Troubles And Corrective Measures - JUKI MOJ-2500N Instruction Manual

1
22. TROUBLES AND CORRECTIVE MEASURES
CAUSES
1
CORRECTIVE MEASURES
I
1
Needle breaking
i
I I) Needle type is wrong.
! ( 2 )
h'eedle size is not correct.
I
( 3 ) Needle is not installed correctly.
i 4 ) Needle is not straight.
( 5 ) Keedle-to-needle guard relation is bad
-
1
t
61 Needle-to-looper relation
I S
bad.
T - - - . .
2 , cloth
Is
not cut
( I ) Position of the upper and lower knife is
I inadequate.
/
(21 Knife blade has worn out
,3
Use a specified needle.
0
Use a needle size suitable to the thread gauge
and type of fabrics.
3
Install the needle correctly (See 8).
0
Use a straight needle.
0
Correct the relation (See 2 1
).
c
Correct the needle t o looper relation (See 15).
~
-
.
--
~ ~
-
Adjust the knife position (See 20).
0
Sharpen the lower knife or renew the upper
knife.
3. Stitch skipping
4. Thread breaking
(
I
)
Needle-to-looper relation is wrong.
( 2 ) Looper blade is blunt.
( 3 ) Needle is threaded with S-twist (or left-
hand twist) thread.
( 4 ) Thread tension is wrong.
( 5 ) Double chain looper thread tension is not
enough.
(
1
)
Quality of the thread is poor.
( 2 ) Thread is too t h c k for the needle size.
( 3 ) Needle is installed in a wrong way.
(4) Thread tension is too high.
( 5 ) There is a scratch or bruise on the surface
of needle, looper, throat plate or needle
guard.
0
Correct the needle-to-looper relation (See 1 5 ) .
0
Correct the shape of the looper blade using
an oilstone, or replace it.
0
Use a Z-twist (or right-hand twist) thread witb
the needle.
0
Adjust the thread tension (See 10).
0 .
Correct the position of the chain looper t h r e a ~
cam (See 18).
0
Use a thread of good quality.
0
Select a suitable needle or thread.
0
Install the needle correctly (See
8).
0
Adjust the thread tension
0
Remove scratches and bruises using an oil-
stone or buffing machine.
5.
Double chain-off
thread stitcfung
failure
(MOG-25 16N)
6 . Puckering
7 . Irregular stitching
( I ) Presser foot does not evenly act on the feed
dog.
(
2) Rear presser is shaking.
( 3 ) Needle thread and looper thread tensions
are not correct.
( 4 ) Double chain looper is installed in a wrong
way
( 1 ) Needle is too thick
Thread tension is too high.
Pressure applied b y the presser foot is too
high or too low.
Feed dog comes up too much from the
throat plate surface.
( 5 ) Knife fails t o cut the fabrics sharply.
(6) Differential feed mechanism is not set
correctly.
(
1
)
Thread is not supplied smoothly.
1
0
Correct the relation of the presser foot with
the feed dog.(See 17).
0
Adjust the rear presser for smooth and
steady motion.
0
Adjust the thread tension (See 10).
0
Correct the double chain looper (see 15).
0
Select a suitable needle size for the thread
and materials.
0
Adjust the thread tension.
0
Correct the presser foot pressure (See 1 1
) .
0
Lower the feed dog.
0
Sharpen the lower knife.
0
Correct the differential feed mechanism
(See 16).
0
Use smooth thread with even thickness or
( 2 ) Thread tension is too low.
( 3 ) Needle is blunt.
(4) Pressure applied by the presser foot is
inadequate.
( 5 ) Height of the feed dog is wrong.
clean up the thread path.
0
Increase the thread tension.
0
Use a new needle.
0
Adjust the presser foot pressure (See 11).
0
Adjust the height of the feed dog (See 17).