1. Needle problem
(1) Check whether the upper thread has been threaded wrongly or missed a certain thread position.
(2) Check whether the needle is installed correctly, such as the long groove of the needle is installed reversely or skewed.
(3) Check whether the needle model is applicable, whether the height of the needle bar adjustment is accurate, and check whether the needle is close to the top of the needle bar. If the needle is installed too high or too low, it will affect the hook thread.
(4) Check whether the needle is distorted. When sewing with a distorted needle, the hook cannot pick up the suture because the loop formed is far away from the hook. Slightly bent needles are difficult to identify directly with the naked eye, and can be identified by turning the needle on the platform.
(5) Check whether the movement time of the needle and the hook coincide. The movement time of the needle and the hook is fully matched, so that the hook can accurately hook the suture.
(6) Check whether the thickness of the needle and the sewing thread are appropriate. The use of a large needle with a thin sewing thread will also cause the thread to jump. This is because the needle eye of the large machine needle is longer and wider, and the hole position for piercing the fabric is larger, so that the thin sewing thread has a larger space to move. If it exceeds the hook and hook thread range, a jumper will appear;
(7) Check whether the needle eye of the machine needle is blocked due to the melting of chemical fiber sewing thread scraps, so that the suture cannot be conveyed normally and cannot form a loop. Caster
Second, the presser foot problem
Check whether the presser foot is installed too high and the feeding speed is too fast. If the presser foot is installed too high, the pressing force of the presser foot to feed the fabric will be insufficient. At this time, the fabric will oscillate with the presser foot, so that the upper thread cannot be pressed to form a loop; the presser foot feed speed is too fast, and the fabric will be transported. Take the upper thread quickly with the fabric, the hook cannot catch the upper thread.
Third, the sewing thread problem
(1) Check whether the sewing thread is too thick, uneven in thickness or the texture of the sewing thread is too soft.
(2) Check whether the tension of the upper thread is too tight. The upper thread tension is too tight, and the needle loop formed under the machine tool is too small, and the hook cannot be hooked.
Four, other issues
(1) Check whether the hook is defective. The missing hook cannot be hooked with sutures.
(2) Check whether the needle plate hole is too large. Many manufacturers did not replace the matching needle plate in time after changing to smaller needles in the production of thin materials. The large needle plate hole causes the fabric to be carried in or out of the round hole position by the machine needle, and the sewing thread cannot be compressed to form a loop, and it will also cause the thread to jump.
(3) Check whether the feeding teeth, shuttle bed, etc. are silted with cotton dust and dust, and care should be taken to keep them clean to avoid affecting the formation of thread steps.
Disconnected
1. Sewing thread problem
(1) Check whether the quality of the sewing thread is qualified. Sutures that are moldy, spoiled, or have nodules are most vulnerable to breakage.
(2) Check whether the selected sewing thread matches the needle. The sewing thread is too fine and easy to break due to insufficient toughness; a thin machine needle with a too thick sewing thread will make the sewing thread unable to pass through the needle hole smoothly and be cut.
(3) Check whether the upper thread tension is too tight. If the tension is too tight, the thread will break easily.
(4) Check whether the needle hole of the machine has accumulated debris, which causes the sewing thread to be transported unsmoothly and breaks.
2. Needle problem
(1) Check whether the sutures are melted due to the heat of the needle, especially when using chemical fiber sutures, due to the high-speed running of the sewing machine, the needle repeatedly pierces the fabric and generates heat, causing the chemical fiber sutures with lower melting points to be melted. .
(2) Check whether the hook position of the hook is proper. If the hook is too close to the needle hole, it is easy to break the suture when taking the thread.
Three, other issues
(1) Check whether the needle and needle plate are firmly installed. A loose needle or needle plate will cause the needle and needle plate to touch each other, and the upper thread will be broken.
(2) Check all the places where the upper thread passes (including loops, needle holes, hooks, needle plate holes, presser foot holes, etc.) for bends or defects to avoid the sewing thread from being hooked.
(3) Check whether the bobbin thread drum is too full or unevenly wound. The bobbin thread drum is too full or the bobbin thread is not evenly wound, and the bobbin thread is not conveyed smoothly, which may cause the bobbin thread to break.
In addition, poor gestures of the operator or lack of rhythm in the speed of the vehicle will pull the fabric and cause the upper thread to be cut by the feed dog, or cause the thread take-up hook to move up and down unevenly and tear the upper thread.
Solution
To solve the problem of wire jumper and disconnection, different treatment methods should be adopted according to the cause of the jumper and disconnection:
1. Solutions to jumper and disconnection caused by needle problems
(1) Needle needles with blunt tips are not used, and should be inspected regularly and replaced in time.
(2) A blowing device is installed beside the needle to accelerate the heat dissipation of the needle.
(3) Choose a needle with a special surface treatment, as shown in Figure 1. Among them, the machine needle covered with Teflon film can reduce the frictional resistance between the fabric and the fabric when stitching, inhibit the high heat generated by the needle, prevent the suture from being melted and melted by the heat of the needle, and avoid the thread jumper. , Disconnection and other phenomena.