Common faults and solutions of sewing machines

1、 Skip stitch: It is a phenomenon where the hook at the bottom of the machine tool cannot hook onto the surface thread or slips after hooking onto the surface thread, resulting in the sewing machine being unable to continuously form thread steps.
1. The threading method is incorrect. Please re thread according to the "threading diagram".
2. The installation of the straight needle is incorrect. Check the height and orientation of the needle so that it moves slightly downwards in front of the needle plate hole.
3. If the needle tip becomes straight or bent, replace it with a new one.
4. The tip of the bending needle becomes blunt, which can be polished with oilstone or fine sandpaper, or replaced with a new bending needle.
5. If the suture tension is too high or too low, adjust the suture tension appropriately.
6. The curved needle cannot cover the thread ring of the right straight needle, and the right needle of the lower decorative line jumps. The coil of the straight needle is too small, increase the amount of jumper appropriately.
7. The looping of the left straight needle cannot be hooked by the curved needle. The left stitch of the lower decorative line is too looped and the straight needle is too looped, so the amount of jumper should be appropriately reduced.
8. The curved needle cannot simultaneously grasp the middle and left straight needle coils, and both the middle and left needles of the lower decorative line should jump. The amount of jump wires should be appropriately reduced.
9. The middle left needle on the back of the curved needle cannot penetrate the triangular area of the knitting needle and the curved needle, and the middle of the back of the left needle jumps. Check if the sewing thread passes through the thread clamp, check the synchronous operation of the bottom thread cam, and readjust according to the standard if there are any problems.
10. Improper cooperation between needles and curved needles and Youyou Resource Network. Check the height of the needle bar and the synchronization between the needle and the curved needle. If there are any issues, readjust according to the standards.
11. The needle and needle protection device do not match. Check the position of the needle and needle guard.
12. The needle on the decorative thread jumps due to improper matching with the tension needle or incorrect position of the tension needle. Check the fit size of the needle and tension needle, and check the thread yield of the tension needle.
2、 Thread breakage: Thread breakage in a sewing machine refers to the phenomenon where the hook at the bottom of the machine tool cannot hook onto the surface thread or the thread slips behind the hook, resulting in the inability to form a continuous thread step during the sewing process.
1. The threading method is incorrect. Please re thread according to the "threading diagram".
2. The needle is not installed correctly. Reinstall the needle so that the needle slot faces the operator.
3. The needle eye and slot of the machine needle are not smooth, replace with a new machine needle.
4. If the suture tension is too high, adjust the suture tension appropriately.
5. The quality of the stitching is too poor, use better stitching instead.
6. The stitching is thicker than the needle eye, so use medium stitching or machine needles instead.
7. If there are burrs or scratches on the needle, bending needle, needle plate, pressure tongue, thread hole and other thread holes, they should be re polished with oilstone or fine sandpaper, or the scratched part should be replaced with Youyou Resource Network.
8. If the machine needle does not fit properly with the bending needle and extension needle, readjust according to the matching standards of the machine needle with the bending needle and extension needle.
3、 Broken needle: Broken needle refers to the breaking of machine needles or bent needles due to unexpected resistance and obstacles during the sewing process.
If the pressure on the presser foot is too low and the needle breaks due to poor feeding, increase the pressure on the presser foot appropriately to ensure normal feeding.
2. When the bending needle and the straight needle collide, adjust the matching position of the bending needle and the straight needle according to the standard.
3. When the tension needle and straight needle collide, adjust the matching position of the tension needle and straight needle according to the standard.
If the straight needle and needle protector do not match, adjust the matching between the needle and needle protector according to the standard.
5. The curved needle tip is bald and should be replaced with a new one.
6. Excessive wear on the needle rod and needle rod sleeve, resulting in loose fit between the needle rod and needle rod sleeve. Replace the needle rod and needle rod sleeve.
7. The needle hole on the needle board is too small. Update the large needle hole needle plate or replace the small needle.
8. The parts are loose. Check the fit and wear of the hook mechanism parts, adjust the dimensions according to standards, and replace severely worn parts.
4、 Needle tying: Different thicknesses can result in different tension when the suture passes through the thread, uneven amount of thread drawn out, and may also lead to needle tying.
1. If the straight needle is too low, it will cause the straight needle coil to be too large, causing the coils to interweave with each other, and reposition according to the straight needle height positioning standard.
