3. Seam Engineering
•It includes seam and stitch
construction.
•The more thread a stitch consumes,
the greater is the strength!
•This is clearly visible when we
compare lock stitch and chain stitch.
•Lock stitch is one in which thread
is locked both sides of the fabric and
starts with 301 lock stitch.
•It go through more shearing as
compared to chain stitch and over
edge stitch.
•As in lockstitch threads are
interlocked rather than inter-
looped
5. a. Quality is the customers' perception (awareness)
of the value of the suppliers' work output.
b. In manufacturing, quality is a practical explanation
as the non-conformity of product ; it is also defined
as fitness for purpose.
c. To Support personnel measure quality in the
degree that a product is reliable, maintainable, or
sustainable. A quality item has the ability to
perform satisfactorily in service and is suitable for
its intended (planned) purpose.
d. For the Textile & Apparel industry, product quality
is calculated in terms of quality & standard of
fibers, yarns, fabric construction, color fastness,
designs and the final finished garments.
e. Etc..
Quality?Quality?
7. Fabric OZ/Sq. Yd. Grams/ SQ. Mtr thread Tex size needle Size
Ex. Light 2 -4 oz. 68 – 136gr. Tex 16, 18, 21, 24 60, 65
Light 4-6 oz. 136 – 204gr. Tex 24, 27, 30 70, 75
Medium 6-8 oz. 204 – 272gr. Tex 30, 35, 40 80, 90, 100
Med. Heavy 8 -10 oz. 272 – 339gr. Tex 40, 45, 50, 60 100, 110
heavy 10-12 oz. 339 – 407gr. Tex 60, 80, 90, 105 120, 140
Ex. Heavy 12 -14 oz. 407 – 475gr. Tex 105, 120, 135 + 140, 160
Related >> Fabric Weight / Typical Thread Sizes / Needle Sizes
8. Common Seam Example : All Types…Common Seam Example : All Types…
Stitch Type matrix
PDF File
Needle Types PDF
File
Decorative Stitch
matrix
9. Common Seam Quality defects: Stitch Balance 301 lock stitch
DESCRIPTION: Where loops are seen
either on the bottom side or topside of
the seam. This is particularly evident
with different colored needle and bobbin
threads. Also, where the stitch is too
loose.
SOLUTIONS: 1) Use a quality thread
with consistent frictional characteristics;
2) Properly balance the stitch so that the
needle and bobbin threads meet in the
middle of the seam. Always start by
checking the bobbin thread tension to
make sure it is set correctly, so that the
minimum thread tension is required to
get a balanced stitch.
Poor Stitch Balance - Too Loose
10. Common Seam Quality Defects,
Improper Stitch Balance - 401 Chain stitch
DESCRIPTION: Where the loops on
the bottom-side of the seam are
inconsistent and do not appear
uniform.
SOLUTIONS:
1) Use a quality thread with consistent
frictional characteristics;
2) Properly balance the stitch so that
when the lopper thread is unraveled,
the needle loop lays over half way to
the next needle loop on the underside
of the seam.
Stitch Too Loose
Proper Stitch Balance
11. Common Seam Quality Defects
Improper Stitch Balance - 504 Overedge Stitch
DESCRIPTION: Where the needle
loop is not pulled up to the underside
of the seam and the "purl" is not on the
edge of the seam.
SOLUTIONS: 1) Use a quality thread
with consistent frictional
characteristics;
2) Properly balance the stitch so that
when the looper thread is unraveled,
the needle loop lays over half way to
the next needle loop on the underside
of the seam.
Improper Stitch Balance
Proper Stitch Balance
12. Needle Cutting on Knits
DESCRIPTION: Where needle
holes appear along the stitch line
that will eventually turn into a
"run". Generally caused by the
needle damaging the fabric as it is
penetrating the seam.
MINIMIZING NEEDLE CUTTING
ON KNITS:
1) Make sure the proper thread
size and needle type and size are
being used for the fabric
2) Make sure the fabric has been
properly stored to prevent drying
out and has been finished
properly;
3) Check with your fabric
manufacturer
13. Description:
Where the stitch line is still intact but the yarns in the fabric have ruptured.
MINIMIZING SEAM FAILURES - FABRIC:
1) Reinforce stress points with Bartacks. Make sure the bartacks are the proper length and
width for the application;
2) Check to make sure the patterns have been designed for proper fit;
3) Make sure the ideal seam construction is being used
4) Contact your fabric supplier.
Open Seam Failure - Fabric
Bartacks Used to Reinforce Fly Seam
14. DESCRIPTION:
Where the yarns in the fabric pull out of the seam from the edge. This often
occurs on fabrics constructed of continuous filament yarns that are very smooth and
have a slick surface. Also caused by loosely constructed fabrics.
