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12. Troubles and corrective measures
1. Thread breakage 1-1) Threading 1-A)
Thread jamming at thread
6. Refer to “How to conduct threading".
guide, threading error
1-2) Thread path 2-A)
Flaws, burrs, rust generation,
Take measures to remove flaws, burrs, etc., and
and the like can be a finish the thread path neatly.
cause of resistance in In this case, however,the lower looper, throat
operation if they are present
plate, bobbin thread cam, and such important
in needles, throat plate, parts should be replaced if their shapes
small thread tension, seem to have changed.
needle thread rocking
thread path, needle thread
guide thread path, lower
looper, bobbin thread
guide pipe, bobbin thread
cam, lower thread path
guide, and thread tension
disc.
1-3) Rear needle guide 3-A)If contact between the Replace the needle, and replace the part if
needle and rear needle the rear needle guide is worn.
guide is excessive, needle
grooves are created on
he rear needle guide,
resulting in thead cut.
1-4) Needle 4-A)The needle is too thin Use an appropriate needle.
for the thread that is
now used.
1-5) Needle heat 5-A)
Thread cut occurs because
Reduce the needle size. Reduce the sewing
of heated needle depen speed. Use needle cooling air.
ding on the material type,
the number of superimposed
materials, and sewing speed.
1-6) Thread 6-A)Poor quality of the thread Use a high-quality thread.
1-7) Thread tension 7-A)Excessive thread tension Reduce the thread tension. Thread tension is
excessive because the needle thread adjust-
ing thread path has been lowered too much.
1-8) Contact 8-A)
The lower looper touches
Set the lower looper in the proper position.
the feed dog or throat
plate because of an
improper lower looper
position. The looper
touches the rear needle
guide because of
insufficient looper return.
1-9) Idle loop error 9-A)Coordination is awkward Set the lower looper in the proper position.
between needle and
looper timing. Position
of the bobbin thread
cam is inadequate.
Clearance is too much
between the upper feed
roller and the upper face
of the throat plate.
Trouble Cause (1) Cause (2) Check and corrective measures
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