The influence of the shaping process in post-finishing on the twill twist of knitted fabrics

We all know that the setting process in post-finishing can control the slope and twist of the fabric to a certain extent. After the fabric is dyed, it is dehydrated and dried. Before setting, the twill can be measured, and then the twill can be measured. The degree ratio sets the conditions for the twill to enter the machine, and can predict the degree of twisting.

Remove a needle from the cylindrical fabric to form a row of empty loops on the fabric. After dyeing, this row of empty loops will be slanted from one side of the cylindrical fabric to the other side, and spiral upward. If you do not open the width according to this empty needle position , the opening width of the cylindrical cloth edge is smooth, the twist of this cloth is zero or close to zero, but there are twill weaves on the fabric surface.

On the contrary, if the width is opened according to the empty needle position, there will be a slope on the left and right edges of the fabric. When setting the shape, a reasonable slope should be determined according to this slope. The twill is put into the machine for correction and shaping, but the fabric will have internal tension accordingly. When the residual tension is left after washing, The tension is released into torsion, causing the fabric to twist.

At present, the market generally requires the twist to be within 5%, some customers require it to be within 3%, and the twill is within 10%, and some customers require it to be within 8%. The two standards, the shaping process can only be modified within the standard range according to the actual situation. . In terms of actual garments, high-count fabrics have a thin body and fine knitted loops, so the twill stitches on the fabric surface are not easily noticeable. The requirements for twill should be lower, and the twist requirements should be higher. On the contrary, low-count fabrics have a thick body and thick knitted coils, and the twill of the coils on the fabric is easy to detect. The requirements for twill should be higher and the twist requirements should be lower.

In addition to the above-mentioned effects, some prevention methods can be used to improve twill twist, such as using yarns with lower twist, trying to spin low-count yarns with cotton with high micronaire, or using cotton yarn as Steaming yarn can also help a little. The selection of loom should match the fabric, pay attention to density, etc. Any method that can reduce the overall skew will be considered.

The current effective method is to use ply yarn, or use cotton yarn with S and Z twist directions to alternately weave in the gaps, but the customer must accept the cloth surface effect, or use resin control method after finishing.

Effect of ply yarn on skew: (Tested by U.S. Cotton Company)

Using 18-knit fabric and 100% cotton 40S single yarn air-jet spinning, the result is:

S and Z are wound in parallel without twisting, skew 1.2, skew = right.

Z and Z are wound parallel to each other without twisting, skew 21.0, skew = right.

Z and Z are combined and twisted 2.5T.P.I., the strands are S twisted, skew 17.0, skew = right. ??

Z and Z are combined and twisted 6.5T.P.I., the strands are S twisted, skew 11.3, skew = right. ??

Z and Z combined twist 12.5T.P.I., strands are S twisted, skew 0.0, skew = none. ??

Z and Z are combined and twisted 14.5T.P.I., the strands are S twisted, skew 3.5, skew = left.

The above results show that S and Z are wound in parallel without twisting, and the twist directions cancel each other out, leaving only a small amount of skew. Z and Z double yarn weaving has a large skew. Z and Z are combined and twisted for 12.5T.P.I., and the strands are S-twisted, which is a reasonable strand twist, so the skew is 0.0, and the skew direction = none. Beyond the reasonable twist, slightly tends to the left.