MINIMIZING SEAM FAILURES - SEAM SLIPPAGE:
1) Consider changing the seam construction to a French seam construction; 2)
Increase the seam width or width of bite; 3) Optimize the stitches per inch; 4)
Contact your fabric supplier.
16. DESCRIPTION: Where the seam does
not lay flat after stitching.
SOLUTIONS:
1) If sewing machines are equipped
with differential feed, set them properly
for the fabric;
2) Use minimum presser foot pressure
during sewing; and
3) Observe operator for correct
handling techniques. Too much
stretching of the fabric by the sewing
operator will cause this problem.
17. DESCRIPTION: Where the seam does
not lay flat and smooth along the stitch
line. Caused by one of the following:
1) Feed Puckering - where the plies of
fabric in the seam are not being
aligned properly during sewing;
2) Tension Puckering - where the
thread has been stretched and sewn
into the seam. The thread then causes
the seam to draw back and pucker;
3) Yarn Displacement or structural
jamming - caused by sewing seams
with too large of thread that causes the
yarns in the seam to be displaced,
giving a puckered appearance.
18.
19. DESCRIPTION: Where the edge of the
seam is either extremely "ragged" or
"rolls" inside the stitch.
SOLUTIONS: 1) Make sure the sewing
machine knives are sharpened and
changed often; 2) The knives should
be adjusted properly in relationship to
the "stitch tongue" on the needle plate
to obtain the proper seam width or
width bite. In the photo, the trimming
knives have been set wider than the
"stitch tongue" on the needle plate
causing the "ropy" appearance.
20. DESCRIPTION: Where a "joint" occurs
on the stitch line. If this occurs on
Topstitching, then the seam does not
appear to be 1st quality merchandise.
Caused by 1) thread breaks or thread
run-out during sewing; or 2) cut or broken
stitches during a subsequent treatment of
the finished product (i.e., stone
washing).
MINIMIZING THREAD BREAKAGE: 1)
Use a better quality sewing thread. This
will help to minimize sewing interruptions.
and/or Minimizing Thread Breakage &
Skipped Stitches
2) Insure proper machine maintenance
and sewing machine adjustments; 3)
Make sure sewing machines are properly
maintained and adjusted for the fabric
and sewing operation. 4) Observe sewing
operators for correct material handling
techniques.
21. DESCRIPTION: Where the stitch
balance is not properly adjusted (stitch
too loose) and you can see the seam
opening up. To check for Seam Grin,
apply normal seam stress across the
seam and then remove the stress. If
the seam remains opened, then the
seam has too much "grin through".
SOLUTIONS: To correct, readjust the
sewing machine thread tensions so
that the proper stitch balance is
achieved. Too much tension will cause
other problems including seam failures
("Stitch Cracking"), excessive thread
breakage, and skipped stitches.
22. DESCRIPTION: Where the stitch length is inconsistent, possibly
appearing as double the normal stitch length; or where you can see that
the threads in the stitch are not properly connected together. Caused by
the stitch forming device in the sewing machine missing the thread loop
during stitch formation causing a defective stitch. On looper type
stitches, this will allow the stitch to unravel causing seam failure.
MINIMIZING SKIPPED STITCHES: 1) Use a better quality sewing
thread & Top stitch on the inside sewing allowance . This will include a
higher performance thread designed to minimize sewing interruptions.
2) Insure proper machine maintenance and sewing machine
adjustments; 3) Make sure sewing machines are properly maintained
and adjusted for the fabric and sewing operation. 4) Observe sewing
operators for correct material handling techniques.
23. 301 Lockstitch Seams
For 301 lockstitch seams, Generally recommend using the same needle thread size
as the bobbin thread size in the seam. Why? Because “a chain is only as strong as
its weakest link.”
If a smaller, weaker thread is used in the bobbin, then the seam will only be as
strong as the bobbin thread. This is particularly true with lockstitch seams because
of the way the needle and bobbin threads are interlocked together.
This does have exceptions. Sometimes a smaller size thread with a different fiber
type and/or thread construction can be used and still maintain seam performance.
An example would be to use a higher tenacity Corespun in place of a Spun thread.
To take this a step further, you can use an Anecord Nylon® monocord bobbin
instead of a spun or corespun thread in the seam. Also, exceptions can be made
when a larger topstitching thread is desired to give a bold appearance on the
outside of the garment when it is not necessarily being used to add strength or
durability to the seam.
