How to solve the defects that are easy to appear in the production of spandex knitted fabrics?
When producing spandex fabrics on large circular knitting machines, it is prone to phenomena such as flying spandex, turning spandex, and broken spandex. The causes of these problems are analyzed below and the solutions are explained.
1 Flying spandex
Flying spandex (commonly known as flying silk) refers to the phenomenon that spandex filaments run out of the yarn feeder during the production process, causing the spandex filaments to fail to feed into the knitting needles normally. Flying spandex is generally caused by the yarn feeder being too far or too close to the knitting needle, so the position of the yarn feeder needs to be re-adjusted. In addition, when flying spandex occurs, the drawing and winding tension should be increased appropriately.
2 turn spandex
Turning spandex (commonly known as turning silk) means that during the weaving process, the spandex yarn is not woven into the fabric, but ran out of the fabric, causing unevenness on the surface of the fabric. The causes and solutions are as follows:
a. Too small spandex tension can easily lead to the phenomenon of turning over. Therefore, it is usually necessary to increase the spandex tension. For example, when weaving a spandex fabric with a yarn density of 18 tex (32S) or 14.5 tex (40S), the spandex tension should be controlled at 12 ~15 g is more appropriate. If the yarn turning phenomenon has occurred, you can use a knitting needle without a needle to swipe the spandex on the reverse side of the fabric, so that the cloth surface will be smooth.
b. Improper position of the sinker ring or dial can also cause wire turning. Therefore, it is necessary to pay attention to the positional relationship between the knitting needle and the sinker, the cylinder needle and the dial needle when adjusting the machine.
c. Too high yarn twist will increase the friction between spandex and yarn during knitting, resulting in turning over. This can be solved by improving yarn twist (such as scouring, etc.).
3 Broken spandex or tight spandex
As the name implies, broken spandex is the break of spandex yarn; tight spandex refers to the tension of spandex yarn in the fabric, causing wrinkles on the surface of the fabric. The causes of these two phenomena are the same, but the degrees are different. The causes and solutions are as follows:
a. The knitting needles or sinkers are severely worn, and the spandex yarn is scratched or broken during knitting, which can be solved by replacing the knitting needles and sinkers;
b. The position of the yarn feeder is too high or too far, which causes the spandex yarn to fly first and then break during partial weaving, and the position of the yarn feeder needs to be adjusted;
c. The yarn tension is too large or the spandex passing position is not smooth, resulting in broken spandex or tight spandex. At this time, adjust the yarn tension to meet the requirements and adjust the position of the spandex lamp;
d. Flying flowers block the yarn feeder or the spandex wheel does not rotate flexibly. At this time, clean the machine in time.
4 Eat spandex
Eating spandex means that spandex yarn and cotton yarn are fed into the yarn feeder at the same time, instead of entering the needle hook in the correct way of adding yarn, which causes the position of a stretch of spandex yarn and yarn to be exchanged on the cloth surface.
In order to avoid the phenomenon of eating spandex, the position of the yarn and spandex weaving should not be too close, and the machine fly should be cleaned. In addition, if the yarn tension is too high and the spandex tension is too small, the problem of eating spandex is prone to occur. The mechanic needs to adjust the tension and check whether the spandex itself meets the order requirements.