61
Thread Break
⑦
Use of low-quality thread
(loose thread twist, uneven
thread thickness, bad thread
winding, too weak or too
old thread, etc.)
⑧
Use the thread twisted in
the right direction (S-shape
twist)
⑨
Too strong tension of the
upper and lower thread
⑩
Uneven tension of the
upper and lower threads
⑪
Excessive tension and
stroke of the thread take-up
lever spring
■
Replace the thread for high-
quality one
■
Use the thread twisted in
the left direction (Z-shape
twist)
■
Adjust the tension
■
Adjust the tension
■
Adjust the tension and
stroke of the thread take-up
spring
Check the thread used
※
Tips for thread
selection
■
The thread used
should be soft and
constant in thickness.
Its tension should be
stable.
■
The thread twist shall
be tight and be made
in the left direction.
■
Z-shape twist (left
direction)
■
S-shape twist (right
direction)
Corrective Action and Check Point
Cause of Trouble
Type
Remarks