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Solutions to some minor faults of industrial sewing machines

  • Release Time:2021-07-01
  • 209 Views

Collected some common sense of sewing machine, industrial sewing machine strikes, small problems can be solved by themselves.


One: Failure in feeding


(1) Fault feature: sewing material wrinkles.

Product reasons: broken needle tip, excessive bobbin thread tension, improper adjustment of the differential mechanism.

Solution: Replace the needle with a new one, loosen the bobbin spring screw, and readjust the differential mechanism.


(2) Fault feature: the bottom of the sewing material is "chewed" to form a tooth mark.

Product reason: the feeding teeth are too sharp and the pressure of the presser foot is too high.

Treatment method: Use oilstone to grind the tooth tip and loosen the pressure adjusting screw.


(3) Fault feature: The sound of the thread breaking the fiber suddenly when sewing the thread under the sewing material.

Product reason: The needle is broken or blunt.

Solution: Replace the needle.


(4) Fault feature: the sewing material is stagnant.

Product reason: the feed dog is too low and the presser foot pressure is too high.

Treatment method: Raise the feed dog and tighten the pressure regulating screw.


(5) Fault feature: sewing material goes back and forth.

Product reason: the feed tooth is too high.

Treatment method: adjust the feed dog.


(6) Fault feature: the sewing material cannot be sewn backwards.

Product reason: the feeding cam is shifted.

Solution: Adjust the position of the feeding cam.


(7) Fault feature: The sewing material goes diagonally irregularly.

Product reason: The feed dog is installed crookedly or the screw of the feed dog is loose.

Solution: Correct the feed dog and tighten the screws.


Two: Trouble in stitch


(1) Fault characteristics: The upper thread is floating.

Product reason: the pressure of the clamp is too small.

Treatment method: Tighten the thread clamp to increase the tension of the cotton thread.


(2) Fault characteristics: the bottom line is floating.

Product reason: the bobbin spring is too loose.

Solution: Tighten the bobbin spring screw to increase the tension of the bottom thread.


(3) Fault characteristics: the stitch length is long and short.

Product reason: the pressure of the presser foot is too small.

Treatment method: Tighten the pressure regulating screw.


(4) Fault characteristics: there is a thread sleeve under each needle under the sewing material, which is like a towel thread sleeve.

Product reason: the cloth feeding and thread take-up actions are not compatible, and the cloth feeding action is fast.

Treatment method: adjust the cloth feeding cam screw to make the cloth feeding and thread take-up actions harmonized.


Three: Operational failure


(1) Fault feature: The nose is rotating and sluggish.

Product reason: wrong lubricating oil, especially vegetable oil. There is too much dirt in the shuttle bed, and the connecting rod screws and cone screws are installed too tightly.

Treatment method: After flushing with kerosene, refill the sewing machine oil. Clean the shuttle bed and loosen the screws to ensure a certain gap.


(2) Fault characteristics: When sending, the half circle is stagnant, the half circle is lightly slippery or there is a stagnation point for each circle. The inner wheel of the shuttle bed not only stagnates half a turn when the thread head is running, but also is accompanied by severe jitter and noise.

Product reason: The position of the feed dog is too high or dirt accumulates in the gap of the teeth, which makes the feed dog collide with the needle plate when it rises.

Treatment method: clean the shuttle bed and add a little sewing machine oil. Clean or lower the feed dog. Replace or straighten the needle bar.


(3) Fault characteristics: The machine head is stuck and cannot move.

Product reason: The position of the feed dog is too front or too back, touching the needle board. The needle bar is installed too high, and the needle clamp is touching the casing.

Treatment method: adjust the position of the feed dog, re-align the needle, and adjust the height of the needle bar.


(4) Fault feature: the noise comes from the needle mechanism.

Product reason: the needle bar, needle bar cover, small connecting rod, etc. wear and move too much. The small connecting rod screw needle bar crank screw is loose.

Treatment method: Replace with new parts and tighten.


(5) Fault characteristics: the noise comes from the feeding mechanism.

Product reason: the large pointed cone screw is worn or loose, the feed dog touches the needle plate, and the needle pitch adjustment mechanism is loose.

Treatment method: grinding or readjusting, readjusting, readjusting or tightening screws.


(6) Fault feature: the noise comes from the shuttle mechanism.

Product reason: The wear of the shuttle and the shuttle bed causes the gap to be large, and the gap between the shuttle and the shuttle holder is too large, resulting in an impact.

Treatment method: Replace with new parts, adjust or replace with new parts.


(7) Fault characteristics: general noise.

Product reason: the upper shaft, lower shaft and shaft sleeve are worn out, causing movement up and down, and the machine is short of oil.

Treatment method: replace with new parts, or adjust the gap between the upper and lower shaft planes, pay attention to maintenance, and refuel on time.


Four: Broken needle


(1) Fault feature: needle breakage when sewing thick material.

Product reason: The needle is too thin or bent, the thickness of the sewing material is uneven, and the needle bar moves too much.

Treatment method: replace the thick needle with a new one, adapt to slow down the sewing speed and help feed the material by hand, replace with a new needle bar or needle bar cover.


(2) Fault characteristics: the short stitch length keeps the needle, the long stitch length breaks the needle.

Product reason: the action of the feed dog is lagging, the feed dog is unqualified, and the needle breaks when the machine needle touches the back end of the feed dog.

Solution: Adjust the positioning of the feeding cam, appropriately shorten the stitch length or replace the feeding dog with a new one.


