Skip stitch: In long-term sewing, the skip stitch caused by the bending of the machine needle and the operator's installation of the machine needle will also skip the stitch. If the rotary hook tip is too far from the concave surface of the machine needle, it will also skip the stitch. The gap between the rotary hook tip and the concave surface of the machine needle will be adjusted to 0.05mm, and if the thread clamp and take-up spring are too tight, the small amount of thread will be released, resulting in skip stitch. The tension of the thread clamp and take-up spring will be adjusted accordingly, such as the wear of the rotary hook tip during long-term sewing If the defect is no longer able to be hooked and a jumper occurs, it is necessary to replace it with a new rotary hook. In addition, when sewing the wrap on the knitted collar, due to its thickness, the machine needle used is a 9 # imported needle, which is also a high and low fabric sewing product, which can cause skipped stitches. However, the process requirements also do not require the use of the 11 # machine needle, as the needle hole is large, the needle rod can be adjusted downward by 0.2mm to increase the thread output. When the needle rod picks up and the hook tip is 0.1mm above the needle hole, the thread can be hooked, Because the thread loop starting at this time is most easily hooked, it can solve the problem of skipped stitches.

Cross section line: First, check if each thread passing through the surface line is threaded incorrectly. Check if the machine needle is bent and if there are burrs in the needle hole. If there are any, cross section lines can also be generated. Replace the machine needle, and during long-term sewing, if the threading hole of the thread take-up rod has grooves that cause the thread to be uneven and produce cross section lines. Check if there are too many needle marks left after the needle plate hole is broken, causing burrs in the needle plate hole and the cross section line. Check if there are concave burrs in the positioning hook of the rotary hook, After filing off the burrs with a small circular file, polish the grooves and burrs with sandpaper or cloth strips, and check if the screw heads on the shuttle shell are too long. During movement, the surface thread is prone to being damaged by screws, resulting in cross section lines. Replace the large and small screws. If the gap between the grooves of the new rotary hook, the inner rotary hook, and the burrs is small, resulting in wire clamping and cross section lines, use grinding paste to grind them to solve the problem of wire clamping and cross section lines.

Broken needle: First, check if the needle is bent, causing the needle to break due to the needle plate. Then, check if the needle is misaligned with the needle plate hole, causing the needle to break. Adjust the position of the needle plate and the tooth holder so that the needle is in the center of the needle plate hole. If the fabric is thick and the needle is small, or if the needle is small and misaligned when threading the fabric, causing the needle to break, replace the corresponding needle. Check if the feeding is too early or too late, which may also cause the needle to break, Adjust the synchronization between the feeding cam and the needle. Debugging method: Turn the needle tip of the machine to the position where it aligns with the needle plate and the upper plane of the needle plate when the teeth are feeding the material to the bottom. Check if the position of the rotary hook is misaligned, causing the needle to break. Adjust the gap between the rotary hook and the concave surface of the machine needle to 0.05mm. Check if the needle rod is placed too low, which may cause the needle to collide with the shuttle core and cause the needle to break. Adjust the height of the needle rod to use the scale on the needle rod as the standard, or check if the shuttle core is deformed, Replace the shuttle core.

Bottom line breakage: Check if the fit between the shuttle shell and the core is too tight. If the core is deformed and causes too tight, it can also cause the bottom line breakage. Therefore, it is necessary to replace the shuttle core. Check if the shuttle skin on the shuttle shell has been used for a long time and the wire groove is formed, which can cause the bottom line breakage during the wire discharge. Therefore, it is necessary to replace the shuttle skin.

Noise: There are many reasons for it, such as: prolonged working vibration causing screws to loosen, low oil content causing large clearance of the bevel gear, noise caused by wear and tear of the feeding cam after prolonged use, large clearance between the needle rod connecting rod and the needle roller bearing, clearance between the needle rod and the upper and lower sleeves of the needle rod, large clearance between the rotary hook and the inner rotary hook, etc. Various reasons can cause noise. Check if the screws are loose or listen carefully to which part of the sound is emitted. If the parts are severely worn, they must be replaced.