Suture is composed of two or more strands of twisted yarn, twisted after the suture fibers or strands were inclined, this tilt direction we call “twist”, twist to “S twist” and “Z twist”, also known as “left twist” and “right twist”.
High-speed sewing machine should be used in the upper thread “S twist.” Otherwise, a strong & quot; back twist & quot; occurs when the upper thread crosses the pinhole from left to right. According to estimates, sewing a fixed point on the line, you need to repeat through the pinhole about 70 times, in order to combine with the bottom line in the fabric. This repetitive process results in a severe & quot; back twist & quot; of the & quot; Z twist & quot; suture. “Undone” serious sewing thread, will hinder the base parts of the formation of wire loop lead to jumper, but also prone to frequent suture strength decreased due to disconnection.
“S-twist” suture in the friction with the pinhole, the twist to the relationship is relatively difficult because of the “back twist”, the suture can maintain a high physical strength and performance, less prone to jumper and break phenomenon.
The left needle of the double needle machine is another case. The “Z twist” line is required in order to avoid severe “untwisting” because the wire direction is opposite to that of a conventional flatbed sewing machine. Otherwise, there will be a long hair-like broken ends were broken, affecting the production efficiency and quality of suture.
At this point if no “Z twist” line, should be on the left hook hook fine-tuning machine, transferred to the hook tip line as close to the left machine needle, and a corresponding reduction in pressure wire spring pressure and hook thread trip, reduce the sewing thread Twist to bring the adverse effects. In addition, should also use three shares of twist of the sewing thread, in order to improve resistance to “untwisting” performance.
As for the twisting direction of the bottom line of the sewing machine, there is no restriction, and both the single needle and the double needle sewing machine can do so.