(3) Fault feature: The needle is broken under the needle plate.

Product reason: The needle position is too low, the needle touches the shuttle, the shuttle bed is not installed properly, the tip of the shuttle touches the needle, the gap between the shuttle holder and the needle end is too small or too large, the shuttle holder touches the needle or is missing Needle protection.

Treatment method: adjust the position of the needle bar or the needle, reinstall the shuttle, and adjust the gap between the shuttle holder and the needle.


(4) Fault feature: The needle is broken on the needle plate.

Product reason: The sewing material is pulled too hard, causing the needle to bend, the presser foot screw is loose, causing the presser foot to sway and touch the needle, the displacement of the cloth feed cam causes the sewing material to break the needle, and there is a hard object in the sewing material that makes the needle touch Off.

Treatment method: strengthen the operation practice, adjust the presser foot to tighten the screw, and adjust the position of the cloth feeding cam screw.


Five: disconnection


(1) Fault characteristics: The first needle is broken, and the broken thread is cut.

Product reason: The needle is installed backwards or the needle is not installed enough, which causes the needle to be too low. The sewing material is too hard, the needle is too thin or the presser foot pressure is too high.

Solution: Check whether the needle is installed and the needle bar connecting shaft screw is loose. Change the needle or adjust the presser foot pressure.


(2) Fault characteristics: The suture is curled at both ends of the broken ends with short whiskers.

Product reason: the thread is too tight or the thread is twisted during sewing. The suture is squeezed into the guide groove of the shuttle bed by the shuttle. The sutures are rotten, brittle and easy to knot, with poor quality, and there are burrs at the thread passing parts.

Treatment method: change the pressure of the clamping piece and check the threaded line to eliminate the winding. Check the wear of the shuttle, and replace the shuttle if necessary. Sand the threaded area and replace the suture.


(3) Fault characteristics: The bottom part of the sewing material is heavy, and the stitch length cannot be formed and the thread is broken, and the broken thread is ponytail-like.

Product reason: the feed tooth is too low, and the sewing material does not stop and the thread is too much and breaks. The cloth feed is out of step with the thread and is broken. The presser foot and the needle are loose, hindering the sewing material from running.

Treatment method: raise the feed dog, adjust the positioning angle of the feed cam, tighten the presser foot and the needle screw.


(4) Fault characteristics: the thread suddenly breaks during sewing, and the upper thread fluctuates in a curved shape.

Product reason: the position of the shuttle bed is not installed with the noodle thread rolled into the shuttle bed. The bobbin case is locked at the end or suddenly shifted during sewing. Poor shuttle quality. The bobbin spring is too long or the core sleeve is oval.

Treatment method: readjust the position of the shuttle bed, reinstall the shuttle, and change the shuttle with the core sleeve.


(5) Fault feature: the bottom thread suddenly breaks during sewing. The bobbin case is unqualified and the inner diameter is elliptical.

Product reason: the bobbin case is unqualified, and the inner diameter is elliptical, causing the bobbin to fail to rotate. The bobbin spring screw is too tight, so that the bobbin pressure is too small. The bobbin winding is too full or too loose and messy. The bottom thread is rotten and brittle and has knots, which prevents the bottom core from passing through the bobbin spring.

Solution: Replace the bobbin case, loosen the bobbin spring screw, rewind the bobbin thread, and replace the bottom thread.


Six: Jumper


(1) Fault characteristics: the bottom line cannot be drawn.

Product reasons: the shuttle thread is too short, the shuttle thread is clamped in the shuttle door, the needle is too high, and the shuttle cannot hook the thread loop.

Treatment method: extend the shuttle thread, check whether the bottom thread is jammed, and eliminate it. The needle bar connecting shaft is loosened and the needle bar moves up. The needle bar should be lowered, the needle should be re-aligned, and the fastening nails should be tightened.


(2) Fault feature: the needle bar moves.

Product reasons: Needle bar hole, needle bar wear, needle bar connecting screw loose, needle bar displacement.

Treatment method: change the needle bar cover, or select a new needle bar, re-align the needle; and tighten the set screw.


(3) Fault feature: one stitch skips over several stitches.

Product reasons: the shuttle is worn, the tip of the shuttle is too blunt, and the needle is too high or too low.

Treatment method: change the shuttle, adjust the height of the needle bar or the height of the needle, and re-align the needle.


(4) Fault feature: Continuous jumper or one stitch can not be sewn.

Product reason: Poor quality of the needle or bending of the needle can not normally produce thread loops. The needle is too high to catch the thread loop, and the sewing material and sewing machine needles are not properly matched. Long-term use of the shuttle, swing bed and other parts are severely worn or broken.

Treatment method: replace the qualified needle or straighten the needle. Adjust the height of the needle bar or needle. Under normal circumstances, the shuttle or shuttle bed can be replaced, and overhaul if necessary.


(5) Fault characteristics: thin seam without jumper, thick seam jumper.

Product reasons: Insufficient presser foot pressure, too thin needle, serious wear of parts such as thread hooking mechanism.

Treatment method: adjust the pressure of the presser foot, change the needle, replace the parts, and repair.


(6) Fault features: thick stitches, thin stitches.

Product reasons: the needle-containing hole of the needle plate is worn too much, the needle is too thick, the bottom of the presser foot is worn, or the presser foot pressure is too small.

Treatment method: change the needle plate, change the fine needle, change the presser foot, change the presser foot, or adjust the presser foot pressure.