Troubles And Corrective Measures - JUKI MS-3580 Serie Manual De Instrucciones

% . TROUBLES AND CORRECTIVE MEASURES

Trouble
1. Thread breakage 1-1) Threading
1-2) Thread path
1-3) Rear needle guard
1-4) Needle
1-5) Needle heat
1-6) Thread
1-7) Thread tension
1-8) Contact
1-9) Idle loop error
Cause (1) Cause (2)
1-A) Thread jamming at thread
guide, threading error
2-A) Flaws, burrs, rust
generation, and the
like can be a cause of
resistance in operation
if they are present in
needles, throat plate,
small thread tension,
needle thread rocking
thread path, needle
thread guide thread path,
lower looper, looper
thread guide pipe, looper
thread cam, lower thread
path guide, and thread
tension disc.
3-A) If contact between the
needle and rear needle
guard is excessive,
needle grooves are
created on he rear needle
guard, resulting in thread
cut.
4-A) The needle is too thin for
the thread that is now
used.
5-A) Thread cut occurs
because of heated
needle depen ding on
the material type, the
number of superimposed
materials, and sewing
speed.
6-A) Poor quality of the thread
7-A) Excessive thread tension
8-A) The lower looper
touches the feed dog
or throat plate because
of an improper lower
looper position. The
looper touches the
rear needle guard
because of insuffi cient
looper return.
9-A) Coordination is awkward
between needle and
looper timing. Position of
the looper thread cam is
inadequate.
Clearance is too much
between the upper feed
roller and the upper face
of the throat plate.
− 47 −
Check and corrective measures
Refer to "#- 5. How to conduct threading".
Take measures to remove fl aws, burrs,
etc., and fi nish the thread path neatly.
In this case, however, the lower looper,
throat plate, looper thread cam, and such
important parts should be replaced if their
shapes seem to have changed.
Replace the needle, and replace the part if
the rear needle guard is worn.
Use an appropriate needle.
Reduce the needle size. Reduce the
sewing speed. Use needle cooling air.
Use a high-quality thread.
Reduce the thread tension. Thread tension
is excessive because the needle thread
adjusting thread path has been lowered
too much.
Set the lower looper in the proper position.
Set the lower looper in the proper position.