2. The tongue of the needle plate is too narrow, making it easy to splice straight needle coils. Replace with a new needle plate.
3. If the lower part of the bent needle is too narrow or too round, it can easily cause the straight needle coils on the bent needle to detach from each other, causing the coils to intertwine and produce flower needles. Replace the bent needle with a new one.
4. Poor coordination between straight and curved needles. Adjust the matching position of straight and curved needles according to the standard.
5、 Sewing material wrinkling
1. If the differential feed ratio is not appropriate, the differential feed ratio should be adjusted appropriately.
2. The height and front and rear positions of the feeding teeth are not suitable, and the height and front and rear positions of the feeding teeth should be readjusted according to the standard.
3. If the suture tension is too high, adjust the suture tension appropriately.
4. If the pressure on the presser foot is too high or too low, please adjust the pressure appropriately.
5. The small presser foot loses its flexibility in moving up and down, and there are stitches or rust embedded between the large presser foot and the small presser foot. Remove foreign objects between the large and small pressure feet, remove rust from the outside, or replace the rusted pressure feet.
6、 Poor stitching
1. The thickness of the wires varies, so use better stitching.
2. The wire clamp is not working properly. Remove dust from the wire clamp to ensure smooth wire passing.
3. The position of the threading device is incorrect, adjust the tension of the surface thread, curved surface thread, and tension surface thread.
4. The wire hole is not smooth, and the wire hole is polished or polished.
7、 Pinhole
It refers to the phenomenon of the needle piercing the coil of the fabric during the sewing process, causing the yarn to break and the stitch hole to expand, resulting in the coil falling off and the hole appearing at the seam. Under external influence, these small holes are easy to expand, leading to a decrease in the sewing fastness of the product and seriously affecting the appearance quality of the finished garment.
If the needle tip of a straight needle becomes blunt or hairy, please replace the needle.
Compared to sewing materials, the needle is too thick, so use a thicker needle instead.
3. If the needle plate eye is too small or has corners, please round the needle plate eye.
8、 Wrinkling of sewing sliding seam material
1. The proportion of feeding deficit is too small; Move the differential wrench downwards until the sewing material becomes flat.
2. The bottom surface of the presser foot is uneven with the plane of the feeding tooth; Adjust according to technical requirements.
3. The wire control pressure is too high; Readjust the wire control intensity.
4. The pressure of the clamping device is too strong or too weak; Adjust the pressure strength of the clamp.
5. The feeding teeth are too protruding from the needle plate; Adjust the correct height of the feed teeth.
6. The knife cannot cut quickly. 6. Sharpen the blade or replace it with a new one, and check the fit of the upper and lower blades.
7. Mismatch of differential feeding; Adjust the appropriate differential feed
8. The needle is too thick; Choose the appropriate thread and needle for the fabric.
9. The folding width is narrower than the needle tongue; Adjust the seam width or replace the needle tongue.
9、 Sewing elastic sewing material causes swelling.
1. The surplus ratio of the feed teeth is too small, resulting in elongation; Move the differential wrench to the "0" position until the sewing material becomes flat.
2. Excessive feed tooth ratio leads to shortening; Move the differential wrench to the "0" position.
10、 The upper and lower seams are uneven, and the lower layer is short.
1. The pressure on the presser foot is too loose; Increase the pressure of the pressure adjustment screw
2. The pressure foot resistance is too high or uneven; Polish the front of the presser foot or flatten the presser foot.
3. The differential gear and feed gear are not in the same plane; Adjust the height of the feed teeth as needed to make the two tooth surfaces flush.
11、 Sound
1. Loose or colliding parts; Carefully inspect all parts and tighten the screws to correct collisions or looseness.
2. Oil circuit blockage; After removing the oil pan, clean the garbage outside the oil pump to ensure smooth oil flow in and out of the oil pump.
3. The rubber pad of the oil pan is uneven; Check if there is a collision sound between the oil pan and the chassis. If there is, lay it flat to prevent contact.
12、 Machine weight
1. Caused by impure oil quality; Clean the oil stains with gasoline, then pour in new engine oil and lubricate for a few minutes.
2. Because the parts are too tight or not allowed; Carefully inspect and correct the screws on all parts to ensure a reasonable gap between them.
13、 Oil leakage
The oil proof plate of the feeding rack is damaged or the cover plate is uneven; Replace the oil deflector, inspect other parts or replace the sealing rubber to make the cover plates of each part flat, and then tighten the screws of each cover plate.