Apparel Engineering II

1. Presented By
Md. Shamsuzzaman
B.Sc. (WUB), M.Sc. (BUTEX)
Lecturer,
Department of Textile Engineering
World University of Bangladesh
Contact: +880 1814 868653
Email: shamsuzzaman@textiles.wub.edu.bd
7/15/2020Slide Prepared by- Md. Shamsuzzaman
Stitch (Part-2)
Course Name: Apparel Engineering II
Course Code: TE 703

2. 1. Properties of stitch
2. Factors affecting stitching quality
3. Faults of Stitching
4. Causes and Remedies of Stitching
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Fig: Stitch
1. Stitch tension
2. Stitch sequence
3. SPI
4. Thread tension
5. Elongation
6. Elasticity
7. Resilience
8. Fabric distortion
9. Yarn severance
10. Abrasive strength

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Factors affecting the properties of Stitch
3. Elongation
 Sewing thread elongation
 Stitch elongation
 Fabric elongation
2. Sewing thread
 types and construction
 Thread tension
1. SPI
 High SPI
 Low SPI
https://www.researchgate.net/publication
/338854075_Impact_of_Thread_Count_
and_Stitch_Density_on_Plain_Woven_F
abric
https://www.researchgate.net/publication
/339585849_International_Journal_of_S
cience_and_Business_Effect_of_Thread
_Count_and_Stitch_Density_SPI_on_21
_Twill_Woven_Fabric_International_Jour
nal_of_Science_and_Business

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Sewing Faults/Stitching Faults
1. Skipped stitches
2. Unbalance stitch
3. Staggered stitch
4. Variable stitch density
5. Seam puckering
6. Bobbin or looper thread breakage
7. Needle thread breakage
8. Thread fusing when sewing machine stops

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Different parts of Sewing machine

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Skipped stitches
Causes Remedies
Failure of hook or looper and
needle to enter loop at correct
time.
Examine the setting and
timing between needle and
hook or looper.
Irregular thread tension on
upper or lower loop.
The tension of thread should
be adjusted.
Due to needle deflection. Needle should be changed.
If needle thread loop size is too
small.
Needle size and thread
should be adjusted.
When flagging of fabrics is
happened during sewing
The pressure of pressure
foot should be adjusted
perfectly.
If sewing thread is unable to
form loop. Thread should be changed.

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Unbalance stitch
Causes Remedies
Incorrect tension of sewing thread. Setting of accurate tension to the thread.
Used incorrect thread path. Using of accurate thread path.
Incorrect adjustment of needle thread path. Using of right thread path.
Snagging of needle with bobbin case and
positioning finger.
Bobbin case to be smooth and finger
positioning to be set again.
If sewing threads are not lubricated. Better quality threads must be used here.

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Staggered stitch
Causes Remedies
Due to needle deflection.
Needle size should be
increased.
Due to wrong needle point. Needle should be changed.
Incorrect adjustment of needle
and thread size.
Needle size and thread size
should be changed.
Due to defected motion of feed
dog.
Feed dog motion should be
adjusted.
If fabrics not controlled
properly in the feed
mechanism.
Accurate pressure of pressure
foot should be adjusted.

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Variable stitch density
Causes Remedies
Incorrect unwinding of thread
form package during sewing.
The position of thread guide should
be 2.5 times higher than the position
ofthread package.
Twisting of needle thread in the
bottom of thread package.
Foam pad should use to the bottom
of thread package.
Twisting of thread in thread
guide.
Correct threading of sewing thread
during sewing.
Excessive tension of thread.
Tension of thread should be less or
use of higher strength threads.
Using of broken check spring. Check spring should be changed.
Fraying of thread in the needle.
Finer threads should be used or to be
used heavy needle.
Becoming more heated of
sewing thread.
Needle lubricant and needle cooler
should be used.
Becoming more heated of hook.
Lubricant should be available and
test the distance between needle and
hook.
Using of low quality sewing
thread. Sewing thread should be changed.

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Seam puckering
Causes Remedies
Higher thread tension. Bobbin tension should be kept as low as possible.
Improper thread balance.
Proper thread balance should be ensured between
top and bottom thread.
Incorrect thread types Have to maintain tension guides properly.

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Bobbin or looper thread breakage
Causes Remedies
Incorrect winding of
threads on to the bobbin.
Proper winding of
threads on to the bobbin.
Excessive tension to the
bobbin threads.
The tension should be
adjusted to the bobbin
threads.
If the edges bobbin case,
looper eye and so on are
more sharpened.
The edges should be
smooth.
Incorrect fitting of bobbin
case.
Test the size and types of
bobbin.

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Needle thread breakage
Causes Remedies
Incorrect winding of threads on to
the bobbin.
Proper winding of threads on to
the bobbin.
Excessive tension to the bobbin
threads.
The tension should be adjusted to
the bobbin threads.
If the edges bobbin case, looper
eye and so on are more sharpened. The edges should be smooth.
Incorrect fitting of bobbin case. Test the size and types of bobbin.

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Causes Remedies
Faulty sewing thread. Should be used better quality thread.
Densely woven fabric which is poorly finished. Should be improved fabric finishing
Damaged needle after sewing thread breakage. Should be changed the needle.
Thread fusing when sewing machine stops

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https://www.sciencedirect.com/topics/engineering/stitch-type
Further Study
https://www.youtube.com/watch?v=SgHxs6ukadM

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THE END