24. Common Seam Class Example : 400 & 401 lock stitchCommon Seam Class Example : 400 & 401 lock stitch
25. 504 Overedge Seams
504 Overedge seams have basically the
same needle thread formation as the
needle thread on a 401 chainstitch
seam. Therefore, the same rule
applies. You can use a looper thread
approximately 60% of the needle thread
size without adversely affecting the
seam strength (for example: T-24 needle
thread – T-18 looper threads). Just
remember that smaller looper threads
will not give the seam coverage of larger
thread sizes.
Factors that Affect Seam Strength
Five factors that determine the strength of a
seam include:
Fabric type and weight.
Thread fiber type, construction, and size.
Stitch and seam construction.
Stitches per inch.
Stitch balance.
26. DESCRIPTION: Where a tail
of thread is visible on the
topside of the button and when
pulled, the button falls off.
SOLUTIONS: 1) Use a quality
sewing thread to minimize
skipped stitches; 2) Specify
attaching the buttons with a
Lockstitch instead of a single
thread Chain stitch Buttons
sewing machine.
27. STITCH ESTIMATING GUIDE:
1 square inch of “Fill” stitches at a
normal density with a stitch of
6mm = 1000 stitches. This is for a
basic fill to cover an area with no
stitching on top.
1 square inch of “Fill” stitches at a
normal density with a stitch of 4
mm = 1500 stitches.
This is for a basic “Fill” to cover an area
that would have lettering or other
stitching on top. The stitch length is
shortened to prevent the stitches from
pulling apart when the additional
stitching is put on top.
28. DESCRIPTION:
Used to cover large areas. There are
many different “Fill” stitch patterns
and they can differ in direction, angle,
and pattern. “Fill” stitches are
used to cover large areas. (Also
known as Tatami stitches.) With
today’s modern digitizing programs,
there are many “Fill” stitch patterns
that can be selected to give varying
design appearance. Curved, fill
stitches are becoming more popular in
the industry. Using a “Fill” stitch in a
curve can add more dimension to a
design. This type of stitch is very
useful for hair and water.
29. DESCRIPTION:
Consists of forming three stitches between two
points primarily used for outlining work. “Bean”
stitches are more pronounced than Running
Stitches.
STITCH ESTIMATING GUIDE:
Triple Running Line (Bean Stitch) = 37 per inch
30. DESCRIPTION:
Consist of a single line of stitching
primarily used for outlining and detail
work. They are also used as the
foundation of most “underlays” and
“Fill” stitches. Areas that are under
1mm in width are usually done with a
running stitch.
STITCH ESTIMATING GUIDE:
Single Running Line = 12 per inch
Double Running Line = 25 per inch
(Normal Outlining Stitches)
Triple Running Line (Bean Stitch) = 37 per
inch
4-Ply Running Line = 48 per inch
(Alternative to Satin Stitch
31. The friction between the needle blade and the
fabric creates needle heat. The following
factors can have an impact on the amount of
heat that is generated:
Fabric thickness
Fabric finish or density
Fabric color or density (darker colors normally
are worse than lighter colors)
Sewing machine speed
Needle contact surface
Needle Size or diameter
Needle length
Type of needle blade
Type of needle finish
Needle heat is usually more of a problem when
sewing either synthetic threads and / or
synthetic fabrics and can cause excessive
thread breakage and / or damage to the fabric
being sewn.
32. The thread characteristics that impact loop formation include:
Elongation or stretchiness of the thread.
Initial modulus or initial resistance to stretching.
Twist direction & twist level.
Liveliness of the thread.
Frictional characteristics needed to set a balanced stitch
If the needle size - thread size relationship is improper, the thread will not be properly
clamped on the scarf side of the needle and poor loop formation will occur. If the seam is
not held in a stationary position when the needle is rising, the seam will rise with the
needle and not form a proper needle loop. This condition, called flagging, is one of the
most common causes of skipped stitches and thread breakage.
33. The physical properties in thread that impact how much the thread is stretched during the
sewing process include:
Elongation properties of the fiber being used.
Frictional characteristics of the thread needed to set a balanced stitch.
Note: Regardless of the type of thread being used, as more and more tension is applied to
the thread, the thread will stretch more, affecting loop formation. Improper loop
formation will result in a higher frequency of sewing interruptions. This is why it is
recommended to always adjust the sewing machines thread handling system to sew with
minimum thread tension.
Below is a recommended procedure for balancing the stitch on a any sewing machine:
Set the bottom tension (bobbin or looper) to a minimum that still forms a consistent
stitch.
Reduce the needle thread tension until the stitch appears to be loose on the bottom side
of the seam then tighten the top tension until a balanced stitch is achieved.
34. Seam elasticity can be accomplished by a combination of having the
correct number of stitches per inch and having the proper stitch balance.
The more stretch the fabric has, the more stitches per inch that are
required. Common ranges of stitches per inch are from 12 to 14 spi.
