It is more difficult for the sewing thread to have a good pair of needles. The main problem is that the direction of one of the two needles is reversed, and the sewing thread in the opposite direction will produce the effect of retreat. The sewing thread is generally In the S direction (clockwise), the line that is going in the opposite direction will loosen, knot or even break because of the retreat.
To solve the problem of double needle sewing, we must avoid the problem of unwinding and loosening the strands. If we do not loosen the sewing thread, we can avoid the unwinding. When weaving the thread, we must add a low-melting-point thermal fuse inside the thread. After being heated and set, the strands are bonded together as a whole. This non-distributive sewing thread is called bonded sewing threads. When the Bondi twin-needle needles are stitched, the sewing thread is single-stranded. It is the best choice of sewing thread for solving the double needle sewing.