At present, high-speed sewing equipment is becoming more and more popular, and the correct selection of sewing threads has a high effect on ensuring the sewing quality of garments.
The suture is made by twisting two or more single yarns. After twisting, the fibers or strands in the suture are inclined, and we call this inclined direction.“twist direction”, the twist direction is divided into“S twist”and“Z twist”, also known as“left twist”and“right twist”.
The upper thread of the high-speed lockstitch machine should be selected“S twist”.
Otherwise, when the upper thread passes through the needle hole from left to right, a strong“untwist”. According to estimates, a fixed point on the sewing upper thread needs to be repeatedly passed through the needle hole about 70 times before it can be combined with the bottom thread on the fabric. This iterative process leads to“Z twist”Sutures occur violently“untwist”.
“untwist”Serious sewing thread will hinder the formation of thread loops at the bottom hook and lead to skipping threads, and it is also prone to frequent thread breakage due to reduced thread strength.
“S twist”When the suture is repeatedly rubbed against the pinhole, it is relatively difficult to be severe due to the twist direction relationship.“untwist”, It can keep the suture with high physical strength and performance, and it is not easy to cause jumper and disconnection.
The left needle of a double needle machine is another case.
Since its wire direction is opposite to that of conventional lockstitch machines, it is necessary to use“Z twist”line to avoid violent“untwist”. Otherwise, long-haired thread breakage will often occur, affecting production efficiency and stitching quality.
At this time if there is no“Z twist”The thread should be fine-tuned on the left rotary hook of the double-needle machine. When the hook tip is adjusted to be as close to the left needle as possible, the pressure of the thread pressing spring and the stroke of the thread take-up hook should be correspondingly reduced, so as to reduce the adverse effect of the twisting direction of the sewing thread.
In addition, 3 strands of twisted sewing thread should also be used to improve the resistance“untwist”performance.
As for the twist direction of the bottom thread of the sewing machine, there are no restrictions, both single-needle and double-needle sewing machines.