article.
Positive feed devices [1, 2, 3]
Positive feed devices are designed by positively supplying yarn at the correct rate underlow tension to the knitting point instead of allowing the latch needles or loop formingsinkers to draw loops whose length could be affected by varying yarn input tensionduring weft knitting. Positive feed devices offset the densities of packing of cones on yarn stands and variations intensions at each feed. Thequality is controlled by stitchlength and the latter iscontrolled by feeding exactlythe same amount of yarn tothe needles. But whenpatterned fabric is produced,positive feed arrangement isnot suitable because of the vastly different rates of yarninput at different feeds.Positive feed system feedsthe same amount of yarn toall feeds regardless of stitchadjustment. Some of themostly used positive feeddevices are capstan feed(cylindrical or tapered), nipfeed (garment lengthmachines), tape feed (asshown in Fig (i)),
By: Biswajit Saha
Introduction
Control of yarn tension is one of the most important factors in knitting industry. Yarninput tension (YIT) to the knitting zone must be maintained between limits in order toproduce knitted fabric without faults. For preventing faults, however, YIT is not the onlyparameter to control and monitor. The knitting elements and the knitting machine itselfshould be monitored to improve productivity and quality. As far as YIT is concerned,defects may be prevented or quickly detected by using YIT as a means of process control.This has been found to be a valuable approach to accomplish this task, since it reflectsthe general behavior of the knitting machine. There are several ways to control YIT which are being practiced now-a-days or which can be implemented industrially asinnovative means to control the whole process. Monitoring, measurement and control of yarn tension in knitting process have been discussed briefly in this article.
Positive feed devices [1, 2, 3]
Positive feed devices are designed by positively supplying yarn at the correct rate underlow tension to the knitting point instead of allowing the latch needles or loop formingsinkers to draw loops whose length could be affected by varying yarn input tensionduring weft knitting. Positive feed devices offset the densities of packing of cones on yarn stands and variations intensions at each feed. Thequality is controlled by stitchlength and the latter iscontrolled by feeding exactlythe same amount of yarn tothe needles. But whenpatterned fabric is produced,positive feed arrangement isnot suitable because of the vastly different rates of yarninput at different feeds.Positive feed system feedsthe same amount of yarn toall feeds regardless of stitchadjustment. Some of themostly used positive feeddevices are capstan feed(cylindrical or tapered), nipfeed (garment lengthmachines), tape feed (asshown in Fig (i)),